bluuebunny/crossref_metadata_2025 huggingface dataset:
A STUDY OF MRAS BASED SPEED ESTIMATION OF SENSORLESS INDUCTION MOTOR USING MATLAB AND SIMULINK MODELLING
Authors: Pattanayak Surya Prakash , Pattanayak Divya Prakash
Published: April 2020

Model reference adaptive system(MRAS) based techniques are one of the best method to estimate the rotor speed due to its performance and straight forward stability approach.These techniques use two different models which have made the speed estimation a reliable scheme especially when the variations.The scheme use the stator equation and rotor equation as the reference model and the adjustable model respectively.The output error from both models is tuned using a PI controller yielding the estimated rotor speed.It presents the identification and parameter estimation of an induction motor model with parameters varying as functions of the operating conditions. A Sensorless torque control system for induction motors is developed. The system allows for fast and precise torque tracking over a wide range of speed.The induction motor is controlled through field orientation techniques that require knowledge of the rotor speed.Since speed sensors decrease the reliability of a drive system (and increase its price), a common trend in motor control is to use an observer to estimate speed.
THE RELATIONSHIP BETWEEN URBAN ENVIRONMENTAL QUALITY AND MENTAL HEALTH (DEPRESSION SCALE): EVIDENCE FROM IRAN
Authors: Azadeh Seyed Reza , Mohammadi Jamal , Doost Hamid Taher Neshat
Published: April 2020

According to the recent studies, there are wide range of psychological disorders in developed and developing countries with different levels of economic conditions. One of the most important psychological disorders and pressures is depression. An issue that has been neglected so far is impact of urban environmental quality on psychological health. Housing in this physical environment plays a very important role in psychological health indexes such as depression. The main purpose of this research is to investigate the relationship between qualitative indexes of housing and depression with a case study of at MoftAbad and Mardavij neighborhoods in Isfahan. Pearson correlation coefficient and linear regression have been used for data analysis. Independent variables of study include qualitative variables of housing that have been studied in accordance with literature in both internal and external dimensions. Dependent variable of study is depression. Depression Inventory Questionnaire of Beck et al. (1996) with 21 questions, used to measure depression. Results showed that variables such as interior design, indoor greenbelt, natural received light, natural ventilation, and plant diversity, walking possibility, quality of public spaces, and environmental cleanliness and security have most impact on level of depression of residents in urban neighborhoods.
IS CONGESTION PRICING AN URBAN MOBILITY SOLUTION TO BRAZILIAN CITIES?
Authors: Oliveira Leise Kelli de , Souza Sayonara Lopes , Cardoso Leandro , Bessa Jr José Elievam , Oliveira Renata Lúcia Magalhães de , Bracarense Lílian Santos Fontes Pereira
Published: April 2020

The congestion pricing is a measure of travel demand management to discourage car use with low public and political acceptability. In the Brazilian context, the Urban Mobility Policy considers this measure to mitigate the congestion. In this paper, we present an exploratory analysis to identify the characteristics considered important by Brazilian transport experts to the implementation of the congestion pricing. The residents assessed these characteristics to identify the preference and acceptability of this scheme in Belo Horizonte (Brazil). We obtained the data from a Web-based survey from experts and residents. With the results, we simulated scenarios reducing the number of private cars in order to evaluate the real benefits of congestion price in a real network. According to Brazilian transport experts, the congestion pricing can be an efficient and well-accepted demand management measure, if the profit subsidises the public transportation systems (bus and rail) and the infrastructure to non-motorized transportation, with active public participation in the decision-making. Considering the residents’ results, we identified favourable public acceptability considering the benefits of public transport investment from the revenue obtained out of the congestion charges. However, availability for payment has a high rejection rate, although implementation strategies are perceived as advantages. The simulation indicates the reduction of travel time (seconds/km), delay time (seconds/km), queue length (vehicle) and density time (vehicle/km) indicating congestion reduction and, consequently, improving the urban mobility. The contribution of this paper is one methodology considering the Brazilian context to evaluate the congestion-pricing scheme from experts and residents point of view. Also, the results could support the discussion about the implementation of the congestion charging in Brazilian cities.
MODELLING SYSTEM DYNAMICS TO EVALUATE URBAN WATER SUPPLY MANAGEMENT AND PRODUCTION OF FUTURE SCENARIOS
Authors: Silva Sidnei Pereira , Teixeira Bernardo A. N.
Published: April 2020

This paper analyzes, evaluates and simulates a water catchment and consumption process using a system dynamics model to support water resources management. After creating a theoretical model, real data from São Carlos in Brazil were used. The water availability situation was assessed using the catchment data analysis of the main surface and groundwater sources and the supply data, subdivided into four categories of use. Simulations were carried out by evaluating historical data and further simulations of future scenarios. The average annual consumption was 15.8 million m3. The volume of water catchment in 2017 was more than 35 million m³, and from this total 43.5% of treated water was wasted due to losses. Domestic consumption accounts for more than 80% of the total and greywater reuse can reduce this impact, which means economizing approximately 9 million m3/year. Modeling allows decision makers to analyze the evolution of parameters and the scenario projection.
INNOVATIVE PROPOSITION AND PREDICTION OF URBAN WET WEATHER WASHOFF USING SIMULATED RAINFALL
Authors: Yakubu Mahadi Lawan
Published: April 2020

Washoff is an important process that describes the transportation of pollutants into water ways during the wet weather event. Washoff is a multifarious phenomenon that encapsulated other varied processes ranging from the pollutants deposition during the dry weather period (buildup), to the higher load transport at the beginning of the storm (first flush). Most of the washoff studies were localised to non-tropical regions, where the laxity to wait for dry weather period exist. However, in the tropical regions, the assurance for prolonged dry weather period is near absent, due to frequency of rainfall. This research experimented two new approaches to washoff sampling suitable for tropical regions, alongside with the traditional washoff sampling method. To obtain highly accurate data, the rainfall parameters were confined to selection by employing a very efficient rainfall simulator to gain the washoff data. The washoff of Total suspended solids (TSS) as an indicator of pollution under different simulated rainfalls was established. The result indicated higher mobilisation of the TSS in the first five minutes of rain, and disposes to a steady mobilisation rate after 40 minutes of simulated rain. The washoff percentages for the three road surfaces suggests that the rain intensity plays a more prominent role in washoff prior to the occurrence of first flush, while intense rain mobilises higher amount of TSS within shorter duration of rain. The first flush effect was quantified based on the common definitions of pollutants load-volume relationships of 20/80, 30/80, and 20/40. In all the road surfaces, at least 40% of the pollutants loads were transported in the first 20% of the runoff volumes.
Knowledge of final-year medical students at the University of KwaZulu-Natal about family medicine, and long-term career choices
Authors: Ali R. Omed , Ross A. J. , Nkabinde T. C.
Published: April 2020

Background: While international experience suggests that well-trained primary care physicians improve the quality and cost effectiveness of health care, family medicine (FM) as the discipline of the specialist primary care physician appears to not be an attractive career for medical graduates in South Africa (SA). The aim of this study was to establish final-year medical students’ knowledge about FM and its relevance to the healthcare system, explore their perceptions of the discipline’s relevance, and identify their specialty preference.Methods: This was a descriptive study conducted amongst final-year medical students at the University of KwaZulu-Natal (UKZN) in 2017 at the conclusion of their seven-week FM module. Data were collected using a self-administered questionnaire and results were analysed descriptively.Results: The response rate of completed questionnaires was 80.2% (157/196). Students reported limited exposure to FM in their early undergraduate years and low levels of awareness about essential public health programmes. Students showed good awareness of the six roles of family physicians (FPs), but FM was only the sixth most popular choice for specialisation.Conclusions: In general, students had favourable views concerning FM and its role in the future of healthcare delivery in SA, although their knowledge of essential health programmes was poor. The majority of students had limited interest in pursuing a career in FM. A key recommendation to address these issues is to introduce FM into the curriculum earlier, to cover the key roles of the FP, and provide teaching that highlights the relevance of FM to health system programmes.
The profile of deliberate self-poisoning cases presenting at the emergency department of Pelonomi Regional Hospital, Bloemfontein
Authors: Benedict M. O.A. , Van Loggerenberg C. J. , Steinberg W. J.
Published: April 2020

Background: A common method engaged in suicide is deliberate self-poisoning (DSP). Substances implicated in DSP include prescription and over-the-counter medicines, drugs, household chemicals, agrochemicals and herbal mixtures. Few studies have been conducted on DSP in South Africa, despite its occurrence and high management cost. This study aimed to determine the profile of patients treated for DSP at the emergency department of Pelonomi Regional Hospital, Bloemfontein, between January 2010 and July 2011. A profile of DSP cases will allow practitioners in this region to be aware of the magnitude, causes and common substances used, which will enable them to plan and execute an adequate management protocol to reduce mortality.Methods: This was a retrospective, descriptive study. All DSP patients treated during the 18-month study period were identified from the emergency department register. The clinical files of these patients were reviewed and relevant information captured.Results: In total, 260 DSP patients presented at the emergency department. Files for 212 (81.5%) patients had sufficient information and were included in the study. Two-thirds (66.0%, n = 140) of the patients were female and the highest percentage was in the age group 20–29 years (44.8%, n = 94). Most patients were black (81.1%, n = 150). Most resided in areas associated with low socioeconomic status, including informal settlements, farms and townships. The highest percentage of patients took paracetamol (21.7%, n = 46), while 19.3% (n = 41) ingested household chemicals and 9.9% (n = 21) antiretroviral medication. Only 81 of the 212 patient files had the reason for the DSP captured. Of these, half (49.4%) reported troubled relationships.Conclusion: This study showed that DSP mostly occurred among females in the age group 20–29 years. Most of the patients resided in areas with poor socioeconomic status, and faced relationship, marital, employment and other psychosocioeconomic problems.
An overview of analgesics: opioids, tramadol, and tapentadol (Part 2)
Authors: Van Rensburg R. , Reuter H.
Published: April 2020

Pain can be caused by several mechanisms, and the development of chronic pain (also known as pain chronification) is a complex and often unpredictable process. Opioids, tramadol, and tapentadol provide pharmacological solutions to chronic pain of cancer or non-cancer origins, particularly if central sensitization is present. It may also be indicated for short-term use in acute pain. Despite large studies and meta-analyses of opioids for a variety of pain conditions, the evidence for its clinical effectiveness is still unclear. This is, however, mostly due to significant heterogeneity and bias between studies assessed. The dual analgesic mechanisms of tramadol and tapentadol appear to be effective options for pain relief, with an overall lower incidence of opioid-related adverse effects. Tapentadol has an analgesic effect comparable to the strong opioids, which appears to be mediated by its greater mu opioid receptor activity and more selective noradrenaline reuptake inhibition. Tramadol produces less analgesia than tapentadol, but it is also associated with reduced opioid-related adverse effects and dependence. The opioids and tramadol may be significantly affected by polymorphisms of CYP2D6, while this effect is lessened with tapentadol.
Prevalence and predictors of Implanon uptake in Ugu (Ugu North Sub District) 2016/17
Authors: Moodley Anudha , Mahomed Ozayr
Published: April 2020

Background: The contraceptive implant (Implanon) has been recognised as one of the most effective family planning methods and is a healthier choice for women in Africa due to its efficacy and convenience. Despite the evidence of effectiveness and safety of the implant, the actual uptake for Implanon use in the Ugu district of KwaZulu-Natal is relatively low. The aim of the study was to determine factors associated with Implanon uptake in Ugu North Sub District 2016/17.Methods: An observational cross-sectional study with an analytical component using self-administered questionnaires to collect information from 385 participants using randomised systematic sampling was conducted at family planning clinics at GJ Crookes Hospital and seven surrounding primary health care clinics. The chi-square test and multivariate logistic regression was used to determine associations.Results: Some 16% (n = 60) of the participants utilised Implanon. Despite having the correct knowledge 65.7% (n = 220) were not willing to use Implanon if it were offered. In addition, 55% of participants (n = 177) believed Implanon had more side effects. Parity ( 4 children) was found to be a statistically significant protective factor against (p 0.05) Implanon uptake.Conclusion: Implanon is a highly unattractive method of contraception for women residing in the Ugu North Sub District. Fear of side effects and invasive method of insertion were identified as the major barriers to Implanon use. Education and increased patient awareness are strategies to increase the desirability and uptake of Implanon.
Prevalence and determinants of self-directed referrals amongst patients at hospitals in eThekwini District, KwaZulu-Natal 2015
Authors: Rajman A. , Mahomed O. H.
Published: April 2020

Background: Non-compliance with designated referral pathways has ramifications such as increased patient waiting time, overburdening of higher levels of care and increasing healthcare costs on patients and the healthcare system. The purpose of this study was to assess the determinants of self-directed referrals amongst patients attending hospitals in the eThekwini district of KwaZulu-Natal.Methods: An analytic, cross-sectional study was conducted at the Medical Outpatient Departments across five district hospitals in eThekwini using interviewer-administered questionnaires. Descriptive statistics were used to determine the proportion and the most frequent factors contributing towards patient self-referral. The likelihood of patients to self-refer was tested using chisquare (X2) and a multivariate regression model.Results: There were 315 patients interviewed with 35% (n = 109/315) having self-referred. The majority (51%; 55/107) of selfreferrals were male and were of African race (74%; n = 80/107). Five institutional factors, namely: availability of medication at the pharmacy (98%); quality of care at the facility (93%); waiting time at facility (92%); services provided (90%); and attitude of healthcare workers (87%), were ranked as the main drivers of self-referral. Multivariate logistic regression established a significant positive association between patient self-referral and male gender (OR 1.73; CI 1.04–2.87, p 0.05). Age 39 years (OR 0.96; CI 0.94–0.99, p 0.05); and patient awareness of a referral letter (OR 0.28; CI 0.09–0.86, p 0.05) emerged as protective factor against self-referrals.Conclusion: Males patients tend to bypass the referral pathway whilst younger patients and patients who were aware of a referral letter were less likely to bypass the referral system. In addition to addressing the systemic challenges of waiting times, quality of care and availability of medication, a patient-oriented approach that comprises education, encouragement and increased patient awareness is an important strategy to improve referral pathway compliance.
Determinants of serum 25-hydroxyvitamin D levels in healthy young adults living in the Western Cape, South Africa
Authors: Visser J. , Knight K. , Philips L. , Visser W. , Wallace M. , Nel D. G. , Blaauw R.
Published: April 2020

Background: Vitamin D deficiency is fast emerging as a global pandemic. In South Africa few studies have been conducted to determine the vitamin D status of the healthy population.Methods: This prospective study with an analytical component investigated vitamin D status of healthy undergraduate students at two time points (winter and summer) at Stellenbosch University. Serum 25(OH)D was determined, anthropometric measurements taken and dietary vitamin D intake estimated (food-frequency questionnaire). Skin tone was determined (Fitzpatrick skin type classification), and a skin reflectometry device used to measure dermal melanin content.Results: Results of 242 students indicated a mean serum 25(OH)D of 63.80 ± 41.35 ng/ml and a high prevalence of vitamin D sufficiency (88%). Significantly more females experienced suboptimal vitamin D levels than males (18 vs. 5%; p 0.01). Participants with lighter skin tones had higher levels of 25(OH)D than those with darker skin tones (chi-square = 24.02; p = 0.02). The majority (60.74%) had a normal BMI, although there was no significant relationship between BMI and serum 25 (OH)D (Spearman’s r=–0.11; p = 0.09). Total mean dietary vitamin D intake was 7.99 ± 13.81 mcg, with 87.2% having inadequate intake ( 15 mcg). The relationship between total vitamin D intake and serum 25(OH)D was found to be significant in winter (p 0.001) and summer (p = 0.01). Serum vitamin D levels were significantly higher in the winter phase (p 0.001).Conclusions: A low prevalence of vitamin D deficiency was found amongst healthy young adults, despite low dietary vitamin D intakes. Significant relationships were found between serum 25(OH)D and gender, skin tone and vitamin D intake. Further studies need to be conducted, especially in high-risk groups, before results are applied to the greater South African public.
A ‘look’ into conjunctivitis
Authors: Kathrada F.
Published: April 2020

Conjunctivitis is a common condition characterised by inflammation of the conjunctiva and is the most likely diagnosis in a patient with a red eye and discharge. Acute conjunctivitis is usually a self-limiting condition or one that is easily treated with topical ophthalmic preparations in most cases. Viral conjunctivitis is the most common cause of conjunctivitis followed by bacterial conjunctivitis. Purulent discharge and adherence of the eyelids upon awakening are strong indicators of bacterial conjunctivitis, however other similarities in presentation of conjunctivitis often leads to misdiagnoses. Acute viral conjunctivitis is most commonly caused by adenoviruses and allergic conjunctivitis is usually caused by seasonal pollens. Acute viral conjunctivitis is treated symptomatically while the use of topical antibiotics are useful in limiting the duration of conjunctivitis with a bacterial aetiology. Allergic conjunctivitis is also treated symptomatically with topical antihistamine/mast cell stabiliser preparations. Conjunctivitis secondary to sexually transmitted diseases such as chlamydia or gonorrhoea require systemic antimicrobials in addition to topical treatment.
Mastering your Fellowship
Authors: Von Pressentin K. B. , Naidoo M. , Mabuza L. H. , Mash R. J. , Ras T.
Published: April 2020

The series, “Mastering your Fellowship”, provides examples of the question format encountered in the FCFP(SA) examination. The series aims to help family medicine registrars and their supervisors prepare for this examination. Model answers are available online.
European osteoporosis pharmacological guidelines confirm current recommended treatment whilst answering important management questions
Authors: De Wet H.
Published: April 2020

No abstract available.
Treating complexity in the older adult - the role of the geriatric giants
Authors: Greenstein L. , Abraham A. , Tipping B.
Published: April 2020

As people age, they accumulate medical conditions. Geriatric giants comprise a group of conditions that lead to significant mortality and morbidity and contribute to the complexity in treating geriatric patients. They are common and rarely occur in isolation. The 5 Is of geriatric giants are: iatrogenesis, immobility, instability, incontinence and impaired cognition. Consequences for the patient and their caregivers include loss of functional independence, institutionalisation and caregiver burnout. Primary care practitioners are often the first port of call for geriatric patients in South Africa and by asking a few key questions and performing a thorough examination; these conditions can be recognised early. Whilst there are often limitations to cure, the main aim is to maintain the older adult’s functional independence as much as possible, and by following an organised management approach to each of these conditions, the quality of life of patients can be improved.
Modeling of the potential distribution of Eichhornia crassipes on a global scale: risks and threats to water ecosystems
Authors: Cordeiro Pedro Fialho , Goulart Fernando Figueiredo , Macedo Diego Rodrigues , Campos Mônica De Cássia Souza , Castro Samuel Rodrigues
Published: April 2020

The water hyacinth (Eichhornia crassipes) is listed among the 100 worst invasive plants and was ranked as the 11th worst invasive species in Europe, being a threat to aquatic biodiversity and water-provision. Predicting species distribution is the first step to understanding niche suitability, forecasting the invasion impact and building resilience against this species. In this study, we used a potential distribution model to assess the global risk of water hyacinth invasion by overlapping maps of highly suitable areas for water hyacinth occurrence and areas of biological importance and water scarcity.  The MaxEnt - Maximum Entropy algorithm was used in the construction of the model and included five global bioclimatic layers and one of urbanized areas. Among the variables used, occurrence is mainly explained by urban areas, highlighting the importance of cities as a source or dispersion mechanism of the water hyacinth. Global biodiversity hotspots are predominantly situated in high suitability regions for the species. Ramsar sites and global protected areas are at a lower risk level compared to hotspots; however, future climate change and urban growth scenarios could put these areas at higher risk for invasion. Threats posed by the water hyacinth are possibly more acute in regions suffering from current or chronic drought. The results suggest that niche models that do not consider anthropic variables may be underestimating potential distribution of invasive species. Furthermore, the ecological plasticity of the water hyacinth and its close association with cities increase the concern about the impact of this species on the environment and on water security.
Enriching Systems Theory Based Cyber-Security and Safety Analysis Using Stakeholder Value Networks
Authors: Sidhu Amardeep , Moulton Allen
Published: April 2020

System-theoretic process analysis for security (STPA-Sec) is a powerful safety and security analysis method that focuses on unsafe and unsecure interactions between subsystems rather than component failure and its resulting chain-of-event failure modes. The first step of STPA-Sec requires the analyst to identify the system boundary and list the system losses and hazards. Current approach to performing this first and critical step of STPA-Sec requires interviewing the stakeholders and could potentially result in a narrow focus due to stakeholder’s mental model and resulting answers to questions. In some cases, stakeholders are not available for interviews and we risk influencing the system loss identification by the mental model of the analyst. We believe these two potential issues in the STPA-Sec analysis: narrow focus and missing access to stakeholder, can be address by factoring additional system information through stakeholder analysis. To illustrate the benefit of this approach a mining system is considered. Stakeholders in the mining system are identified and then classified based on the role that they play in the expected emergent behavior of the system. Stakeholder needs are identified and ranked. A stakeholder value network (map) is created with stakeholder as nodes and value exchanges between them representing the connections. A ranked list of value exchanges is created based on the impact of cybersecurity on the stakeholder map. System level-losses are identified from high impact value exchanges, which can then be fed into the step 1 of STPA-Sec analysis. A system level goal statement, derived from the stakeholder analysis, is used as a guiding statement and an aid in drawing a boundary around the system.
Artificial Neural Network Based Predictive Approach in Vehicle Thermal Systems Applications
Authors: Mirzabeygi Pooya , Natarajan Shankar
Published: April 2020

In the automotive industry, there is an abundance of test data collected at different stages of a vehicle’s development. Heavy reliance on testing can lead to a significant increase in a vehicle program’s design costs and further delay in the development timing as vehicle instrumentation and testing is costly and time-consuming. This paper focuses on a novel approach using the Artificial Neural Network (ANN). ANNs are computing systems inspired by the brain’s biological networks that can learn by considering examples. The “trained” network can then be used to predict the system’s performance in a reliable and efficient manner. This is particularly useful in the automotive industry as there exists a considerable amount of test data in the system, sub-system or component level that can be used to train the ANN. The trained ANN can then be used as an alternative for performance prediction and reduce the reliance on additional physical testing. The study focuses on thermal and climate control systems and the application of ANNs to predict the thermal performance. It is shown that ANNs are very robust at predicting a system’s thermal performance after being trained on system and bench level test data, and can potentially reduce the need to conduct additional testing.

Furthermore, there are certain variables of thermal systems such as vehicle cabin humidity and HVAC fresh air purge that are very difficult to capture using physics based transient simulation at vehicle level. ANNs modeling methodology is developed and shown to be able to reliably predict these variables; the methodology is then implemented in a 1D numerical model.
Development of Cooling Fan Model and Heat Exchange Model of Condenser to Predict the Cooling and the Heat Resistance Performance of Vehicle
Authors: Fukuchi Yuichi , Yoshitake Kunihiko , Yokota Kazutaka
Published: April 2020

The cooling performance and the heat resistance performance of commercial vehicle are balanced with aerodynamic performance, output power of powertrain, styling, cost and many other parameters. Therefore, it is desired to predict the cooling performance and the heat resistance performance with high accuracy at the early stage of development. Among the three basic forms of heat transfer (conduction, convection and radiation), solving thermal conduction accurately is difficult, because modeling of “correct shape” and setting of coefficient of thermal conductivity for each material need many of time and efforts at the early stage of development. Correct shape means that each part should be attached correctly to generate the solid mesh with high quality. Therefore, it is more efficient and realistic method to predict the air temperature distribution around the rubber/resin part instead of using the surface temperature at the preliminary design stage. The air temperature distribution in the engine compartment is dominated by the flow distribution from fans, the heat rejected by heat exchangers, AC-generator and the convecting heat by surface temperature of parts. In the case of steady middle/high vehicle speed modes, thermal convection has larger effects on the air temperature distribution. To predict these phenomena with high accuracy, the fan model and condenser model are developed. The fan model provides the accurate P-Q performance based on a specification and the flow distribution based on the LES results of the sliding mesh method with low computational cost. The heat rejection by the condenser is concentrated around the inlet tube of core. To reproduce this distribution, the phase change of refrigerant is solved in the condenser model. The accuracy of these models is confirmed by using component experiments and vehicle measurements. Accuracy of heat-exchanger coolant temperature is within 2K and air temperature in the engine compartment is 5K respectively.
Elastomeric Component Fatigue Analysis: Rubber Fatigue Prediction and Correlation Comparing Crack Initiation and Crack Growth Methodologies
Authors: Zarrin-Ghalami Touhid , Datta Sandip , Bodombo Keinti Robert , Chandrashekar Ravish
Published: April 2020

Many elastomeric components in automotive industry applications are subjected to dynamic service loads. Fatigue must be a consideration in the design of these components.

The two approaches in rubber fatigue analysis discussed in this study are the conventional crack initiation approach, based on continuum mechanics parameters versus life, and the crack growth approach, based on fracture mechanics parameters. These methodologies are demonstrated for a passenger vehicle engine mount here. Temperature effects are not considered since testing was performed at ambient room temperature and with a low frequency, typically less than 5 Hz.

The promising methodology for fatigue life prediction, discussed in this paper, is a critical plane approach based on crack energy density. Rainflow cycle counting method and Miner’s damage rule are used for load cycle characterization and damage accumulation respectively. A fracture mechanics approach is implemented based on specimen crack growth data.

This methodology is validated with component testing under constant amplitude experiments. Results are investigated through analysis of critical stress locations hot spots, life values, and strain states. Comparative results are presented. Numerical results show reasonable correlation with experimental data.
The Effects of Thick Thermal Barrier Coatings on Low-Temperature Combustion
Authors: Yan Ziming , Gainey Brian , Gohn James , Hariharan Deivanayagam , Saputo John , Schmidt Carl , Caliari Felipe , Sampath Sanjay , Lawler Benjamin
Published: April 2020

An experimental study was conducted on a Ricardo Hydra single-cylinder light-duty diesel research engine. Start of Injection (SOI) timing sweeps from -350 deg aTDC to -210 deg aTDC were performed on a total number of five pistons including two baseline metal pistons and three coated pistons to investigate the effects of thick thermal barrier coatings (TBCs) on the efficiency and emissions of low-temperature combustion (LTC). A fuel with a high latent heat of vaporization, wet ethanol, was chosen to eliminate the undesired effects of thick TBCs on volumetric efficiency. Additionally, the higher surface temperatures of the TBCs can be used to help vaporize the high heat of vaporization fuel and avoid excessive wall wetting. A specialized injector with a 60° included angle was used to target the fuel spray at the surface of the coated piston. Throughout the experiments, the equivalence ratio, ϕ, was maintained constant at 0.4; the combustion phasing was consistently matched at 6.8 ± 0.4 deg aTDC. It can be concluded that the thick TBC cases achieved 1 to 2 percentage points improvement in combustion efficiency, and generally, a ~2 percentage points increase in indicated engine efficiency. It is also noticed that applying a dense top sealing layer to the TBC further improves the UHC emissions compared to the TBC coated piston with an unsealed surface. From the heat release analysis, it can be concluded that the TBCs have no significant impact on the heat release process and knock intensity while matching the combustion phasing; however, it reduces the intake temperature requirement by up to 20 K. The exhaust gas temperatures were expected to increase for the TBC cases, but the expected increase in exhaust temperature was not conclusive from the results observed in this study.
Optimization of Lambda across the Engine Map for the Purpose of Maximizing Thermal Efficiency of a Jet Ignition Engine
Authors: Peters Nathan , Krishna Pothuraju Subramanyam Sai , Bunce Michael , Blaxill Hugh , Cooper Adrian
Published: April 2020

Progressively more stringent efficiency and emissions regulations for internal combustion engines have led to growing interest in advanced combustion concepts for spark ignition engines. MAHLE Jet Ignition® (MJI) is one such concept which enables ultra-lean (λ > ~1.6) combustion via air dilution. This pre-chamber-based combustion system has demonstrated highly efficient lean operation, producing efficiencies competitive with those of advanced compression ignition concepts. Compared to a traditional spark ignition engine, the additional degrees of freedom associated with Jet Ignition introduce further complexity when optimizing the system for peak efficiency throughout the engine map. The relationship between operating condition and the lambda at which peak efficiency occurs for a Jet Ignition engine has been presented in prior work by the authors. This paper further explores this complex relationship, introducing new interdependencies which must be considered in order to improve brake thermal efficiency (BTE).

Experimental data is obtained from a 1.5L 3-cylinder gasoline-fueled Jet Ignition engine. An engine map of BTE is presented. An analysis at several key points throughout the engine map shows how certain parameters are adjusted to optimize BTE, providing a peak value >42%. Insight into the factors affecting efficiency is provided through parameter sweeps of pre-chamber fuel and analysis of high-speed pressure measured in both the pre-chamber and the main combustion chamber. The impact of precise fuel metering on BTE and combustion stability is highlighted. Finally, an analysis of trends in burn duration segments, pre-chamber combustion metrics, and cycle-by-cycle variation in these parameters qualifies the challenges associated with accurate prediction of lean stability limits in a jet ignition engine operating in the ultra-lean region, as well as the opportunities for further efficiency improvement through manipulation of in-pre-chamber conditions.
Review of Vehicle Engine Efficiency and Emissions
Authors: Joshi Ameya
Published: April 2020

This review covers some of the major advances pertaining to reducing tailpipe emissions of greenhouse gases and criteria pollutants. Discussed are both new and upcoming regulations, and technologies being developed for improving engines and after-treatment systems.

There is clearly a focus on reducing greenhouse gas emissions in major countries, implemented through ambitious CO2 and electrification targets. Several mature IC engine (ICE) technologies are reviewed which promise to deliver double digit reductions in CO2 emissions. We cover some of these in detail, including gasoline compression ignition, pre-chamber combustion, water injection, and cylinder deactivation. Electrification of the powertrain and synergistic gains with advanced engine technologies are examined. The case is made for the need for cradle-to-grave analyses when evaluating various powertrain choices, and highlight the role hybrids can play in achieving significant and immediate CO2 reductions. For the first time, also briefly discussed are the role of advanced fuels and their potential for improving emissions.

On criteria pollutants, the focus remains on reducing NOx and particulates. California is leading the charge on an omnibus rulemaking for heavy-duty trucks, targeting a 90% reduction in NOx emissions, and elements of the proposal are discussed. The challenge is to achieve this reduction without affecting CO2 emissions. Various studies are underway and technological pathways are being proposed and we cover the leading concepts. These include close-coupled SCR with dual dosing, innovative solutions for low temperature urea dosing, cylinder deactivation, advanced combustion techniques, electrification and natural gas engines.

For light-duty vehicles, real-world driving emission (RDE) norms seem to be addressing the discrepancy between lab and on-road NOx emissions, and the relevant data are discussed. Discussions are ongoing for post Euro-6 light duty regulations, and both the possible regulatory changes as well as after-treatment system developments are covered. A major focus will remain on reducing cold-start emissions and studies for both diesel and gasoline engines are reviewed.

Particle number standards in Europe and China have enforced gasoline particulate filters (GPFs) in those markets, and improvements in that technology are summarized. Filtration efficiency requirements are expected to increase with further tightening of regulations, and GPFs are also expected to be required for port fuel injected vehicles in the future.
Catalysts for Post Euro 6 Plug-In Hybrid Electric Vehicles
Authors: Zhang Jun , Richter Joerg-Michael , Kaczmarek Christoph
Published: April 2020

Due to benefits from the use of electric power, Hybrid Electric Vehicles (HEVs) and Plug-in Hybrid Electric Vehicles (PHEVs) are regarded to be superior over conventional Internal Combustion Engine (ICE) only vehicles in fuel economy and emissions. However, recent studies find out that this is not always true. On certain conditions, hybrid vehicles can be even more polluted.

In order to identify these challenges and develop catalysts to meet more stringent emission requirement in the future, e.g. Euro 7, for hybrid application, as a part of our xHEV project, this study includes exclusively extensive investigation on a latest Euro 6d temp Parallel PHEV.

Key parameters including driving modes, Status of Charge (SOC), were investigated under World harmonized Light vehicles Test Cycle (WLTC) and Real Driving Emission (RDE) tests on the chassis dyno, and their influences on engine behaviours and emissions were studied, in comparison with emissions from the ICE only counterpart under the same legislation. Besides regulated emissions, secondary emissions and Particle Number (PN) and size distribution, including those under 23 nm were also analysed. It was found out cold start and hot restart emission control were critical for PHEV in order to fulfil our assumed Euro 7 legislation. Particle emissions were worst when the engine kicked in during the acceleration in the high-speed phase, i.e. cold catalyst under high space velocity exhaust and gas emissions were worst in the “Battery Control” mode when the ICE had to propel the vehicle while charging the battery.

Two new and improved aftertreatment systems were then proposed and evaluated that addressed the hybrid emission challenges without modifying the current vehicle calibration: The first was designed for overall best emission performance and the second was designed to meet the emission target at a lower cost. Both can reduce the hybrid vehicle emissions further and have the potential to meet the Euro 7 requirements for all gaseous and PN requirements.
Use of Nitric Acid to Control the NO
2
:NO
X
Ratio within the Exhaust Composition Transient Operation Laboratory Exhaust Stream
Authors: Henderson Robert , Hartley Ryan , Henry Cary
Published: April 2020

The Exhaust Composition Transient Operation LaboratoryTM (ECTO-LabTM) is a burner system developed at Southwest Research Institute (SwRI) for simulation of IC engine exhaust. The current system design requires metering and combustion of nitromethane in conjunction with the primary fuel source as the means of NOX generation. While this method affords highly tunable NOX concentrations even over transient cycles, no method is currently in place for dictating the speciation of nitric oxide (NO) and nitrogen dioxide (NO2) that constitute the NOX mixture. NOX generated through combustion of nitromethane is dominated by NO, and generally results in an NO2:NOX ratio of < 5 %. Generation of any appreciable quantities of NO2 is therefore dependent on an oxidation catalyst to oxidize a fraction of the NO to NO2. Presented within this manuscript is a method for precise control of the NO2:NOX ratio within the ECTO-Lab exhaust stream by using nitric acid as the NOX precursor molecule in lieu of nitromethane. While decomposition of nitromethane generates NO as the dominate component of the NOX mixture, nitric acid decomposition produces primarily NO2. The method described herein entails metering a 70 % aqueous nitric acid solution into an upstream decomposition furnace prior to injection into the ECTO-lab exhaust. By use of nitric acid as the precursor NOX molecule, and precisely controlling the conditions at which decomposition of nitric acid occurs, the ECTO-Lab may be used as a platform to evaluate catalytic activity in absence of a diesel oxidation DOC, coming one step closer to a full engine simulator. In this study, concentrations of NO2 well in excess of the theoretical thermodynamic equilibrium value were achieved by specifying the residence time and temperature of the nitric acid within the decomposition oven.
A New Approach to Understanding Planetary Gear Train Efficiency and Powerflow
Authors: Attibele Pradeep
Published: April 2020

Understanding planetary gear efficiency is more involved than understanding efficiency of external gears because of the recirculating power that is inherent in planetary gear operation. There have been several publications going back several decades on this topic. However, many of these publications are mathematical in their approach and tend to be overlooked by practicing engineers. This paper brings a new, more visual and more intuitive approach to the problem. It uses lever diagrams, which have been a standard tool in the transmission engineer’s arsenal for almost four decades, to visualize the power flow and develop analytical expressions for the efficiency of simple and compound planetary gears. It then extends the approach to more complex gear trains.
Dynamic Modeling of an Interior Permanent Magnet Machine with Space-Vector-Modulation-Based Voltage Source Inverter
Authors: Li Yihui , Howey Brock , Liang Jianbin , Sayed Ehab , Qazalbash Arfakhshand Ali , Kasprzak Michael , Al-Ani Dhafar , Emadi Ali , Bilgin Berker
Published: April 2020

This paper presents a dynamic model for an interior permanent magnet (IPM) machine with a space-vector-modulation-based voltage source inverter. The dynamic model considers spatial harmonics, cross-coupling and magnetic saturation. In order to include the nonlinear electromagnetic characteristics of the IPM machine, the dynamic model is built based on the current-flux look-up tables obtained from finite element analysis (FEA). The model is co-simulated with the drive system, which considers the effects of the modulation technique and the switching frequency. The dynamic performance of a 60/8 IPM machine is analyzed using the dynamic model at different operating conditions and then validated with the torque waveforms obtained from FEA. The results show that dynamic performance can be analyzed accurately and more quickly using the dynamic model presented in this paper.
Noise, Vibration, and Harshness Considerations for Autonomous Vehicle Perception Equipment
Authors: Gates Charlie , Bastiaan Jennifer , Jadhav Prashant , Baqersad Javad , Peters Diane
Published: April 2020

Automakers looking to remake their traditional vehicle line-up into autonomous vehicles, Noise, Vibration, and Harshness (NVH) considerations for autonomous vehicles are soon to follow. While traditional NVH considerations still must be applied to carry-over systems, additional components are required for an autonomous vehicle to operate. These additional components needed for autonomy also require NVH analysis and optimization. Autonomous vehicles rely on a suite of sensors, including Light Detection and Ranging (LiDAR) and cameras placed at optimal points on the vehicle for maximum coverage and utilization. In this study, the NVH considerations of autonomous vehicles are examined, focusing on the additional perception equipment installed in autonomous vehicles. In particular, the nature of modifications to existing vehicles to increase the level of autonomy, and the associated NVH characteristics of these alterations, are reviewed with suggestions for future application to autonomous vehicles. A case study in the design of an original autonomous vehicle based on a production all-electric car, a 2017 Chevrolet Bolt, is outlined. A detailed description of the NVH design and verification process for this vehicle is provided, with results giving insight into the NVH design of autonomous vehicles and the challenges that are created.
Pre-design Investigation of Resonant Frequency Effects on Gas Exchange Efficiencies of a One-kW Natural-Gas Linear Engine Alternator
Authors: Zamani Meymian Nima , Darzi Mahdi , Johnson Derek , Famouri Parviz
Published: April 2020

Performance of a natural gas two-stroke engine incorporated in a 1-kW free-piston oscillating Linear Engine Alternator (LEA) - a household electricity generator - was investigated under different resonant frequencies for pre-design phase purposes. To increase the robustness, power density, and thermal efficiencies, the crank mechanism in free-piston LEA is omitted and all moving parts of the generator operate at a fixed resonant frequency. Flexure springs are the main source of the LEA’s stiffness and the mass-spring dynamics dominates the engine’s speed. The trade-off between the engine’s performance, mass-spring system limits, and power and efficiency targets versus the LEA speed is very crucial and demands a careful investigation specifically at the concept design stages to find the optimum design parameters and operating conditions. CFD modeling was performed to analyze the effects of resonant frequency on the engine’s gas exchange behavior. To take combustion effects into account, a semi-empirical method was employed to obtain the initial and boundary conditions during the gas exchange from experiments and imported into CFD simulation. The numerical results of the gas exchange were validated at the engine speed of 5400 RPM with the experimental results. The semi-empirical method eliminated the complicated combustion simulation and significantly reduced the computational time and well-matched with experiments within 1 % error. Results showed enhanced trapping efficiency of 7.1% per 1000 RPM, and reduced scavenging efficiencies of 5.5% per 1000 RPM as speed engine’s speed increased. Comparison of the trapping and scavenging efficiencies showed an improved fuel/power efficiency equal to about 1.45 % per each 15 Hz increase in the LEA resonant frequency.