bluuebunny/crossref_metadata_2025 huggingface dataset:
Family planning desires of older adults (50 years and over) in Botswana
Authors: Ola Ama Njoku , Olaomi John O.
Published: April 2020

Background: This study analysed the views of a stratified sample of 444 older adult women from selected health districts in Botswana on their family planning (FP) use, knowledge, accessibility and availability.Methods: Four health districts (two rural and two urban) were purposively selected. The sample of 444 older adults was proportionally allocated to the districts. The snowball technique was used in identifying older adults from each district.Results: Contraceptive prevalence among the older adults is low (25. 2%); ever used rate was 23.6%, with unmet need as high as 75.2%. The traditional methods are mainly used. Knowledge, availability and accessibility of the natural methods are high. The likelihood ratio test shows that age, educational status, marital status and employment jointly significantly predicts (p 0.05) the use of FP.Conclusion: Family planning programme developers and policy-makers should develop educational interventions that will be age specific and relevant to older adults.
Modifiable factors within the prevention of mother-to-child transmission programme associated with failure to prevent HIV transmission in the Onandjokwe district of Namibia
Authors: Shayo Flavia Strato , Mash Bob
Published: April 2020

Background: Ending new paediatric HIV infections continues to be a global health priority. Cuba and other countries have demonstrated that elimination of mother-to-child transmission is possible through Prevention of Mother-to-Child Transmission (PMTCT) interventions. As Namibia works on improving PMTCT there is a need to identify the local modifiable factors to achieve zero new HIV infections.Aim: This study aimed to identify the modifiable factors within the PMTCT programme, which contributed to the acquisition of HIV infection among children.Setting: The study was carried out in the Onandjokwe District, Northern Namibia.Methods: A descriptive audit was undertaken of 59 medical records of mothers and their children under two years, who acquired HIV despite the PMTCT programme between 2014 and 2016.Results: The study found that overall HIV transmission was only 2%, but 80% of the paediatric HIV infections could be prevented by implementing the existing Namibian PMTCT recommendations. Overall 61% of modifiable factors were related to mothers, 30% to health workers and 10% to the health system. The top three modifiable factors were the mother defaulting on ART during pregnancy or breastfeeding, the health worker not intervening when the mother failed the first-line ART regimen, and poor coordination of care between the hospital and primary care.Conclusion: Although overall transmission is low with the PMTCT programme, the majority of remaining HIV infections among children under two years could be prevented by addressing the modifiable factors identified in this study.
Compliance with local diabetic guidelines at a district hospital in KwaZulu-Natal, South Africa
Authors: Rampersad K. , Rangiah S. , Kendon M.
Published: April 2020

Background: Diabetes mellitus (DM) represents a major health-related problem in South Africa and throughout the world. The management goals of diabetes are first to maintain normal blood glucose levels and second to prevent the development of complications. Local guidelines developed by the Society for Endocrine Metabolism and Diabetes South Africa (SEMDSA) have shown that tight glycaemic control and appropriate monitoring can prevent or delay the development of diabetic complications. The demographic profile of patients with type 2 DM and the compliance of doctors to the guidelines were determined.Methods: Five hundred records of patients with type 2 DM were selected from the medical outpatients’ department (MOPD) by systematic sampling. Demographic information on age, sex and ethnicity was obtained. The performance and timing of recommended investigations were recorded and compared with the 2012 SEMDSA guidelines.Results: The mean age of patients was 61 years. Black and Indian patients formed the majority, comprising 44.4% and 43.0% respectively. Glycated haemoglobin was measured in 29.2% of patients once and 13.2% of patients twice in the past year. Lipid studies were done on 40.4% of patients. A serum creatinine (sCr), estimated glomerular filtration rate (eGFR) and serum potassium were done on 38.2% of patients. Eye examinations were done on 13.60% patients and examination of the foot was done on 7.8% of patients. Some 15% had a urine dipstick test done at least once in the past year and 10.4% had a urine albumin/creatinine ratio (ACR) requested. Only 21 patients (4.2%) were compliant with the SEMDSA guidelines. Measurements of blood pressure and blood glucose were 100% compliant. Anthropometric measurements (height, weight and body mass index), dietitian referral and foot examinations were the least compliant, being performed 4.2%, 5.0% and 7.8% of the time respectively.Conclusion: Black and Indian patients formed the majority of the study population. The screening for chronic complications of type 2 DM was poor in the majority of patients. Evaluation of selected records demonstrated compliance with the SEMDSA guidelines in only 4.2% of patients. There is an urgent need to review barriers to the implementation of guidelines in South Africa.
Two medicolegal issues of concern
Authors: Lundgren A. C.
Published: April 2020

No abstract available.
Peripartum Cardiomyopathy
Authors: Leonard T. G.A.
Published: April 2020

No abstract available.
The use of emergency hormonal contraception in South Africa: current and future perspectives
Authors: Dahan-Farkas N. , Vally M.
Published: April 2020

Emergency hormonal contraceptives play an important role in preventing unplanned pregnancies in South Africa. In this review, we discuss the levonorgestrel emergency contraceptive, the combined estrogen and progestin regimen (also known as the Yuzpe method) and the use of Ulipristal acetate. The levonorgestrel and the combined estrogen, progestin regimen are available in South Africa. The specific mechanisms of action of each of these emergency hormonal contraceptives will be discussed as well as their efficacy, the side effects associated with each of these preparations and the drug interactions. Levonorgestrel can be used as a single dose (1.5 mg) instead of two doses (0.75 mg) 12 hours apart. Levonorgestrel is very effective, with fewer adverse effects than the combined estrogen and progestogen administration. Levonorgestrel and the Yuzpe method have demonstrated good efficacy when utilised within 72 hours after unprotected intercourse or contraceptive failure. These emergency hormonal contraceptives should not be used as regular contraception. It is essential that all health professionals and educators inform women of reproductive age about the risks and common side effects of emergency hormonal contraceptives.
Exercise, illness and drug use: guiding principles for approaching a complex triad
Authors: Steyn S. F. , Brand L. , Wolmarans D.
Published: April 2020

No abstract available.
Burning issues in the prevention of heart failure
Authors: Ker J. A. , Outhoff K.
Published: April 2020

Chronic heart failure is common, debilitating, and often the culmination of pervasive cardiovascular insults that systematically undermine the heart’s circulatory capacity and invoke counterproductive neuro-hormonal compensatory changes. Prevention of chronic heart failure therefore requires minimising the impact of traditional cardiovascular risk factors with incisive treatment of hypertension and type II Diabetes Mellitus (T2DM) and prompt lifestyle interventions for smoking, lack of exercise, obesity and hypercholesterolemia. This review is narrative, with selected emphasis on major studies, rather than structured on a specific clinical question, and should be read as such.
The sore throat: a clinical approach to tonsillopharyngitis
Authors: Marais A. , Leuschner M.
Published: April 2020

Acute sore throat is a common complaint encountered by medical practitioners and health care workers routinely. The disease is mostly caused by viral infections of the upper respiratory tract and is usually self-limiting. Symptoms rarely exceed two weeks, irrespective of the cause. Group A beta-haemolytic streptococci accounts for the majority of bacterial instances of tonsillopharyngitis. Clinical examination is not always adequate to diagnose bacterial infections, resulting in the irrational and over-prescribing of antibiotics, especially in upper respiratory tract infections, contributing to communal antimicrobial bacterial resistance. A few scoring systems are available to assist physicians in deciding on the aetiology without resorting to unnecessary laboratory investigations. This article briefly reviews the scoring systems and antimicrobial management of streptococcal throat infections.
Perceptions of community health workers on their training, teamwork and practice: a cross-sectional study in Tshwane district, Gauteng, South Africa
Authors: Nyalunga S. L.N. , Ndimande J. V. , Ogunbanjo G. A. , Masango-Makgobela A. , Bogongo T.
Published: April 2020

Background: In 2011, South Africa established ward-based outreach teams (WBOTs) comprising Community Health Workers as part of strategies to strengthen primary healthcare. The new community health workers (CHWs) lacked experience of the programme. This study aimed at assessing perceptions of community health workers on their training, teamwork and practice.Methods: This was a cross-sectional study conducted among CHWs in the seven regions of Tshwane health district between October and November 2015. Data were collected from 431 CHWs in eight Community Health Centres and 11 clinics using a pre-tested, self-administered questionnaire. Outcome measures were CHWs’ perceptions on training, teamwork and practice regarding WBOT programme.Results: A total of 431 CHWs formed the study sample. Participants had a mean age of 36 years (SD ± 9.46). The majority (88.2%) were female. Some 77% had completed secondary school. Overall, most CHWs perceived their training (86.4%), teamwork(87.6%) and practices (67.7%) to be good (p = 0.001). The majority were able to provide efficient health care despite the challenges experienced, which were lack of equipment, walking long distances, and safety on the streets and in households with patients who had mental health problems among others. Fisher’s exact test showed a significant association between training and work challenges (p = 0.006).Conclusion: The study findings showed that most CHWs had good perceptions regarding their training, teamwork and practice. Several concerns raised by CHWs suggest the need for stakeholders to ensure availability of resources for optimal functioning of CHWs.
Mastering your Fellowship
Authors: Von Pressentin K. B. , Naidoo M. , Ras T. , Torlutter M.
Published: April 2020

The series, “Mastering your Fellowship”, provides examples of the question format encountered in the written and clinical examinations, Final Part A of the FCFP(SA) examination. The series is aimed at helping family medicine registrars prepare for this examination. Model answers are available online.
An assessment of erectile dysfunction among male diabetics attending Temba Community Health Centre, Pretoria
Authors: Bongongo T. , Ndimande J. V. , Tumbo J.
Published: April 2020

Introduction: Erectile dysfunction is common among men with diabetic mellitus and has a negative effect on their quality of life. The proportion of male diabetics who disclosed their problematic sexual performance was increasing at Temba Community Health Centre (CHC), which motivated a survey that was conducted from April 2015 till April 2016.Aim: Assessment of erectile dysfunction among male diabetics attending Temba Community Health Centre.Setting: Temba Community Health Centre, Pretoria, South Africa.Method: A cross-sectional survey was conducted using a piloted, structured questionnaire adapted from the International Index of Erectile dysfunction (IIRF-5) questionnaire. Convenience sampling was used to select 191 participants.Result: From the selected sample, 97.3% of male diabetics were suffering from erectile dysfunction. Among them, 120 (62.8%) were between 41 and 60 years of age, 96 (50.2%) were employed, 81 (42.4%) had a secondary level of education and 84 (44.4%) were married. The duration of diagnosed diabetes varied between 2 months and 564 months (42 years). Hypertension and HIV, as co-morbidities, affected 12.7% of the participants and 56% of participants consulted primarily for erectile dysfunction, not knowing that it was a complication of diabetes mellitus.Conclusion: The assessment of erectile dysfunction among male diabetics attending Temba CHC in Pretoria showed that more than two-thirds of the selected sample of patients suffered from erectile dysfunction, from a mild to a severe form of the condition. Most of those participating were between 41 and 60 years old, half of them were married, have a secondary level of education and were unaware that erectile dysfunction is a complication of diabetes mellitus.
Factors associated with physical activity amongst patients with hypertension in two community health centres in uMgungundlovu health district, KwaZulu-Natal, 2018
Authors: Mbambo S. W. , Tlou B. , Dlungwane T. P.
Published: April 2020

Background: Hypertension (HPT) is a global public health challenge. It predisposes to cardiovascular diseases, kidney diseases and disability as well as contributing to high death rates. HPT is increasing tremendously in sub-Saharan Africa with HPT-related mortality risk having increased by 25% in less than 10 years in South Africa. Physical activity is a cost-effective way of reducing, controlling and preventing hypertension. The aim of the study was to establish the level of physical activity, and factors associated with physical activity, amongst patients with hypertension, in two community health centres in uMgungundlovu Health District, KwaZulu-Natal, 2018.Methods: An observational, cross-sectional descriptive study with an analytic component was implemented. Data were collected utilising an interviewer-administered questionnaire. Frequency distribution tables and the chi-square test were used in the analysis of data. A p-value less than 0.05 was deemed statistically significant.Results: A total of 374 questionnaires were administered of which 373 were adequately completed, yielding a response rate of 99.7%. The results showed that 39.1% were highly physical active, 32.4% were moderately physical active and 28.4% had low physical activity. Age, marital status, employment status and level of education were significantly associated with physical activity. Major barriers to physical activity included health problems and having no time to exercise. Health-related reasons were reported to be the major motivator towards physical activity.Conclusion: Over a third of the participants presented with high levels of physical activity. Health education should focus on promoting physical activity for HPT clients.
The quality of feedback from outpatient departments at referral hospitals to the primary care providers in the Western Cape: a descriptive survey
Authors: Mash Robert , Steyn Herma , Bello Muideen , Von Pressentin Klaus , Rossouw Liezel , Hendricks Gavin , Fouche Germarie , Stapar Dusica
Published: April 2020

Background: Coordinating care for patients is a key characteristic of effective primary care. Family physicians in the Western Cape formed a research network to enable them to perform practical research on key questions from clinical practice. The initial question selected by the network focused on evaluating the quality of referrals to and feedback from outpatient departments at referral hospitals to primary care providers in the Western Cape.Methods: A descriptive survey combined quantitative data collected from the medical records with quantitative and qualitative data collected from the patients by questionnaire. Family physicians collected data on consecutive patients who had attended outpatient appointments in the last three months. Data were analysed using the Statistical Package for the Social Sciences.Results: Seven family physicians submitted data on 141 patients (41% male, 59% female; 46% metropolitan, 54% rural). Referrals were to district (18%), regional (28%) and tertiary hospitals (51%). Referral letters were predominantly biomedical. Written feedback was available in 39% of patients. In 32% of patients, doctors spent time obtaining feedback; the patient was the main source of information in 53% of cases, although many patients did not know what the hospital doctor thought was wrong (36%). The quality of referrals differed significantly by district and type of practitioner, while feedback differed significantly by level of hospital.Conclusion: Primary care providers did not obtain reliable feedback on specialist consultations at referral hospital outpatients. Attention must be given to barriers to care as well as communication, coordination and relationships across the primary–secondary interface.
Analysis of LiDAR and Camera Data in Real-World Weather Conditions for Autonomous Vehicle Operations
Authors: Goberville Nick , El-Yabroudi Mohammad , Omwanas Mark , Rojas Johan , Meyer Rick , Asher Zachary , Abdel-Qader Ikhlas
Published: April 2020

Autonomous vehicle technology has the potential to improve the safety, efficiency, and cost of our current transportation system by removing human error. With sensors available today, it is possible for the development of these vehicles, however, there are still issues with autonomous vehicle operations in adverse weather conditions (e.g. snow-covered roads, heavy rain, fog, etc.) due to the degradation of sensor data quality and insufficiently robust software algorithms. Since autonomous vehicles rely entirely on sensor data to perceive their surrounding environment, this becomes a significant issue in the performance of the autonomous system. The purpose of this study is to collect sensor data under various weather conditions to understand the effects of weather on sensor data. The sensors used in this study were one camera and one LiDAR. These sensors were connected to an NVIDIA Drive Px2 which operated in a 2019 Kia Niro. Two custom scenarios (static and dynamic objects) were chosen to collect sensor data operating in four real-world weather conditions: fair, cloudy, rainy, and light snow. An algorithm developed herein was used to provide a method of quantifying the data for comparison against the other weather conditions. The results from these performance algorithms show that sensor data quality degrades by an average of 13.88% for static objects and 16.16% for dynamic objects while operating in these conditions, with operations in rain proving to have the most significant effect on sensor data degradation. From this study, it is hypothesized that advancements in data processing algorithms can improve the usability of this degraded data. In future work, we seek to explore fault-tolerant sensor fusion algorithms that can overcome the effects of adverse weather.
Vehicle Trajectory Prediction Based on Motion Model and Maneuver Model Fusion with Interactive Multiple Models
Authors: Xiao Wei , Zhang Lijun , Meng Dejian
Published: April 2020

Safety is the cornerstone for Advanced Driver Assistance Systems (ADAS) and Autonomous Driving Systems (ADS). To assess the safety of a traffic situation, it is essential to predict motion states of traffic participants in the future with mathematic models. Accurate vehicle trajectory prediction is an important prerequisite for reasonable traffic situation risk assessment and appropriate decision making. Vehicle trajectory prediction methods can be generally divided into motion model based methods and maneuver model based methods. Vehicle trajectory prediction based on motion models can be accurate and reliable only in the short term. While vehicle trajectory prediction based on maneuver models present more satisfactory performance in the long term, these maneuver models rely on machine learning methods. Abundant data should be collected to train the maneuver recognition model, which increases complexity and lowers real-time performance. In this paper, a vehicle trajectory prediction method based on motion model and maneuver model fusion with Interactive Multiple Model (IMM) is proposed. Firstly, Constant Turn Rate and Acceleration (CTRA) motion model and Unscented Kalman Filter (UKF) are used to predict vehicle trajectory with uncertainty in the future. Then, vehicle trajectory prediction based on simplified maneuver recognition model is conducted, using temporal and spatial relationship between vehicle historical trajectory and lane lines. After that, vehicle trajectory prediction by integrating motion model and maneuver model with IMM is conducted. Finally, the proposed method is compared with CTRA motion model based vehicle trajectory prediction and lane keeping model (LKM) based vehicle trajectory prediction in two simulation test scenarios. The simulation results indicates that the IMM-based method achieves both excellent prediction accuracy and appropriate prediction uncertainty in the whole prediction horizon. This research can be used to support decision making for Advanced Driver Assistance Systems (ADAS) and Autonomous Driving Systems and leads to improvement of traffic safety.
Experimental Investigation of Axial Cutting of AA6061 Extrusions under a Tension Deformation Mode
Authors: Gudisey Anthony , Altenhof William , Magliaro John
Published: April 2020

A plethora of applications in the transportation industry for both vehicular and roadside safety hardware, especially seatbelts, harnesses and restraints, rely on tensile loading to dissipate energy and minimize injury. There are disadvantages to the current state-of-the-art for these tensile energy absorbers, including erratic force-displacement responses and low tensile force efficiencies (TFE). Axial cutting was extensively demonstrated by researchers at the University of Windsor to maintain a stable reaction force, although exclusively under compressive loading. A novel apparatus was investigated in this study which utilized axial cutting under a tensile loading condition to absorb energy. A parametric scope was chosen to include circular AA6061 extrusions in both T4 and T6 temper conditions with an outer diameter of 63.5 mm and wall thickness of 3.18 mm. The experiments were performed quasi-statically utilizing a custom, hydraulically powered long stroke tension/compression testing machine with a maximum capacity of 300kN. Strain-gauge based load cells and non-contact displacement transducers were implemented to measure the cutting force and displacement response of the setup. The results demonstrated highly stable force responses, with cutting force efficiencies typically in the vicinity of 90%. The experimental force-displacement responses exhibited a high degree of repeatability and correlation to the analytical model. Critical performance metrics, including the mean load and total energy absorption, were predicted to within 5 %. Additionally, the complete force-displacement response was predicted utilizing an analytical modeling approach with an average validation metric of approximately 0.92.
A Fast Modeling Approach for the Numerical Prediction of Urea Deposit Formation
Authors: Budziankou Uladzimir , Quissek Max , Lauer Thomas
Published: April 2020

The permanently tightening emission regulations for NOx pollutants force further development of automotive exhaust aftertreatment systems with selective catalytic reduction (SCR). Of particular interest is the long-term reliability of SCR systems with regard to unfavorable operating conditions, such as high injection rates of urea water solution (UWS) or a low exhaust gas temperature. Both of them may lead to formation of solid deposits which increase backpressure and impair ammonia uniformity.

A fast modeling approach for numerical prediction of deposit formation in urea SCR systems is desired for optimization of system design. This paper presents a modified methodology for the modeling of deposit formation risk. A new determination of the initial footprint of the spray, where the deposit formation is inhibited, is proposed. The threshold values for the evaluation of the film transport were validated based on experimental results. To achieve a more realistic simulation in terms of wall wetting and cooling, the impingement heat transfer as well as the impingement model were modified based on optical investigations.

In order to accomplish the modeling of deposit formation with typical time ranges of several minutes, a recently developed injection source approach was applied. The substitution of the Lagrange-particles with source terms of mass, momentum and energy allowed to reduce simulation time by a factor of 30. The presented modeling approach was validated against both, the experimental data from an optical box and an exhaust aftertreatment system. The comparison of measured and simulated results shows the capability of the presented modeling approach to predict the position and the severity of solid deposits.
Designing Regenerators of Thermoacoustic Engines for Automotive Waste Heat Recovery
Authors: Zhou Jianhua , Karlsson Mikael , Abom Mats
Published: April 2020

Extraction and utilization of automotive waste exhaust heat is an effective way to save fuel and protect the environment. One promising technology for this purpose is the thermoacoustic engine, where thermal energy is converted to mechanical energy in terms of high amplitude oscillations. The core component in a travelling-wave thermoacoustic engine is its regenerator where the process of energy conversion is mainly realized. This paper introduces a strategy for the design of the regenerator for applications in typical light- and heavy-duty vehicles. Starting from 1-D linear thermoacoustic theory, the nonlinear effects (given by the high amplitude oscillations) are modelled as acoustic resistances and introduced into the basic linear equations to estimate the nonlinear dissipations in the regenerator. Then, a few dimensionless parameters are derived by normalizing these thermoacoustic equations. This yields a good overview of how different design parameters such as the geometrical dimensions, operating temperature, and thermal boundary conditions influence the performance of the regenerator. For the application of automotive waste heat recovery, the thermal properties of the actual exhaust gas are accepted to be the boundary condition for the heat matching. The results obtained in the current work show that the optimum designs for the regenerators in travelling-wave thermoacoustic engines aimed at light- and heavy-duty applications widely differ due to the different thermal properties of their exhaust gas. Finally, two possible optimal designs of the regenerators in travelling-wave thermoacoustic engines for the typical light- and heavy-duty applications are presented. The designs are based on heat matching between the required heat by the regenerators and the available heat from the exhaust gases.
Investigation of the Effect of Tire Deformation on Open-Wheel
Aerodynamics
Authors: Eder Philipp , Gerstorfer Thomas , Lex Cornelia , Amhofer Thomas
Published: April 2020

This paper introduces a finite element (FE) approach to determine tire
deformation and its effect on open-wheeled racecar aerodynamics. In recent
literature tire deformation was measured optically. Combined loads like
accelerating at corner exit are difficult to reproduce in wind tunnels and
requires several optical devices to measure the tire deformation. In contrast,
an FE approach is capable of determining the tire deformation in combined load
states accurately. The FE tire model was validated using computer tomography
images, 3D scan measurements, contact patch measurements and stiffness
measurements. The deformed shape of the FE model was used in a computational
fluid dynamics (CFD) simulation. A sensitivity study was created to determine
the effect of the tire deformation on aerodynamics for unloaded and loaded
tires. In addition, the influence of these tire deformations was investigated in
a CFD study using a full vehicle model. The CFD model was validated through full
scale wind tunnel tests as well as on-road tests. Finally, a straight-line and a
steady state cornering maneuver based on a vehicle dynamics simulation were
simulated using this combined approach of FE and CFD. The tire deformation
included proper wheel load, wheel speed and slip angle for each wheel. The CFD
full vehicle model took chassis slip angle, body roll angle and wheel steering
angle into account in order to match the real driving situation. The results
show that realistic tire deformations provide better insight into the effect of
rotating wheels on aerodynamics of full vehicles, especially that of race
cars.
CAD-Based Optimization of a Race Car Front Wing
Authors: Tolchinsky Ilya , Carrigan Travis , Dawson Joshua
Published: April 2020

The aerodynamics of the front wing of modern race cars are critical to the performance of the vehicle. The Formula 1 line up represents the state of the art in this field as there are some very complex aerodynamic designs on display. It is strange, however, that there is no agreement on twist direction for the multiple wing sections of the front wing. This paper addresses this question by posing it as an optimization problem. The geometry of the wings has been simplified so that the twist of the upper sections could be studied in isolation. The whole assembly consisted of only two high lift surfaces. The forward wing remained fixed for the study, and twist of the secondary wing became the primary focus. Its geometry was generated by lofting a set of cross-sections at specified angles to create the surface. The resulting geometry was automatically meshed and then evaluated using CFD. This fully automated process was then used to find an ideal twist distribution of the secondary wing. The results show that a higher angle of attack at the tip of the wing produces superior aerodynamic performance. One of the advantages of this approach is that the final output of the process will be a CAD geometry, as opposed to a modified FEM. It avoids a manual step of putting the results back into CAD before being able to share the optimal geometry with other design teams. By removing a manual step, it makes it possible to integrate this method with other disciplines such as structural analysis and enable MDO.
Influence of Background Spectral Distribution on Perceptions of Discomfort Glare
Authors: Nagare Rohan M. , Bullough John D.
Published: April 2020

The advent of light-emitting diode (LED) technology for automotive lighting allows flexibility of the spectral distribution of forward headlighting systems, while meeting current requirements for “white” illumination. As vehicle headlights have become whiter (with more short-wavelength light output) over the past several decades, their potential impacts on visual discomfort for oncoming and preceding drivers have been hotly debated. It is known that a greater proportion of short-wavelength energy increases discomfort glare, and that increasing the background light level (e.g., through roadway lighting) will decrease perceptions of discomfort. More recently it has been demonstrated that the visual system exhibits enhanced short-wavelength sensitivity for perceptions of scene brightness. As a result, roads illuminated by light sources with higher correlated color temperatures (CCTs) will be judged as appearing to be brighter than those illuminated to the same light level by sources with lower CCTs. The present laboratory study was conducted to identify whether the increased scene brightness of a road illuminated with greater short-wavelength light helps to mitigate discomfort glare more than the same scene illuminated to the same light level, but with less short-wavelength light. The results indicate that the spectral distribution of the background plays little role in the degree to which it lessens discomfort glare. The implications of these results for vehicle and road lighting practices are discussed.
A Quasi-1D Model for the Description of ECN Spray a Combustion Process
Authors: Garcia-Oliver Jose M , Novella Ricardo , Pastor Jose M , Pachano Leonardo , Naud Bertrand
Published: April 2020

An existing one-dimensional (1D) spray model, which successfully captures inert spray processes, has been extended to enable prediction of ignition delay and lift-off length under reacting conditions. For that purpose, an additional transport equation for the progress variable has been incorporated, which includes detailed chemistry effects by means of a tabulation method based upon an external flamelet solver. The transport equation for the progress variable is solved in a quasi-1D fashion, along presumed mixture fraction trajectories, while the 1D approach is retained for the mixture fraction and axial velocity fields.

The paper includes the model development, as well as the validation against Spray A measurements from the Engine Combustion Network. In spite of the simplified approach, the model captures some of the experimental trends of the lift-off length and ignition delay with a quite low computational cost. The approach reinforces the hypothesis of lift-off stabilization due to autoignition process. It also provides an explicit link between the chemical mechanism and the spray ignition and lift-off phenomena.
Advances in Experimental Vehicle Soiling Tests
Authors: Schilling Felix , Kuthada Timo , Gaylard Adrian , Wiedemann Jochen , Wagner Andreas
Published: April 2020

The field of vision of the driver during wet road conditions is essential for safety at all times. Additionally, the safe use of the increasing number of sensors integrated in modern cars for autonomous driving and intelligent driver assistant systems has to be ensured even under challenging weather conditions. To fulfil these requirements during the development process of new cars, experimental and numerical investigations of vehicle soiling are performed. This paper presents the surface contamination of self- and foreign-soiling tested in the wind tunnel. For these type of tests, the fluorescence method is state-of-the-art and widely used for visualizing critical areas. In the last years, the importance of parameters like the contact angle have been identified when designing the experimental setup. In addition, new visualization techniques have been introduced. Based on these developments the complete process using the fluorescence method was evaluated and updated to the available technology. Various factors in the experimental setup were identified to improve the reliability and a resulting high repeatability of the experiments between different test sessions is shown. Additionally, new visualization techniques are introduced for enhanced data evaluation which allows an easier identification of possible measures. Due to the increased repeatability, it is now possible to calculate the absolute difference between two analyzed vehicle configurations. For the side mirror glass, the quality of the results is improved by image detection methods. In the end it is shown that these modifications to the process are helpful in evaluating the results of computational fluid dynamics.
Comparison of CNN and LSTM for Modeling Virtual Sensors in an Engine
Authors: Bellone Mauro , Faghani Ethan , Karayiannidis Yiannis
Published: April 2020

The automotive industry makes extensive use of virtual models to increase efficiency during the development stage. The complexity of such virtual models increases with the complexity of the process that they describe, and thus new methods for their development are constantly evaluated. Among many others, data-driven techniques and machine learning offer promising results, creating deep neural networks that map complex input-output relations. This work aims at comparing the performance of two different neural network architectures for the estimation of the engine state and emissions (flow fuel, NOx and soot). More specifically, Convolutional Neural Network (CNN) and Long-Short Term Memory (LSTM) will be evaluated in terms of performance, using different techniques to increase the model generalization. During the learning stage data from different engine cycles are fed to the neural networks. In order to evaluate the generalization of the model, the networks are tested over new, previously unseen, engine cycles. Results show that our models over-perform other state-of-the-art models, the best performance was found for the LSTM model with 2.40%, 2.80% and 18.19% error for flow fuel, NOx and soot sensor respectively.
Optical Characterization of the Combustion Process inside a Large-Bore Dual-Fuel Two-Stroke Marine Engine by Using Multiple High-Speed Cameras
Authors: Hult Johan , Matamis Alexios , Baudoin Eric , Mayer Stefan , Richter Mattias
Published: April 2020

Dual-fuel engines for marine propulsion are gaining in importance due to operational and environmental benefits. Here the combustion in a dual-fuel marine engine operating on diesel and natural gas, is studied using a multiple high-speed camera arrangement. By recording the natural flame emission from three different directions the flame position inside the engine cylinder can be spatially mapped and tracked in time. Through space carving a rough estimate of the three-dimensional (3D) flame contour can be obtained. From this contour, properties like flame length and height, as well as ignition locations can be extracted. The multi-camera imaging is applied to a dual-fuel marine two-stroke engine, with a bore diameter of 0.5 m and a stroke of 2.2 m. Both liquid and gaseous fuels are directly injected at high pressure, using separate injection systems. Optical access is obtained using borescope inserts, resulting in a minimum disturbance to the cylinder geometry. In this type of engine, with fuel injection from positions at the rim of the cylinder, the flame morphology becomes asymmetric. The optical spatial mapping and tracking method is demonstrated to be well suited for the study of such an asymmetric combustion system. Spatial mapping and tracking of flame position is applied to both engine operating modes; normal diesel operation and dual-fuel operation with diesel pilot ignition of the gas. Similarities and differences between diesel and gas flame shape and development can thus be visualised directly. The effects of changing charge density, gas injection pressure and injection nozzle geometry on the flame geometry and development are also studied.
Development and Demonstration of a Class 6 Range-Extended Electric Vehicle for Commercial Pickup and Delivery Operation
Authors: Jeffers Matthew A. , Miller Eric , Kelly Kenneth , Kresse John , Li Ke , Dalton Jesse , Kader Michael , Frazier Cole
Published: April 2020

Range-extended hybrids are an attractive option for medium- and heavy-duty commercial vehicle fleets because they offer the efficiency of an electrified powertrain with the driving range of a conventional diesel powertrain. The vehicle essentially operates as if it was purely electric for most trips, while ensuring that all commercial routes can be completed in any weather conditions or geographic terrain. Fuel use and point-source emissions can be significantly reduced, and in some cases eliminated, as many shorter routes can be fully electrified with this architecture.

Under a U.S. Department of Energy (DOE)-funded project for Medium- and Heavy-Duty Vehicle Powertrain Electrification, Cummins has developed a plug-in hybrid electric Class 6 truck with a range-extending engine designed for pickup and delivery application. The National Renewable Energy Laboratory (NREL) assisted by developing representative workday drive cycles for Class 6 operation and an adapted cycle to enable vehicle track testing. A novel, automated driving system was utilized by Southwest Research Institute (SwRI) to improve the repeatability of the track testing conducted to quantify vehicle energy consumption. Cummins used a drivetrain model to design the hybrid control system for increased fuel savings. The control system functionality and fuel savings objective of 50% or more were confirmed by track testing described in this paper.
Characterization of Seat Lateral Support as a Mechanical Behavior
Authors: O'Bannon Terry , Thomas Bonita , Weierstall Mark , Shahid Muhammad , Khaja Iqbal
Published: April 2020

Seat lateral support is often talked about as a design parameter, but usually in terms of psychological perception. There are many difficulties in quantifying lateral support mechanically to the engineering teams: Anthropometric variation causes different people to interact with the seat in different places and at different angles, BPD studies are usually planar and don’t distinguish between horizontal support and vertical resistance to sinking in, most mechanical test systems are typically single-DOF and can’t apply vertical and horizontal loads concurrently, and there is scant literature describing the actual lateral loads of occupants. In this study, we characterize the actual lateral loading on example seating from various sized/shaped occupants according to dynamic pressure distribution. From this information, a six-DOF load and position control test robot (KUKA OccuBot) is used to replicate that pressure distribution. The effect of various sizes and shapes of indenters is explored. We suggest some mechanical methods to assess seat lateral support. We believe such testing will be useful in benchmarking, setting design goals and tracking progress towards those goals through the design process.
Reduced Power Seat Heater System Using Thermal Wave Technology
Authors: Ziolek Scott
Published: April 2020

This paper presents a method of controlling the seat heater using intentional oscillations between multiple, independently controlled temperatures (each with its own tolerance range). The amplitude and frequency of these oscillations can be changed based on secondary trigger events such as changes in the interior temperature. The benefits of using this technique to heat the seat surface are improved thermal sensation and reduced energy usage over the typical drive time.
Feedback Control of Synchronizers for Reducing Impacts during Sleeve
to Gear Engagement
Authors: Piracha Muddassar Zahid , Grauers Anders , Hellsing Johan
Published: April 2020

This paper presents a feedback control strategy aimed to reduce noise and wear
during gearshifts in conventional and hybrid Dual Clutch Transmissions (DCT and
DCTH) and Automated Manual Transmissions (AMT). The control strategy is based on
a new dog teeth position sensor developed by China Euro Vehicle Technology AB
and existing speed sensors in the transmission. During gear shifting, noise is
generated by impacts between the sleeve teeth and the idler gear dog teeth after
speed synchronization. Besides noise, these impacts are also responsible for
delaying the completion of shift and contribute to wear in the dog teeth, hence
reducing the lifespan of the transmission. The presented control strategy
controls speed synchronization such that the impact between sleeve and idler
gear dog teeth, before the start of torque ramp up, is avoided. Since drag
torque is an important factor in speed synchronization, this paper also contains
an algorithm to identify friction torque coefficient in the transmission. The
identification method ensures that the controller adapts to varying conditions
without the need for offline calibration. The control strategy is developed for
standard automatic gear shifting operations but minor adaptations in the
algorithm also make it capable of handling gear shifts requested by the driver.
The output signal of the control strategy is acceleration request on idler gear
during speed synchronization. To make controller easier to implement and
minimize shift time, the acceleration request only has two values, either
maximum value or zero. The control strategy is designed in such a way that it
can easily be integrated in the existing transmission control software. By
applying the control strategy on a detailed simulation model, it is shown that
the impacts during gear engagement are significantly reduced.
Driveline Torque Profiling Based on Speed Estimation for xEVs
Authors: Oh Jiwon , Eo Jeong Soo , Kim Sung Jae , Kim Dohee
Published: April 2020

This paper suggests a method to formulate the driveline torque command for vehicles that use electric motor as part of their sources for providing driving power. The shape of the driveline torque profile notably influences the drivability criteria of the vehicle, and among them, driveline NVH and responsiveness are often tradeoffs for each other. Hence the real-time computed driveline torque profiling (DTP) enables formulation of the effective torque command at any given time to simultaneously satisfy both NVH and responsiveness criteria. Such task is fulfilled by using a shaft distortion prediction model based on a motor speed observer. A compensation torque command based on the amount of shaft distortion is formulated to prevent the shaft distortion with minimum effort. The effectiveness of the suggested driveline torque profiling method is verified using an actual vehicle, and the vehicle NVH and responsiveness are numerically assessed for comparison.
Further Experiments on the Effect of Bulk In-Cylinder Temperature in the Pressurized Motoring Setup Using Argon Mixtures
Authors: Caruana Carl , Farrugia Mario , Sammut Gilbert , Pipitone Emiliano
Published: April 2020

Mechanical friction and heat transfer in internal combustion engines have long been studied through both experimental and numerical simulation. This publication presents a continuation study on a Pressurized Motoring setup, which was presented in SAE paper 2018-01-0121 and found to offer robust measurements at relatively low investment and running cost. Apart from the limitation that the peak in-cylinder pressure occurs around 1 DegCA BTDC, the pressurized motoring method is often criticized on the fact that the gas temperatures in motoring are much lower than that in fired engines, hence might reflect in a different FMEP measurement. In the work presented in SAE paper 2019-01-0930, Argon was used as the pressurization gas due to its high ratio of specific heats. This allowed to achieve higher peak in-cylinder temperatures which close further the gap between fired and motored mechanical friction tests. In 2019-24-0141, Argon was mixed in different proportions with Air to synthesize gases with different ratios of specific heats in the aim of observing any abrupt transitions in the FMEP with different peak in-cylinder temperatures. In this publication, a higher loading test matrix to that published in 2019-24-0141 is presented, with an engine speed ranging from 1400 rpm to 3000 rpm and ratios of specific heats varying from that of Air (γ = 1.4) to that of Argon (γ = 1.67). The peak in-cylinder pressure was kept at a constant 103 bar. Results obtained in this work strengthen further the observations made in 2019-24-0141; where the measured FMEP is found to be insensitive to the different peak in-cylinder temperatures. In this study, a fast-response thermocouple of the eroding type was also fitted in the combustion chamber and gas-wall interface temperature histories were recorded. The transient heat flux was also computed through a spectral analysis and reported in this publication.