bluuebunny/crossref_metadata_2025_split huggingface dataset:
Feature Extraction Methods for Prognosis Maintenance Model
Authors: Bakir Azman Ahmad , Hassan Adnan , Hamid Mohd Foad Abdul 
Published: July 2020

Abstract
Research in prognosis maintenance, a branch of condition-based maintenance has received more attention from researchers lately. They focus on predicting when is the most suitable time to perform maintenance. Our review suggests that investigation on feature extraction in development of prognosis prediction model is still limited. This paper presents our study to find the most effective method for features extraction from maintenance monitoring data. The chosen features set should effectively improve the prognosis maintenance model performance. There have been several investigations to study feature extraction methods; however, the appropriate one is yet to be identified. In this research, we used datasets publicly available from National Aeronautics and Space Administration (NASA) army research laboratory. These datasets were generated through a simulation of the turbofan engine by using Commercial Modular Aero-Propulsion System Simulation (CMAPSS) software developed by NASA army research laboratory. Features extraction methods such as correlation among sensors, correlation among the outputs, variable weighing and treated data methods were studied in this research. Next, the extracted features were applied to the regression tree for searching an appropriate prognosis model. Based on the Remaining Useful Life (RUL) prediction results, the correlation among sensors method was found as the best method that can represent the most useful features for the prediction model.
Multivariate Change Point Estimation in Covariance Matrix Using ANN
Authors: Firouzi Alireza , Yusof Noordin Bin Mohd , Lee Muhammad Hisyam 
Published: July 2020

Abstract
In statistical process control, change point estimation is an essential requirement for diagnosing the source of a deviation when a process is out of control. In this study, an ANN- based method is proposed to estimate the change point in the multivariate normal process which is subjected to covariance variation. Since in a physical system parameter is correlated, correlation is kept constant to obtain realistic simulated data. Employing statistical simulation, different out of control scenarios are simulated and statistics are calculated for each scenario. This study is to predict the change point in the control chart using the simulated set and corresponding statistical sets, an ANN is adopted. The resulting model achieved a high accuracy of 90% in training and 80% testing with a reasonable level of confidence in the prediction. Also, results show that Bayesian reaches a higher accuracy than Levenberg in ANN training.
A novel double chamber rotary sleeve air compressor -part II: friction losses model
Authors: Alduqri Y A , Kamar H M , Musa M N , Kamsah N B , Idris N R N , Alqaifi Gamal 
Published: July 2020

Abstract
This paper presents the friction loss model of a novel double chamber rotary sleeve air compressor (DCRSC) concept. The compressor mechanism is similar to that of rotary compressor whereby the novelty transpires in the instalment of two rotating sleeves and a secured vane that has one end fixed to an outer sleeve and the other end to a rotor, respectively. This Part II of the paper series presents the friction losses analysis of the compressor. Thermodynamic and leakage losses models were respectively presented in Part I and Part III of this paper series. The primary aim of this paper is to formulate and analyse the friction loss model at the radial and axial contact regions of DCRSC at different rotational speed. The variations of the mechanical power and efficiency were evaluated based on the adiabatic, polytropic and isothermal thermodynamic principles as illustrated in Part I of this paper series. Considering the design simplicity of cylindrical shaped components, at maximum rotational speed of 1500 rpm, the DCRSC mechanical efficiencies are 72.43%, 66.2% and 59% when air undergoes adiabatic, polytropic and isothermal compression process, respectively. it is believed that the DCRSC is well suited for compressed air systems and air-conditioning applications.
Predictive Numerical Analysis on the Fuel Homogeneity in a Rotating Detonation Engine (RDE) Implementing Radially-Entered Fuel Injection Scheme
Authors: Rahman M N , Wahid M A , Mohd Yasin M F 
Published: July 2020

Abstract
The potential for a continuous detonation wave in rotating detonation engine (RDE) hugely rely on the homogenous fuel-air mixture within annular chamber. Using that motivation, a comprehensive numerical study on the non-reacting flow field was carried out to investigate the mixing of hydrogen (H2)and oxygen (O2) in a RDE, allowing this study to represent the flow behavior at the split second before ignition. A validation with the published experimental data was successfully done by comparing the predicted detonation front displacement, r and velocity, vD
. Below than 10 % error was detected from both variables. New parameter representing fuel homogeneity was introduced which is the magnitude of maximum deviation from the H2 mean mass fraction, |S
max|. A comparison in the |S
max| generated from RDE implementing axially-entered fuel (AEF) injection with RDE implementing radially-entered fuel (REF) injection was carried out. Based on the numerical results, the |5max| value from AEF injection is lower than REF injection implying the capability of AEF injection to produce better fuel homogeneity. Via AEF injection, the injected fuel stream has a direct impingement with the injected oxidizer stream allowing proper mixing of the reactants. In REF injection, thedistancefrom fuel injectortooxidizerinjector, R was varied to foresee the impact of R in |S
max | value. The outcome shows that as the value of Rincreases, the value of |S
max| increases as well. Thisisduetotheformation of vortex between the reactant streams plus the increased in distance between both streams which further reduced the reactants interaction. In the cases of R3 and R4 where the values of R are 7 and 9 mm respectively, the homogeneity of fuel is severed in the upstream region. This is a major concern since the ignition happened in that particular area. Thus, it is crucial for the reactants to mix properly within the upstream region.
An investigation of computational fluid dynamics of human nasal airflow using LS-DYNA®
Authors: Riazuddin V N , Chen C C , Faridzul Ahmad , Jasni M A , Chen J 
Published: July 2020

Abstract
Understanding the properties of airflow in the nasal cavity is essential in determining the nasal physiology and in diagnosis of various anomalies associated with the nose. This numerical study presents the characteristics of flow features inside a human nasal cavity. A three dimensional nasal cavity model is constructed from computed tomographic images of a healthy adult nose. Pressure inlet of 0 Pa is defined at the left and right nostril inlets representing the atmospheric condition. Negative pressure value is defined at the pharynx outlet to model the airflow suction during inhalation. This study shows the flow charcateristics and distribution in the nasal cavity is dependent on the complex geometry of the nasal airway. This simulation of breathing airflow enables us to visualize the flow features inside the complicated human nasal cavity which is otherwise impossible to be determined by any other method.
Fit Mix Effect Modelling of Physio-Mechanical Properties of Experimental Al-Zn-Mg-Cu Alloy Stir-Cast from Recycled Beverage Can
Authors: Kazeem A , Badarulzaman N A , Wan Ali W F F 
Published: July 2020

Abstract
The unique properties of aluminium and its alloyability with metals and non-metals made it one among most studied materials. It has vast areas of application in the automobile and aerospace industries. More than 97 % of aluminium used in beverage cans (BCs) are recoverable. Bulk of efforts were channelled to reuse of BCs to produce another can. Casting of a new Al-Zn-Mg-Cu alloy from BCs, adoption of Fit Mix Effect (FME) to model the physical and mechanical properties of the novel alloy were lacking in previous studies. Ingots were cast from BCs and spent batteries. Weight percent (Weight wWt. %) Zn were alternated between 4, 4.5 and 5 to produce nine (9) sections. Tensile and hardness pieces were heat treated. Largely, S3 delivered the peak UTS of 362.935 MPa, hardness of 113.06 Hv, 1.38 mm elongation and density of 2.8001 g/cm3. The empirical properties were used in delivering the FME model after fitting. The model was significant (P=0.991) and fully represent the properties of this alloy. Further studies may adopt this model to predict the properties of similar alloy and validate with experimental outcomes. Simulation of the properties are equally open for further investigations. Simulation of the properties are equally open for further investigations.
First-principles investigation of the effect of Co in stabilizing the structures of layer-structured cathodes in delithiated state
Authors: Kim Yongseon 
Published: July 2020

Abstract
The structural and chemical features of delithiated layer-structured cathodes (Li0.333TMO2, TM = Ni and Co) are investigated. Energetically stable structures are evaluated by combing particle swarm optimization algorithm and density functional theory calculations. The concentration of defects is calculated assuming that the entire crystal is the statistical combination of the lowest-energy structures. TM antisites that occupy Li sites and interstitial Li ions at tetrahedral sites are the major defect types in Li0.333TMO2; their prevalence decreases with increase in Co content. The oxidation state of Ni ions increases in the presence of Co, because the Co ions sustain low oxidation numbers, which results in decrease in the possibility of Ni2+ formation. In addition, the covalent bond of Co–O appears to be stronger than that of Ni–O. Therefore, the suppression of Ni2+ formation and the strong covalent bonding are proposed as the mechanisms underlying the stabilizing effect of Co.
Effect of initial texture on the {10–12} twinning variants selection mechanism in AZ31 magnesium alloy
Authors: Su Hui , Chu Zhibing , Xue Chun , Li Yugui , Ma Lifeng 
Published: July 2020

Abstract
The influence of the initial texture of the {10–12} twinning variants selection mechanism of the magnesium alloy was investigated using the compression test, the EBSD technology, the trace method, the orientation rotation method, and the Schmid’s law. Results show that various {10–12} twin patterns are observed in the AZ31 E90 sample subjected to compression. In the multi-twins inside a grain pattern, the high Schmid factor (SF) variant is activated first to coordinate the externally imposed strain, and the ortho-position (OP) variant with the best strain compatibility is activated. Typical case of paired twins in two neighboring grains usually have high SF, and the activation of corresponding variants follows the Schmid’s law. When E45 sample is compressed, the

SF

45
°

of a pair of relative variants among the six twin variants in the crystal is very large and favorable for local strong basal texture formed by the two adjacent grains for the twin-transfer phenomenon. When E0 sample is compressed, the activation of the corresponding variants follows the Schmid’s law and is linked to the stress fluctuation at the grain boundary.
The study on bending performance of aluminum alloy honeycomb panel-beam composite grid structure
Authors: Wang Gang , Zhao Caiqi , Gu Ye , Ma Jun 
Published: July 2020

Abstract
Long-span space structures are particularly sensitive to their self-weight. In this paper, a honeycomb plate with a high strength and light weight is reliably connected to a single-layer aluminium alloy lattice shell to form a new type of combined lattice shell structure, which substantially improves the overall stiffness and stability of the lattice shell without a plate. The bending performance of the aluminium alloy honeycomb panel-beam combined grid structure (AAH combined grid structure) plays a key role in the stability of the combined lattice shell structure. Therefore, the bending performance of the AAH combined grid structure was studied through six groups of tests and refined finite element models. Then, the calculation formula for the equivalent bending stiffness of the AAH combined grid structure was obtained through a theoretical analysis. The results show that the contribution of the honeycomb structure to the stiffness of the structure is very obvious, and the proposed formula provides the theoretical basis and a practical method for the engineering design of new aluminium alloy combined lattice shell structures in the future.
Application of change-point analysis to the selection of representative data in creep experiments
Authors: Zomorodpoosh Setareh , Volz Nicklas , Neumeier Steffen , Roslyakova Irina 
Published: July 2020

AbstractThe high volume of data resulting from a rapidly increasing number of experiments in materials science necessitates an efficient preparing of the data before any analysis. In addition, due to the large datasets in some experiments, it is essential to reduce the data sample to a small number of representative data points. In this study, three statistical methods for the change-point analysis are tested for the automated selection of representative creep data which provides large possibilities to speed up the data preparation for their further analysis. Moreover, this approach aids the practitioner to produce consistent and unique representative data for each experiment more efficiently.
Machine learning in physics: the pitfalls of poisoned training sets
Authors: Fang Chao , Barzeger Amin , Katzgraber Helmut G 
Published: July 2020

AbstractKnown for their ability to identify hidden patterns in data, artificial neural networks are among the most powerful machine learning tools. Most notably, neural networks have played a central role in identifying states of matter and phase transitions across condensed matter physics. To date, most studies have focused on systems where different phases of matter and their phase transitions are known, and thus the performance of neural networks is well controlled. While neural networks present an exciting new tool to detect new phases of matter, here we demonstrate that when the training sets are poisoned (i.e. poor training data or mislabeled data) it is easy for neural networks to make misleading predictions.
Characterization of FFPE-induced bacterial DNA damage and development of a repair method
Authors: Flores Bueso Yensi , Walker Sidney P , Tangney Mark 
Published: July 2020

AbstractFormalin-fixed, paraffin-embedded (FFPE) specimens have huge potential as source material in the field of human microbiome research. However, the effects of FFPE processing on bacterial DNA remain uncharacterized. Any effects are relevant for microbiome studies, where DNA template is often minimal and sequences studied are not limited to one genome. As such, we aimed to both characterize this FFPE-induced bacterial DNA damage and develop strategies to reduce and repair this damage. Our analyses indicate that bacterial FFPE DNA is highly fragmented, a poor template for PCR, crosslinked and bears sequence artefacts derived predominantly from oxidative DNA damage. Two strategies to reduce this damage were devised – an optimized decrosslinking procedure reducing sequence artefacts generated by high-temperature incubation, and secondly, an in vitro reconstitution of the base excision repair pathway. As evidenced by whole genome sequencing, treatment with these strategies significantly increased fragment length, reduced the appearance of sequence artefacts and improved the sequencing readability of bacterial and mammalian FFPE DNA. This study provides a new understanding of the condition of bacterial DNA in FFPE specimens and how this impacts downstream analyses, in addition to a strategy to improve the sequencing quality of bacterial and possibly mammalian FFPE DNA.
Hypertension and Alzheimer’s disease: indirect effects through circle of Willis atherosclerosis
Authors: Eglit Graham M L , Weigand Alexandra J , Nation Daniel A , Bondi Mark W , Bangen Katherine J 
Published: July 2020

AbstractHypertension is common among older adults and is believed to increase susceptibility to Alzheimer’s disease, but mechanisms underlying this relationship are unclear. Hypertension also promotes circle of Willis atherosclerosis, which contributes to cerebral hypoperfusion and arterial wall stiffening, two potential mechanisms linking hypertension to Alzheimer’s disease. To examine the role of circle of Willis atherosclerosis in the association between hypertension and Alzheimer’s disease neuropathology, we analysed post-mortem neuropathological data on 2198 decedents from the National Alzheimer’s Coordinating Center database [mean (standard deviation) age at last visit 80.51 (1.95) and 47.1% female] using joint simultaneous (i.e. mediation) modelling. Within the overall sample and among Alzheimer’s dementia decedents, hypertension was indirectly associated with increased neuritic plaques and neurofibrillary tangles through its association with circle of Willis atherosclerosis. Similar indirect effects were observed for continuous measures of systolic and diastolic blood pressure. These results suggest that hypertension may promote Alzheimer’s disease pathology indirectly through intracranial atherosclerosis by limiting cerebral blood flow and/or dampening perivascular clearance. Circle of Willis atherosclerosis may be an important point of convergence between vascular risk factors, cerebrovascular changes and Alzheimer’s disease neuropathology.
China’s Belt and Road Initiative: Patron-Client and Capture in Cambodia
Authors: Young Sokphea 
Published: July 2020

Abstract
The launch of China’s Belt and Road Initiative (BRI) has sparked scholarly interest in understanding how global Chinese capital has entered and faced the unique challenges often associated with the business and regulatory environments of developing economies. Drawing on the case of Cambodia, this article seeks to understand: (i) how the new generation of overseas Chinese investors and companies, in the era of BRI, acquire licences and secure business operation in developing economies and (ii) how these investments cope with the host country’s regulatory institutions, including grassroots communities and civil society organizations. The article argues that, while the BRI’s Chinese investors have played a crucial role in the Cambodian economy, this injection of capital has co-opted and exacerbated the ambiguity of Cambodia’s regulatory environment. These Chinese investors have perpetuated the host country’s socio-political culture of patron-client networks, partly entrenched by the Sino-Cambodian elites. These networks are necessary to tap into secure investment operations, and they duly capture (and influence) regulatory institutions at the expense of marginalized communities and civil society organizations. Drawing on Cambodia’s case, the article contributes to the understanding of patron-client relations and regulatory capture in the context of socio-legal studies and the political economy of China’s global capitalism.
Acquired aortopulmonary fistula: a case report
Authors: Mahmoud Osama , Elias Hadi , Rafiq Arsalan , Alsaid Amro 
Published: July 2020

Abstract

Background
Aortopulmonary fistula is a rare complication of ascending aorta pathology. Presentation is most commonly dramatic with acute onset chest pain or heart failure secondary to left to right shunting. We describe a patient with acquired aortopulmonary fistula who had an insidious onset of heart failure as his presenting complaint. We also highlight the utility of multimodality cardiac imaging in establishing the diagnosis.

Case summary
A 79-year-old male patient with a history of coronary artery bypass graft surgery and mechanical aortic valve replacement, 23 years prior, presented with exertional dyspnoea of 7 months duration. An initial workup that included transthoracic and transoesophageal echocardiography as well as coronary and bypass graft angiography failed to diagnose an acquired aortopulmonary fistula complicating an ascending aortic pseudoaneurysm. Upon referral to our institution, the correct diagnosis was suspected on off-axis transthoracic echocardiography. The fistula was subsequently confirmed, and the extent of ascending aorta pathology defined via a multimodality imaging approach that consisted of transoesophageal echocardiography and cardiac computed tomography. The patient underwent successful surgical repair and was discharged in a stable condition.

Discussion
Acquired aortopulmonary fistula is a rare clinical entity. We describe a patient who had an insidious presentation of heart failure and found to have a large ascending aortic aneurysm that eroded into the main pulmonary artery creating a fistulous communication. The diagnosis was delayed and required a high index of suspicion and multimodality cardiac imaging.
A case report of myocardial infarction with non-obstructive coronary artery disease: Graves’ disease-induced coronary artery vasospasm
Authors: Klomp Margo , Siegelaar Sarah E , van de Hoef Tim P , Beijk Marcel A M 
Published: July 2020

Abstract

Background
Coronary artery spasm can occur either in response to drugs or toxins. This response may result in hyper-reactivity of vascular smooth muscles or may occur spontaneously as a result of disorders in the coronary vasomotor tone. Hyperthyroidism is associated with coronary artery spasm.

Case summary
A 49-year-old female patient with a 2-day history of intermittent chest pain and electrocardiographic evidence of myocardial ischaemia was referred for emergency coronary angiography. This revealed severe right coronary artery (RCA) and left main (LM) coronary artery ostial vasospasm, both subsequently relieved with administration of multiple doses intracoronary nitroglycerine. Intravascular optical coherence tomography showed absence of atherosclerosis and no evidence of thrombus or dissection confirming the diagnosis of coronary artery vasospasm. Laboratory tests of the thyroid function were performed immediately after coronary angiography revealing Graves’ disease as the cause of vasospasm.

Discussion
Our case represents a rare presentation of Graves’ disease-induced RCA and LM coronary artery ostial vasospasm. In patients with coronary artery vasospasm thyroid function study should be mandatory, especially in young female patients.
Endovascular iliac vein recanalization for permanent pacemaker implantation in a patient who has long-term haemodialysis: a case report
Authors: Stoyanov Nikolay , Goranovska Valya , Gegouskov Vassil , Velchev Vasil 
Published: July 2020

Abstract

Background
In chronic haemodialysis patients central veins occlusion occur very often. In such patients, permanent pacemaker placement implantation can be challenging and alternative approaches should be used.

Case summary
This is a case of 66-year-old male patient with complete atrioventricular block after a mitral valve (MV) surgery for endocarditis. The patient has a permanent surgically inserted haemodialysis catheter in right heart atrium after several unsuccessful attempts of endovascular recanalization of superior vena cava. A lead was implanted in the right ventricle after successful endovascular revascularization of the right iliac vein. The pacemaker was placed in a pouch on the right lower abdominal wall.

Discussion
To our knowledge, this is the first reported case where a permanent single-chamber pacemaker was implanted through the right iliac vein after successful endovascular recanalization in chronic haemodialysis patient post-MV replacement.