Deletion Of Element Research Articles

Super‐detailed FEM simulations for full‐scale steel structure with fatal rupture at joints between members—Shaking‐table test of full‐scale steel frame structure to estimate influence of cumulative damage by multiple strong motion: Part 1

AbstractThere have been several studies on analyses using finely meshed finite‐element (FE) models to understand in detail the behaviors of buildings during severe earthquakes. The accuracy of such analyses is often validated by comparing the results to the corresponding full‐scale shaking‐table test. While this approach is highly successful in terms of accuracy, no studies have considered the effect of fractures of members. In this study, numerical analyses are conducted for a steel structure subjected to multiple series of excitations in a full‐scale shaking‐table test considering fractures. The structure is modeled with planar and solid finite elements, and the fracture is treated by the mandatory deletion of elements at the time at which the fracture is observed in the experiment. The results show that by considering the fracture of steel members with the deletion of elements, the history of input excitations, and the resulting damages, the behaviors can be simulated analytically with a much higher accuracy.

CRISPR/Cas9-Mediated Genome Editing in Epstein-Barr Virus-Transformed Lymphoblastoid B-Cell Lines.

Epstein-Barr virus (EBV) efficiently transforms primary human B cells into immortalized lymphoblastoid cell lines (LCLs), which are extensively used in human genetic, immunological and virological studies. LCLs provide unlimited sources of DNA for genetic investigation, but can be difficult to manipulate, for instance because low retroviral or lentiviral transduction frequencies hinder experiments that require co-expression of multiple components. This unit details Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 engineering for robust LCL genome editing. We describe the generation and delivery of single-guide RNAs (sgRNAs), or dual-targeting sgRNAs, via lentiviral transduction of LCLs that stably express Cas9 protein. CRISPR/Cas9 editing allows LCL loss-of-function studies, including knock-out of protein-coding genes or deletion of DNA regulatory elements, and can be adapted for large-scale screening approaches. Low transfection efficiencies are a second barrier to performing CRISPR editing in LCLs, which are not typically lipid-transfectable. To circumvent this barrier, we provide an optimized protocol for LCL nucleofection of Cas9/sgRNA ribonucleoprotein complexes (RNPs) as an alternative route to achieve genome editing in LCLs. These editing approaches can also be employed in other B-cell lines, including Burkitt lymphoma and diffuse large B-cell lymphoma cells, and are highly reproducible. © 2018 by John Wiley & Sons, Inc.

Identification of a candidate enhancer for DMRT3 involved in spastic cerebral palsy pathogenesis

Cerebral palsy (CP) is a major neuronal disease and the most common movement disorder in children. Although environmental factors leading to CP have been greatly investigated, the genetic mechanism underlying CP is not well understood. Here we focused on two clinical reports that characterized a deletion involving the KANK1 gene locus in the 9p24.3 region. One report shows spastic CP and the other shows no spastic CP phenotype. Based on the epigenetic status and evolutionary conservation, we first found a functional genomic element at the noncoding region that was deleted only in patients with spastic CP. This element contains the retinoic acid receptor/retinoid X receptor (RAR/RXR) complex-binding motif that is widely conserved among placental mammals. RAR/RXR ChIP-seq data from mouse F9 embryonal carcinoma cells that were treated with trans-retinoic acids showed that the element has a binding ability. In addition, data regarding chromosome conformation capture from mouse neural progenitor and ES cells suggested that the element spatially interacts with the Doublesex and mab-3 related transcription factor 3 (Dmrt3) gene promoter that is located approximately 120 kb downstream of the RAR/RXR-binding site. Dmrt3 is detected in the developing mouse forebrain and in some interneurons in the spinal cord, and it works as a locomotion coordinator in horses and mice. Thus, the deletion of the cis-regulatory element for DMRT3 in humans may cause impaired development of the forebrain and gait abnormalities, resulting in spastic CP. In conclusion, this study provides new mechanistic insights into the genetic basis of CP.

Evolutionary processes in nature, technology and society –a few common trends

The diversity of branches of knowledge, within which evolutionary approaches are applied to significantly different objects and processes, includes those branches which are especially interesting due to the implementation of the Darwin’s concepts of variation, heredity and selection. This is what is interpreted by some authors as universal selectionism. In this case, objects of evolution may be represented as sequences of symbols, code lines or graphs. This is a method to record heredity of an individual. The recording format allows for mutation (substitution, addition or deletion of certain elements of an individual) and crossing-over during production of offspring from a pair of parent individuals. The approach also allows for a quantitative assessment of the “value” of an individual for evolutionary selection. Such evolution includes, first of all, evolutionary computation, computer-aided modelling of evolution, directed evolution of biomolecules, biological evolution, evolution of technology etc. If we consider the above mentioned examples successively, from computer-based examples to humanitarian one, we can observe definite trends. Firstly, we can see a trend of using “languages” of higher levels to implement an evolutionary problem. Secondly, we can observe a trend of forming “building blocks” in heredity structures as well as a crossing-over mechanism which retains the said blocks. Thirdly, “variation” of an individual is carried out by increasingly high-intelligent methods. Studying of main trends and mutually enriching interchange of experience between such different branches of knowledge may enable to make more reasonable and exact predictions of the results of evolutionary processes and to achieve higher effectiveness of evolutionary search in application areas.

Fracture simulation of cold roll forming process for aluminum 7075-T6 automotive bumper beam using GISSMO damage model

This study deals with cold roll forming process of automotive bumper beam with aluminum 7075 T6. The simulation method for predicting crack during roll forming process of aluminum 7075-T6 automotive bumper beam was developed. Practically W shape bumper beam was tried out cold forming by 12 stages roll forming process. The cracks were observed at some bending regions. Through the numerical analysis result, the cause of crack occurrence and its propagation was judged as caused by multi-axial strain state of coil during roll forming process. So, GISSMO damage model (Generalized Incremental Stress State Dependent Damage model) was adopted for the fracture simulation. In order to find GISSMO damage parameters, tensile tests were conducted on various load paths to derive fracture strains according to triaxiality. Numerical analyses for the tensile test were conducted to correlate element deletion along to element size with load drop obtained by experiments. As results, predicted cracks through the roll forming simulation with GISSMO damage are close to actual try-out result. Besides, a roll design remedies for preventing crack were suggested.

Application of Coupled Ductile Fracture Criterion to Plane Strain Plates

The paper presents a complex material model which covers the elastic-plastic behavior, material deterioration and ductile fracture. The calibration of such model was conducted for Aluminum Alloy (AA) 2024-T351 using specimens with various geometries and loading which covers various stress states. The model was then applied to the simulations of tensile test of plates. The computations were carried out in Abaqus/Explicit using the user subroutine Vectorized User MATerial (VUMAT), where the crack initiation and subsequent propagation was realized using the element deletion technique. The results were compared to the experimental observation in the end.

A novel approach for simulation of soil-tool interaction based on an arbitrary Lagrangian–Eulerian description

Simulation of soil-tool interaction is a challenging task due to the large deformation of soil around the tool, the unconstrained deformation of the free soil surface and the dynamic soil-tool interaction behavior at the interface. In this paper, a novel approach based on an arbitrary Lagrangian-Eulerian finite element (ALE-FE) formulation is used for simulating the soil-blade interaction. Problems associated with severe mesh distortions in a Lagrangian description and those associated with deformable material boundaries in an Eulerian description can be solved by this formulation. By introducing the Eulerian boundaries, the cutting action is simulated as the flow of soil against a stationary blade. No element deletion is needed in ALE-FE method and thus the complete contact surface of soil is retained. The extended Drucker-Prager constitutive law is used to simulate the mechanical behavior of soil. Results indicate that the ALE-FE approach is a useful tool in investigating soil-tool interaction and it is especially suitable for cases where large plastic deformation of soil occurs. Simulations under different cutting conditions demonstrate the robustness and effectiveness of the proposed ALE-FE method. The influences of cutting angle and depth on cutting are also investigated. The failure angle, soil deformation and draft force predicted by ALE-FE model are in good agreement with the published experimental data.

Interlaminar thermal effect analysis of steel bridge deck pavement during gussasphalt mixture paving

ABSTRACTIn this research, the effect of high-temperature asphalt concrete paving on the interlaminar shear behaviour between the steel bridge deck pavement (SBDP) and the orthotropic steel bridge deck (OSBD) is the main objective. A thermal field model of steel box-girder was established based on the transient thermal field theory, and the element deletion method was used to simulate the dynamic paving process of gussasphalt mixture (GAM). The thermal field model was validated by the field monitoring data of Taizhou Yangtze River Highway Bridge in China, and the temperature variations in OSBD during the paving was summarised. Applying the most unfavourable temperature load during GAM paving to the steel box-girder mechanical model, the interlaminar shear stress distribution was calculated, and combined with the shear strength variation of waterproof bonding material during GAM paving, the interlaminar thermal effect of SBDP was evaluated. Results show that the thermal field of steel bridge presents temporal and spatial variation characteristic. The interlaminar shear stress during GAM paving in the low-temperature season is much larger than that in the high-temperature season, but the interlaminar thermal effect is more severe in the high-temperature construction season due to the more inferior shear performance of waterproof bonding material.

Numerical simulations of impact fracture behavior of an automotive windshield glazing: An intrinsic cohesive approach

As an important component of a vehicle, the automotive windshield glazing normally consists of two glass sheets bonded with one polyvinyl butyral (PVB) film. In the context of pedestrian-vehicle accidents, the impact cracking mechanism of the windshield is conductive to pedestrian safety protection and traffic accident reconstruction. The purpose of this paper is to validate the capacity of the intrinsic cohesive zone model (CZM) in impact fracture simulations of a windshield. A windshield finite element (FE) model is established, where cohesive elements are inserted into all the common faces between glass hexahedral finite elements. The fracture behavior of a windshield impacted by a standard adult headform impactor is simulated with the commercial explicit finite element code LS-DYNA. Numerical simulation results are validated by comparison with the corresponding experimental outcomes. For comparison, additional simulations have been performed by the widely used element deletion method (EDM) with a plasticity strain failure criterion. Simulation results show that the intrinsic CZM is more suitable to capture the impact failure characteristics of windshield. Finally, the effects of the glass cohesive strength, mechanical properties of PVB and interfacial adhesion on the impact fracture behavior of the windshield are investigated.

Modeling of Metallic Glass Matrix Composites Under Compression: Microstructure Effect on Shear Band Evolution

The relationship among processing, microstructure, and mechanical performance is the most important for metallic glass matrix composites (MGCs). Numerical modeling was performed on the shear banding in MGCs, and the impacts of particle concentration, morphology, agglomerate, size, and thermal residual stress were revealed. Based on the shear damage criterion, the equivalent plastic strain acted as an internal state variable to depict the nucleation, growth, and coalescence of shear bands. The element deletion technique was employed to describe the process of transformation from shear band to micro-crack. The impedance effect of particle morphology on the propagation of shear bands was discussed, whereby the toughening mechanism was clearly interpreted. The present work contributes to the subsequent strengthening and toughening design of MGCs.

Nasal and otic placode specific regulation of Sox2 involves both activation by Sox-Sall4 synergism and multiple repression mechanisms

Transcription factor gene Sox2 is expressed throughout sensory development, but the enhancers that regulate the gene vary depending on the developmental stages and tissues. To gain new insights into the gene regulatory network in sensory placode specification, regulation of the nasal-otic bispecific NOP1 enhancer of Sox2 was investigated in chicken embryos. Deletion and mutational analyses using electroporation showed that transcriptional repression mechanisms in combination with activation mechanisms determine placodal specificity. Activation of the NOP1 enhancer involves synergistic action by Sall4 and SoxB1/SoxE factors that bind to the adjacent sites. Deletion of repressive elements resulted in widening of the tissue area for enhancer activity to a region where the expression of Sall4 and SoxB1/E overlaps, e.g., the CNS and neural crest. Among multiple repressive elements that contribute to the placodal confinement of the NOP1 enhancer activity, CACCT/CACCTG motifs bound by Zeb/Snail family repressors play important roles. Overexpression of δEF1 (Zeb1) or Snail2 (Slug) strongly inhibited NOP1 activity. These data indicate that both activation by Sall4-Sox synergism and multiple repression mechanisms involving Zeb/Snail factors are essential for Sox2 regulation to be confined to the nasal and otic placodes.

A contact and sliding interface algorithm for the combined particle-element method

This article presents a new contact and sliding interface algorithm for the Combined Particle-Element Method (CPEM) as applied to intense loading computations that include severe distortions. The CPEM is a recent development that allows for conversion of distorted elements into meshless particles. The advantages of this method are that the lower-strained particles (stress points) are computed with a fast and accurate finite-element formulation, and the higher-strained particles are computed with a meshless-particle formulation that can handle severe distortions. Furthermore, the meshless-particle algorithm, with Moving Least Squares (MLS) strain rates and Element-Free Galerkin (EFG) weak-form forces, is consistent and does not exhibit tensile instabilities. It is also well suited for conversion of finite elements into variable-connectivity meshless particles because the conversion does not require deletion of elements and addition of particles. Instead there is simply a branch point based on equivalent plastic strain. The basic approach can also be used for the element algorithm only or the particle algorithm only. Unfortunately, the CPEM has some characteristics that can introduce significant inaccuracies when used with existing contact/sliding algorithms. This article identifies and evaluates these issues, it provides a new and improved algorithm, and it demonstrates the capabilities and accuracy of the new algorithm with example computations.

Loss of p53-inducible long non-coding RNA LINC01021 increases chemosensitivity.

We have previously identified the long non-coding RNA LINC01021 as a direct p53 target (Hünten et al. Mol Cell Proteomics. 2015; 14:2609-2629). Here, we show that LINC01021 is up-regulated in colorectal cancer (CRC) cell lines upon various p53-activating treatments. The LINC01021 promoter and the p53 binding site lie within a MER61C LTR, which originated from insertion of endogenous retrovirus 1 (ERV1) sequences. Deletion of this MER61C element by a CRISPR/Cas9 approach, as well as siRNA-mediated knockdown of LINC01021 RNA significantly enhanced the sensitivity of the CRC cell line HCT116 towards the chemotherapeutic drugs doxorubicin and 5-FU, suggesting that LINC01021 is an integral part of the p53-mediated response to DNA damage. Inactivation of LINC01021 and also its ectopic expression did not affect p53 protein expression and transcriptional activity, implying that LINC01021 does not feedback to p53. Furthermore, in CRC patient samples LINC01021 expression positively correlated with a wild-type p53-associated gene expression signature. LINC01021 expression was increased in primary colorectal tumors and displayed a bimodal distribution that was particularly pronounced in the mesenchymal CMS4 consensus molecular subtype of CRCs. CMS4 tumors with low LINC01021 expression were associated with poor patient survival. Our results suggest that the genomic redistribution of ERV1-derived p53 response elements and generation of novel p53-inducible lncRNA-encoding genes was selected for during primate evolution as integral part of the cellular response to various forms of genotoxic stress.

Developing the models of patterns in the design of requirements to an information system at the knowledge level

Results of research into mining and processing of knowledge from IS requirements were analyzed. Modification of the frame-based model of knowledge that allows description of knowledge about structures of data and interaction processes is considered. The essence of modification is to extend the frame with descriptions of a totality of methods, associated with a frame as a whole, as well as descriptions of interfaces of a frame. This modification also makes it possible in a formalized way to describe the problem of automated synthesis of IS information and software as a set of one-to-one mappings of frame descriptions. Theoretical-multiple models of structural IS requirements design patterns at the knowledge level were developed. These models allow describing the knowledge, derived from IS requirements descriptions in the form of a network of frames. This network consists of individual frames, interfaces of frames and relationships between them. The use of these models makes it possible to formalize the process of designing of IS architecture based on knowledge, derived from IS requirements descriptions, which significantly reduces the time spent on IS creation. Theoretical-multiple models of behavioral IS requirements design patterns at the knowledge level were developed. These models establish the main features of operations of addition, modifications and deletion of elements of structural IS requirements design patterns. In addition, developed models describe operations on formation of knowledge-oriented descriptions of IS architecture in the form of a network of frames and interfaces. Application of these models enables us to standardize implementation of operations on the knowledge, derived from patterns, and on patterns of designing structural frames. It was proposed to consider implementation of the developed models in the form of specialized data showcases and sets of SQL-commands that implement developed behavioral patterns.

Experimental and Thermo-Mechanical Modeling Optimization of Thermal Friction Drilling for AISI 304 Stainless steel

The main purpose of this research is to investigate experimentally the optimal process parameters of thermal friction drilling process, based on the design of experiment method coupled with fuzzy logic and analysis of variance techniques, considering the resultant axial force and bushing length. A friction drilling machine is designed, and manufactured in Shoman Company — Egypt to perform the experimental work, and the tools are offered by Flowdrill Company — Netherlands. A temperature-dependent dynamic explicit modeling is applied, considering adaptive meshing, element deletion, and mass scaling techniques. The resultant optimal parameter levels combination is: 9.2mm tool diameter, 30° friction angle, 50% friction contact area ratio, 60mm/min feed rate, and 3500rpm rotational speed. A comparison is performed between the experimental and thermo-mechanical modeling results, considering the axial force, and a similar trend is achieved. Also a regression analysis is applied to predict the expected axial force and bushing length and confirmed by confirmation test.

On the Source of the Systematic Error of the Pressure Measurement Film Applied to Wheel–Rail Normal Contact Measurements

This paper presents research activities regarding the systematic error of the pressure measurement film when measuring the area of the wheel–rail contact. In particular, an explanation for the different error values shown by the different film types was sought. A finite element model was created based on the assumption that not only the film, but also the microcapsules on top of it alter the results. The performance of the existing film models was enhanced by defining microcapsules with element failure and deletion behaviors. The new model was capable of reproducing the trend shown by the systematic error in the experiments. The simulation results confirmed that the measurement error of a certain film type is not only caused by the film itself, but also depends on the failure pressure and especially the diameter of the capsules.

Evaluation of wood material models for the numerical assessment of cutting forces in chipping processes

Generally, wood chipping represents an important procedure in the wood processing and forestry industry. To improve structural components like chipping tools, knowledge of the properties of local timber including resistance against chipping as well as the dynamically acting process forces is of utmost significance. The aim of this work is to experimentally evaluate service-induced stresses on machinery parts to create a numerical material model, which is capable of revealing similar resistance against cutting as natural wood. To this end, a small-scale cutting machine has been designed, incorporating a bladeholder with strain gauges applied, measuring the resulting mechanical stresses during the chipping process by focussing on different wood species. Spruce is utilized as a variety with a lower density and European beech for higher density timber applications. The test results demonstrate a distinct difference by cutting both materials, whereby European beech indicates more than twice the resistance against chipping compared to spruce. Setting two different, relatively acute rake angles on the cutting tool does not reveal a fundamental difference for chipping. To evaluate the numerical wood material model, an isotropic ductile damage model, usually applied to ductile metals, was implemented in this study. Based on a sensitivity study of the material properties in the course of the numerical simulation, a possible approach is presented that explains how to change the cutting resistance, depending on the blade movement direction and the angle of the main grain of the timber. In a comparison of different types of mechanical stress from the numerical analysis and experimental tests, the results exhibit strong correlation. Element damage and deletion correspond at similar load levels, exhibiting a deviation of no more than 24%.

Long non-coding RNA SeT and miR-155 regulate the Tnfα gene allelic expression profile.

It is becoming increasingly appreciated that the non-coding genome may have a great impact on the regulation of chromatin structure and gene expression. The innate immune response can be mediated upon lipopolysaccharide stimulation of macrophages which leads to immediate transcriptional activation of early responsive genes including tumor necrosis factor alpha (Tnfα). The functional role of non-coding RNAs, such as lncRNAs and microRNAs, on the transcriptional activation of proinflammatory genes and the subsequent regulation of the innate immune response is still lacking mechanistic insights. In this study we wanted to unravel the functional role of the lncRNA SeT, which is encoded from the murine Tnfα gene locus, and miR-155 on the transcriptional regulation of the Tnfα gene. We utilized genetically modified mice harboring either a deletion of the SeT promoter elements or the mature miR-155 and studied the response of macrophages to lipopolysaccharide (LPS) stimulation. We found that decreased expression of the lncRNA SeT in murine primary macrophages resulted in increased mortality of mice challenged with LPS, which was corroborated by increased Tnfα steady state mRNA levels and a higher frequency of biallelically expressing macrophages. On the contrary, miR-155 deletion resulted in reduced Tnfα mRNA levels supported by a lower frequency of biallelically expressing macrophages upon stimulation with LPS. In both cases, in the absence of either lncRNA SeT or miR-155 we observed a deregulation of the Tnfα allele homologous pairing, previously shown to regulate the switch from mono- to bi-allelic gene expression. Although lncRNA SeT was not found to be a direct target of miR-155 its stability was increased upon miR-155 deletion. This study suggests a role of the non-coding genome in mediating Tnfα mRNA dosage control based on the regulation of homologous pairing of gene alleles and their subsequent biallelic expression.

Modeling of thermal response and ablation in laminated glass fiber reinforced polymer matrix composites due to lightning strike

Abstract Thermal response and ablation of laminated glass fiber reinforced polymer matrix composites subjected to lightning strike are studied. The associated nonlinear time-dependent heat transfer model includes specific features of lightning arcs observed in physical measurements such as lightning channel radius expansion, non-uniform lightning current density, and associated heat flux. Moving spatially and temporally non-uniform lightning-current-induced heat flux boundary and moving boundary due to material phase transition caused by rapid surface ablation are also included. To predict moving phase boundary in the laminated anisotropic composites, an element deletion method is developed and embedded into finite element analysis (FEA), which is performed using ABAQUS. The Umeshmotion + ALE method based on the user subroutine Umeshmotion and arbitrary Lagrangian–Eulerian (ALE) adaptive mesh technique is also used, when applicable (i.e., moving phase boundary is confined within a top layer of the composite laminate). Heat transfer analysis is performed for a non-conductive laminated glass fiber reinforced polymer matrix composite panel representing the SNL 100-00 wind turbine tip. Thermal response of the panel subjected to pulsed and continuing lightning currents at three different lightning protection levels, LPL I, LPL II, and LPL III, is studied. Temperature-dependent anisotropic thermal properties of the composite panel are included in the analysis. The FEA results include temperature distributions and ablation zone profiles. The results show the Umeshmotion + ALE method is sufficient for the pulsed lightning current at all three LPL levels since the moving phase boundary, i.e. the ablation front, is found to be confined within the top layer of the laminate. For the continuing lightning currents at all three LPL levels, the Umeshmotion + ALE method is not applicable since the moving phase boundary comes to rest at depths exceeding the thickness of the top layer of the composite laminate.

09.10: Shear damage evaluation of bolted steel joints

ABSTRACTThe purpose of this study is to address a way of predicting the ductility capacity of steel joints. Recent research studies show that a joints’ ability to perform under elevated deformations, without fracturing, is a key factor in enabling mechanisms preventing collapse to be developed, and thus, improve the overall robustness of steel framed structures. This theme is becoming rather timely as building owners and insurers try to assess the collapse risk of their buildings, and the probability of a wide spread collapse if subjected to extreme events, either due to natural or terrorist causes. However, regarding this matter, current design code guidelines are limited to a prescriptive approach, by recommending a nominal tying force to be met, or quantifying a force that reproduces accidental scenarios, such as an impact of a vehicle, ships or helicopters, which do not address the overall behavior and performance of the structure.This paper presents an evaluation of the shear damage state of a bolted steel joint. For that, it is necessary to establish the shear damage parameters that are required to numerically obtain the rupture of steel elements, allowing the prediction of the ductility of steel joints. Previous authors’ research has showed that a ductile damage model may be insufficient to capture its end‐plate fracture and to establish a joints’ rupture. Hence, this study looks forward to improve the damage threshold for smaller triaxial stress states, within the shear and compression zones.In order to achieve this objective, a finite element model is developed and compared with real scale test results of a bolted steel joint under bending. The numerical model takes into account the strain softening of the material by means of a continuum damage mechanics approach and making use of the “element deletion” technique to approximate the fracture pattern of the studied joint. The analyses are carried out using the finite element software ABAQUS.