bluuebunny/crossref_metadata_2025 huggingface dataset:
Congenital facial palsy and emotion processing: The case of Moebius syndrome
Authors: De Stefani Elisa , Nicolini Ylenia , Belluardo Mauro , Ferrari Pier Francesco
Published: January 2019

According to the Darwinian perspective, facial expressions of emotions evolved to quickly communicate emotional states and would serve adaptive functions that promote social interactions. Embodied cognition theories suggest that we understand others' emotions by reproducing the perceived expression in our own facial musculature (facial mimicry) and the mere observation of a facial expression can evoke the corresponding emotion in the perceivers. Consequently, the inability to form facial expressions would affect the experience of emotional understanding. In this review, we aimed at providing account on the link between the lack of emotion production and the mechanisms of emotion processing. We address this issue by taking into account Moebius syndrome, a rare neurological disorder that primarily affects the muscles controlling facial expressions. Individuals with Moebius syndrome are born with facial paralysis and inability to form facial expressions. This makes them the ideal population to study whether facial mimicry is necessary for emotion understanding. Here, we discuss behavioral ambiguous/mixed results on emotion recognition deficits in Moebius syndrome suggesting the need to investigate further aspects of emotional processing such as the physiological responses associated with the emotional experience during developmental age.
Frequency of ABO/Rhesus (D) blood groupings and ethnic distribution in the Greater‐Accra region of Ghana, towards effective blood bank inventory
Authors: Doku George Narh , Agbozo William Kweku , Annor Rabia Asiba , Kisseh Gladis Doeyo , Owusu Matilda Ampomah
Published: January 2019

Knowledge on blood group phenotypes is of key importance in clinical practice. It used in blood transfusion practice to determine the direction of recruitment of voluntary donors as required for each population within a country, and for disease association and population genetics studies. This study aimed at reporting the frequency of ABO and Rhesus (Rh) groups in the population of the Greater‐Accra region of Ghana and amongst their various ethnic groups. A retrospective study in 11 main hospitals within the region was done. Data collected provided information on the blood group status of persons (both blood donors and recipients) who visited the selected hospitals. Medical records used were within the years 2012–2017. A total of 42,317 (26,802 males and 15,515 females) data were retrieved and analysed. The frequencies of the blood groups O, A, B and AB were 50.0%, 24.3%, 20.7% and 5.0%, respectively. Rhesus‐positive to negative ratio was 93.2%/6.2%. Frequencies of blood group O was highest (49.1%–53.6%) in all ethnic groups. The second most dominant blood group was B (24.2%–25.4%) in the Ga‐Adamgbe, Akan and Ewe ethnic groups, whilst blood group A (25.0%–26.9%) was the second most dominant in the Northerners and non‐Ghanaians. Blood group distribution amongst gender and different age groups showed no significant differences but followed the same pattern for the general population. The study provides data on the ethnic distribution and frequency of ABO and Rhesus blood groupings in the Greater‐Accra region of Ghana. It also informs the need for blood banks in the region to increase the proportion of stockpiled Rhesus‐positive blood groups especially for O, B and A that may be high in demand.
A variable neighborhood search heuristic algorithm for the double vehicle routing problem with multiple stacks
Authors: Chagas Jonatas B. C. , Silveira Ulisses E. F. , Santos André G. , Souza Marcone J. F.
Published: January 2019

This paper addresses the double vehicle routing problem with multiple stacks (DVRPMS) in which a fleet of vehicles must collect items in a pickup region and then travel to a delivery region where all items are delivered. The load compartment of all vehicles is divided into rows (horizontal stacks) of fixed profundity (horizontal heights), and on each row, the unloading process must respect the last‐in‐first‐out policy. The objective of the DVRPMS is to find optimal routes visiting all pickup and delivery points while ensuring the feasibility of the vehicle loading plans. We propose a new integer linear programming formulation, which was useful to find inconsistencies in the results of exact algorithms proposed in the literature, and a variable neighborhood search based algorithm that was able to find solutions with same or higher quality in shorter computational time for most instances when compared to the methods already present in the literature.
Rediscovery of Leptopanchax splendens (Cyprinodontiformes: Aplocheilidae): a seasonal killifish from the Atlantic Forest of south‐eastern Brazil that was recently considered extinct
Authors: Costa Wilson J. E. M. , Mattos José L. O. , Amorim Pedro F.
Published: January 2019

A recent collection of the seasonal killifish found Leptopanchax splendens c. 5 km from the type locality, 74 years after its last record. The species was historically common in its type locality, the Estrela River basin in south‐eastern Brazil, until 1950, after which it was not encountered and thought to have become extinct due to widespread deforestation and urbanization in the region. Despite the rediscovery, this study finds that other recently published reports of L. splendens are misidentifications.
Meta‐analysis of the mental health status of left‐behind children in China
Authors: Wu Wei , Qu Guangbo , Wang Lingling , Tang Xue , Sun Ye‐Huan
Published: January 2019

The aims of this study were to systematically evaluate and comparatively analyse the mental health status of left‐behind children (LBC) in China and to provide a scientific basis for mental intervention and healthy education for LBC. Six electronic databases were searched for studies (published from 1 January 2010 to 5 March 2018) of the mental health of LBC using the Mental Health Test scale. We only selected original articles that either reported the incidence of serious mental health status or the means and standard deviations of each factor score of the scale. The pooled rates and weighted mean difference were calculated. The results indicated that the incidence of serious mental health status of LBC is nearly 2.7 times higher than that of non‐LBC. The scores for most of the factors analysed by the Mental Health Test of LBC were higher than those of non‐LBC. In addition, the mental health status of left‐behind girls is worse than that of left‐behind boys. Except for impulsive tendency, there was no significant difference in the mental health status of LBC in primary and junior high schools. In terms of the different types of guardianship, the mental health status of LBC under a grandparent's guardianship and parental peer' guardianship is more serious than that of LBC under a single‐parent guardianship. The mental health status of LBC is poor, particularly for left‐behind girls. The primary mental problems faced by LBC are learning anxiety, social anxiety and physical symptoms. It is necessary to develop more targeted measures to prevent and manage LBC.
Vincristine and sirolimus in the treatment of kaposiform haemangioendothelioma
Authors: Peng Suhua , Yang Kaiying , Xu Zhicheng , Chen Siyuan , Ji Yi
Published: January 2019

Aim

Kaposiform haemangioendothelioma (KHE) is a rare, potentially life‐threatening vascular tumour that is often associated with thrombocytopenia and coagulopathy, known as the Kasabach‐Merritt phenomenon (KMP). Because of the rarity and complexity of KHE, the optimal paradigm for treating KHE has yet to be elucidated. We aim to assess the efficacy and safety of vincristine and sirolimus for the treatment of KHE.

Methods

A comprehensive review of the literature was conducted from January 1993 to June 2018. A total of 15 studies were selected for the meta‐analysis. Five studies included 75 individuals and reported the response and side effects to vincristine in the treatment of KHE with or without KMP. A total of 10 studies that included 127 individuals reported the response and safety of sirolimus for treating KHE with or without KMP.

Results

The pooled odds ratio (OR) for the effectiveness of vincristine was 0.72. The pooled OR for the effectiveness of sirolimus was 0.91. The side effects associated with vincristine during the treatment included neuropathy, abdominal pain, loss of appetite and mild elevations of aspartate aminotransferase (AST) and alanine aminotransferase (ALT). The side effects associated with sirolimus therapy included bronchitis; lymphopenia; elevated AST, ALT and platelets; hyperlipidaemia; opportunistic infection; mild reversible leukopenia; mucositis; fever; pain and skin rash/vomiting and diarrhoea.

Conclusions

This systematic review showed a high efficacy of vincristine and sirolimus in the treatment of KHE. Based on the available data in the literature, it appears that sirolimus is potentially an efficacious and safe treatment option for KHE. Further randomised, controlled trials are recommended.
Targeting EphA2 with miR-124 mediates Erlotinib resistance in K-RAS mutated pancreatic cancer
Authors: Du Jing , He Yuanqiao , Wu Weiquan , Li Peng , Chen Youwei , Hu Zhiming , Han Yong
Published: January 2019

Objectives

Chemotheraputic drug resistance is a critical factor associated with the poor survival in advanced/metastatic pancreatic cancer (PC) patients.

Methods

Human pancreatic cell lines Capan-1 and BXPC-3 were cultured with different concentrations of erlotinib (0, 10, 50, and 100 μm) for 48 h. The relative cell viability and apoptosis was detected using MTT assays and flow cytometry apoptosis analysis, respectively. Transfection of pcDNA-EphA2, si-EphA2 and miR-124 mimic/inhibitor was used to modulate the intracellular level of EphA2 and miR-124. The interaction between miR-124 and the 3′UTR of EphA2 was explored using dual luciferase reporter assay.

Key findings

Compared with BXPC-3 cells, Capan-1 cells showed resistance to differential concentration treatment of erlotinib. The expression of EphA-2 was significantly increased and the expression of miR-124 was significantly decreased in Capan-1 cells. Overexpressing EphA2 induced resistance of BXPC-3 cells to erlotinib treatment. And EphA2 was identified as a novel target gene for miR-124. MiR-124 overexpression was able to sensitize the response of Capan-1 cells to erlotinib through inhibiting EphA2. Furthermore, both miR-124 overexpression and EphA2 inhibition sensitized Capan-1 cells to erlotinib in xenograft model.

Conclusions

Our study demonstrated that EphA2 rescued by miR-124 downregulation conferred the erlotinib resistance of PC cell Capan-1 with K-RAS mutation.
Biofortification of hens’ eggs with microelements by innovative bio‐based dietary supplement
Authors: Witkowska Zuzanna , Świniarska Marita , Korczyński Mariusz , Opaliński Sebastian , Konkol Damian , Michalak Izabela , Saeid Agnieszka , Mironiuk Małgorzata , Chojnacka Katarzyna
Published: January 2019

New bio‐based dietary supplement with micronutrients for livestock was elaborated. The new preparation was tested on laying hens to determine the influence of new biological feed additives on the level of trace elements in egg content. The diet of laying hens (Hy‐Line Brown, 30 weeks of age) was supplemented with soya bean meal enriched with Cu(II), Zn(II), Fe(II) and Cr(III) by biosorption. A total of 150 laying hens were divided into five groups: one control and four experimental. In the control group, microelements were supplemented in the inorganic form, whereas in experimental groups, Cu, Zn, Fe and Cr were replaced with soya bean meal enriched with a given microelement ion. The feeding experiment was conducted for 12 weeks and was divided into three series. The results showed that adding the new feed additives to the diet of laying hens had an impact on microelement transfer to eggs, in particular with increased dosing. Eggs were biofortified with iron, zinc and copper and to a lesser extent with chromium. The microelements were accumulated primarily in the albumen because soy protein was the carrier of micronutrient ions in hens’ diet. Transfer of trace elements to eggs was not linearly dependent on the dosage of biologically bound microelements in the diet.
The Sensitivity of Country Ranks to Index Construction and Aggregation Choice: The Case of Immigration Policy
Authors: Bjerre Liv , Römer Friederike , Zobel Malisa
Published: January 2019

How sensitive are country ranks to the aggregation function used in index construction? This paper tests whether different aggregation functions come to different results in regard to the ranking of countries. Indices within the field of immigration and integration policy are analyzed, yet, the results pertain to index building across the social sciences. The paper discusses three aggregation methods: the arithmetic mean, the geometric mean, and a noncompensatory/non‐linear aggregation function based on the Condorcet method. In the empirical part, these three aggregation functions are applied to the family indicators for the year 2010 of the Immigration Policies in Comparison (IMPIC) dataset, a new dataset which measures immigration policies’ restrictiveness, as well as to the eight policy strands of the Migrant Integration Policy Index for the year 2014. Results show that the methods react differently to extreme values and thus result in different rank orders in the middle range. In the politicized field of immigration and integration policies, country ranks play a crucial role and this is shown to have profound real‐world implications. The paper thus urges researchers to be reflective of the assumptions of different aggregation functions, as these lead to different results.
Non‐Linearity and Cross‐Country Dependence of Income Inequality
Authors: Kalliovirta Leena , Malinen Tuomas
Published: January 2019

We use top income data and the newly developed regime‐switching Gaussian mixture vector autoregressive model to explain the dynamics of income inequality in developed economies within the past 100 years. Our results indicate that the process of income inequality consists of two equilibria identifiable by high inequality and high income fluctuations, and low inequality and low income fluctuations. Our results also imply that income inequality in the United States is the driver of income inequality in other developed economies. High wages and capital gains are found to be the likely channels for the U.S. influence.
Ryleev, Pushkin, and the Poeticization of Russian History
Authors: WANG EMILY
Published: January 2019

The historical poetry of Kondratii Ryleev–in particular, the lyrics he called dumy, or meditations–reveals how central emotion was to the Decembrist worldview. In particular, these poems promote an attitude towards political feeling that I call “civic sentimentalism.” Influenced by thinkers like Rousseau and organizations like the Freemasons, the Decembrists divided emotion into positive sentiments and negative passions: the former fostered virtue and, eventually, improved society, while the latter did just the opposite. Ryleev strove to improve Russian society by using a poeticized version of the nation’s history to inspire patriotic feelings in his readers. In addition, this piece examines how Alexander Pushkin–a writer whose worldview has historically been elided with that of the Decembrists–actually critiqued Ryleev’s historical poetry for the way its civic sentimentalism simplified complex historical issues.
“Fallen but Charming Creatures”: The Demimondaine in Russian Literature and Visual Culture of the 1860s
Authors: LUCEY COLLEEN
Published: January 2019

This article examines the portrayal of the demimondaine in Russian literature and visual culture of the 1860s. Often referred to as kamelii (camellias) after Alexandre Dumas fils’ La Dame Aux Camelias (1848), such “fallen women” entered the cultural imagination through works of art and fiction that associated the demimondaine with pleasure and leisure. Taking the work of Vsevolod Krestovskii (1840–95) as case study, I compare the author’s short story “Pogibshee, no miloe sozdanie” (“A Fallen but Charming Creature,” 1861) with a virtually unknown album of salacious lithographs for which Krestovskii provided prurient captions. Titled Pogibshie no milye sozdaniia (Fallen but Charming Creatures, 1862–63) in reference to his earlier tale, the album glorifies the demimondaine as a new kind of urban woman who possesses sexual and financial agency. Analyzing the depiction of kamelii in these two works–one fiction, the other visual–shows that although they differ in focus, both the story and album commodify the demimondaine for mass circulation.
Reading and Recycling: The Soviet Paper Debate and Makulatura Books, 1974–91
Authors: PRISTED BIRGITTE BECK
Published: January 2019

This article examines the joint makulatura campaign of 1974–91 by the Soviet Supply Committee (Gossnab) and the State Committee for Publishing (Goskomizdat), a campaign in which readers could exchange collected wastepaper for vouchers to obtain the popular and otherwise unavailable titles of the makulatura book series. Through analysis of the debate in Literaturnaia gazeta on the perceived waste and shortage of printing paper, the official campaign instructions, and the changing “editorial” paratexts of the makulatura books, the article sheds light on the public negotiations about the campaign and the value and reuse value of paper and reading matter in late Soviet society. By materializing the abstract relation between paper and books, the makulatura experiment turned both paper scrap and books into collection items and readers into paper suppliers. This materialization gave both readers and writers a marked awareness of paper as a raw material and a medium of cultural production. However, the shift of readers from the receiver to the producer side of the textual communication circuit also implied a collision of logics from the different perspectives of authors, collectors, publishers, and supply agencies.
Comparison of two alternative approaches to quality STEM teacher preparation: Fast‐track licensure and embedded residency programs
Authors: Mentzer Gale A. , Czerniak Charlene M. , Duckett T. Ryan
Published: January 2019

Alternative pathways to teaching licensure were developed to address teacher shortages. These programs differ widely, making it difficult to generalize the effects. This study compares the impact of two alternative licensure programs on the development of fundamental elements of science teacher preparation and persistence. The fast‐track programs include a 6‐month teacher preparation program and a one‐year residency teacher preparation program. The study concluded that licensure type was unassociated with the impact on teaching self‐efficacy, beliefs about teacher‐focused/student‐focused teaching, preferences for inquiry instructional practices, and experiences with student misbehavior. However, the study revealed that licensure type was associated with a number of other variables: residency students had more confidence in their ability to provide quality instruction; preferred inquiry‐based instruction more often; and may be better prepared for the high‐needs classroom. Those in the 6‐month program were more likely to score higher on practical versus theoretical approaches to teaching, and while they had a more realistic idea of how to measure success in the high‐needs classroom, the residency students had more knowledge of educational theory and how to apply it. Findings suggest that more traditionally licensed teachers may be more inclined to use inquiry‐based methods suggested in current reforms.
Impact loading and modelling a multilayer aluminium corrugated/fin core: The effect of the insertion of imperfect fin layers
Authors: Sarıkaya Mustafa , Taşdemirci Alper , Güden Mustafa
Published: January 2019

The quasi‐static compression (0.0048 m/s) and Taylor‐like impact (135, 150, and 200 m/s) loading of a multilayer 1050 H14 aluminium corrugated core were investigated both experimentally and numerically in LS‐DYNA using the perfect and imperfect sample models. In the imperfect sample models, one or two layers of corrugated fin structure were replaced by the fin layers made of bent‐type cell walls. The localised deformation in the quasi‐static imperfect models of cylindrical sample started at the imperfect layers, the same as the tests, and the layers were compressed until about the densification strain in a step‐wise fashion. The localised deformation in the perfect models, however, started at the layers at and near the top and bottom of the test sample. In the shock mode, the sample crushed sequentially starting at the impact end layer regardless the perfect or imperfect sample models were used. Furthermore, the perfect and imperfect models resulted in nearly the same initial crushing stresses in the shock mode. The layer strain histories revealed a velocity‐dependent layer densification strain. Both model types, the imperfect and perfect, well approximated the stress‐time histories and layer deformations of the shock mode. The rigid perfectly plastic locking model based on the numerically determined densification strains also showed well agreements with the experimental and numerical plateau stresses of the shock mode.
Enhancing microRNA167A expression in seed decreases the α‐linolenic acid content and increases seed size in Camelina sativa
Authors: Na GunNam , Mu Xiaopeng , Grabowski Paul , Schmutz Jeremy , Lu Chaofu
Published: January 2019

Despite well established roles of microRNAs in plant development, few aspects have been addressed to understand their effects in seeds especially on lipid metabolism. In this study, we showed that overexpressing microRNA167A (miR167OE) in camelina (Camelina sativa) under a seed‐specific promoter changed fatty acid composition and increased seed size. Specifically, the miR167OE seeds had a lower α‐linolenic acid with a concomitantly higher linoleic acid content than the wild‐type. This decreased level of fatty acid desaturation corresponded to a decreased transcriptional expression of the camelina fatty acid desaturase3 (CsFAD3) in developing seeds. MiR167 targeted the transcription factor auxin response factor (CsARF8) in camelina, as had been reported previously in Arabidopsis. Chromatin immunoprecipitation experiments combined with transcriptome analysis indicated that CsARF8 bound to promoters of camelina bZIP67 and ABI3 genes. These transcription factors directly or through the ABI3‐bZIP12 pathway regulate CsFAD3 expression and affect α‐linolenic acid accumulation. In addition, to decipher the miR167A‐CsARF8 mediated transcriptional cascade for CsFAD3 suppression, transcriptome analysis was conducted to implicate mechanisms that regulate seed size in camelina. Expression levels of many genes were altered in miR167OE, including orthologs that have previously been identified to affect seed size in other plants. Most notably, genes for seed coat development such as suberin and lignin biosynthesis were down‐regulated. This study provides valuable insights into the regulatory mechanism of fatty acid metabolism and seed size determination, and suggests possible approaches to improve these important traits in camelina.
Study on Optimization of Pressure Ratio Distribution in Multistage Compressed Air Energy Storage System
Authors: Chen Shang , Zhu Tong , Zhang Huayu
Published: January 2019

In this study, the round trip efficiency of a multistage adiabatic compressed air energy storage (A-CAES) system was optimized by differential evolution (DE) algorithm, and decision variables were the pressure ratio of each compressor/expander. The variation of the pressure ratio of each compressor/expander leads to different inlet air temperatures of the heat exchanger. Thus, this optimization method provides more heat energy recovery from compression to increase the inlet air temperature of expanders. Results indicate that the optimization method is effective for the pressure ratio allocation, improving the system efficiency by ∼1% and exergy efficiency of the heat storage process by 5.3% to the maximum compared with an equal pressure ratio distribution A-CAES system. Besides, a uniformity factor of temperature difference (UFTD) of multistage heat exchangers is proposed to analyze the temperature uniformity of the multistage heat exchangers, which indicates that decreasing the UFTD contributes to an increased uniformity of the temperature field and an improvement in heat transfer efficiency. The study is extended onto optimal off-design system configuration and the recommendations are proposed, which provides a guidance for A-CAES system design.
Fuel Cell Backup Power System for Grid Service and Microgrid in Telecommunication Applications
Authors: Ma Zhiwen , Eichman Joshua , Kurtz Jennifer
Published: January 2019

This paper presents the feasibility and economics of using fuel cell backup power systems in telecommunication cell towers to provide grid services (e.g., ancillary services, demand response (DR)) as well as power for cell towers during emergency conditions. This study evaluates the strategic integration of clean, efficient, and reliable fuel cell systems with the grid for improved economic benefits. The backup systems can potentially enhance capabilities through information exchange with the power grid, which adds value for grid services that depend on location and time. The economic analysis focused on the potential revenue for distributed telecommunications fuel cell backup units to provide value-added power supply. This paper includes case studies on current fuel cell backup power locations and regional grid service programs. The grid service benefits and system configurations for different operation modes provide opportunities for expanding backup fuel cell applications responsive to grid needs. The objective of this work is primarily on how fuel cells can become a significant part of the telecom backup power fleet to reduce system costs, environmental impact, and dependence on fossil fuels, while ensuring continuity of indispensable service for mobile users. The study identifies different fuel cell applications and nano/microgrid approaches for an extensive network of fuel cells as distributed energy resources. The possibilities of various application scenarios extend to fuel cell technologies and microgrids for reliable power supply.
Effect of Carbon Dioxide on the Laminar Burning Speed of Propane–Air Mixtures
Authors: Yelishala Sai C. , Wang Ziyu , Metghalchi Hameed , Levendis Yiannis A. , Kannaiyan Kumaran , Sadr Reza
Published: January 2019

This experimental research examined the effect of CO2 as a diluent on the laminar burning speed of propane–air mixtures. Combustion took place at various CO2 concentrations (0–80%), different equivalence ratios (0.7<ϕ<1.2) and over a range of temperatures (298–420 K) and pressures (0.5–6.2 atm). The experiments were performed in a cylindrical constant volume chamber with a Z-shaped Schlieren system, coupled with a high-speed CMOS camera to capture the propagation of the flames at speeds up to 4000 frames per second. The flame stability of these mixtures at different pressures, equivalence ratios, and CO2 concentrations was also studied. Only laminar, spherical, and smooth flames were considered in measuring laminar burning speed. Pressure rise data as a function of time during the flame propagation were the primary input of the multishell thermodynamic model for measuring the laminar burning speed of propane-CO2-air mixtures. The laminar burning speed of such blends was observed to decrease with the addition of CO2 and to increase with the gas temperature. It was also noted that the laminar burning speed decreases with increasing pressure. The collected experimental data were compared with simulation data obtained via a steady one-dimensional (1D) laminar premixed flame code from Cantera, using a detailed H2/CO/C1–C4 kinetics model encompassing 111 species and 784 reactions.
Second-Law Thermodynamic Analysis in Premixed Flames of Ammonia and Hydrogen Binary Fuels
Authors: Zhang Jiabo , Zhong Anhao , Huang Zhen , Han Dong
Published: January 2019

A theoretical analysis based on the second law of thermodynamics was conducted for the ammonia/hydrogen/air premixed flames at different initial pressures. The irreversibility causing exergy losses in premixed flames was divided into five parts, namely, heat conduction, mass diffusion, viscous dissipation, chemical reaction, and incomplete combustion, respectively. The results revealed that as the hydrogen percentage in fuel blends increased from 0% to 100%, the total exergy losses decreased. Specifically, the exergy destructions induced by heat conduction and mass diffusion decreased with the increasing hydrogen percentage. The exergy loss induced by incomplete combustion increased with hydrogen addition, as more incomplete combustion products such as H2, H, and OH were generated with the increasing hydrogen percentage. The exergy destruction by chemical reactions first decreased and then increased with the increasing hydrogen percentage, which was attributed to the combination effects of the increased entropy generation rate and reduced flame thickness. Compared to the other four sources, the exergy destruction induced by viscous dissipation was negligible. Furthermore, at the elevated pressure of 5 atm, the effects of hydrogen blending were similar to those at the atmospheric condition. However, the exergy destructions by heat conduction and mass diffusion increased while the exergy destruction by the chemical reaction and the exergy loss by incomplete combustion were both reduced, with the overall exergy loss decreased by 1–2% as the pressure increased from 1 atm to 5 atm.
Study on the Phenomenological Spray Modelling of Heavy Oil for Marine Diesel Engines
Authors: Han Changfu , Liu Long , Liu Dai , Peng Yan
Published: January 2019

In recent years, to satisfy the more and more stringent energy efficiency and pollutants emission regulations of ship, which had been issued by the International Marine Organization (IMO), the combustion improvement of the two-stroke low-speed diesel engines has been paid much attention. The phenomenological combustion model, as an effective and economic approach, is widely used for parametric study on diesel engine combustion process. However, the fuel of two-stroke low-speed diesel engine is heavy oil, and there are few researches focused on the modeling of heavy oil spray. Therefore, a spray model that can describe the heavy oil spray evolution is needed. In this study, a one-dimensional discrete diesel spray model based on the conservation of the momentum flux and mass flow rate along the spray axis is modified for heavy oil. By in-depth analysis of physical properties of diesel and heavy oil, viscosity is found to be the main factor that results in the difference of the fuel concentration and velocity distribution over the spray cross-sectional area. According to the turbulent jet theory, the Schmidt number, which represents the capability of mass and momentum diffusion, proves to be inversely related to fuel viscosity. In order to involve the viscosity effects into the one-dimensional diesel spray model, the relation between viscosity and Schmidt number is derived as a simple formulation to account for the fuel concentration and velocity distribution. The calculation of heavy oil spray penetration is validated by the experiment data, and the results shows that the improved spray model has the capability to predict the propagation of heavy oil spray.
Direct Simultaneous Measurement of Particulate Matter and Ammonia Storage on Combined Selective Catalytic Reduction Filter Systems Using Radio Frequency Sensors
Authors: Ragaller Paul A. , Sappok Alexander , Qiao Jie , Liu Xiaojin , Aguilar Jonathan
Published: January 2019

Tightening global emissions regulations are motivating interest in the development and implementation of Selective Catalytic Reduction + Filtration (SCRF) systems, which are designed to reduce the concentration of tailpipe particulate matter (PM) and NOx emissions. These systems allow designers to combine the NOx reduction capability of an SCR with the filtration capability of a particulate filter on a single unit. Practical implementation of these systems requires reliable measurement and diagnosis of their state — both with respect to trapped particulate matter as well as adsorbed ammonia. Currently, these systems rely on a variety of gas sensors, mounted upstream or downstream of the system, that only provide an indirect inference of the operation state.

In this study, a single radio frequency (RF) sensor was used to perform simultaneous measurements of soot loading and ammonia inventory on an SCRF. Several SCRF core samples were tested at varying soot and ash loads in a catalyst reactor bench. Soot levels were measured by monitoring changes in the bulk dielectric properties within the catalyst using the sensor, while ammonia levels were determined by feeding selected regions of the RF spectrum into a pretrained generalized regression neural network model. Results show the RF sensor is able to directly measure the instantaneous ammonia inventory, while simultaneously providing soot loading measurements within 0.5 g/L. These results confirm that simultaneous measurements of both the PM and ammonia loading state of an SCRF are possible using a single RF sensor via analysis of specific features in the full RF spectrum. The results indicate significant potential to remove the control barriers typically associated with the implementation of advanced SCRF systems.
Powertrain Resilient Mounting Design Analysis
Authors: Parikyan Tigran , Naranca Nikola , Neher Jochen
Published: January 2019

For efficient modeling of engine (or powertrain) supported by non-linear elastic mounts, a special methodology has been elaborated. Based on it, software tool has been developed to analyze the motion of rigid body and elastic mounts, which comprises of three modules:

• Non-linear static analysis;

• Modal analysis (undamped and damped);

• Forced response (in frequency domain).

Application example of a large V12 marine engine illustrates the suggested workflow.

The results are verified against other software tools and validated by measurements.
Simulation and Experimental Study of a Diesel Engine Based on an Electro-Hydraulic FVVA System
Authors: Lu Yong , Li Jian , Xiong Lijun , Li Bo
Published: January 2019

Variable valve timing technologies for internal combustion engines are used to improve power, torque, reduce emissions and increase fuel efficiency. Firstly, the paper presents a new electrohydraulic FVVA system which can control the seating velocity of engine valve flexibly. Secondly, based on the NSGA-II genetic algorithm, outlines multi-objective optimization strategy, the paper designs the parameters of FVVA system to make the system easier to implement. Thirdly, the paper builds the combined FVVA engine simulation model. The combined simulation and experimental are executed to validate the designed FVVA engine. Simulation results show brake power is improved between 1.31% and 4.48% and torque is improved by 1.32% to 4.47%. Brake thermal efficiency and volumetric efficiency also show improvement. Experimental results have good agreement with simulation results. The research results can provide a basis for engine modification design.
Damköhler Number Analysis on the Effect of Ozone on Auto-Ignition and Flame Propagation in Internal Combustion Engines
Authors: Keum Seunghwan , Kuo Tang-Wei
Published: January 2019

Ozone assisted combustion has shown promise in stabilizing combustion and extending operating range of internal combustion engines. However, it has been reported that sensitivity of ozone quantity on combustion varies significantly dependent on combustion modes. For example, auto-ignition driv3en combustion in homogeneous charge compression ignition (HCCI) engine was found to be highly sensitive to the ozone concentration, and up to 100 PPM was found to be sufficient to promote combustion. On the other hand, flame propagation in spark-ignited (SI) engine has been reported to be much less sensitive to the ozone amount, requiring ozone concentration about 3000∼6000 PPM to realize any benefit in the flame speed. A better understanding on the ozone sensitivity is required for combustion device design with ozone addition. In this study, a Damköhler number analysis was performed to analyze the vast difference in the ozone sensitivity between auto-ignition and flame propagation. The analysis showed that, for ozone to be effective in flame propagation, the contribution of ozone on chemistry should be large enough to overcome the diffused radical from the oxidation layer. It is expected that similar analysis will be applicable to any additives to provide an understanding of their effect.
Effects of Outlier Flow Field on the Characteristics of In-Cylinder Coherent Structures Identified by POD-Based Conditional Averaging and Quadruple POD
Authors: Gao Rui , Shen Li , Teh Kwee-Yan , Ge Penghui , Zhao Fengnian , Hung David L. S.
Published: January 2019

Proper Orthogonal Decomposition (POD) offers an approach to quantify cycle-to-cycle variation (CCV) of the flow field inside the internal combustion engine cylinder. POD decomposes instantaneous flow fields (also called snapshots) into a series of orthonormal flow patterns (called POD modes) and the corresponding mode coefficients. The POD modes are rank-ordered by decreasing kinetic energy content, and the low-order, high-energy modes are interpreted as constituting the large-scale coherent flow structure that varies from engine cycle to engine cycle. Various POD-based analysis techniques have thus been proposed to characterize engine flow field CCV using these low-order modes. The validity of such POD-based analyses rests, as a matter of course, on the reliability of the underlying POD results (modes and coefficients). Yet a POD mode can be disproportionately skewed by a single outlier snapshot within a large data set, and an algorithm exists to define and identify such outliers. In this paper, the effects of a candidate outlier snapshot on the results of POD-based conditional averaging and quadruple POD analyses are examined for two sets of crank angle-resolved flow fields on the mid-tumble plane of an optical engine cylinder recorded by high-speed particle image velocimetry. The results with and without the candidate outlier are compared and contrasted. In the case of POD-based conditional averaging, the presence of the outlier scrambles the composition of snapshot subsets that define large-scale flow pattern variations, and thus substantially alters the coherent flow structures that are identified; for quadruple POD, the shape of coherent structures as well as the number of modes to define them are not significantly affected by the outlier.
Fundamental Study of Diesel-Piloted Natural Gas Direct Injection Under Different Operating Conditions
Authors: Fink Georg , Jud Michael , Sattelmayer Thomas
Published: January 2019

Natural gas as an alternative fuel in engine applications substantially reduces both pollutant and greenhouse gas emissions. High pressure dual fuel direct injection of natural gas and Diesel pilot has the potential to minimize methane slip from gas engines and increase the fuel flexibility, while retaining the high efficiency of a Diesel engine. Speed and load variations as well as various strategies for emission reduction entail a wide range of different operating conditions. The influence of these operating conditions on the ignition and combustion process is investigated on a rapid compression expansion machine. By combining simultaneous Shadowgraphy and OH* imaging with heat release rate analysis, an improved understanding of the ignition and combustion process is established. At high temperatures and pressures the reduced pilot ignition delay and lift-off length minimize the effect of natural gas jet entrainment on pilot mixture formation. A simple geometrical constraint was found to reflect the susceptibility for misfiring. At the same time natural gas ignition is delayed by the early pilot ignition close to the injector tip. The shape of heat release is only marginally affected by the operating conditions and mainly determined by the degree of premixing at the time of gas jet ignition. Luminescence from the sooting natural gas flame is generally only detected after the flame extends across the whole gas jet at peak heat release rate. Termination of gas injection at this time was confirmed to effectively suppress soot formation, while a strongly sooting pilot seems to intensify soot formation within the natural gas jet.
Defining the Boundary Conditions of the CFR Engine Under RON Conditions for Knock Prediction and Robust Chemical Mechanism Validation
Authors: Salih Saif , DelVescovo Daniel , Kolodziej Christopher P. , Rockstroh Toby , Hoth Alexander
Published: January 2019

In order to establish a pathway to evaluate chemical kinetic mechanisms (detailed or reduced) in a real engine environment, a GT Power model of the well-studied Cooperative Fuels Research (CFR) engine was developed and validated against experimental data for primary reference fuel blends between 60 and 100 under RON conditions. The CFR engine model utilizes a predictive turbulent flame propagation sub-model, and implements a chemical kinetic solver to solve the end-gas chemistry. The validation processes were performed simultaneously for thermodynamic and chemical kinetic parameters to match IVC conditions, burn rate, and knock prediction. A recently published kinetic mechanism was implemented in GT-Power, and was found to over-predict the low temperature heat release for iso-octane and PRF blends, leading to advanced knock onset phasing compared to experiments. Three reaction rates in the iso-octane and n-heptane pathways were tuned in the kinetic mechanism in order to match experimental knock-point values, yielding excellent agreement in terms of the knock onset phasing, burn rate, and the thermodynamic conditions compared to experiments. This developed model provides the initial/boundary conditions of the CFR engine under RON conditions, including IVC temperature and pressure, MFB profile, residual fraction and composition. The conditions were then correlated as a function of CFR engine compression ratio, and implemented in a 0-D SI engine model in Chemkin Pro in order to demonstrate an application of the current work. The Chemkin Pro and GT-Power simulations provided nearly identical results despite significant differences in heat transfer models and chemical kinetic solvers. This work provides the necessary framework by which robust chemical kinetic mechanisms can be developed, evaluated, and tuned, based on the knocking tendencies in a real engine environment for PRF blends.
Effects of Various Discharge Strategies on Ignition of Lean Methane/Air Mixture
Authors: Huang Shuai , Li Tie , Wu Chongmin , Wang Bin , Zheng Ming
Published: January 2019

Ultra-lean burn with high turbulence has high potential for improving thermal efficiency and reducing NOx emissions in spark-ignition engines. Formation of initial flame kernel in high-turbulence flow by advanced ignition technologies is crucial for successful implementation of the ultra-lean burn concept.

In this study, a four-coil ignition system is designed to enable temporally flexible discharge, including the single strike, multi-strike and continuous discharge with the discharge energy range from 100 to 300 mJ. The performance of the different discharge strategies on igniting the lean methane-air mixture is evaluated in an optically accessible constant volume vessel. The initial mixture pressure of 3.0 MPa and temperature of 388 K are set to simulate typical conditions near TDC (top dead center) of turbocharged large-bore natural gas engines. Both the flow and quiescent conditions around the spark plug are taken into account with and without gas flows in the vessel. The flame kernel formation and developing processes are captured by using the Schlieren imaging technique with a high-speed CMOS video camera, while evolution of both the voltage and current in the circuit are well monitored by the high-voltage probe and current clamp.

With the continuous discharge ignition, the lean limit is remarkably extended in the case of the flow condition, while it is changed only slightly under the quiescent condition, compared with the other strategies. Analysis of the current and voltage waveforms shows that the continuous discharge strategy can enable a steadier and longer discharging period than the other strategies, regardless of conditions with and without gas flow. Besides, the continuous discharge strategy can accelerate the initial flame propagation compared with the other strategies. Once the flame kernel is successfully established, an increase in the discharge energy of single strike has no obvious effects on the flame development, but it is necessary for maintaining the lean limit. Although, in principle, the multi-strike discharge strategy can increase the ignition energy released to the mixture, the current waveform is prone to be interrupted with the discharge channel strongly distorted by the gas flow under the high-pressure condition. The flame propagation speed of the ultra-lean mixture is rather slow under the high ambient pressure quiescent condition compared with the high ambient pressure flow condition. Enhancement of turbulent flow in the mixture is very crucial for realizing the highly efficient and stable combustion of the lean mixture.
Ignition of Diesel Pilot Fuel in Dual-Fuel Engines
Authors: Grochowina Marcus , Hertel Daniel , Tartsch Simon , Sattelmayer Thomas
Published: January 2019

Dual-Fuel (DF) engines offer great fuel flexibility combined with low emissions in gas mode. The main source of energy in this mode is provided by gaseous fuel, while the Diesel fuel acts only as an ignition source. For this reason, the reliable autoignition of the pilot fuel is of utmost importance for combustion in DF-engines. However, the autoignition of the pilot fuel suffers from low compression temperatures caused by Miller valve timings. These valve timings are applied to increase efficiency and reduce nitrogen oxide emissions. Previous studies have investigated the influence of injection parameters and operating conditions on ignition and combustion in DF-engines using a unique periodically chargeable combustion cell. Direct light high-speed images and pressure traces clearly revealed the effects of injection parameters and operating conditions on ignition and combustion. However, these measurement techniques are only capable of observing processes after ignition. In order to overcome this drawback, a high-speed shadowgraph technique was applied in this study to examine the processes prior to ignition. Measurements were conducted to investigate the influence of compression temperature and injection pressure on spray formation and ignition. Results showed that the autoignition of Diesel pilot fuel strongly depends on the fuel concentration within the spray. The high-speed shadowgraph images revealed that in the case of very low fuel concentration within the pilot spray only the first-stage of the two-stage ignition occurs. This leads to large cycle-to-cycle variations and misfiring. However, it was found that a reduced number of injection holes counteracts these effects. The comparison of a Diesel injector with 10-holes and a modified injector with 5-holes showed shorter ignition delays, more stable ignition and a higher number of ignited sprays on a percentage basis for the 5-hole nozzle.