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discrete element method

Ruth A Bush, Cynthia D Connelly, Alexa Pérez, Halsey Barlow, George J Chiang
BACKGROUND: Little is known about the health care utilization patterns of individuals with pediatric autism spectrum disorder (ASD). OBJECTIVES: Electronic health record (EHR) data provide an opportunity to study medical utilization and track outcomes among children with ASD.  Methods: Using a pediatric, tertiary, academic hospital's Epic EHR, search queries were built to identify individuals aged 2-18 with International Classification of Diseases, Ninth Revision (ICD-9) codes, 299...
July 19, 2017: Applied Clinical Informatics
A Menżyk, A Martyna, G Zadora
Polymers have become a ubiquitous element of our culture. Therefore, these materials may play an important role in forensic investigations, serving as mute witnesses of occurrences such as car accidents. In this study, the possibilities provided by the likelihood ratio (LR) approach to estimate the evidential value of observed similarities and differences, and to discriminate among NIR spectral data originating from polypropylene automotive parts and household items, were investigated. Since the construction of LR models requires the introduction of only a few variables, the main objective was to reduce the dimensionality of registered spectra, which are characterised by over a thousand variables...
September 15, 2017: Analyst
In Sook Park, Yeon Ok Suh, Hae Sook Park, So Young Kang, Kwang Sung Kim, Gyung Hee Kim, Yeon-Hee Choi, Hyun-Ju Kim
Purpose: The purpose of this study was to improve the quality of items on the Korean Nursing Licensing Examination by developing and evaluating case-based items that reflect integrated nursing knowledge. Methods: We conducted a cross-sectional observational study to develop new case-based items. The methods for developing test items included expert workshops, brainstorming, and verification of content validity. After a mock examination of undergraduate nursing students using the newly developed case-based items, we evaluated the appropriateness of the items through classical test theory and item response theory...
September 11, 2017: Journal of Educational Evaluation for Health Professions
W Aerts, A Scarton, F De Groote, A Guiotto, Z Sawacha, C Cobelli, J Vander Sloten, I Jonkers
Plantar pressure simulation driven by integrated 3D motion capture data, using both a finite element and a discrete element model, is compared for ten healthy and ten diabetic neuropathic subjects. The simulated peak pressure deviated on average between 16.7 and 34.2% from the measured peak pressure. The error in the position of the peak pressure was on average smaller than 4.2 cm. No method was more accurate than the other although statistical differences were found between them. Both techniques are thus complementary and useful tools to better understand the alteration of diabetic foot biomechanics during gait...
September 12, 2017: Computer Methods in Biomechanics and Biomedical Engineering
Baderaldeen A Altazi, Geoffrey G Zhang, Daniel C Fernandez, Michael E Montejo, Dylan Hunt, Joan Werner, Matthew C Biagioli, Eduardo G Moros
Site-specific investigations of the role of radiomics in cancer diagnosis and therapy are emerging. We evaluated the reproducibility of radiomic features extracted from (18) Flourine-fluorodeoxyglucose ((18) F-FDG) PET images for three parameters: manual versus computer-aided segmentation methods, gray-level discretization, and PET image reconstruction algorithms. Our cohort consisted of pretreatment PET/CT scans from 88 cervical cancer patients. Two board-certified radiation oncologists manually segmented the metabolic tumor volume (MTV1 and MTV2 ) for each patient...
September 11, 2017: Journal of Applied Clinical Medical Physics
Manuel Zündel, Edoardo Mazza, Alexander E Ehret
In this paper, a discrete random network modelling approach specific to electrospun networks is presented. Owing to the manufacturing process, fibres in these materials systems have an enormous length, as compared to their diameters, and form sparse networks since fibre contact over thickness is limited to a narrow range. Representative volume elements are generated, in which fibres span the entire domain, and a technique is developed to apply computationally favourable periodic boundary conditions despite the initial non-periodicity of the networks...
September 6, 2017: Soft Matter
Peter Loidolt, Stefan Madlmeir, J G Khinast
Filling a dosator nozzle moving into a powder bed was investigated using the Discrete Element Method (DEM). Various particle diameters and contact properties were modeled. The simulations qualitatively showed the influence of powder properties on the amount of dosed powder. Two factors that influence the dosed mass were observed. First, the ratio between the particle and dosator diameters affects the packing of particles inside the dosator chamber. Second, the flow behavior of the powder significantly modifies its filling and compression behavior...
September 1, 2017: International Journal of Pharmaceutics
Pengfei Liu, Qinyan Xing, Dawei Wang, Markus Oeser
Analyses of dynamic responses are significantly important for the design, maintenance and rehabilitation of asphalt pavement. In order to evaluate the dynamic responses of asphalt pavement under moving loads, a specific computational program, SAFEM, was developed based on a semi-analytical finite element method. This method is three-dimensional and only requires a two-dimensional FE discretization by incorporating Fourier series in the third dimension. In this paper, the algorithm to apply the dynamic analysis to SAFEM was introduced in detail...
August 30, 2017: Materials
Carlos Calderilla, Fernando Maya, Víctor Cerdà, Luz O Leal
The development of advanced manufacturing techniques is crucial for the design of novel analytical tools with unprecedented features. Advanced manufacturing, also known as 3D printing, has been explored for the first time to fabricate modular devices with integrated features for disk-based automated solid-phase extraction (SPE). A modular device integrating analyte oxidation, disk-based SPE and analyte complexation has been fabricated using stereolithographic 3D printing. The 3D printed device is directly connected to flow-based analytical instrumentation, replacing typical flow networks based on discrete elements...
December 1, 2017: Talanta
Hong Sui, Yuzhou Rong, Jing Song, Dongge Zhang, Haibo Li, Peng Wu, Yangyang Shen, Yujuan Huang
Mechanochemical destruction has been proposed as a promising, non-combustion technology for the disposal of toxic, halogenated, organic pollutants. In the study presented, additives including Fe, Zn, Fe-Zn bimetal, CaO and Fe2O3 were tested for their effectiveness to remove DDTs by MC. The results showed that Fe-Zn bimetal was the most efficient additive, with 98% of DDTs removed after 4h. The Fe-Zn mass ratio was optimized to avoid possible spontaneous combustion of the ground sample during subsample collection...
August 12, 2017: Journal of Hazardous Materials
M Dorn, F Eschbach, D Hekmat, D Weuster-Botz
It is well known that packing non-uniformity may cause peak asymmetry and limit the performance of packed-bed chromatographic columns. However, understanding of the reasons leading to packing non-uniformity is still limited. Therefore, the effect of different column packing methods, i.e. dynamic axial compression (DAC), flow packing, and combinations of both on the hydrodynamic packing heterogeneity and stability of packings composed of polymer-based compressible porous resins with a mean diameter of 90μm was investigated experimentally as well as in-silico...
August 8, 2017: Journal of Chromatography. A
Adam J Brown, David C James
Promoter functionality is highly context dependent, as exemplified by gene-specific expression profiles across different tissues and cell types. Cell type-specific promoter regulation is a function of each cell's unique complement of transcriptional machinery components. Accordingly, to achieve high levels of transcriptional activity within a particular cell type, synthetic promoters must be specifically designed to harness those cells discrete repertoire of available transcription factors . Here, we describe a method for constructing very strong cell type-specific synthetic promoters for use in any given mammalian host cell...
2017: Methods in Molecular Biology
Meng-Shan Wu, Hui-Li Han, Cui Yao, Xiao-Rong He, Jun-Yi Zhang, Ting-Yun Shi
We calculate the rovibrational bound levels with total angular momentum J = 0, 1 of (40)Ar2(84)Kr trimer using the slow variable discretization method combined with the finite-element method-discrete variable representation basis. The statistical distributions of the rovibrational levels for J(Π)=0(e), 1(e), and 1(o) symmetries are presented and the effects of the Axilrod-Teller potential term are considered. For the 0(e) and 1(e) symmetries, the Axilrod-Teller term makes the spectra become fully chaotic. However, for the 1(o) symmetry, statistical properties depend mainly on the coupling between K = 0 and K = 1 and the Axilrod-Teller term has a small effect...
August 7, 2017: Journal of Chemical Physics
Ning Zhu, Dennj De Meo, Erkan Oterkus
An ordinary state-based peridynamic formulation is developed to analyse cubic polycrystalline materials for the first time in the literature. This new approach has the advantage that no constraint condition is imposed on material constants as opposed to bond-based peridynamic theory. The formulation is validated by first considering static analyses and comparing the displacement fields obtained from the finite element method and ordinary state-based peridynamics. Then, dynamic analysis is performed to investigate the effect of grain boundary strength, crystal size, and discretization size on fracture behaviour and fracture morphology...
December 2, 2016: Materials
Zixin Yin, Yuxing Peng, Zhencai Zhu, Zhangfa Yu, Tongqing Li
The impact behavior between the charge and lifter has significant effect to address the mill processing, and is affected by various factors including mill speed, mill filling, lifter height and media shape. To investigate the multi-body impact load behavior, a series of experiments and Discrete Element Method (DEM) simulations were performed on a laboratory-scale mill, in order to improve the grinding efficiency and prolong the life of the lifter. DEM simulation hitherto has been extensively applied as a leading tool to describe diverse issues in granular processes...
July 31, 2017: Materials
Daisuke Nishiura, Hide Sakaguchi, Akira Aikawa
Simulation of a large number of deformable bodies is often difficult because complex high-level modeling is required to address both multi-body contact and viscoelastic deformation. This necessitates the combined use of a discrete element method (DEM) and a finite element method (FEM). In this study, a quadruple discrete element method (QDEM) was developed for dynamic analysis of viscoelastic materials using a simpler algorithm compared to the standard FEM. QDEM easily incorporates the contact algorithm used in DEM...
June 3, 2017: Materials
Tongqing Li, Yuxing Peng, Zhencai Zhu, Shengyong Zou, Zixin Yin
Aiming at predicting what happens in reality inside mills, the contact parameters of iron ore particles for discrete element method (DEM) simulations should be determined accurately. To allow the irregular shape to be accurately determined, the sphere clump method was employed in modelling the particle shape. The inter-particle contact parameters were systematically altered whilst the contact parameters between the particle and wall were arbitrarily assumed, in order to purely assess its impact on the angle of repose for the mono-sized iron ore particles...
May 11, 2017: Materials
Erkai Watson, Martin O Steinhauser
In this paper, we introduce a computational model for the simulation of hypervelocity impact (HVI) phenomena which is based on the Discrete Element Method (DEM). Our paper constitutes the first application of DEM to the modeling and simulating of impact events for velocities beyond 5 kms(-1). We present here the results of a systematic numerical study on HVI of solids. For modeling the solids, we use discrete spherical particles that interact with each other via potentials. In our numerical investigations we are particularly interested in the dynamics of material fragmentation upon impact...
April 2, 2017: Materials
Amin Yaghoobi, Mi G Chorzepa, S Sonny Kim, Stephan A
Concrete is a complex heterogeneous material, and thus, it is important to develop numerical modeling methods to enhance the prediction accuracy of the fracture mechanism. In this study, a two-dimensional mesoscale model is developed using a non-ordinary state-based peridynamic (NOSBPD) method. Fracture in a concrete cube specimen subjected to pure tension is studied. The presence of heterogeneous materials consisting of coarse aggregates, interfacial transition zones, air voids and cementitious matrix is characterized as particle points in a two-dimensional mesoscale model...
February 10, 2017: Materials
Xiaolin Huang, Qi Zhao, Shengwen Qi, Kaiwen Xia, Giovanni Grasselli, Xuguang Chen
This paper numerically investigates the seismic response of the filled joint under high amplitude stress waves using the combined finite-discrete element method (FDEM). A thin layer of independent polygonal particles are used to simulate the joint fillings. Each particle is meshed using the Delaunay triangulation scheme and can be crushed when the load exceeds its strength. The propagation of the 1D longitude wave through a single filled joint is studied, considering the influences of the joint thickness and the characteristics of the incident wave, such as the amplitude and frequency...
December 27, 2016: Materials
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