bluuebunny/crossref_metadata_2025_split huggingface dataset:
Combined Smoothed Particle Hydrodynamics - Ray Tracing Method for Simulations of Keyhole Formation in Laser Melting of Bulk and Powder Metal Targets
Authors: Shah Deepak , Volkov Alexey N. 
Published: January 2020

Abstract
A robust numerical method based on smoothed particle hydrodynamics (SPH) is developed for simulations of laser melting of metals and melt pool dynamics. The method accounts for all major interfacial effects, including surface tension, Marangoni stress, recoil force due to vapor pressure, as well as mass removal and cooling due to evaporation. The developed SPH method is combined with a classical ray tracing method for prediction of propagation and absorption of laser radiation. The optimum values of artificial viscosity coefficient and number of SPH particles for developed method are found in preliminary simulations of the keyhole drilling by a continuous wave laser. The method is then used to study melt expulsion from a keyhole during laser drilling in two-dimensional simulations. It is also shown that the method can be used to predict the keyhole formation and material binding in selective laser melting of metal powders.
Energy and Economic Analysis of a Novel Hybrid Photovoltaic-Thermoelectric System for Building Cooling Applications
Authors: Seyednezhad Mohadeseh , Najafi Hamidreza 
Published: January 2020

Abstract
An energy and economic analysis of a novel hybrid photovoltaic-thermoelectric (PV-TEC) system for building cooling applications is presented. It is considered that the roof is constructed from building integrated photovoltaic panels (BIPV) and thermoelectric (TEC) cooling modules are installed on top of the ceiling. The TEC modules are supplied by the PV panels, reducing the ceiling temperature and therefore maintaining a comfortable temperature for the occupants. A mathematical model is developed in MATLAB to simulate the performance of the hybrid PV-TEC system. A building energy model is also developed in eQuest to simulate the performance of a case study office building in Melbourne, FL. The hourly cooling demands are evaluated from the building model, and the PV-TEC system is sized to satisfy the cooling loads accordingly. The total annual energy consumption of the PV-TEC system is then calculated for various operating conditions according to the given characteristics for the selected TEC module and the required number of PV panels to supply the thermoelectric system with adequate electricity is evaluated. The cost of the system and associated savings are determined and discussed in detail. The results show that the proposed system is capable of maintaining the set point temperature for occupants’ comfort. The initial estimated cost of the hybrid PV-TEC system is found significantly higher than conventional air conditioning systems. However, the attractive features of the proposed system including high controllability and maintenance free operation as well as no need to refrigerant or major moving part are some of the aspects that are promising for building cooling applications.
Designing a Robotic Mechanism for Cleaning Trench Drains
Authors: Kaushik Adithya , Dong Janet , Gao Ce , Elzarka Hazem 
Published: January 2020

Abstract
This paper discusses the testing of a robotic mechanism for cleaning trench drains. The robot runs and operates inside the drain and cleans it without interfering with the surrounding traffic or the drain itself. The robot combines a three-step cleaning process to achieve maximum efficiency in cleaning of the drains. This three-step process includes breaking the dirt down inside the drain, sucking the dirt out of the drain, and transporting it to a collection unit. There is a drive system to move the robot inside the drain. The drive is bidirectional to control the robot motion as required. The robot also has a suction tube and cutting assembly with cutting arms to better facilitate the suction. The cutting arms have metal brushes installed, the rotation of which loosen the debris and push it towards the drain surface. Over the course of developing this robot, two prototypes were designed and built. All aspects relating to the fabrication and testing of the robot prototypes will be discussed in this paper.
Effect of Bolted Joints on Shock Propagation Across Structures Under Medium Impact Loading
Authors: Shojaei Pouya , Trabia Mohamed , O’Toole Brendan 
Published: January 2020

Abstract
A bolted joint is one of the most common fastening techniques. While the behavior of bolted joints under static or quasi-static conditions is well documented, their behavior under shock/impact loading is not well-understood. In many applications, where a bolted joint connects a sensitive component to the rest of a structure, it is important to interpret shock propagation through the bolted joints. This problem is further complicated owing to the fact that a bolted joint exhibits multiple types of nonlinearities, due to the interaction between the bolts and clamped parts, thread friction between the shank and nut, pre-tension, damping characteristics, and interference with the hole.
This study was focused on developing computational techniques for understanding shock propagation through a bolted joint. As a case study, the behavior of a bolted joint within a two-component cylindrical structure subjected to impact loading was considered. A finite element (FE) model of the fixture was developed. Two different approaches were considered. The first one modeled the bolt assembly as one part. The second model had the bolt and nut as separate parts. In this model, the tie contact between the bolt shank and the nut was defined using a shear failure criterion. Both models included bolt pre-tension. The two models were compared based on energy balance, acceleration signal, and displacement at the base of the fixture. The results indicated that the model with the separate bolt and nut resulted in a more realistic performance.
Damage Classification of Composites Using Machine Learning
Authors: Dabetwar Shweta , Ekwaro-Osire Stephen , Dias João Paulo 
Published: January 2020

Abstract
Composite materials have tremendous and ever-increasing applications in complex engineering systems; thus, it is important to develop non-destructive and efficient condition monitoring methods to improve damage prediction, thereby avoiding catastrophic failures and reducing standby time. Nondestructive condition monitoring techniques when combined with machine learning applications can contribute towards the stated improvements. Thus, the research question taken into consideration for this paper is “Can machine learning techniques provide efficient damage classification of composite materials to improve condition monitoring using features extracted from acousto-ultrasonic measurements?” In order to answer this question, acoustic-ultrasonic signals in Carbon Fiber Reinforced Polymer (CFRP) composites for distinct damage levels were taken from NASA Ames prognostics data repository. Statistical condition indicators of the signals were used as features to train and test four traditional machine learning algorithms such as K-nearest neighbors, support vector machine, Decision Tree and Random Forest, and their performance was compared and discussed. Results showed higher accuracy for Random Forest with a strong dependency on the feature extraction/selection techniques employed. By combining data analysis from acoustic-ultrasonic measurements in composite materials with machine learning tools, this work contributes to the development of intelligent damage classification algorithms that can be applied to advanced online diagnostics and health management strategies of composite materials, operating under more complex working conditions.
Integration and Optimization of Supercritical Carbon Dioxide Brayton Cycle and Goswami Cycle
Authors: Guillen Diego , Leveni Martina , Manfrida Giampaolo , Sanjuan Marco 
Published: January 2020

Abstract
Utilization of waste heat from an energy conversion process is a key step in improving the overall energy system conversion efficiency and reducing the cost of energy. Since a supercritical CO2 Brayton power cycle is being considered as an important cycle for the conversion of solar energy to power, we propose to utilize the heat rejected from this cycle to feed a bottoming thermodynamic cycle. Goswami cycle can utilize the low temperature waste heat to produce both power and cooling in the same loop. Moreover, refrigeration and space cooling are usually more expensive than heating in most applications. This paper describes the modeling and simulation results of the combined Brayton and Goswami cycles. The mass flow ratio of the two cycles is determined by the heat exchanger effectiveness method, constraining the minimum allowed temperature difference. The operating parameters that yield the best performance in terms of overall cycle efficiency, net work, and cooling outputs were found through the optimization of a numerical model developed in MATLAB. The cooling production in the Goswami cycle is maximized at the expense of the net work in order to produce the maximum refrigeration output. A maximum combined efficiency for power and cooling generation above 45% can be found when the inlet temperature at the Brayton cycle is set at 700 °C.
Centrifugal Compressor Performance Prediction Using Gaussian Process Regression and Artificial Neural Networks
Authors: Cutrina Vilalta Pau , Wan Hui , S. Patnaik Soumya 
Published: January 2020

Abstract
In this paper, we use various regression models and Artificial Neural Network (ANN) to predict the centrifugal compressor performance map. Particularly, we study the accuracy and efficiency of Gaussian Process Regression (GPR) and Artificial Neural Networks in modelling the pressure ratio, given the mass flow rate and rotational speed of a centrifugal compressor. Preliminary results show that both GPR and ANN can predict the compressor performance map well, for both interpolation and extrapolation. We also study the data augmentation and data minimzation effects using the GPR. Due to the inherent pressure ratio data distribution in mass-flow-rate and rotational-speed space, data augmentation in the rotational speed is more effective to improve the ANN performance than the mass flow rate data augmentation.
Optimization of Heat Treatment Aging Process Parameters for 7050 and 7075 Aluminum Alloys
Authors: James Sagil , Roy Ambarneil 
Published: January 2020

Abstract
Among the different commercially used Al alloys, the 7000 series offers some of the highest mechanical properties making them the material of choice for several critical engineering applications. These Al alloys often required to undergo a heat treatment process to enhance its mechanical properties to the desired levels. This process, known as Heat Treatment (HT) is a multi-step procedure which involves heating of the alloy to a set temperature followed by rapid quenching in a solution consisting of either water or glycol. Finally, the quenched alloys are subject to aging at near room or elevated temperatures which results in achieving the desired temper that has the mechanical and metallurgical properties that are needed for the application. Achieving the desired results in the HT process is extremely challenging and time-consuming. The most common industry practice is to rely on both metallurgical and manufacturing experts and resort to the costly trial-and-error approach which results in lower productivity, poor quality, and a massive waste of time, money, and energy. While there exist standard industrial specifications on the range of values to be used for heat temperatures, age soak times, and quench rates, the range is often too broad to be of any practical significance.
The operators have to resort to a stop/restart approach while intermittently evaluating and testing the mechanical properties until the desired level is reached. Currently, there is a growing need to know the optimal operating parameters for the HT process. This study uses commercially available software to optimize the results for the heat treatment aging parameters using mechanical testing data such as hardness, yield strength, and electrical conductivity. Aging is the final step, and most of the time the longest step, in the HT process and therefore it is vital that the values such as age soak time are dialed in as much as possible to achieve the desired properties as soon as possible without wasting time, effort and energy.
Effect of External Magnetic Field on the Microstructure of 316L Stainless Steel Fabricated by Directed Energy Deposition
Authors: Wang Jin , Wang Yachao , Shi Jing , Su Yutai 
Published: January 2020

Abstract
Directed energy deposition (DED) is a major additive manufacturing (AM) process, which employs high energy beams as the heat source to melt and deposit metal powder in a layer-by-layer fashion such that complex components can be manufactured. In this study, a magnetic-field-assisted DED method is applied to control the microstructure and element distribution in the deposited materials. For this purpose, to control the microstructure of DED-built 316L stainless steel, a horizontal magnetic field is introduced during the DED process at different levels of magnetic field intensities (i.e., 0T, 1.0T and 1.8T). Scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDS) are used to characterize the microstructure of components obtained with different magnetic field strengths. The results show that the microstructure of deposited materials is significantly affected by the external magnetic field. Also, the result of interdendritic microsegregation pattern presents a transformation from continuous morphology to discrete morphology because of the applied magnetic field. Along with the increasing horizontal magnetic field intensity, nickel and chromium content are changed significantly in austenite and ferrite.
Impact of adult weight management interventions on mental health: a systematic review and meta-analysis protocol
Authors: Jones Rebecca A , Lawlor Emma R , Griffin Simon J , van Sluijs Esther M F , Ahern Amy L 
Published: January 2020

IntroductionThe effects of interventions targeting weight loss on physical health are well described, yet the evidence for mental health is less clear. It is essential to better understand the impact of weight management interventions on mental health to optimise care and minimise risk of harm. We will assess the effect of behavioural weight management interventions on mental health in adults with overweight and obesity.Methods and analysisThe systematic review will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance. We will include behavioural weight management interventions with a diet and/or physical activity component focusing on weight loss for adults with a body mass index ≥25 kg/m2. Randomised controlled trials (RCTs) and cluster RCTs will be the only eligible study designs. Outcomes of interest will be related to mental health. The following databases were searched from inception to 07 May 2019: MEDLINE, Embase, Cochrane database (CENTRAL), PsycINFO, ASSIA, AMED and CINAHL. The search strategy was based on four concepts: (1) adults, defined as ≥18 years, with overweight/obesity, defined as BMI ≥25kg/m², (2) weight management interventions, (3) mental health outcomes and (4) study design. The search was restricted to English-language published papers, with no other restrictions applied. Two stage screening for eligibility will be completed by two independent reviewers, with two independent reviewers completing data extraction and risk of bias assessment. Data permitting, a random-effects meta-analysis of outcomes, subgroup analyses and meta-regression will be conducted. If not appropriate, narrative synthesis and ‘levels of evidence’ assessment will be completed.Ethics and disseminationEthical approval is not required as primary data will not be collected. The completed systematic review will be disseminated in a peer-reviewed journal, at conferences and contribute towards the lead author’s PhD thesis.PROSPERO registration numberCRD42019131659.
Emergency healthcare needs in the Lavender Hill suburb of Cape Town, South Africa: a cross-sectional, community-based household survey
Authors: Hodkinson Peter W , Pigoga Jennifer Lee , Wallis Lee 
Published: January 2020

ObjectiveEmergency care is a key component of healthcare systems, but little is known about its real impact on communities. This study evaluated access, utilisation and barriers to healthcare, and specifically emergency care, in the low socioeconomic Cape Town suburb of Lavender Hill.DesignA cross-sectional, community-based household survey.SettingLavender Hill suburb in the Cape Flats of Cape Town, South Africa.ParticipantsTwo-stage cluster sampling was used to identify approximately 13 households in each of 46 clusters, for a total of 608 households. A senior householder responded on behalf of each household surveyed.Primary outcome measuresAccess to, utilisation of and unmet needs related to healthcare at large and emergency care.ResultsIn August 2018, 608 households were surveyed, encompassing 2754 individuals, with a response rate of 96.4%. Almost a quarter of respondents (n=663, 24.1%) used the healthcare system within the last year. Female gender, advancing age, lower levels of education, recipients of disability grants, smaller household sizes and living in formal dwellings were factors associated with increased risk of unmet healthcare and emergency care needs. Only a small proportion of respondents (n=39, 1.4%) reported having unmet emergency healthcare needs, with wait times at facilities (n=9, 23.1%), emergency medical service delays (n=7, 17.9%) and personal safety (n=6, 15.4%) being prominent. There was a high prevalence of chronic medical conditions (hypertension, diabetes and dyslipidaemias) and recent deaths predominantly from trauma and malignancy.ConclusionThe emergency healthcare needs of the community appear to be well catered for, although community expectations may not be high and many barriers exist, particularly in accessing emergency care—be it via ambulance services or at healthcare facilities—and caring for chronic diseases in the ageing population. The Lavender Hill community could benefit from programmes addressing chronic disease management and emergency care delivery within the community.
Quality improvement of intravenous to oral medication conversion using Lean Six Sigma methodologies
Authors: Downen Julie , Jaeger Cassie 
Published: January 2020

IntroductionLack of medication conversion from intravenous to oral contributes to increased risk of infection, delayed discharges and higher medication costs. At our institution, intravenous to oral medication conversion rate was 76% with missed opportunity for conversion of 37%. The goal of the project was to reduce the percent of missed opportunities for intravenous to oral conversion for applicable medications.MethodsA pharmacy-driven intravenous to oral policy and procedure was implemented. To identify potential opportunities, a patient worklist of applicable intravenous to oral medications was created for pharmacy review in real time. An intravenous to oral conversion order was implemented in the computerised provider order entry. ‘Convert to oral’ was added as an option in the electronic medication request and highlighted reminders were added to the electronic medication administration record for eligible medications.ResultsAfter improvements, the missed opportunity rate for intravenous to oral conversion decreased from 37% (19/51) to 21% (24/113) (p=0.04, two-proportion test), a 43% improvement. The trend in intravenous to oral conversion rate increased from 76% (39/51) to 85% (171/201) and severity adjusted length of stay was reduced from 8.1 days to 6.4 days post improvements (p<0.001, t-test).
Changes in the prevalence and profile of users of contraception in Britain 2000–2010: evidence from two National Surveys of Sexual Attitudes and Lifestyles
Authors: French Rebecca S , Gibson Lorna , Geary Rebecca , Glasier Anna , Wellings Kaye 
Published: January 2020

AimTo describe prevalence and trends in contraceptive method use in Britain through a comparison of the second and third National Surveys of Sexual Attitudes and Lifestyles (Natsal-2 and Natsal-3).MethodsCross-sectional probability sample surveys. General population sample of women aged 16–44 years, resident in Britain, with ever-experience of vaginal sex and, for analysis by sociodemographic characteristics, vaginal sex in the last year. Main outcome measure was current contraceptive method use (‘usual these days’), categorised by effectiveness.ResultsPrevalence of current contraceptive use among women who had ever had vaginal sex declined between Natsal-2 and Natsal-3, 83.5% (95% CI 82.4 to 84.5) and 76.4% (95% CI 75.0 to 77.7), respectively. The condom and oral contraceptive pill remain the most commonly used methods. One in five women reported use of a most effective method. While no difference was found between surveys in use of most effective methods, a decline in sterilisation use was compensated by an increase in long-acting reversible contraceptive (LARC) use. Increased LARC use was particularly evident among under-25s compared with women aged 40–44 years (OR 11.35, 95% CI 3.23 to 39.87) and a decline was observed among those with two or more children relative to those with none (OR 0.21, 95% CI 0.13 to 0.35).ConclusionsStrategies to improve access to LARC methods have been particularly successful in increasing uptake among young people in the first decade of the 21st century. Whether this trajectory is maintained given changing sociodemographic characteristics and more recent financial cuts to sexual health service provision will warrant investigation.