bluuebunny/crossref_metadata_2025 huggingface dataset:
Translational cell biology of highly malignant osteosarcoma
Authors: Roessner Albert , Lohmann Christoph , Jechorek Doerthe
Published: February 2021

Highly malignant osteosarcoma (HMO) is the most frequent malignant bone tumor preferentially occurring in adolescents and children with a second more flat peak in patients over the age of 60. The younger patients benefit from combined neoadjuvant chemotherapy with 65–70% 5‐year survival rate. In patients with metastatic HMO the 5‐year survival rate is consistently poor with approximately 30%. In the last several years strategies for target therapies have been developed by using next generation sequencing (NGS) for defining targetable molecular factors. However, it has so far been challenging to establish an effective target therapy for so‐called ‘orphan tumors’ without recognizable driver mutations, including HMO. The molecular genetic studies using NGS have shown that HMOs are genomically unstable tumors with highly complex chaotic karyotypes. Before the background of this genetic complexity more investigations should be performed in the future for defining targetable biological factors. As the prognosis could not be improved for 40 years one may expect improvements for patients only by gaining a deeper understanding of the cell and molecular biology of HMO. The cell of origin of HMO is being clarified now. The majority of studies indicate that an osteoblastic progenitor cell is probably the cell of origin of HMO and not an undifferentiated mesenchymal stem cell. This means that the established histopathological definition of HMO through verification of osteoid production by the osteoblastic cells is well justified and will probably be the cornerstone for a precise differential diagnosis of HMO also in the years to come.
Resource Publicness Matters in Organizational Perceptions
Authors: Xu Chengxin , Li Huafang
Published: February 2021

Publicness theory deepens our understanding of differences and similarities of organizational behavior. However, in areas in which public, nonprofit, and private organizations compete to serve people, it remains unclear how the level of dimensional publicness influences individuals’ perceptions and choices of organizations. In this study, we present evidence from two online experiments examining the way people's perceptions of resource publicness (operationalized as government funding, donations, and service fees) of elderly care centers in the U.S. influence their judgment of organizations and service choices. Findings suggest that people perceive donative organizations to be the warmest and most competent, followed by government‐funded and commercial organizations. We conclude that individuals' perceptions of resource publicness lead to different judgment that may influence their service choice decisions.
Identification of specificity‐defining amino acids of the wheat immune receptor Pm2 and powdery mildew effector AvrPm2
Authors: Manser Beatrice , Koller Teresa , Praz Coraline Rosalie , Roulin Anne C. , Zbinden Helen , Arora Sanu , Steuernagel Burkhard , Wulff Brande B.H. , Keller Beat , Sánchez‐Martín Javier
Published: February 2021

Plant nucleotide‐binding leucine‐rich repeat receptors (NLRs) act as intracellular sensors for pathogen‐derived effector proteins and trigger an immune response, frequently resulting in the hypersensitive cell death response (HR) of the infected host cell. The wheat (Triticum aestivum) NLR Pm2 confers resistance against the fungal pathogen Blumeria graminis f. sp. tritici (Bgt) if the isolate contains the specific RNase‐like effector AvrPm2. We identified and isolated seven new Pm2 alleles (Pm2e–i) in the wheat D‐genome ancestor Aegilops tauschii and two new natural AvrPm2 haplotypes from Bgt. Upon transient co‐expression in Nicotiana benthamiana, we observed a variant‐specific HR of the Pm2 variants Pm2a and Pm2i towards AvrPm2 or its homolog from the AvrPm2 effector family, BgtE‐5843, respectively. Through the introduction of naturally occurring non‐synonymous single nucleotide polymorphisms and structure‐guided mutations, we identified single amino acids in both the wheat NLR Pm2 and the fungal effector proteins AvrPm2 and BgtE‐5843 responsible for the variant‐specific HR of the Pm2 variants. Exchanging these amino acids led to a modified HR of the Pm2–AvrPm2 interaction and allowed the identification of the effector head epitope, a 20‐amino‐acid long unit of AvrPm2 involved in the HR. Swapping of the AvrPm2 head epitope to the non‐HR‐triggering AvrPm2 family member BgtE‐5846 led to gain of a HR by Pm2a. Our study presents a molecular approach to identify crucial effector surface structures involved in the HR and demonstrates that natural and induced diversity in an immune receptor and its corresponding effectors can provide the basis for understanding and modifying NLR–effector specificity.
Disentangling cause and consequence: genetic dissection of the DANGEROUS MIX2 risk locus, and activation of the DM2h NLR in autoimmunity
Authors: Ordon Jana , Martin Patrick , Erickson Jessica Lee , Ferik Filiz , Balcke Gerd , Bonas Ulla , Stuttmann Johannes
Published: February 2021

Nucleotide‐binding domain–leucine‐rich repeat‐type immune receptors (NLRs) protect plants against pathogenic microbes through intracellular detection of effector proteins. However, this comes at a cost, as NLRs can also induce detrimental autoimmunity in genetic interactions with foreign alleles. This may occur when independently evolved genomes are combined in inter‐ or intraspecific crosses, or when foreign alleles are introduced by mutagenesis or transgenesis. Most autoimmunity‐inducing NLRs are encoded within highly variable NLR gene clusters with no known immune functions, which were termed autoimmune risk loci. Whether risk NLRs differ from sensor NLRs operating in natural pathogen resistance and how risk NLRs are activated in autoimmunity is unknown. Here, we analyzed the DANGEROUS MIX2 risk locus, a major autoimmunity hotspot in Arabidopsis thaliana. By gene editing and heterologous expression, we show that a single gene, DM2h, is necessary and sufficient for autoimmune induction in three independent cases of autoimmunity in accession Landsberg erecta. We focus on autoimmunity provoked by an EDS1‐yellow fluorescent protein (YFP)NLS fusion protein to characterize DM2h functionally and determine features of EDS1‐YFPNLS activating the immune receptor. Our data suggest that risk NLRs function in a manner reminiscent of sensor NLRs, while autoimmunity‐inducing properties of EDS1‐YFPNLS in this context are unrelated to the protein's functions as an immune regulator. We propose that autoimmunity, at least in some cases, may be caused by spurious, stochastic interactions of foreign alleles with coincidentally matching risk NLRs.
Impact of body weight on hemoglobin increments in adult red blood cell transfusion
Authors: Lo Brian D. , Cho Brian C. , Hensley Nadia B. , Cruz Nicolas C. , Gehrie Eric A. , Frank Steven M.
Published: February 2021

Background

Though weight is a major consideration when transfusing blood in pediatric patients, it is generally not considered when dosing transfusions in adults. We hypothesized that the change in hemoglobin (Hb) concentration is inversely proportional to body weight when transfusing red blood cells (RBC) in adults.

Methods

A total of 13,620 adult surgical patients at our institution were assessed in this retrospective cohort study (2009–2016). Patients were stratified based on total body weight (kg): 40–59.9 (16.6%), 60–79.9 (40.4%), 80–99.9 (28.8%), 100–119.9 (11.3%), and 120–139.9 (2.9%). The primary outcome was the change in Hb per RBC unit transfused. Subgroup analyses were performed after stratification by sex (male/female) and the total number of RBC units received (1/2/≥3 units). Multivariable models were used to assess the association between weight and change in Hb.

Results

As patients' body weight increased, there was a decrease in the mean change in Hb per RBC unit transfused (40–59.9 kg: 0.85 g/dL, 60–79.9 kg: 0.73 g/dL, 80–99.9 kg: 0.66 g/dL, 100–119.9 kg: 0.60 g/dL, 120–139.9 kg: 0.55 g/dL; p < .0001). This corresponded with a 35% difference in the change in Hb between the lowest and highest weight categories on univariate analysis. Similar trends were seen after subgroup stratification. On multivariable analysis, for every 20 kg increase in patient weight, there was a ~6.5% decrease in the change in Hb per RBC unit transfused (p < .0001).

Conclusions

Patient body weight differentially impacts the change in Hb after RBC transfusion. These findings justify incorporating body weight into the clinical decision‐making process when transfusing blood in adult surgical patients.
The use of fluorine‐18‐fluorodeoxyglucose‐positron emission tomography/computed tomography as an effective method for staging in dogs with primary appendicular osteosarcoma
Authors: Crooks Clifton , Randall Elissa , Griffin Lynn
Published: February 2021

Fluorine‐18‐fluorodeoxyglucose (18F‐FDG) positron emission tomography/computed tomography (PET/CT) has been utilized in veterinary medicine to improve the detection and characterization of primary, recurrent, and secondary neoplasms; but its use as a staging tool for dogs diagnosed with appendicular osteosarcoma has not been published. The purpose of this retrospective, case series, descriptive study was to detail the use of18F‐FDG PET/CT for staging a population of dogs with appendicular osteosarcoma, report the detection rate of secondary neoplastic lesions, and compare findings with published detection rates for other historically used imaging modalities. Seventy‐one client‐owned dogs with a confirmed diagnosis of appendicular osteosarcoma and staged with a whole‐body18F‐FDG PET/CT scan near the time of initial diagnosis were included. Each PET/CT study was re‐evaluated for malignancy distinct from the primary disease entity based on a collective qualitative and quantitative assessment of18F‐FDG uptake, CT appearance, and contrast enhancement characteristics. Following re‐evaluation of each study, information pertaining to tissue sampling performed on identified lesions was retrieved from the medical record when available. Staging with18F‐FDG PET/CT identified 17 of 71 (23.9%) and 12 of 71 (16.3%) dogs with a high suspicion or confirmation of a metastatic or comorbid malignant neoplasm respectively, with eight of 71 (11.3%) having both metastatic and comorbid lesions. The results of this study are suggestive that18F‐FDG PET/CT is effective in identifying both osseous and soft tissue secondary neoplastic lesions in dogs afflicted with appendicular osteosarcoma, yielding an increased detection rate of all lesions compared those previously reported for skeletal scintigraphy or whole‐body CT.
Diagnostic accuracy of positive oral contrast in abdominal computed tomography for non-traumatic pathologies: a systematic review protocol
Authors: Winner Catherine , Mander Gordon T.W.
Published: February 2021

Objective:

The objective of this review is to determine the diagnostic accuracy of positive oral contrast versus no oral contrast for common, non-traumatic computed tomography abdominal indications in adults.

Introduction:

Positive oral contrast is regularly administered to patients to drink prior to computed tomography scans of the abdomen and pelvis. The purpose of the preparation is to improve visualization of the bowel, however, technological advances in scanner design may mean positive oral contrast is no longer required.

Inclusion criteria:

Eligible studies will consider the use of positive oral contrast in non-traumatic indications for computed tomography of the abdomen and pelvis to include appendicitis, bowel obstruction, diverticulitis, intestinal neoplasms and metastasis (screening or staging), or acute abdomen. The review will use the discharge diagnosis as the reference standard. Studies that describe adult patients (18+) and published from 2000 on will be considered.

Methods:

MEDLINE Complete, Embase, CINAHL, and Scopus will be searched, along with Google Scholar and numerous radiology college websites. Screening of potential titles and abstracts, retrieval of full-text studies, assessment of methodological quality, and data extraction will be performed independently by two reviewers. Meta-analyses will be performed, if possible, and a Grading of Recommendations, Assessment, Development and Evaluation Summary of Findings presented.

Systematic review registration number:

PROSPERO (CRD42020184285)
An Experimental Towing Tank for Small Models
Authors: Davidson Kenneth S. M.
Published: February 2021

This paper considers the relationship between the resistances of small models of surface vessels as obtained in a towing tank, and the resistances of the corresponding full-size hulls. Tests of the bare model hulls are compared with tests of the same models roughened at the bow by applying narrow strips of comparatively coarse sand. The effects of the artificial stimulation of turbulence caused by this roughening, both in hastening the transition from laminar to turbulent friction and in altering the point of separation of the boundary layer, are discussed. Resistance curves for full-size hulls, as developed from tank tests of their models made with induced turbulence, are compared with direct measurements of full-size resistances, as obtained in open-water tests of the full-size hulls. The test results are presented graphically, and the work of other investigators in the field is included.
Stability of Rectangular Plates Under Shear and Bending Forces
Authors: Way Stewart
Published: February 2021

The author first discusses the problem of a plane, simply supported rectangular plate loaded by shearing forces in the plane of the plate on all four edges. There are two stiffeners attached one third and two thirds of the way along the plate. The critical load is calculated for various stiffener rigidities. Also, the rigidity necessary to keep the stiffeners straight when the plate buckles is found. This stiffener rigidity is found to be slightly larger than that necessary for a plate with one stiffener and the same panel dimensions as the plate with two stiffeners.

The second problem discussed by the author is that of a plane, simply supported rectangular plate loaded by uniformly distributed edge shearing forces in the plane of the plate and linearly distributed tension and compression in the plane of the plate at the ends. The end forces vary from tension hσo, at one corner to—hσo, at the other corner, so that their resultant is a bending moment. The presence of the edge shearing forces is found to diminish the critical bending stress in this case. Calculations are made for various magnitudes of bending and shearing forces for plates of various proportions.
Stresses in Symmetrically Loaded Hemispherical Shells Having Tapered Edges
Authors: Hollister S. C.
Published: February 2021

The author points out that when a thin hemispherical shell is fixed at the edge and subjected to internal pressure, bending stresses are set up in a meridional element near the edge of the shell. Where these bending stresses are large, the shell can be improved by a uniform tapering of the shell thickness near the edge. The author supplies methods of solving for stresses in such a shell with a thickened periphery when the shell is subjected to internal pressure and fixed at its edge, when it is only partially restrained at its edge, and when the shell is loaded symmetrically to its axis of rotation, but in a manner other than by internal pressure.
A Theory of Sharp-Edged Orifices
Authors: Howland W. E.
Published: February 2021

The author presents a figure in which the coefficient of discharge Cd, velocity Cv, and contraction Cc determined by several investigators are plotted logarithmically as points against Reynolds’ numbers. Curves for the coefficients drawn by the author, based on theoretical considerations, show good agreement with the experimental data, thus throwing some light upon the basic phenomena of the discharge of sharp-edged orifices. The variation of the coefficient of discharge of a circular orifice as a function of the Reynolds number is explained as a purely viscous phenomenon for low Reynolds numbers, and by means of a momentum analysis for higher speeds. The analysis presented by the author leads to the development of several formulas for the discharge coefficient, which formulas are in fair agreement with experimental results.
Stress Systems in a Circular Disk Under Radial Forces
Authors: Mindlin Raymond D.
Published: February 2021

The transformation of inversion is employed in this paper to generalize a particular solution obtained by Michell (1), for plane stress in a circular disk. In Michell’s solution the disk is loaded in its plane with a pair of equal and opposite forces; one at the center of the disk and the other on the periphery as shown in Fig. 1. In the transformed state, the force in the interior of the disk is no longer at the center, as shown in Fig. 3 and represented by Equation [9]. By simple superposition, the transformed solution is extended to include any self-equilibrating system of radial forces applied in the plane of the disk as shown in Fig. 6b.

The transformation would involve only straightforward calculation were it not for the fact that the disk is multiply connected. This condition is caused by the presence of a singularity in the interior of the disk at the point of application of the force. In the inversion of plane stress in a multiply connected plate, the displacement functions for the transformed state are not necessarily single-valued even though they may have arisen from single-valued displacements in the original plate. This difficulty is overcome by the introduction of suitable functions which remove the many valued terms in the displacements, but do not disturb the stress conditions on the boundaries of the transformed disk.

The solution is shown to include, as particular cases two well-known problems: (a) A disk loaded on its periphery by forces acting along a diameter as shown in Fig. 4; and (b) a semi-infinite plate loaded near its edge by a force normal to the boundary as shown in Fig. 5.
Torsion of Rectangular Tubes
Authors: Hovgaard William
Published: February 2021

This paper is a report on experiments with the torsion of rectangular mild-steel tubes undertaken to test the correctness of the now generally accepted theory of R. Bredt, based on a hydrodynamical analogy. The angles of torsion were determined, and the strains were measured with Huggenberger tensometers. While most of the strains were measured on the external surface of the tubes, internal strains were measured in one tube. The observed angles of torsion were found to be in fair agreement with the theory, but the shearing stresses on the external surface were much higher and those on the internal surface much lower than the theoretical stresses. Breakdown of the tubes occurred while the theoretical shearing stress was still far below the yield point in shearing of the material. It appears that the theory does not give a true picture of the stress distribution after plastic flow has occurred at the re-entrant corners, and as this may happen very early, dependent on the radius of the fillets, the theory may in some cases lead to a dangerous overestimate of the strength of such tubes.
Fatigue Life of Tapered Roller Bearings
Authors: Clinedinst William O.
Published: February 2021

This paper develops a general fatigue expression, together with a series of formulas covering contact stresses. The general equation is applied to the individual parts of the bearing and mathematical expressions for the radial and thrust capacities are developed for all operating conditions. Using the equation covering the radial capacity of a rotating cone as a basis, equivalent loading formulas are developed to cover other operating conditions. The use and limitations of the various formulas are discussed, together with the effect of materials, surface finishes, and manufacturing tolerances on bearing life.
Modern Aids to Vibration Study
Authors: Hull E. H.
Published: February 2021

Many advantages are pointed out for the portable cathode-ray oscillograph combined with an electrical vibration pickup for general vibration study. Representative types chosen from the three principal classes of vibration pickups (displacement, velocity, and acceleration) are described. The particular uses for these several types of pickup and their assembly with oscillographs and amplifiers are described as well as experimental methods for determining frequency and phase.

The paper concludes with a description of the use of this assembled apparatus in the following four vibration problems: detection of out-of-round journals and other extraneous causes of vibration when balancing large machines; comparison of the residual sources of vibration in well-balanced ball-bearing high-speed motors; measurement of commutator roughness; and the investigation of high-frequency noise in small single-phase motors.
The Stability of a Clamped Elliptic Plate Under Uniform Compression
Authors: Voinovsky-Krieger S.
Published: February 2021

The energy criterion of stability, investigated by G. N. Bryan and S. Timoshenko, has been applied with great success to numerous problems of buckling of thin elastic plates submitted to compressive or shearing forces in their own plane. The cases discussed up to the present have concerned almost exclusively rectangular plates, this form of the plate being practically the most important. The application of the energy method to plates bounded curvilinearly will now be illustrated by the case of the elliptic plate.
Natural Frequencies of Uniform Cantilever Beams of Symmetrical Cross Section
Authors: Jacobsen Lydik S.
Published: February 2021

During the last ten years numerous observations of vibrational periods of buildings have been made, especially by the Seismological Division of the United States Coast and Geodetic Survey in California. Even before the results of these observations were available it was recognized that the factors influencing the periods of buildings are many and involved, and that a rational approach to the problem must necessarily ignore a number of the factors. The debatable question has been, and perhaps still is: Which of the factors must not be ignored?

If the discussion be restricted to apply to multistory buildings of relatively symmetrical plan, there is a temptation to consider the buildings cantilever beams planted in or on an elastic ground. However, a multistory building is not necessarily a slender structure. For this reason the degree to which flexural and shearing distortions of the cantilever beam representing the building assume importance for the period determinations is not obvious quantitatively. Similarly, the type of ground deformation or elastic yielding that must be considered varies with the slenderness of the building as well as with the type of foundation and ground.

The present study attempts to show that a rational treatment of the problem becomes greatly involved and therefore impractical if too many factors have to be taken into account. Moreover, the study enables the investigator to form an intelligent estimate of the relative importance of the influence on the periods of the factors that he is forced to neglect.
Stress Model of a Complete Airship Structure
Authors: Donnell L. H. , Shaw E. L. , Potthoff W. C.
Published: February 2021

The authors discuss considerations in designing stress models in general, and the construction, rigging, and testing of an airship model in particular. A new type of girder representation is described, having the unusual advantages of varying the axial, bending, and torsional characteristics independently, and of incorporating convenient and sensitive means for measuring the corresponding stresses. Tests on a separate braced-ring model are compared with theory, and appear to be in good agreement. Similar tests on a duplicate ring in the complete model show the influence of the surrounding structure.
Backfill of Radioactive Waste Disposal: Feasibility Study of Argillite/Bentonite (COx/MX80) Pellets
Authors: Tyri Danai , Ly Bui Quoc Huy , Nader François , Djeran-Maigre Irini , Robinet Jean-Claude , Zghondi Jad
Published: February 2021

A pelletized solution composed of COx argillite and MX80 bentonite is examined as backfill for the deep geological disposal of radioactive waste (Cigéo project). The implementation is studied in terms of installation and hydration conditions as well as their influence on the hydromechanical behavior of the mixture. In the beginning, the optimum grain size distribution (GSD) of pellets assembly is determined to minimize initial voids. A series of discrete element method (DEM) simulations on ternary samples made of spheres is carried out, investigating the optimal conditions in terms of sizes and proportions. Density maximization occurs when the maximum diameter is the dominant size, while minimum and medium diameters are following. As optimum GSD, sizes of 16 mm, 10 mm, and 4 mm in 60%, 10%, and 30% respectively are chosen. The pelletization of the selected sizes is optimized using an adapted tablet machine to carry out the pellet fabrication. A detailed analysis of influential parameters related to the machine accessories and the inserted raw materials is presented. After modifications, quasi-spherical pellets presenting a density of at least 1.95 Mg/m3 are produced. COx/MX80 pellets hydromechanical response is indirectly assessed by studying the swelling potential of COx/MX80 powdered mixtures at equivalent emplaced densities. The influence of density, stress, and MX80 content on swelling is obtained.
Feature-Based CAPP System for the Machining of Dies
Authors: Mawussi Kwamivi , Bernard Alain
Published: February 2021

The manufacturing of dies holds an important place in the manufacturing process of rough parts because it shows the validation of design tasks and determines the production of parts. This manufacturing can be conducted by: copying from master models, electro-discharge or chip removing machining. In the last two cases, the machining of a die or an electrode is based on the manufacturing preparation which is an essential function. When realizing this function, the information required for the machining stage are generated in relation with the design or definition data.

In this paper we propose an original method to automatically generate the machining process of dies (or electrodes). This method, which is applied as part of the manufacturing preparation function, is based on the “machining state” concept and the association of machining knowledge to the sets of complex features. The machining knowledge are specified according to the know-how of mouldmakers and the complex features are defined in the design model of the (or the electrode).
Computation of Radiative Heat Transfer in a Cylindrical Enclosure
Authors: Fu Huiyu , Veshagh Ali
Published: February 2021

A radiative heat transfer model for cylindrical enclosure in which the gas and temperature are axi-symmetrically distributed was developed using the zone method of analysis. A rigorous numerical integration scheme was devised to calculate various types of direct exchange areas between different zones. The radiative heat transfer between gas zones and that between gas zones and surface zones could therefore be computed accurately based upon distributions of gas temperature and absorption coefficient.

This radiation model was used to compute the radiative heat transfer in a diesel engine combustion chamber. Extensive soot data obtained via a sampling valve were used to calculate the gas absorption coefficient. An attempt was also made to allow for the radiation from the non-luminous gases, i.e. carbon dioxide and water vapour. Temperature distribution was obtained from a multi-zone combustion model. Results showed that the radiative heat transfer to the combustion chamber walls was negligible during the early stage of combustion, but represented a significant part of the total heat transfer when it reached its peak value. The results also showed the importance of radiative heat transfer between the various gas zones in the combustion chamber.
Integrated Part Feature Modeling and Process Planning for Concurrent Engineering
Authors: Cherng John G. , Shao Xin-yu , Li Pei-gen , Sferro Peter R.
Published: February 2021

This paper presents the methodologies and technologies of integrated part feature modeling and process planning for Concurrent Engineering (CE) applications. The part feature modeling is constructed on the basis of a hierarchical and dynamic structure that consists of feature syntax, feature semantics, and feature operations. A discussion is given on part function representation and function mapping mechanism for CE realization. A CE-oriented Computer-Aided Process Planning (CAPP) is advocated to not only fulfill both variant and generative design tasks, but also perform part manufacturability evaluation by using multi-level knowledge reasoning. The knowledge representation as well as a system structure of integrated part feature modeling and process planning for CE application are discussed.
Relations Between Features: Prototyping Object-Oriented Language Extensions on an Industrial Example
Authors: Brett Brendan D. , Peters Thomas J. , Demurjian Steven A. , Needham Donald M.
Published: February 2021

Feature-based design techniques are being broadly incorporated into supporting CAD/CAM software. Object-oriented methodologies effectively capture parent-child relationships between features. However, realistic design, manufacturing and assembly domains often require more subtle inter-relationships between features, where contemporary object-oriented languages lack capabilities to facilitate such modeling. This research focuses upon prototyping object-oriented techniques to express non-ancestral relationships between features.

This research was undertaken to support an industrial design team and our research goals were to:

• determine critical feature inter-relationships,

• prototype object-oriented software mechanisms for expressing these non-ancestral inter-relationships, and

• equip those mechanisms with methods for change notification.
Using Virtual Node Generation to Speed Up Sheet Metal Bending Operation Planning
Authors: Gupta Satyandra K. , Bourne David A.
Published: February 2021

A large number of manufacturing operation planning problems can be formulated as state-space search problems. In case of sheet-metal bending operation planning, processing a search node involves extensive geometric reasoning and many other types of complex computation steps. Such computation-intensive node-processing limits the number of search nodes that can be expanded in a reasonable amount of time, making it difficult to solve real-life operation planning problems.

In this paper, we describe a scheme to speed up operation planning by virtual generation of state-space nodes. In this scheme, we eliminate unnecessary computation at the time of node generation by extracting the required information from already generated nodes. Although generation of two different search nodes rarely involves identical computation steps, there is considerable overlap in node generation steps. We have divided the node generation step into a number of computation subproblems. When we need to generate a new node, we first try to see if any of the node generation subproblems have been solved for any of the already generated nodes. If any subproblem has already been solved for some other node, then we use the solution of that subproblem to save computation time. In such cases, we do not perform node generation computation steps, and therefore we call such node generation virtual.

The scheme presented in this paper increases the node generation capability and allows us to generate many more search nodes. We believe that the ability to consider more search nodes will help us in solving more complex problems and finding better operation plans.
Optimal Process Planning for Four-Axis Turning Centers
Authors: Veeramani Dharmaraj , Stinnes Andreas H.
Published: February 2021

This paper addresses the problem of process plan generation and optimization for dual-spindle/dual-turret CNC mill-turn centers (commonly referred to as four-axis turning centers) that are capable of both parallel and simultaneous machining modes. The number of alternative process plans for machining a given workpiece on this class of machines can be large, and the process plan optimization problem can, therefore, be complex. Due to the lack of a computer-aided process plan generation and optimization system, these highly flexible machines are being used in industry today as dedicated, mass-production machines. In this paper, we present research (being conducted in close cooperation with industry) on the development of a computer-aided process planning system for four-axis turning centers. In particular, we describe the representation schemes and Tabu Search based strategy for process plan generation and optimization, and present results demonstrating the effectiveness of this approach.
System Behavior Modeling As a Basis for Advanced Failure Modes and Effects Analysis
Authors: Eubanks Charles F. , Kmenta Steven , Ishii Kosuke
Published: February 2021

This paper presents a method for developing a device behavior model to enhance reliability at the early stages of conceptual design. The model facilitates a semi-automated advanced failure modes and effects analysis (FMEA). The model performs analyses and simulations of device behavior, reasons about conditions that depart from desired behaviors, and analyzes the results of those departures. The proposed method rigorously specifies pre- and post-conditions, yet is flexible in the syntax of device operation. The paper shows how the method can capture failures normally missed by existing FMEA methods. An automatic ice maker serves as an example application.
An Approach to Virtual Prototyping for Product Disassembly
Authors: Siddique Zahed , Rosen David W.
Published: February 2021

An important aspect of Design for the Life Cycle is assessing the disassemblability of products. A product designed for disassembly can be quickly and easily broken down so its components can be recycled or refurbished. The use of virtual prototyping is proposed to aid the assessment of product disassembly by enabling the designer to virtually disassemble the product. A virtual prototype is a model of a product and a process that the product undergoes. Virtual prototyping is defined as the generation of a virtual prototype and its simulation or assessment. Factors involved in generating product disassembly processes include: determining the disassembly sequence of a product, the disassembly paths of components, tool change sequences, etc. In recent years, disassembly processes have been generated either by using interactive or automated approaches, but these have limitations. However, by combining the two approaches, disassembly processes of complex assemblies can be generated without extensive user input. This type of interaction can be facilitated by using virtual prototyping. The purpose of this paper is to illustrate the development of a virtual environment that will support the generation of virtual prototypes for evaluating product disassembly. Issues involved in transformation of CAD models to virtual prototypes for disassembly are also discussed. Application to an automotive center console is illustrated.
Computer Programs for Fire Simulation
Authors: Lilley David G.
Published: February 2021

Computer programs for simulating fire development in a multi-room building complements the experimental approach and/or post-fire on-site investigations. A variety of computer calculations can help to validate or deny a suggested fire scenario and witness statements. Thus they help to discriminate between alternative fire scenarios by evaluating the consequences and comparing them with observations. In this way computer simulation helps to rule in or rule out the suggested ignition and spread of the fire.
Numerical Simulation of Complex Geometries
Authors: Lin Wanlai , Chen Ching Jen
Published: February 2021

The numerical simulation of fluid flows and heat transfer over complex geometries, especially for three dimensional problems, remains a challenging problem in computational fluid dynamics. This paper proposes a method to approximate the contour of irregular geometries in Cartesian coordinates. In order to achieve a smooth boundary representation, both diagonal segments and Cartesian grid lines are utilized in the approximation. When the geometric object is specified with a set of discrete points, the approximate representation of the object contour is drawn based on the local monotonic principle such that the essential topographical character of the object is preserved. The accuracy of approximated contour on the Cartesian coordinate is estimated by the convergence of contour length and normal distance between the approximated and original contour. The proposed techniques is illustrated by the contours of complex lake banks, multi-cylinder, porous media and the sphere, which are often encountered in fluid devices and heat exchangers.
Design and Implementation of a Linear Testbed for Encoder Validation
Authors: Pulanco William Michael , Derby Stephen
Published: February 2021

It was desired to build a test station that would test the maximum operating speed and assist in the adjustment of the potentiometer during assembly of the linear encoders. A linear slide table provides the best linear motion to test encoders. It was also decided that a belt drive system would allow for the desired performance. The belt drive system is connected to a motor which needs some type of control. Many different options were considered for controlling the motor and some tried, but the final solution was to use a stand alone controller that would take input from a control panel. The total test station includes a motor & encoder, controller, amplifier, power supply, and interface board. The controller is a stand alone unit, that is programmed from the RS232 port on a personal computer. The controller can also send data back through the RS232 port for analysis purposes.
Enhancing Mechanism Simulation in Engineering Education by a Hypermedia System
Authors: Giannotti E. , Galletti C.
Published: February 2021

An attempt to focus problems encountered in teaching mechanics of machines to engineering students has stimulated the authors of this paper to develop specific software, lectures and laboratory activities with different emphases and relations between the teacher’s and students’ tasks. A multi-year study has been made to test if and how simulation, based on a hypermedia system, can be used in developing educational tools for this new courseware. As a result, new tools for learning mechanics of machines are proposed.
Dynamic Response of a Generic Vehicle Floor Model to Coupled Transient Loads
Authors: Gupta Aaron D.
Published: February 2021

A dynamic elastic large displacement response analysis of the bottom floor of a generic vehicle hull model subjected to empirically obtained coupled blast and impact loads has been conducted using three-dimensional (3-D) shell elements in the ADINA nonlinear dynamic finite element analysis code. For the impulse-dominated problem, the impact load is a square wave step function concentrated load while the blast loads from the detonation of an explosive are a series of distributed pressure loads approximated as triangular impulse loads with linear decay and varying arrival and duration times.

The 3-D numerical model has been generated using the PATRAN3 modeling code and converted to the ADINA finite element input data deck using the ADINA translator and careful inclusion of appropriate material properties as well as initial and boundary conditions. Monolithic single-layered four-noded quad shell elements were sufficient to model the bottom floor and the left- and right-horizontal and vertical sponsons as well as the lower front glacis.

Although several simplifying assumptions and approximations are made during the generation of the basic floor model, material properties, and the forcing functions, the investigation gives valuable insight into the response behavior of a generic hull bottom floor to externally applied coupled blast and impact loads and provides an inexpensive nondestructive method of evaluation of the structural integrity of modern vehicles subjected to spatially varying transient loads.
A New Finite Element Analysis of Frictional Contact Using Nondifferential Optimization
Authors: Refaat M. H. , Meguid S. A.
Published: February 2021

Current solution schemes of variational inequalities arising in frictional contact problems adopt penalty and regularization techniques. The convergence and accuracy of these schemes are governed by user-defined parameters. To overcome the difficulties associated with the ad hoc use of such parameters, the variational inequality of the general frictional contact problem is treated in this paper using mathematical programming. A new non-differential optimization (NDO) technique, in association with quadratic programming, is used to treat the resulting variational inequalities.
Determination of Reflection and Transmission Coefficients in Rigidly Connected Beams Using Timoshenko Beam Theory
Authors: Stolte James , Santiago Joseph M.
Published: February 2021

Knowledge of the behavior of a wave incident at a joint is necessary to properly analyze the vibration of a structure. We need to know how much energy is reflected and transmitted and also the type of wave carrying the energy. Typically, Euler beam theory is used to derive the reflection and transmission coefficients at high frequencies. Errors can become unacceptably large in the frequency range currently being analyzed using Statistical Energy Analysis (SEA) and the Power Flow Finite Element Method (PFFEM). We derive reflection and transmission coefficients due to a bending wave incident on a rigid joint between two infinitely long beams using Timoshenko theory and compare results to those obtained using Euler theory. We also compute the reflection and transmission efficiencies that determine the amount of power carried by each wave.
Blending Hierarchical Economic Decision Matrices (EDM) With FE and Stochastic Modeling: I — Methodology and Refining EDM
Authors: Majerus J. N. , Jannone J. A. , Lanphear S. P. , Tenney D. A.
Published: February 2021

This paper introduces the concept of a three-level hierarchy of economic-decision matrices (EDM) and discusses how finite element (FE) and stochastic modeling can be coupled in decisions on quality control. A disadvantage of the deterministic-engineering approach is that quality control cannot be properly accessed by a corresponding EDM. A five-step design-strategy is outlined and various suggestions associated with these steps are presented in the paper. This design-strategy is then quantified by the consideration of a hypothetical reverse-engineering problem involving a U-shaped bracket with cut-outs and holes. The paper presents the results of numerical experiments (sensitivity study) involving six preliminary variates (Yield Strength, Young’s Modulus, thicknesses, magnitude and phase of the forces, and displacement B.C). The final primary variates are assumed to be governed by a Gaussian distribution, and the methodology of applying the classical Z-statistic method to the FE results are presented.
Blending Hierarchical Economic Decision Matrices (EDM) With FE and Stochastic Modeling: II — Detailing EDM
Authors: Majerus J. N. , Tenney D. A. , Mimnagh M. L. , Lamphear S. P. , Jannone J. A.
Published: February 2021

The purpose of the Detailing EDM is to “fine-tune” a previously ameliorated design. First, in order to determine the best fillet radius for formability, forging simulations are conducted using commercial software. Once the fillet dimension is ascertained, the 3-D model is generated and maximum stresses determined for a trial force. Two different commercial programs were used to determine the three dimensional stresses. The only statistical quantities involve the loading (Gaussian distribution), the material “strength” in the Analytical Criteria for Failure (ACF), and possibly, the boundary conditions in the 3-D models. This paper considers the ACF to be the resistance to fatigue-fracture under complete reversal of loads at 5 × 108 cycles. The paper overviews three different methods of combining stochastic behaviour with FE analysis, and presents a methodology for using the interference-method with non-symmetrical distributions. The EDM are then presented for the three Product Criteria of forging — formability, Prime cost and 3-D reliability with respect to the selected ACF.
Time Integration of Impact Phenomena in Solid Mechanics: A One-Dimensional Model Problem
Authors: Chawla V. , Laursen T. A.
Published: February 2021

1D impact between two identical bars is modeled as a simple spring-mass system as would be generated by a finite element discretization. Some commonly used time integrators are applied to the system to demonstrate defects in the numerical solution as compared to the exact analytical solution. Using energy conservation as the criterion for stability, a new time integration scheme is proposed that imposes a persistency condition for dynamic contact. Finite element simulation with Lagrange multipliers for enforcing the contact constraints shows exact energy and momentum conservation.
A Multi-Index Variable Time Step Method for the Dynamic Simulation of Multibody Systems
Authors: Cardenal Jesús , Cuadrado Javier , Bayo Eduardo
Published: February 2021

This paper presents a new multi-index variable time step method for the integration of the equations of motion of constrained multibody systems in descriptor form. The basis of the method is the augmented Lagrangian formulation with projections in index-3 and index-1. The new method takes advantage of the better performance of the index-3 formulation for large time steps and of the stability of the index-1 for low time steps, and automatically switches from one method to the other depending on the required accuracy and values of the time step.

The modification of time steps is accomplished through the use of a global system invariant such as the kinetic energy stored in the penalty system. This energy provides a good measure of the global error introduced by the numerical integration during the simulation process, and permits a simple and reliable strategy for varying the time step. Overall, the new method is quite efficient and robust: it is suitable for stiff and non-stiff systems, it is robust for all time step sizes, it works for singular configurations, redundant constraints and topology changes. Also, the constraints in positions, velocities and accelerations are satisfied to machine precision during the simulation process. The method is always more accurate as the time step size decreases.
Checking Geometric Constraints in Layout Design Using Primitives
Authors: Yim H. , Butler A. C.
Published: February 2021

The use of geometric primitives provides representation of objects in layout design at an appropriate level of abstraction, and it allows the use of two new algorithms which permit improvements in computational speed for constraint checking. These algorithms detect intersections between two rectangles and between a rectangle and circle with improved computational efficiency. The use of this pair of algorithms is demonstrated on test problems executed on a parallel computer, and conclusions are drawn regarding the use of geometric primitives for constraint checking in layout design.