bluuebunny/crossref_metadata_2025 huggingface dataset:
Spinal tuberculosis: A systematic review of case studies and development of an evidence‐based clinical guidance tool for early detection
Authors: Louw Quinette A. , Tawa Nassib , Van Niekerk Sjan‐Mari , Conradie Thandi , Coetzee Marisa
Published: November 2019

Rationale, aims, and objectives

Despite research being done on spinal tuberculosis, diagnosing this condition at an early stage remains problematic due to its insidious onset and the varying symptoms being associated. Most individuals present to the health care facility with either simple back pain at an early stage or neurological complications at a later stage, when spinal compression and vertebral collapse have occurred as a result of delayed diagnosis. The prevention of secondary complications is therefore dependent on early recognition and diagnosis. The objective of this review was to identify common clinical patterns in case presentations and develop an evidence‐based clinical guidance tool to assist clinicians in the early identification of spinal tuberculosis.

Method

A comprehensive literature search was conducted for published spinal tuberculosis case studies, which yielded 28 cases after critical appraisal. Data from the studies were categorized in order to assist with a factor analysis and the development of an evidence framework for screening and diagnosing spinal tuberculosis. An evidence‐based clinical guidance tool was then designed from the data obtained.

Results

Factors associated with spinal tuberculosis and frequently reported symptoms and physical signs with which the patient could present upon assessment were identified. Options for investigations at primary, secondary, and tertiary levels were also identified.

Conclusion

Through the use of an evidence‐based clinical guidance tool, the clinician could be guided in the early suspicion and management of individuals with spinal tuberculosis and prevention of secondary complications.
Social determinants and causes of child mortality in Pakistan: Analysis of national demographic health surveys from 1990 to 2013
Authors: Afshan Kiran , Narjis Ghulam , Qureshi Irfan Z , Cappello Michael
Published: November 2019

Aim

The aim of the study was to define social determinants, causes and trends in child mortality from 1990 to 2013 in Pakistan. Understanding social determinants, causes and temporal trends in child mortality can inform strategies aimed at improving child health in low and middle income countries.

Methods

We characterised temporal trends and social determinants of child mortality in Pakistan using national demographic health survey data (1990–1991, 2006–2007 and 2012–2013). We analysed national data to generate regional estimates of health programme effectiveness.

Results

The annual rates of reduction for child mortality between 1990 and 2013 were estimated as follows: neonatal (−0.33% per annum), post‐neonatal (3.13% per annum), infant (0.9% per annum), child (2.47% per annum) and under 5 (1.19% per annum). Bivariate analyses of 2013 data showed that living in Punjab or Balochistan province, belonging to lowest wealth quintile, lack of maternal education, previous birth interval < 2 years, first birth order and below average birth size were associated (p < 0.05) with greater risk of child mortality in Pakistan. Common factors associated with child mortality were fever, diarrhoea and pneumonia, while among stillbirths, intrapartum asphyxia, unexplained antepartum and antepartum maternal disorders were most frequent.

Conclusion

Child survival strategies should integrate leading biosocial indicators and causes of death. Further research is needed to define the role(s) of social factors in child health and survival. These data should inform the implementation of cost‐effective interventions for child survival and advance targeting of interventions to populations at increased risk of child mortality.
Population dynamics and exploitation patterns of Oreochromis niloticus in Lake Tana, northwest Ethiopia
Authors: Assefa Workiyie Worie , Wondie Ayalew , Enyew Belachew Getnet
Published: November 2019

Oreochromis niloticus is the dominant commercial fish in the Lake Tana region. However, its fishery is progressively declining over time. Little or no updated information exists on the population dynamics and exploitation patterns of the species, which is crucial to guide its sustainable management. Accordingly, the purpose of the present study was to generate essential biological parameters on the growth, mortality and stock status of O. niloticus, using length‐frequency data collected monthly from the commercial fish catches of 1 year (2014–2015). The total mortality coefficient (Z) was derived from the length‐converted catch curve. Biological reference points were predicted from relative yield‐ and biomass‐per‐recruit analyses. The estimated values of the von Bertalanffy growth parameters were L∞ = 44.1 cm, K = 0.44/year, and t0 = −0.34/year, and the growth performance index (Φ′) was 2.93. The total mortality (Z), natural (M) and fishing mortality (F) rates were 2.37, 0.98 and 1.39 per year, respectively. The current fishery exploitation rate of 0.59 exceeds the estimated biological reference points of Emax (0.52), confirming the stock of O. niloticus in the lake is being overexploited above optimum levels. Size indicators of the catches further illustrate 31% of the landed fish are harvested before reaching sexual maturity, with mega‐spawners comprising only 15%. This indicates the stock is suffering from both growth and recruitment overfishing. The logistic selection model indicated 50% of the fish vulnerable to capture was at 18.14 cm TL. The fish exhibited a year‐round recruitment pattern, with a major peak during May and June. Sustainably managing the fishery, therefore, requires increasing the fish size at first capture (Lc) towards Lopt.
Survival of Phortica variegata experimentally and naturally infected with Thelazia callipaeda
Authors: Arme T. M. , Lia R. P. , Annoscia G. , Casalino E. , Pombi M. , Otranto D.
Published: November 2019

Knowledge of the effects that Thelazia callipaeda (Spirurida, Thelaziidae) infection has on the survival of its vector Phortica variegata (Drosophilidae, Steganinae) is scarce. The present study aimed to: (a) assess the rate of infection between experimentally infected (EI) and not experimentally infected (NEI) flies and (b) determine how T. callipaeda infection may affect the survival of P. variegata. In addition, fat composition was evaluated in flies that died during overwintering. Molecular analysis showed that T. callipaeda prevalence in flies that died before experimental infection, plus those from the NEI group, is 0.75% (i.e. 11 out of 1462 individuals). The EI group showed a significantly higher positivity to T. callipaeda (i.e. 51 out of 682 individuals; 7.48%) compared with the NEI group (i.e. 9 out of 750 individuals; 1.2%). Thelazia callipaeda DNA was detected until 147 days after experimental infection. This demonstrates that larvae of this eyeworm may survive in the fly for a significant period of the winter. Fat composition analysis showed that flies produced more unsaturated than saturated fatty acids during diapause, probably because unsaturated fatty acids remain in a liquid state at lower temperatures, providing anti‐freeze properties to survive winter.
Patterns of allele distribution in a hybrid population of the Cryptococcus neoformans species complex
Authors: Samarasinghe Himeshi , Vogan Aaron , Pum Nicole , Xu Jianping
Published: November 2019

Background

The sister yeast species Cryptococcus neoformans (serotype A) and Cryptococcus deneoformans (serotype D) are causative agents of deadly cryptococcosis and fungal meningoencephalitis. These haploid yeasts can hybridise in nature, giving rise to AD hybrids that are predominantly diploid or aneuploid. Despite their increasing prevalence in clinical settings, much remains unknown about the allelic distribution patterns in AD hybrid strains.

Objectives

This study aims to characterise allele distributions in AD hybrids derived from the same basidium as well as from multiple basidia in a laboratory‐derived C neoformans × C deneoformans hybrid cross.

Methods

We dissected a total of 1625 basidiospores from 31 basidia. The 297 basidiospores that successfully germinated were genotyped by molecular characterisation of 33 markers using PCR‐RFLP, with at least two markers on each of the 14 chromosomes in the genome.

Results

Of the 297 strains, 294 contained at least one heterozygous locus, with a mean heterozygosity of ~30% per strain. Most hybrid genomes and chromosomes displayed significantly distorted allele distributions, with offspring originating from the same basidium tended to have alleles at different loci from the same parent. More basidia were skewed in favour of C deneoformans alleles, the mitochondria‐donor parent, than the C neoformans alleles.

Conclusions

The divergence between C neoformans and C deneoformans genomes has likely created co‐adapted allelic combinations, with their co‐segregation in hybrid offspring imparting a significant fitness benefit. However, the diversity of genotypes recovered here in a single hybridisation event indicates the enormous capacity of AD hybrids for adaptation and diversification.
Wood allocation trade‐offs between fiber wall, fiber lumen, and axial parenchyma drive drought resistance in neotropical trees
Authors: Janssen Thomas A. J. , Hölttä Teemu , Fleischer Katrin , Naudts Kim , Dolman Han
Published: November 2019

Functional relationships between wood density and measures of xylem hydraulic safety and efficiency are ambiguous, especially in wet tropical forests. In this meta‐analysis, we move beyond wood density per se and identify relationships between xylem allocated to fibers, parenchyma, and vessels and measures of hydraulic safety and efficiency. We analyzed published data of xylem traits, hydraulic properties and measures of drought resistance from neotropical tree species retrieved from 346 sources. We found that xylem volume allocation to fiber walls increases embolism resistance, but at the expense of specific conductivity and sapwood capacitance. Xylem volume investment in fiber lumen increases capacitance, while investment in axial parenchyma is associated with higher specific conductivity. Dominant tree taxa from wet forests prioritize xylem allocation to axial parenchyma at the expense of fiber walls, resulting in a low embolism resistance for a given wood density and a high vulnerability to drought‐induced mortality. We conclude that strong trade‐offs between xylem allocation to fiber walls, fiber lumen, and axial parenchyma drive drought resistance in neotropical trees. Moreover, the benefits of xylem allocation to axial parenchyma in wet tropical trees might not outweigh the consequential low embolism resistance under more frequent and severe droughts in a changing climate.
Effectiveness of mindfulness‐based cognitive therapy in patients with anxiety disorders in secondary‐care settings: A randomized controlled trial
Authors: Ninomiya Akira , Sado Mitsuhiro , Park Sunre , Fujisawa Daisuke , Kosugi Teppei , Nakagawa Atsuo , Shirahase Joichiro , Mimura Masaru
Published: November 2019

Aim

The primary objective of this study was to examine the effectiveness of mindfulness‐based cognitive therapy (MBCT) in secondary‐care settings where the vast majority of the patients have already undergone pharmacotherapy but have not remitted.

Methods

Eligible participants were aged between 20 and 75 years and met the criteria for panic disorder/agoraphobia or social anxiety disorder specified in the DSM‐IV. They were randomly assigned to either the MBCT group (n = 20) or the wait‐list control group (n = 20). The primary outcome was the difference in mean change scores between pre‐ and post‐intervention assessments on the State–Trait Anxiety Inventory (STAI). The outcome was analyzed using an intent‐to‐treat approach and a mixed‐effect model repeated measurement.

Results

We observed significant differences in mean change scores for the STAI State Anxiety subscale (difference, −10.1; 95% confidence interval, −16.9 to −3.2; P < 0.005) and STAI Trait Anxiety subscale (difference, −11.7; 95% confidence interval, −17.0 to −6.4; P < 0.001) between the MBCT and control groups.

Conclusion

MBCT is effective in patients with anxiety disorders in secondary‐care settings where the vast majority of patients are treatment‐resistant to pharmacotherapy.
Dietary eicosapentaenoic acid and docosahexaenoic acid are linearly retained by common insect crop pests (cabbage looper and bertha armyworm) and alter insect biomass
Authors: Colombo Stefanie M. , Shukla Kruti , Campbell Lesley G. , Tsimbaliouk Alina , Arts Michael T.
Published: November 2019

The long‐chain omega‐3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are prevalent in aquatic ecosystems and are not part of the natural diet of herbivorous, terrestrial insects, which generally consume alpha‐linolenic acid (ALA) and linoleic acid (LNA). However, recent advances in genetic engineering have lead to the development of terrestrial crops that express the novel traits of EPA and DHA production. In the present study, we examine the effects of dietary EPA and DHA on the growth, development and fatty acid content of two crop pest insects: bertha armyworm and cabbage looper. Five experimental diets were formulated to include increasing amounts of pure EPA and DHA (in relation to the total diet lipid level), according to the ratios (EPA + DHA relative to a vegetable oil containing ALA and LNA): 0 (control), 0.25 : 0.75 (lowest), 0.5 : 0.5 (low), 0.75 : 0.25 (medium) and 1 : 0 (high). Dietary EPA and DHA had significant effects on development time, mass and fatty acid content in both species. Dietary treatment (interactive with time) had a significant effect on individual mass of both insects, indicating that, over time, EPA and DHA impacted growth. However, insect mass, development and morphology results are not linearly related with increasing dietary EPA and DHA. Both species retained EPA and DHA in adult form, and the body content of EPA and DHA was significantly, positively correlated with EPA and DHA diet treatments in both the bertha armyworm (r2 = 91.3%) and cabbage looper (r2 = 75.8%). Dietary EPA and DHA could have fitness consequences for these organisms and could be nutritionally transferred to higher consumers.
A low‐cost open‐source workflow to generate georeferenced 3D SfM photogrammetric models of rocky outcrops
Authors: Froideval Laurent , Pedoja Kevin , Garestier Franck , Moulon Pierre , Conessa Christophe , Pellerin Le Bas Xavier , Traoré Kalil , Benoit Laurent
Published: November 2019

Structure‐from‐Motion (SfM) software and unmanned aerial vehicles (UAVs) have been increasingly adopted in the geosciences. The current mainstream generation of 3D models is still expensive as it relies on UAVs, Differential Global Navigation Satellite System (DGNSS) ground control points and commercial software. This paper proposes an end‐to‐end reproducible SfM workflow with minimal legal, financial or field issues. The procedure avoids both UAVs and DGNSS and relies on open‐source software. Interlocked models of a rocky shore in Normandy, France were generated at different scales and point densities, being georeferenced using free spatial data. A spherical target was used for scaling and assessing the relative accuracy, which was better than 1 cm.
Changes in the carbon concentrations and other soil properties of some Scottish agricultural soils: Evidence from a resampling campaign
Authors: Lilly Allan , Baggaley Nikki J. , Edwards Anthony C.
Published: November 2019

The change in soil carbon (C) concentration, soil pH and major nutrients for approximately 1,000 topsoil sampled from on‐farm experimental sites over a thirty‐year period from 1950 to 1980 in north‐east Scotland are summarized. This period coincided with increased agricultural intensification, which included regular liming and fertilizer additions. During 2017, 37 of these sites were resampled and reanlaysed. While pH and extractable phosphorus (P) and potassium (K) increased over this period, there was no detectable change in the percentage loss on ignition. Composite soil samples were taken by auger from a depth of 0–15 cm and compared with the corresponding archived samples collected at the initiation of each experiment. Analysis of these resampled soils indicated no significant change in soil carbon (C), although soil pH, extractable magnesium (Mg) and K and Nitrogen (N) concentrations were significantly greater (p < .001) but extractable soil P concentration was significantly less (p = .015) compared with the original samples. Even though measuring C concentration alone is a poor indicator of overall changes in soil C stocks, it does provide a relative quick “early warning” of C losses that would justify a more comprehensive measure of stocks.
Freezing and storage effects on enzyme, electrolyte, and mineral compositions in canine prostatic fluid
Authors: Umbach Anne‐Kathrin , Failing Klaus , Goericke‐Pesch Sandra , Wehrend Axel
Published: November 2019

Background

There is a paucity of information about the storage stability of seminal plasma components in literature.

Objectives

This study investigates the potential effects of storage at −18.0°C on the enzyme activities and concentrations of selected electrolytes and minerals in canine prostatic fluid.

Methods

Semen was obtained in fractions from ten male dogs, and the third ejaculate fraction was analyzed immediately after sampling and after storage at −18.0°C for 7 days. The following analytes were assessed: gamma‐glutamyl transferase (GGT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), sodium, potassium, total calcium, inorganic phosphate, magnesium, zinc, and copper.

Results

Whereas electrolyte and mineral concentrations were not affected by freezing and 7 days of storage, effects on the enzyme activities were variable. ALP, AST, and LDH activities were significantly decreased (P < .05) in the post‐thaw samples compared with the freshly prepared samples.

Conclusions

Because freezing and storage of seminal plasma at −18°C had an impact on the activity of some enzymes, analyses should be performed in fresh, not frozen samples.
The Real Estate Impact of Recreational Areas on the Residential Property Values in Riyadh, Saudi Arabia
Authors: Alawwad Faisal A. , Alzamil Waleed S.
Published: November 2019

Recreational areas are one of the most important uses in the modern residential neighborhoods because they improve economic resources, social life, and environmental quality. This paper discusses the impact of recreational areas on residential property values in Riyadh. The paper relies on the descriptive and comparative analysis of the case study model 'Al-Hokair Land' by extrapolating the residents' view of the residential properties close to the recreational area in Al-Hamra neighborhood. The paper also analyzed the relationship between recreational area and land price changes in urban communities within Al-Hamra district. The paper found that the average land price in Al-Hamra district is $826 per square meter, which is the highest compared to the neighboring areas. Moreover, land prices in urban communities near the recreational area are the highest with an average of $933 per square meter. Finally, the value of residential properties areas is affected by environmental, security, urban or social factors associated with recreational activity. Therefore, the paper recommends improving the quality of the urban environment to ensure the stability of the residential properties value in line within framework of the Saudi Vision 2030.
Assessing and Managing Geologic Hazards in the Appalachian Region of the United States
Authors: Derby Martin P. , Theriault Bailey
Published: November 2019

Geohazards have the potential to adversely affect the operation or integrity of an existing pipeline, or the routing, design, and construction of a proposed pipeline. Identifying, characterizing, evaluating, and if necessary, mitigating and monitoring geologic hazards have become critical steps to successfully and safely building and operating pipelines in the Appalachian Basin region of the United States. The recent, rapid expansion of pipeline construction and operation in the region, along with natural geologic and geographic conditions which are conducive to landsliding and ground subsidence, have resulted in a recent increase in geohazard-related incidences both during and post-construction of pipelines. As such, there is an increasing need to recognize, understand, and closely manage geohazards in this region, prior to, during, and post-construction of pipelines. This paper will provide an overview of essential tools that have proven most useful in this region, to identify, characterize, and ultimately mitigate and monitor potential geohazards. This paper will also provide insight on how to evaluate specific project needs and best-fit approaches and solutions for the project at hand, to reduce the operator’s risk. A case study will be presented from the Appalachian Basin region, including how a phased approach was used to assess and manage geohazards. The phased approach includes (1) Phase I Assessments, which consist of a regional-scale desktop assessment to identify, initially characterize, and qualitatively classify (e.g., low, moderate, high hazards) geohazards; (2) Phase II Assessments, which consist of a non-intrusive ground reconnaissance completed at targeted sites; and (3) Phase III Assessments, which consist of subsurface investigations such as drilling, test pitting, or geophysical surveys to further characterize specific hazards.

The information obtained from the phased approach can be used for the design of mitigation and/or monitoring, if deemed necessary. Overall approaches to selecting and utilizing best-fit mitigation and monitoring options, both during and post-construction, fit for the regional conditions and to the individual project, will also be discussed.
Highly Iterative Planning of Manufacturing Technologies: Evaluation of Manufacturing Technology Capabilities Considering Information Uncertainties
Authors: Rey Jan , Grünebaum Timm , Trauth Daniel , Bergs Thomas
Published: November 2019

Highly iterative product development is a promising approach, which enables a continuous inclusion of customers in the product development process. A stronger involvement of customers results in more frequent changes of the required product characteristics while the product is being developed. For the planning of manufacturing technologies, which takes place in parallel to product development, this means that very uncertain product and technology information have to be processed. In order to consider these uncertainties when designing technology chains, technology planners have to be able to model and quantify them. Moreover, due to the frequent product changes during the highly iterative development process, an evaluation of how capable manufacturing technologies are for handling future changes of product characteristics is essential for technology planners. This paper presents a new methodology, which enables the evaluation of manufacturing technologies regarding their capability to react to future product changes within the development process. Firstly, a new method based on fuzzy sets and the Dempster-Shafer theory of evidence is presented. It allows an aggregation of uncertain product and technology information from different sources. Afterwards, the influences of manufacturing technologies within a technology chain on the product characteristics are modeled considering the different uncertainties. Finally, a new method to evaluate the capability of manufacturing technologies to cope with future product changes is introduced. This allows technology planners to predict the capability of manufacturing technologies to manufacture the future, fully developed product and hence to identify alternatives to reduce the information uncertainties, for example by executing prototype experiments.
Investigation on Residual Stress Development During Multiple Impacts in Cold Spray Process
Authors: James Sagil , Shah Karan
Published: November 2019

The Cold Spray Process (CS) is a solid-state particle deposition process. Unlike thermal spray coating methods, the CS process does not involve melting of the particles and thus retains the desired original material properties along with oxide-free deposition. As the technology is of dynamic nature with high-velocity particle impacts, the bonding mechanism involved is hugely complicated to understand. Even though the CS process offers great benefits, its potential applications are restrained by a lack of knowledge of the complex operations involved. Preliminary research which used molecular dynamics (MD) simulation of the CS process revealed that factors including the angle of impact, size of particle and impact velocity significantly affect the material deposition. However, the preliminary study only considered a single particle impact during the coating process. The CS process involves the impact of multiple particles on the substrate surface depositing layer-by-layer. This research focuses on investigating the residual stresses distribution caused by the impact of multiple nanoparticles on the substrate surface during the CS process using MD simulation technique. The results obtained by this study are instrumental in further advancing the applications of the CS processes.
Analytical Study on Tooth Profile of Non-Circular Gear Based on Hobbing Process Simulation
Authors: Han Jiang , Li Dazhu , Xia Lian , Tian Xiaoqing
Published: November 2019

Based on the hobbing process simulation of non-circular gears, a method for obtaining the precise tooth profile and evaluating the undercutting characteristics according to the profile generated after the finite number of envelop is proposed. The profile points formed by different hobbing strategies are compared, then the envelope method with uniform accuracy for all teeth is selected. The formation rule of tooth profile morphology is analyzed, and the pickup method with high convergence rate is proposed. The influences of the envelope number and gear parameters on the tooth profile accuracy are analyzed inductively, and the reasonable number of envelopes for expected accuracy is given. The results show that the tooth profile analysis method based on the hobbing process simulation can accurately acquire all feature points of the tooth profile and analysis the undercutting phenomenon.
Testing of the MTConnect–OPC UA Companion Specification
Authors: Fisher Ryan , Shao Guodong
Published: November 2019

Smart Manufacturing (SM) is the future of the manufacturing industry. Seamless, accurate, and fast connection and communications among devices are critical for SM. By leveraging information technologies, devices can dynamically communicate with each other to increase factory production, while decreasing engineering costs. MTConnect and Open Platform Communications - Unified Architecture (OPC-UA) standards facilitate such communication. MTConnect is a manufacturing interoperability standard that provides a semantic vocabulary for manufacturing equipment to provide structured contextualized data with no proprietary format. The OPC-UA is a platform-independent standard through which various systems and devices can communicate by sending messages between clients and servers over various networks. OPC-UA enables syntactic interoperability between clients and servers. The MTConnect - OPC-UA Companion Specification integrates the two standards to provide manufacturers more efficient and powerful interoperability capabilities. In this paper, we report the test of version 1.02 of this companion specification. This specification sets a standard means of communication between MTConnect devices and OPC-UA Clients/Servers based on Extensible Markup Language (XML) structures. To test the standard, the following components have been developed: an OPC-UA Server, an OPC-UA Client, a probe that translates data structures in MTConnect XML format to MTConnect OPC-UA Companion XML format that can be recognized by the server, a MTConnect XML data parser, and a MTConnect device simulator. The activities of the standard testing include passing varying data structures and objects through the server and confirming the information is received accurately by the client. The findings of the standard testing will be provided to the standard developing organizations for improving the future versions of the standard.
On the 3D Printability of Multi-Walled Carbon Nanotube/High Density Polyethylene Composites
Authors: Stan Felicia , Stanciu Nicoleta-Violeta , Fetecau Catalin
Published: November 2019

This study focuses on 3D printing of multi-walled carbon nanotube/high density polyethylene (MWCNT/HDPE) composites. First, rheological properties of 0.1, 1, and 5 wt.% MWCNT/HDPE composites were investigated to estimate the 3D printability window. Second, filaments with 1.75 mm diameter were fabricated and subsequently extruded by a commercial 3D printer. Finally, the filaments and 3D printed parts were tested to correlate the rheological, mechanical, and electrical properties with processing parameters. Experimental results show that flow behavior of MWCNT/HDPE composites is a critical factor affecting the 3D printability. The shear viscosity exhibits good shear thinning behavior at high shear rates and significantly increases with increasing nanotube loading from 0.1 to 5 wt.%, at low shear rates. Reliable MWCNT/HDPE filaments were obtained with smooth surface finish and good mechanical and electrical properties. The 0.1 and 1 wt.% MWCNT/HDPE filaments exhibit very good printing characteristics. However, under the flow conditions of a standard 0.4-mm nozzle, 3D printing of 5 wt.% MWCNT/HDPE filament can be rather difficult primarily due to high shear viscosity and nozzle clogging. Thus, further investigation is needed to fully optimize the 3D printing of MWCNT/HDPE composites.
A Coupling Approach Combining CFD and FEM Methods to Predict Cutting Fluid Effects on the Tool Temperature in Cutting Processes
Authors: Helmig Thorsten , Peng Bingxiao , Ehrenpreis Claas , Augspurger Thorsten , Frekers Yona , Kneer Reinhold , Bergs Thomas
Published: November 2019

In metal cutting processes the use of cutting fluids shows significant effects on workpiece surface quality by reducing thermomechanical loads on cutting tool and workpiece. Many efforts are made to model these thermomechanical processes, however without considering detailed heat transfer between cutting fluid, tool and workpiece. To account for heat transfer effects, a coupling approach is developed which combines CFD (Computational Fluid Dynamics) and FEM (Finite Element Method) chip formation simulation. Prior to the simulation, experimental investigations in orthogonal cutting in dry and wet cutting conditions with two different workpiece materials (AISI 1045 and DA 718) are conducted. To measure the tool temperature in dry as well as in wet cutting conditions, a two color pyrometer is placed inside a EDM drilled cutting tool hole. Besides tool temperature, the cutting force is recorded during the experiments and later used to calculate heat source terms for the CFD simulation. After the experiments, FEM chip formation simulations are performed and provide the chip forms for the CFD mesh generation. In general, CFD simulation and experiment are in reasonable agreement, as for each workpiece setup the measured temperature data is located between the simulation results from the two different tool geometries. Furthermore, numerical and experimental results both show a decrease of tool temperature in wet cutting conditions, however revealing a more significant cooling effect in a AISI 1045 workpiece setup. The results suggest that the placement of drilling holes has a major influence on the local tool temperature distribution, as the drilling hole equals a thermal resistance and hence leads to elevated temperatures at the tool front.
Gaussian Process Tensor Responses Emulation for Droplet Solidification in Freeze Nano 3D Printing of Energy Products
Authors: Segura Luis Javier , Zhao Guanglei , Sun Hongyue , Zhou Chi
Published: November 2019

Freeze nano 3D printing is a novel process that seamlessly integrates freeze casting and inkjet printing processes. It can fabricate flexible energy products with both macroscale and microscale features. These multi-scale features enable good mechanical and electrical properties with lightweight structures. However, the quality issues are among the biggest barriers that freeze nano printing, and other 3D printing processes, need to come through. In particular, the droplet solidification behavior is crucial for the product quality. The physical based heat transfer models are computationally inefficient for the online solidification time prediction during the printing process. In this paper, we integrate machine learning (i.e., tensor decomposition) methods and physical models to emulate the tensor responses of droplet solidification time from the physical based models. The tensor responses are factorized with joint tensor decomposition, and represented with low dimensional vectors. We then model these low dimensional vectors with Gaussian process models. We demonstrate the proposed framework for emulating the physical models of freeze nano 3D printing, which can help the future real-time process optimization.
Microstructure Evolution During Solid-State Selective Laser Sintering of Metallic Materials: A Phase-Field Simulation
Authors: Zhang Xing , Liao Yiliang
Published: November 2019

Selective laser sintering/melting (SLS/SLM) is a rapid prototyping technique that utilizes a high-energy laser beam to bind powder particles together for solid part fabrication. Due to the presence of several factors, microstructure-based material modeling can be of significant importance for optimizing processing parameters. To date, most researchers have put their efforts on simulating the microstructure of SLM-processed component, while few attentions have been paid to investigate the evolving of microstructure during SLS. In this work, a phase-field model is proposed to simulate the microstructure evolution during the solid-state SLS process. The microstructure evolution as affected by the laser power and scanning velocity are studied. It is found that the width of sintering neck increases with the increase of laser power and the decrease of laser scanning velocity. The modeling predictions are compared with the experimental data regarding the neck width between adjacent particles. In addition, it is demonstrated that this model is capable of carrying out large-scale simulations.
Tool Wear of Superhard Ceramic Coated Tools in Drilling of CFRP/Ti Stacks
Authors: Nguyen Dinh , Voznyuk Vadim , Bin Abdullah Mohammad Sayem , Kim Dave , Kwon Patrick Y.
Published: November 2019

This paper aims to investigate the effectiveness of several superhard ceramic coatings on carbide drills when drilling carbon fiber reinforced plastics (CFRP) composite/Ti-6Al-4V alloy (titanium or Ti) stacks. The drilling experiments of CFRP/Ti stack are conducted with diamond-like coating (DLC) coated, alternating layers of the nanocomposite of AlCrN & Si3N4 and TiN or (AlCrSi/Ti)N coated, and uncoated tungsten carbide drills. Tool wear evolution of each drill is measured qualitatively as well as quantitatively using the scanning electron and confocal laser scanning microscopes (CLSM) by interrupting after making certain numbers of hole. Based on our drilling experiments, the performance of each coating when drilling CFRP/Ti stack are discussed. Among these coated and uncoated drills, uncoated and DLC coated drills failed before making 5 holes while (AlCrSi/Ti)N coated drills performed the best making more than 80 holes. The DLC coating, despite of high hardness of DLC coating, does not provide any significant protection especially when drilling Ti layer.
A Novel Laser Shock Surface Patterning Process Toward Tribological Applications
Authors: Mao Bo , Siddaiah Arpith , Menezes Pradeep L. , Liao Yiliang
Published: November 2019

We report a novel laser-based surface processing process, laser shock surface patterning (LSSP) integrating both surface strengthening and patterning effects might lead to broader impacts in tribology research and applications. This process utilizes the laser-induced shockwave loadings to introduce the surface strengthening and patterning effects simultaneously, leading to the fabrication of arrays of micro-indentations or protrusions for the enhanced wear resistance and manipulated friction values. Two process designs, direct-LSSP and indirect-LSSP were proposed and carried out on AZ31B Mg alloys and AISI 1045 steels, respectively. The 3D surface profiles of the samples after LSSP were characterized. The hardness of surface patterns prepared by laser processing was measured. The friction values as affected by laser processing parameters were measured by sliding tests. The relationships among laser processing parameters, micro-feature characteristics, and COF were discussed.
Pressurization and Annealing Effect Analysis Through Hole Expansion
Authors: Nikhare Chetan P.
Published: November 2019

Due to continuous push towards environmental regulations to reduce the impact on the environment by reducing the fuel consumption, and concerns on limited resources, the more sustainable manufacturing is in demand. More abundance material like iron-carbon based alloy are higher strength and easily formable but ways are research to reduce the weight of created part by reducing the thickness due to density issue. Some low dense material is the alternatives but they miss the easy to deform spot. The present study is focused on how to make the material more deformable in the process by evaluating the parameters in deformation through the hole expansion process. For this study, four tests were chosen hemispherical dome test, cylindrical tool test, conical tool test, and biaxial test. In all tests, only the biaxial test machine does not use the rigid tool to deform the hole while all other test used the rigid tool punch to deform the hole. Cruciform specimen dimension was used to make the sample, which fits in all of the considered tests. A hole was created at the center of the specimen which will be expanded in all tests. In all tests the deformation mechanics and hole expansion was studied. Force-displacement curves were plotted and discussed. In addition, tests were also performed on annealed material to understand the hole expansion in ductile material. Based on the results it was observed that biaxial tests do not provide any pressurization effect and all test which includes the rigid tool to deform the hole does. Due to the pressurization effect, the hole was expanded more. It was also noted that the hole expansion was more in ductile material and pressurization effect increases with ductile material.
Some Observations on How Mechanochemical Effect Determines Deformation Mode and Chip Morphology in Cutting of Metals
Authors: Sugihara Tatsuya , Saei Mojib , Viswanathan Koushik , Udupa Anirudh
Published: November 2019

We analyze unsteady plastic flow modes in cutting of metals using high-speed imaging of the deformation zone, in situ. For metals which exhibit high levels of strain hardening, the commonly assumed steady (smooth) flow is inherently unstable. Instead, the cutting is characterized by unsteady sinuous flow, with large-amplitude folding, that is triggered by a plastic buckling instability linked to the material microstructure. A mechanochemical effect caused by Al-Alcohol chemical reaction on workpiece surface, which is coupled to the unsteady flow mode, is highlighted. Experimental results reinforce the hypothesis pertaining to flow stability governing the deformation mode and chip type.
Preliminary Results on Finishing of WC-Co Coating by Magnetorheological Finishing Process
Authors: Ghosh Gourhari , Sidpara Ajay , Bandyopadhyay P. P.
Published: November 2019

Thermal spray coating has the ability to enhance the lifetime of engineering components by reinforcing the surface properties. The surface roughness of the as-sprayed coatings needs to be suitably finished for its end use. The nanofinished WC-Co coatings are widely used in aerospace and automobile industries. In this present investigation, surface grinding followed by the magnetorheological finishing (MRF) processes is employed for finishing of WC-Co coating. Boron carbide (B4C) powder is used as the abrasive particles in the MRF process. MRF spot finishing technique is performed on the ground coating. The plastically deformed layer from the ground surface is removed completely by the gentle mechanical abrasion of MR fluid ribbon. The surface roughness and volume of material removed are measured over the finishing time. It is perceived that the surface roughness of the finishing spot is increased after a threshold machining time. This is attributed to the aging of MR fluid and the mechanical abrasion of wear debris. The experiment is also performed with the assistance of Murakami’s reagent to perform etching and finishing, simultaneously. A comparatively higher finishing rate is observed in this case.
Data Decomposition for Analytics of Engineering Systems: Literature Review, Methodology Formulation, and Future Trends
Authors: Yue Xiaowei
Published: November 2019

Data decomposition is an important step for high-dimensional data analytics of complex engineering systems, but it is less emphasized in our current data analytics domain. This paper summarizes the key techniques for data decomposition, and separates them into two categories. One is deterministic decomposition, and the other is stochastic decomposition. The deterministic decomposition captures geometric or algebraic shape from the high-dimensional datasets directly, which is efficient for feature extraction and dimensionality reduction; while the stochastic decomposition provides probabilistic descriptions, and corresponding statistical distributions are estimated from the datasets. A novel methodology framework of data decomposition is proposed to formulate the existing approaches. Based on this methodology framework, some future research opportunities for new methodology development are discussed for data analytics of engineering systems.
A New Concept of Electrosurgical Tissue Joining Process Using Sequential Compression for Minimal Thermal Damage
Authors: Yang Che-Hao , Amer Maher , Li Wei , Chen Roland K.
Published: November 2019

Minimally invasive surgery is a popular surgical method which allows surgeons to be able to employ small incisions to perform surgical procedures. Electrosurgical tissue joining is one method used in minimally invasive surgery to achieve hemostasis. The two major issues need to be concerned are the quality of the tissue joint and the potential thermal damage to the surrounding tissues. In this study, a new sequential compression concept was introduced. This concept uses a pair of smaller electrodes to sequentially compress and join multiple locations across the tissue to form a joint. Due to the smaller area of the electrode surface, a higher compression level can be achieved with a smaller compressive force. In this study, different joining times including 1.5, 1.6, 1.7, 1.9, 2.1 seconds with a 98% compression ratio were used to join porcine arterial tissue. In each test, three locations were sequentially compressed and joined. The resulting tensile strength, specific strength, energy consumption, and thermal dose from the sequential compression method were compared with those resulting from the nonsequential single compression method. For the 1.9-second joining time, the specific strength is 2.5 times higher than the highest specific strength achieved by the single joining method, meaning that only 40% of energy is needed to achieve an equivalent joint strength. A finite element model was built to estimate the temperature and thermal dose during the sequential joining process and also confirmed that the resulting thermal dose is much lower than the single joining method. The results validated that the sequential compression concept has the potential to minimize the thermal damage during the tissue joining process.
Mechanical and Bond Behavior of an Advanced Quranic Metal-Matrix Composite Material (QMMC)
Authors: Mousa S. , Atta M. , Abd-Elhady A. A. , Abu-Sinna Ahmed , Bafakeeh O. , Sallam H. E. M.
Published: November 2019

The holy Quran, from more than 1400 years, told us that Zul-karnain had made a metallic composite material between iron and copper [1,2] as follows:

“Bring me sheets of iron” — until, when he had leveled [them] between the two mountain walls, he said, “Blow [with bellows],” until when he had made it [like] fire, he said, “Bring me, that I may pour over it molten copper * So Gog and Magog were unable to pass over it, nor were they able [to effect] in it any penetration.”: Translation of verses 96 and 97 in Surah Al-Kahf (18), The holy Quran [3].

According to the above story, the matrix is copper, while reinforcement is iron of this metal matrix composite. The present paper is going to investigate the Metal-Matrix Composite Material (MMC) suggested by Zul-karnain at different manufacturing conditions by using the experimental method. The effect of reinforcement temperature on the integrity of such MMC is one of the main goals of the present work. The mechanical behavior of the present QMMC is also examined in the present research as preliminary study. Furthermore, the finite element method is used to predicate the debonding force of MMC based on Virtual-Crack-Closing-Technique (VCCT).
Image-Guided Variant Geometry Analysis of Layerwise Build Quality in Additive Manufacturing
Authors: Imani Farhad , Chen Ruimin , Diewald Evan , Reutzel Edward , Yang Hui
Published: November 2019

Additive manufacturing (AM) is a new paradigm in design-driven build of customized products. Nonetheless, mass customization and low volume production make the AM quality assurance extremely challenging. Advanced imaging provides an unprecedented opportunity to increase information visibility, cope with the product complexity, and enable on-the-fly quality control in AM. However, in-situ images of a customized AM build show a high level of layer-to-layer geometry variation, which hampers the use of powerful image-based learning methods such as deep neural networks (DNNs) for flaw detection. Few, if any, previous works investigated how to tackle the impact of AM customization on image-guided process monitoring and control. The proposed research is aimed at filling this gap by developing a novel real-time and multi-scale process monitoring methodology for quality control of customized AM builds. Specifically, we leverage the computer-aided design (CAD) file to perform shape-to-image registration and delineate the regions of interests in lay-erwise images. Next, a hierarchical dyadic partitioning methodology is developed to split layer-to-layer regions of interest into subregions with the same number of pixels to provide freeform geometry analysis. Then, we propose a semiparametric model to characterize the complex spatial patterns in each customized subregion and boost the computational speed. Finally, a DNN model is designed to learn and detect fine-grained information of flaws. Experimental results show that the proposed process monitoring and control methodology detects flaws in each layer with an accuracy of 92.50±1.03%. This provides an opportunity to reduce inter-layer variation in AM prior to completion of the build. The proposed methodology can also be generally applicable in a variety of engineering and medical domains that entail image-based process monitoring and control with customized designs.