Computer-aided Study Research Articles

An Optimal Algorithm for Midcourse Guidance Law Under Wind Disturbance

The guidance laws are commonly designed to yield as small a miss distance as possible, harmonious with the missile’s acceleration capability. In recent decades, the concept of optimized guidance law is well understood in applications where information concerning the target range and line-of-sight angle is available. Researchers' efforts have been continually made to apply modern control theory to conventional and adaptive autopilot designs, even though the classical theory is still applicable to autopilots. It can be noted that it is desirable to perform a detailed computer-aided feasibility study within the context of a realistic missile-target engagement model. Development and evaluation of guidance and control laws for simplified missile-target engagement scenarios are extended and adapted to the air-to-air missile situation and implemented in a complete three-dimensional engagement model. Thus, this study proposed a computational method for constructing an optimal midcourse guidance law, which is based on the optimal control theory and initial boundary conditions. This proposed guidance law is derived from an optimal control theory with the boundary conditions such as allowed relative distance between missile and target at the final time, low line-of-sight rate. A numerical simulation verifies the performance of this guidance law with the impact of harmonic wind. The simulation results demonstrate that the quality of effectiveness as well as the applicability of this proposed algorithm.

Sliding instability characteristics and re-stabilization mechanism of key stratum in thin-topsoil SCS mining: a computer-aided case study from the Niushan Coal Mine, China

Roof step subsidence and support crushing accidents caused by the sliding instability of fractured single key stratum often occur in shallow coal seam (SCS). For this reason, the exploration of fracture displacement laws and control mechanism of key stratum in thin-topsoil SCS is of great significance for both roof control and safety production. From this perspective, in this study, numerical simulation and theoretical analysis were conducted to establish a mechanical model of the key stratum structure after sliding instability in thin-topsoil SCS. Moreover, its instability characteristics and re-stabilization control mechanism were analyzed. The results revealed that the fractured key stratum block could reach re-stabilization without any support crushing after sliding instability in thin-topsoil SCS depending on the significant unloading effect of the topsoil. The mechanical model of the key stratum structure after sliding instability was also analyzed to obtain the criterion for the re-stabilization of the sliding instable rock block. The computational analysis corroborated that increasing the support intensity could promote the re-stabilization of fractured key stratum block after sliding instability, and the required support working resistance could be obtained for preventing support crushing incidents.

Computer-Aided Study of Double Extensions of Restricted Lie Superalgebras Preserving the Nondegenerate Closed 2-Forms in Characteristic 2

A Lie (super)algebra with a nondegenerate invariant symmetric bilinear form B is called a nis-(super)algebra. The double extension of a nis-(super)algebra is the result of simultaneous adding to a central element and a derivation so that is a nis-algebra. Loop algebras with values in simple complex Lie algebras are most known among the Lie (super)algebras suitable to be doubly extended. In characteristic 2, the notion of double extension acquires specific features. Restricted Lie (super)algebras are among the most interesting modular Lie superalgebras. In characteristic 2, using Grozman’s Mathematica-based package SuperLie, we list double extensions of restricted Lie superalgebras preserving the nondegenerate closed 2-forms with constant coefficients. The results are proved for the number of indeterminates ranging from 4 to 7—sufficient to conjecture the pattern for larger numbers. Considering multigradings allowed us to accelerate computations up to 100 times.

Optimal Coarse-Grained Site Selection in Elastic Network Models of Biomolecules.

Elastic network models, simple structure-based representations of biomolecules where atoms interact via short-range harmonic potentials, provide great insight into a molecule’s internal dynamics and mechanical properties at extremely low computational cost. Their efficiency and effectiveness have made them a pivotal instrument in the computer-aided study of proteins and, since a few years, also of nucleic acids. In general, the coarse-grained sites, i.e. those effective force centers onto which the all-atom structure is mapped, are constructed based on intuitive rules: a typical choice for proteins is to retain only the Cα atoms of each amino acid. However, a mapping strategy relying only on the atom type and not the local properties of its embedding can be suboptimal compared to a more careful selection. Here, we present a strategy in which the subset of atoms, each of which is mapped onto a unique coarse-grained site of the model, is selected in a stochastic search aimed at optimizing a cost function. The latter is taken to be a simple measure of the consistency between the harmonic approximation of an elastic network model and the harmonic model obtained through exact integration of the discarded degrees of freedom. The method is applied to two representatives of structurally very different types of biomolecules: the protein adenylate kinase and the RNA molecule adenine riboswitch. Our analysis quantifies the substantial impact that an algorithm-driven selection of coarse-grained sites can have on a model’s properties.

A clinicopathological retrospective epidemiological analysis of benign tumors and tumor-like lesions in the oral and maxillofacial region, diagnosed at the University of Szeged, Department of Oral Medicine (1960-2014)

In a clinicopathological retrospective epidemiological study we investigated benign tumors and tumor-like lesions located in the orofacial region, diagnosed at the Universiy of Szeged, Department of Oral Medicine. During a 54-year period (1960-2014), 14661 biopsies were taken. The included subjects were 7491 patients diagnosed with benign tumors and tumor-like lesions. The average age of patients was 55.3 years, 2823 (37.7%) patients were male and 4668 (62.3%) female. The male:female ratio was 1:1.65. Most of the patients included in the study were aged 51-60 (1280, 17.1%). The number of children was 1014 (13.6%) and the number of adults was 6477 (86.3%). The number of non-neoplasms was 6420 (85.7%), being significantly higher than the number of neoplasms (1071, 14.3%). Most of the lesions were of mesenchymal origin (5574, 77.4%); the number of lesions of non-mesenchymal origin was 982 (13.1%). The most prevalent type of lesions was traumatic fibroma (fibrosis): 1806 (32.4%). The most common lesion type in the group of lesions of infectious/inflammational origin was pyogenic granuloma, the number of which was 465 (8.3%). The most common cystic lesion was mucocele (805, 10.7%). Hemangioma was the most frequent lesion type among developmental anomalies with the number of 815 (14.6%). The most common location of the lesions was the lip in 2081 cases (27.8%), followed by the gingiva in 2024 cases (27.0%), bucca in 1069 cases (14.3%), tongue in 981 cases (13.1%), and the facial skin in 695 cases (9.3%). After taking biopsy, the majority of benign lesions were treated with cryo-, laser-, or combined (cryo and laser) surgery. The present computer-aided study showed that irritational fibroma was the most common orofacial benign tumor, and the lip was the most frequent location. The diagnostic classification and the methodology are considerably different in the majority of the studies, which may hinder the exact comparison with other surveys from different regions of the world. Orv Hetil. 2018; 159(37): 1516-1524.

The sextuply shortened binary Golay code is optimal

The maximum size of unrestricted binary three-error-correcting codes has been known up to the length of the binary Golay code, with two exceptions. Specifically, denoting the maximum size of an unrestricted binary code of length n and minimum distance d by A(n, d), it has been known that $$64 \le A(18,8) \le 68$$ and $$128 \le A(19,8) \le 131$$ . In the current computer-aided study, it is shown that $$A(18,8)=64$$ and $$A(19,8)=128$$ , so an optimal code is obtained even after shortening the extended binary Golay code six times.

Geometric and computer-aided spline hob modeling

The paper considers acquiring the spline hob geometric model. The objective of the research is the development of a mathematical model of spline hob for spline shaft machining. The structure of the spline hob is described taking into consideration the motion in parameters of the machine tool system of cutting edge positioning and orientation. Computer-aided study is performed with the use of CAD and on the basis of 3D modeling methods. Vector representation of cutting edge geometry is accepted as the principal method of spline hob mathematical model development. The paper defines the correlations described by parametric vector functions representing helical cutting edges designed for spline shaft machining with consideration for helical movement in two dimensions. An application for acquiring the 3D model of spline hob is developed on the basis of AutoLISP for AutoCAD environment. The application presents the opportunity for the use of the acquired model for milling process imitation. An example of evaluation, analytical representation and computer modeling of the proposed geometrical model is reviewed. In the mentioned example, a calculation of key spline hob parameters assuring the capability of hobbing a spline shaft of standard design is performed. The polygonal and solid spline hob 3D models are acquired by the use of imitational computer modeling.

An Investigation of Failure Envelope for Skirted Foundations in Soft Clay Based on Computer-Aided Analyses

The stability of skirted foundations subjected to combined vertical, horizontal and moment loading is of importance to the offshore engineering. The paper reports a computer-aided study on the effects of strength anisotropy and foundation embedment depth on the combined bearing capacity of skirted foundations. The results show that when the traditional load reference point, i.e. the base center, is utilized, the shape of failure envelope for skirted foundations is strongly dependent on embedment ratio, however independent of soil strength anisotropy. To gain a unified equation to describe the shapes of failure envelopes for skirted foundations with a range of embedment ratios, the searching algorithm for the optimal load reference point is implemented. Based on the optimal load reference point, the failure envelope obtained can be approximated as an ellipse in normalized moment-horizontal load space. Then a closed-form equation is proposed, which can be used to evaluate the bearing capacity of skirted foundations in soft clay considering strength anisotropy effect.

An Integrated Computational Approach for Plant-Based Protein Tyrosine Phosphatase Non-Receptor Type 1 Inhibitors.

Background: Protein tyrosine phosphatase non-receptor type 1 is a therapeutic target for the type 2 diabetes mellitus. According to the International Diabetes Federation 2015 report, one out of 11 adults suffers from diabetes mellitus globally.Objective: Current anti-diabetic drugs can cause life-threatening side-effects. The present study proposes a pipeline for the development of effective and plant-derived anti-diabetic drugs that may be safer and better tolerated.Methods: Plant-derived protein tyrosine phosphatase non-receptor type 1 inhibitors possessing antidiabetic activity less than 10μM were used as a training set. A common feature pharmacophore model was generated. Pharmacophore-based screening of plant-derived compounds of the ZINC database was conducted using ZINCpharmer. Screened hits were assessed to evaluate their drug-likeness, pharmacokinetics, detailed binding behavior, and aggregator possibility based on their physiochemical properties and chemical similarity with reported aggregators.Results: Through virtual screening and in silico pharmacology protocol isosilybin (ZINC30731533) was identified as a lead compound with optimal properties. This compound can be recommended for laboratory tests and further analyses to confirm its activity as protein tyrosine phosphatase non-receptor type 1 inhibitor.Conclusion: The present study has identified plant-derived anti-diabetic virtual lead compound with the potential to inhibit protein tyrosine phosphatase non-receptor type 1, which may be helpful to enhance insulin production. This computer-aided study could facilitate the development of novel pharmacological inhibitors for diabetes treatment.

Survey on Ocular Blood Vessel Segmentation

The eye is sometimes said to provide a window into the health of a person for it is only with the eye that one can actually see the exposed flesh of the subject without using invasive procedures. There are a number of diseases, particularly vascular disease that leave telltale markers in the retina. The retina can be photographed relatively straightforwardly with a funds camera and now with retinal image processing there is much interest in computer analysis of retinal images for identifying and quantifying the effects of diseases such as cardio vascular diseases. A retinal image provides a snapshot of what is happening inside the human body. In particular, the ceremonial of the retinal blood vessels has been shown to imitate the cardiovascular condition of the body. Retinal images provide considerable information on pathological changes caused by local ocular disease which reveals diabetes, hypertension, arteriosclerosis, cardiovascular disease and stroke. Computer-aided study of retinal image plays a central role in diagnostic procedures. However, automatic retinal segmentation is complicated by the fact that retinal images are often noisy, poorly contrasted, and the vessel widths can vary from very small to very large. So in this survey we can review various segmentation techniques to improve the accuracy in blood vessel extraction.

Computer-aided study of the gas flow within a natural gas storage and the associated collection network

The current paper presents a computer-aided analysis of the way in which a natural gas storage created in a depleted gas deposit and the associated gas collection network are operated, both during the extraction phase and during the injection phase. In a first step, an analysis is carried out on a two-dimensional, nonstationary model for the gas storage, based on the deposit’s geometry and the rock properties, but also on the gas motions. Also, a dynamic simulation of the injection and extraction processes is unfolded, allowing the study and optimisation of elements such as well placement and gas flows through the wells with the goal of maximising the storable gas quantities. A second model is then generated for the gas collection network associated with the natural gas storage, using the simulation software Simone. Its main benefit is allowing the simulation and modelling of nonstationary flows through the network. The two models are closely interconnected, in that for the extraction stage, the output from the first model is used as input for modelling the collection network, while for the injection phase, the results from modelling the collection network are used as entry data for the gas storage model.

Specialized simulating complex for studying motion dynamics of the towed underwater system

There is developed a specialized simulating complex for computer-aided study of the efficiency of automatic control systems for the underwater towed system «carrier ship — tether winch — tether — towed underwater vehicle». The complex includes mathematical models of the dynamics of a marine moving object, flexible connection and tether winch. The former is used to simulate the spatial motion dynamics of a towing vessel and a towed underwater vehicle as solid bodies in a water flow. Tether simulation employs a method of simulating a flexible connection with automatic control of the axial motion of its elements, which makes it possible to account for the dynamics of the change in the length of its released part. The model of the tether winch dynamics provides simulation of the tether release and gathering. The simulation complex enables studying the spatial motion of a towed underwater vehicle in the water column in relation to the towing vessel as a control object at the dynamic change of the length of the released part of the tether.

A parametric study on the axial behaviour of elastomeric isolators in multi-span bridges subjected to horizontal seismic excitations

This paper investigates the potential tensile loads and buckling effects on rubber-steel laminated bearings on bridges. These isolation bearings are typically used to support the deck on the piers and the abutments and reduce the effects of seismic loads and thermal effects on bridges. When positive means of fixing of the bearings to the deck and substructures are provided using bolts, the isolators are exposed to the possibility of tensile loads that may not meet the code limits. The uplift potential is increased when the bearings are placed eccentrically with respect to the pier axis such as in multi-span simply supported bridge decks. This particular isolator configuration may also result in excessive compressive loads, leading to bearing buckling or in the attainment of other unfavourable limit states for the bearings. In this paper, an extended computer-aided study is conducted on typical isolated bridge systems with multi-span simply-supported deck spans, showing that elastomeric bearings might undergo tensile stresses or exhibit buckling effects under certain design situations. It is shown that these unfavourable conditions can be avoided with the rational design of the bearing properties and in particular of the shape factor, which is the geometrical parameter controlling the axial bearing stiffness and capacity for a given shear stiffness. Alternatively, the unfavourable conditions could be reduced by reducing the flexural stiffness of the continuity slab.

A systematic study of solvent effect on the crystal habit of dirithromycin solvates by computer simulation

The crystal habits of five dirithromycin solvates were employed to unravel the solvent effect by using the modified attachment energy (AE) model. Solvents with different polarity and hydrogen bond donor/acceptor ability (acetone, 1-propanol, acetonitrile, water and cyclohexane) were studied. The good consistency between experimental results and predictions confirmed the applicability of modified AE model. Simulation results showed that all solvates underwent a change in morphological importance (MI) of crystal faces except for the cyclohexane trisolvate. A detailed analysis of the results indicated that the polar solvent had a stronger interaction with crystal face than the non-polar solvent due to the formation of hydrogen bond. Furthermore, crystals with similar structure in different solvents exhibited different aspect ratios. The computer-aided study approach in this work could be helpful to control the morphology of crystal by tailor-made solvents or additives.

An Experimental Verification of the Predicted Effects of Promoter TATA-Box Polymorphisms Associated with Human Diseases on Interactions between the TATA Boxes and TATA-Binding Protein

Human genome sequencing has resulted in a great body of data, including a stunningly large number of single nucleotide polymorphisms (SNPs) with unknown phenotypic manifestations. Identification and comprehensive analysis of regulatory SNPs in human gene promoters will help quantify the effects of these SNPs on human health. Based on our experimental and computer-aided study of SNPs in TATA boxes and the use of literature data, we have derived an equation for TBP/TATA equilibrium binding in three successive steps: TATA-binding protein (TBP) sliding along DNA due to their nonspecific affinity for each other ↔ recognition of the TATA box ↔ stabilization of the TBP/TATA complex. Using this equation, we have analyzed TATA boxes containing SNPs associated with human diseases and made in silico predictions of changes in TBP/TATA affinity. An electrophoretic mobility shift assay (EMSA)-based experimental study performed under the most standardized conditions demonstrates that the experimentally measured values are highly correlated with the predicted values: the coefficient of linear correlation, r, was 0.822 at a significance level of α<10−7 for equilibrium K D values, (-ln K D), and 0.785 at a significance level of α<10−3 for changes in equilibrium K D (δ) due to SNPs in the TATA boxes (). It has been demonstrated that the SNPs associated with increased risk of human diseases such as α-, β- and δ-thalassemia, myocardial infarction and thrombophlebitis, changes in immune response, amyotrophic lateral sclerosis, lung cancer and hemophilia B Leyden cause 2–4-fold changes in TBP/TATA affinity in most cases. The results obtained strongly suggest that the TBP/TATA equilibrium binding equation derived can be used for analysis of TATA-box sequences and identification of SNPs with a potential of being functionally important.

Computer-aided and experimental study of hardness distribution in cutting tool steel body due to phase transformations during induction hardening

The paper presents the results of numerical and experimental investigations of hardness distribution in specimens of a cutting tool steel body upon induction hardening in media that essentially differ in cooling properties. The heating conditions for the tool body were chosen the same as in the case of induction brazing of a hardmetal insert to a tool body with subsequent hardening. The hardness calculations for various zones of the specimen axial section agree well with the experimental data, thus demonstrating the adequacy of the numerical procedure.

On the trail of EHEC/EAEC—unraveling the gene regulatory networks of human pathogenicEscherichia colibacteria

Pathogenic Escherichia coli, such as Enterohemorrhagic E. coli (EHEC) and Enteroaggregative E. coli (EAEC), are globally widespread bacteria. Some may cause the hemolytic uremic syndrome (HUS). Varying strains cause epidemics all over the world. Recently, we observed an epidemic outbreak of a multi-resistant EHEC strain in Western Europe, mainly in Germany. The Robert Koch Institute reports >4300 infections and >50 deaths (July, 2011). Farmers lost several million EUR since the origin of infection was unclear. Here, we contribute to the currently ongoing research with a computer-aided study of EHEC transcriptional regulatory interactions, a network of genetic switches that control, for instance, pathogenicity, survival and reproduction of bacterial cells. Our strategy is to utilize knowledge of gene regulatory networks from the evolutionary relative E. coli K-12, a harmless strain mainly used for wet lab studies. In order to provide high-potential candidates for human pathogenic E. coli bacteria, such as EHEC, we developed the integrated online database and an analysis platform EhecRegNet. We utilize 3489 known regulations from E. coli K-12 for predictions of yet unknown gene regulatory interactions in 16 human pathogens. For these strains we predict 40,913 regulatory interactions. EhecRegNet is based on the identification of evolutionarily conserved regulatory sites within the DNA of the harmless E. coli K-12 and the pathogens. Identifying and characterizing EHEC's genetic control mechanism network on a large scale will allow for a better understanding of its survival and infection strategies. This will support the development of urgently needed new treatments. EhecRegNet is online via http://www.ehecregnet.de.

Computer-Aided Design and Simulated-Mechanical Study of Individualized Femoral Prosthesis

Objective To construct three-dimensional models of individualized femoral prosthesis by using computer-aided design and to verify whether individualized femoral prosthesis is superior to popular femoral prosthesis via simulating and contrasting mechanical study. Methods Two-dimensional images of fresh femurs were obtained by using total-length CT scanning and processed with computer edge recognition and three-dimensional contour extraction software to identify outer and inner contour of pulp cavity, extract contour data of pulp cavity and prosthesis, and construct three-dimensional models of femur and individualized femoral prosthesis. SolidWorks software was used to establish three-dimensional prosthetic models in common biological and bone cement types; moreover, bone-cement, biological, and individualized femoral prosthesis were replaced via simulating clinical surgery. Results Edge extracting was replaced by Canny operator, characterizing by stable running, credible outcome, and consistent with the primary request. Stress, femoral stress, interface stress, and primary micro-motion of individualized femoral prosthesis were significantly lower than biological and bone-cement femoral prosthesis (P Conclusion The computer-aided design is reliable to perform the assistant design of prosthesis; furthermore, biomechanical properties of the individualized femoral prosthesis are superior to those of popular femoral prosthesis.

Computer-Based Comparison of Structural Features of Envelope Protein of Alkhurma Hemorrhagic Fever Virus with the Homologous Proteins of Two Closest Viruses

The aim of this study was prediction of epitopes and medically important structural properties of protein E of Alkhurma hemorrhagic fever virus (AHFV) and comparing these features with two closely relates viruses, i.e. Kyasanur Forest disease virus (KFDV) and Tick-borne encephalitis virus (TBEV) by bioinformatics tools. Prediction of evolutionary distance, localization, sequence of signal peptides, C, N O glycosylation sites, transmembrane helices (TMHs), cysteine bond positions and B cell and T cell epitopes of E proteins were performed. 2D-MH, Virus-PLoc, Signal-CF, EnsembleGly, MemBrain, DiANNA, BCPREDS and MHCPred servers were applied for the prediction. According to the results, the evolutionary distance of E protein of AHFV and two other viruses was almost equal. In all three proteins of study, residues 1-35 were predicted as signal sequences and one asparagine was predicted to be glycosylated. Results of prediction of transmembrane helices showed one TMH at position 444-467 and the other one at position 476-490. Twelve cysteines were potentially involved to form six disulfide bridges in the proteins. Four parts were predicted as B cell epitopes in E protein of AHFV. One epitope was conserved between three proteins of study. The only conserved major histocompatibility complex (MHC) binding epitope between three viruses was for DRB0401 allele. As there are not much experimental data available about AHFV, computer-aided study and comparison of E protein of this virus with two closely related flaviviruses can help in better understanding of medical properties of the virus.

Does the oestrogen receptor encourage oestrogenicity in environmental pollutants? The case of 4-nonylphenol

A computer-aided docking study was conducted to explore in detail the binding interactions between the structurally unlikely environmental oestrogen 4-nonylphenol (4NP) and three of its metabolites with the human oestrogen receptor alpha (hERα). Docking was done within the Schrodinger Suite 2008 using both a conventional rigid receptor with flexible ligand and the induced-fit docking protocol. Induced-fit docking allows side-chain and backbone movement in the receptor to accommodate the ligand. This study has revealed unconventional interactions between the ligands and the hERα binding pocket that could explain the observed oestrogen-like behaviour of 4NP and suggests some of the metabolites of 4NP may also be oestrogenic.