bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization and biogeographic affinity of megazoobenthos in the Central Mediterranean Sea
Authors: Massi Daniela , Titone Antonino , Gristina Michele , Garofalo Germana , Lauria Valentina , Micalizzi Roberta , Sinacori Giuseppe , Fiorentino Fabio
Published: February 2021

The Strait of Sicily (SoS) is a key area in the Central Mediterranean Sea characterized by high biodiversity and demersal fisheries productivity. Further, it is traditionally considered the main biogeographic boundary between the Western and Eastern basins of the Mediterranean. Due to the poor knowledge on the benthos composition and distribution in this area, we created the first inventory of megazoobenthos recorded on the trawlable soft bottoms of the North‐Western SoS. Samples were collected by bottom trawl surveys between 2003 and 2013 within a depth range of 10–800 m. Overall, 374 taxa with 358 species, belonging to Porifera, Cnidaria, Nemertea, Rotifera, Brachiopoda, Bryozoa, Sipuncula, Annelida, Mollusca, Arthropoda, Echinodermata and Chordata phyla, were found. In addition, the biogeographic affinity of megazoobenthos collected in the SoS to species vulnerable to trawl survey found in other zones of the Central Mediterranean was investigated. Excluding the North Adriatic and the Strait of Messina, moderate affinity values have been recorded within all the biogeographic zones. The benthos species of the North‐Western SoS presented the highest affinity with those of the North Tyrrhenian and Ligurian Sea (about 90% of species in common). However, our results show high similarity with species composition of the South‐Eastern SoS/South Ionian, North Ionian and Central Adriatic (about 80% of species in common). Our study confirms the role as biogeographic transition zone of the SoS for the Mediterranean biota. Furthermore, the lower affinity with native species of the South‐Eastern SoS and the absence of Lessepsian species suggest that the cold waters (due to the permanent up‐welling) off the southern coasts of Sicily may act as thermal barrier for regulating species exchange between the Eastern and Western basins. Some concerns about this role of the northern sector of the SoS were discussed in the light of current climate change.
Genetic loci mediating circadian clock output plasticity and crop productivity under barley domestication
Authors: Prusty Manas R. , Bdolach Eyal , Yamamoto Eiji , Tiwari Lalit D. , Silberman Roi , Doron‐Faigenbaum Adi , Neyhart Jeffrey L. , Bonfil David , Kashkush Khalil , Pillen Klaus , Smith Kevin P. , Fridman Eyal
Published: February 2021

Circadian clock rhythms are shown to be intertwined with crop adaptation. To realize the adaptive value of changes in these rhythms under crop domestication and improvement, there is a need to compare the genetics of clock and yield traits.

We compared circadian clock rhythmicity based on Chl leaf fluorescence and transcriptomics among wild ancestors, landraces, and breeding lines of barley under optimal and high temperatures. We conducted a genome scan to identify pleiotropic loci regulating the clock and field phenotypes. We also compared the allelic diversity in wild and cultivated barley to test for selective sweeps.

We found significant loss of thermal plasticity in circadian rhythms under domestication. However, transcriptome analysis indicated that this loss was only for output genes and that temperature compensation in the core clock machinery was maintained. Drivers of the circadian clock (DOC) loci were identified via genome‐wide association study. Notably, these loci also modified growth and reproductive outputs in the field. Diversity analysis indicated selective sweep in these pleiotropic DOC loci.

These results indicate a selection against thermal clock plasticity under barley domestication and improvement and highlight the importance of identifying genes underlying for understanding the biochemical basis of crop adaptation to changing environments.
‘Stay at home’: Is it good or not for house dust mite sensitized children with respiratory allergies?
Authors: Yucel Esra , Suleyman Ayse , Hizli Demirkale Zeynep , Guler Nermin , Tamay Zeynep Ulker , Ozdemir Cevdet
Published: February 2021

Background

Lockdown was imposed for children for 75 days in Turkey to limit the spread of COVID‐19. During this period, children have to stay indoors, which might probably increase their exposures to indoor allergens and pollutants. Besides, reduced exposures to respiratory tract infections and outdoor pollutants might be favorable outcomes of this lockdown period. We evaluated the effects of the lockdown on house dust mite (HDM)–sensitized children with respiratory allergies.

Methods

Three‐month clinical and medication data of 165 mild‐moderate asthmatic children with or without allergic rhinitis (AR), who were grouped according to their HDM sensitization status, were retrieved from patient records. Demographics, asthma control tests, nasal visual analog scores, and outdoor air quality monitoring data were used for assessments in comparisons with the same period in the previous year.

Results

Eighty‐four patients had asthma, and 81 patients had asthma with AR. Sensitization to HDM was present in 61.8% of the children. Patients experienced reduced numbers of upper respiratory tract infections (P = .008) and reduced asthma exacerbations (P < .001) compared with the same period in the previous year. Asthma control tests were significantly improved (P < .001), and cumulative inhaled corticosteroid usages were significantly reduced (P < .001). Noteworthily, nasal symptoms were significantly worsened in HDM‐sensitized asthmatics with AR (P < .001).

Conclusions

This study highlighted that reduction in respiratory tract infections and outdoor pollution may play roles in asthma control and prevent exacerbations despite continuous indoor allergen exposure. Besides, worsening of nasal symptoms in HDM‐sensitized asthmatics with AR implies the importance of indoor avoidance measures for AR control.
Inborn errors of metabolism in palliative care
Authors: Harputluoğlu Nilgün , Köse Melis , Yılmaz Ünsal , Çelik Tanju
Published: February 2021

Background

In parallel with the increase in the number of children with life‐limiting or life‐threatening diseases, the need for and right to pediatric palliative care is also increasing. This study aimed to examine the metabolic diseases, evaluate the symptoms, and review the needs of children who were admitted to the pediatric palliative care service.

Methods

Following the approval of the local ethics committee (18/7/2019‐107), the computer records of patients hospitalized in the pediatric palliative care service between December 1, 2018 and January 6, 2019 were reviewed retrospectively. Dr Behçet Uz Children's Hospital, Pediatric Palliative Care Center is third center in Turkey. Our pediatric palliative care center has one year of experience.

Results

In the study period, there were 101 patients who were hospitalized in the pediatric palliative care service. Eighteen patients (19.7%) diagnosed with inborn errors of metabolism were included in the study. The mean age was 3.2 ± 2.1 (0–8) years. Although it could not be shown statistically, the duration of hospitalization of patients with congenital malformation was long.

Conclusion

Pediatric palliative care provides the best care with the control of various symptoms in neurodegenerative congenital metabolic diseases that do not have treatment or treatment, but progressive symptoms cannot be prevented.
Effects of prescribed grazing by goats on non‐native invasive shrubs and native plant species in a mixed‐hardwood forest
Authors: Rathfon Ronald A. , Greenler Skye M. , Jenkins Michael A.
Published: February 2021

Invasion of non‐native shrubs comprises a serious economic and ecological problem in North American forests. Prescribed grazing by goats may offer an effective alternative to traditional methods of control, but has received little study in forest settings. In a 5‐year field experiment, we varied the stocking of goats and number of grazing periods to determine effects of prescribed grazing on both invasive shrubs and native plant species. Specifically, we examined how varied stocking levels and grazing periods affect: (1) the cover and height of invasive shrub and native woody species (2) the cover and diversity of herbaceous species, and (3) the density of native tree seedlings. Data were analyzed with linear mixed‐effects models. We found that prescribed grazing by goats significantly reduced the cover and height of invasive shrubs, regardless of goat stocking or duration. Generally, the greatest reductions in invasive shrub cover occurred in treatments with two grazing periods, regardless of goat stocking. While we observed mostly neutral or positive effects on the herbaceous layer, all grazing treatments reduced the cover and height of native understory woody species. While changes were not significant, we observed a general decline in the aggregate height of native tree species regeneration. Our results suggest that prescribed grazing by goats provides an effective and environmentally friendly treatment for heavy invasions of non‐native shrubs such asRosa multiflora, but grazing needs to be followed by focused mechanical or chemical treatments to maintain control while allowing the regeneration of native tree species.
Genetic and mating system assessment of translocation success of the long‐lived perennial shrub Lambertia orbifolia (Proteaceae)
Authors: Monks Leonie , Standish Rachel , McArthur Shelley , Dillon Rebecca , Byrne Margaret , Coates David
Published: February 2021

There is an increasing need to establish populations of threatened plants in threat‐free habitat to prevent species extinction. The amount of genetic diversity in founding plants will influence whether the new population has the capacity to persist and evolve over time, and factors that influence the maintenance of genetic diversity, such as the mating systems, will also play a role in population persistence. We developed 13 nuclear microsatellite markers and used these to evaluate genetic diversity and mating system parameters of three translocated populations of two subspecies of Lambertia orbifolia, and compared these parameters to seven wild populations. Genetic diversity was maintained in the translocated population of L. orbifolia subsp. Scott River Plains, established using a single source population (Nar = 3.270 and He = 0.478 in translocated population; Nar = 3.280 and He = 0.534 in wild populations), and maintained or increased in the two admixed translocated populations of L. orbifolia subsp. orbifolia (Nar = 3.115, 3.830 and He = 0.511, 0.635 in translocated populations; Nar = 2.708 and He = 0.438 in wild populations) compared to wild populations of each subspecies. Mating system parameters were comparable between translocated and wild populations of L. orbifolia subsp. Scott River Plains indicating the likelihood of genetic diversity being maintained in future generations. However, there was increased selfing in translocated populations of L. orbifolia subsp. orbifolia, suggesting suboptimal pollination and high values for the inbreeding coefficient in these admixed populations (Fis = 0.474, 0.275), which may be an artifact of the Wahlund effect or from less fit (inbred) seedlings surviving ex situ propagation and translocation.
Can relic shells be an effective settlement substrate for oyster reef restoration?
Authors: Hanke Marc H. , Bobby Neha , Sanchez Rachel
Published: February 2021

Acute storms (e.g. hurricanes) are major stressors to eastern oysters (Crassostrea virginica) through burying oysters and settlement substrate. Subsequently, managers use many restoration efforts, of which one approach is bag‐less dredging. This resurfaces relic shells as settlement substrate; however, buried shells turn black in anoxic sediments potentially influencing spat settlement. This study compared three shell types: sun‐cured white shell utilized in oyster reef restoration and two representative black shell types for bag‐less dredging. Settlement was significantly higher on sun‐cured white shell suggesting that restoration activities resurfacing black shells may not provide suitable substrate and alternative methods of providing substrate should be prioritized.
Cluster randomized control trial of nursing home residents’ oral hygiene following the Mouth Care Matters education program for certified nursing assistants
Authors: Hartshorn Jennifer E. , Cowen Howard J. , Comnick Carissa L.
Published: February 2021

Aims

The purpose of this study was to determine if the number of certified nursing assistants (CNAs) trained with the Mouth Care Matters (MCM) oral health educational program had an impact on nursing facility (NF) resident oral health.

Materials and methods

Three NFs participated in a cluster randomized control trial. In NF‐A: all CNAs were offered the MCM program, NF‐B: 3 CNAs were offered the MCM program, and NF‐C: Control (no CNAs were offered the MCM program). Demographic information, systemic health data, and oral health data at baseline, 3‐month, and 6‐month intervals were collected and analyzed using Kruskal‐Wallis, Wilcoxon signed‐rank and Wilcoxon rank‐sum tests. A total of 24 dentate residents participated in this study. Plaque control record scores for NF‐A were significantly reduced compared to NF‐B and NF‐C (P < .001 and P = .002 respectively) and gingival bleeding index for NF‐A were significantly reduced compared to NF‐B and NF‐C (P = .002 and P < .001 respectively).

Conclusion

Increasing the number of CNA's trained in the Mouth Care Matters educational program positively impacted NF residents’ oral hygiene.
24‐hour movement behaviors and fitness in preschoolers: A compositional and isotemporal reallocation analysis
Authors: Lemos Luís , Clark Cain , Brand Caroline , Pessoa Maria Luíza , Gaya Anelise , Mota Jorge , Duncan Michael , Martins Clarice
Published: February 2021

This study analyzed the associations between the 24‐hour movement behaviors composition and fitness in preschoolers and investigated predicted changes in fitness when time in active behaviors is reallocated. This cross‐sectional study was carried out with 270 preschoolers (132 boys; 3.97 ± 0.80 years‐old). Light and moderate‐to‐vigorous physical activity (LPA and MVPA), and sedentary behavior (SB) were verified using an accelerometer. Sleep time was obtained through interviews with parents. Components of physical fitness (cardiorespiratory fitness—CRF, speed‐agility, and lower‐body muscular strength) were assessed using the PREFIT Battery. To verify the association between 24‐hour movement behaviors and physical fitness, the compositional analysis was used, and for the time reallocation, the compositional isotemporal substitution analysis was used for active behaviors (LPA and MVPA). The daily composition, adjusted for body mass index, sex, and age, was significantly associated with CRF (P = .007;r2 = 0.29), speed‐agility (P < .001;r2 = 0.14), and lower‐body muscular strength (P = .01;r2 = 0.07). For CRF, the addition of MVPA, at the expense of any other behavior, was associated with significant improvements. For speed‐agility and lower‐body muscular strength, only reallocations between sleep and LPA yielded significant associations. The variation in CRF, speed‐agility, and lower‐body muscular strength was associated with the 24 hours movement composition, and reallocating 5, 10 or 15 minutes of SB or sleep for MVPA was significantly positive for CRF (P < .05). The present findings highlight the relevance of decreasing SB and increasing physical activity practice, particularly at high intensities, to promote a better CRF profile for preschoolers.
Parsing Pegasus: An Infrastructural Approach to the Relationship between Technology and Swiss Security Politics
Authors: Leander Anna
Published: February 2021

How do technologies matter for security politics? This article introduces the kind of arguments aninfrastructural approachwould focus its answer on. It illustrates how the approach would work by focussing on how the spyware Pegasus developed by the Israeli company NSO matters for Swiss security politics. It follows the infrastructural approach showing how and why it would tend to three things primarily: the politics of theinfrastructuresPegasus is inscribed in, the politics of the processes ofinfrastructuringthe software generates and theinfrapoliticsthat sustain and transform these processes and infrastructures. The article also discusses the strengths and weaknesses of infrastructural approaches, underlining that since they are relational, processual and radically open epistemologically and ontologically, infrastructural approaches are suitable for opening new agendas, re‐problematising and re‐imagining the politics of security technologies. They are less suited for studies premised on a fixed understanding of the politics of security technology.
Multimedia and Virtual Reality for the Control of a Multiple Wheeled Mobile Robot System
Authors: Feng Xin , Velinsky Steven A.
Published: February 2021

This paper describes the application of multimedia and virtual reality technology to a multiple wheeled mobile robot system. The system is designed for teleoperation of a variety of highway maintenance and construction tasks, such as automated highway pavement crack sealing. Each robot is tethered to a support truck through linkages, and has its own embedded controller for motion control and posture sensing. A host computer is dedicated to communicate with the robots and to provide a multimedia interface to the operator. A video camera is mounted above the robots’ workspace and live video is taken to the host computer’s video capture card which supports video overlay. The live video of the robot workspace is then overlaid on the robots’ control window and provides an augmented reality for crack detection, path planning, and robot monitoring. By mapping live video on the computer generated interactive robot animation, the operator can simply control any robot through finger motion on a touch screen. The host computer can also provide a virtual environment providing the operator with a sense that he is sitting on the robot, allowing the robot to be easily controlled with a joystick. This paper shows the manner in which fast growing and inexpensive multimedia PC technology, virtual reality concepts, and the newest programming tools like Visual C++ 4.0 and OpenGL 1.1 for Windows 95/NT can be used to build an integrated interactive monitoring and control interface allowing ease in teleoperation of a multiple robot system thus significantly improving operational performance.
1997 Status of the Form Feature Recognition Method Using Convex Decomposition
Authors: Wang Eric , Kim Yong Se
Published: February 2021

This paper describes the current status of our feature recognition method using a convex decomposition method called Alternating Sum of Volumes with Partitioning (ASVP). Volumetric form features are recognized from a part’s boundary representation by applying combination operations to the ASVP decomposition of the part to obtain a Form Feature Decomposition (FFD). The FFD can be post-processed to obtain application-specific feature representations; in particular, the conversion to the Negative Feature Decomposition (NFD), a machining feature representation, is described. Our domain of recognizable parts includes those having planar and cylindrical surfaces such that all cylindrical surfaces are bounded by straight edges and circular arcs, or are blending surfaces resulting from applying constant-radius blending to the part. We report the results of applying our method to the test parts for the 1997 Computers in Engineering Feature Panel Session.
The Ethics Toolkit: A Computer Program for Teaching Ethics to Engineering Students
Authors: Shoup Terry E. , Shanks Thomas
Published: February 2021

This paper describes a new computer application known as the Ethics Toolkit that is useful in enabling engineering students to learn about ethical problem solving. The application runs in a Windows environment and implements five different approaches to ethical problem solving found in the literature. Although the application does not provide absolute answers to ethical problems, it does facilitate the automation, organization and prioritization of solution possibilities.
Exact Reduction by Group Theoretic Approach in Computational Nonlinear Structural Dynamics
Authors: To Cho W. S. , Li Lingchuan
Published: February 2021

The reduction method based on symmetry group or the so-called group theoretic approach (GTA) of Healey and associates for bifurcation analysis and free vibration analysis of geometrically nonlinear systems with symmetries is applied in the investigation reported here to the computations of responses of geometrically nonlinear systems under intensive transient excitations. A digital computer program written in Fortran language has also been developed for the work. Two space trusses discretized by the finite element method are chosen to illustrate the use of the GTA for cases undergoing large deflections. In the response computations for both the full space and reduced space or subspace problems the central difference method is employed. Numerical results are obtained. Comparisons of results for full space problems to subspace problems are made. It is concluded that the GTA is mathematically very elegant and rigorous. Computationally, the solution is exact and it is very efficient for geometrically nonlinear systems undergoing large deformation. The GTA is currently being developed for the response analysis of geometrically nonlinear systems with partial symmetries.
Simplification of the Equations of Nonlinear Vibrations
Authors: Lee W. C. , Ma F.
Published: February 2021

The purpose of this paper is to show that equations of nonlinear vibrations whose linear parts involve two coefficient matrices can be simplified so that the linear portions become uncoupled. Equivalence transformations are utilized in the simplification, which can substantially streamline any subsequent analysis.
Plate Buckling Analysis Using the Linear Finite Element Method
Authors: Persson Thomas , Suchora Daniel H.
Published: February 2021

The objective of this study was to develop new solutions for linear elastic buckling coefficients of rectangular flat plates with support conditions not previously found in the literature. Critical buckling coefficients were found for rectangular flat plates subjected to uniform compression on two opposite edges with one partially supported unloaded edge using the finite element method. Plates with different aspect ratios and with varying support length on the unloaded edges were analyzed. Currently, no solutions are available in the literature for plates subjected to uniform compression and with partially supported unloaded edges. The method developed in this work was verified on problems where closed form mathematical solutions exist.

An engineer will be able to use the solutions developed in this work in the design of components that are susceptible to instability failures.

Another benefit of this work is to demonstrate to practicing engineers that reliable instability results can be obtained by using standard finite element analysis (FEA) methods. This work considers a small subset of instability problems but the FEA method utilized herein can be effectively used to model a large class of practical instability problems.
Task-Based Design of Manipulators: An Agent-Based Approach
Authors: Paredis Christiaan J. J. , Khosla Pradeep K.
Published: February 2021

This paper introduces a novel agent-based solution approach to Task Based Design (TBD) and illustrates it with a fault tolerant manipulator design problem for a satellite docking operation aboard the space shuttle. Task Based Design software is an important component of a rapidly deployable manipulator system. Such a system consists of interchangeable modular manipulator components and includes support software for design, control, and trajectory planning. The TBD software allows the user to determine the manipulator configuration optimally suited for a given task. After the user reconfigures the manipulator to this optimal configuration, the controller and trajectory planner automatically adapt themselves to the new configuration so that the manipulator is ready for immediate deployment.
Synthesis of a Large Oscillation Four-Bar Mechanism
Authors: Starns Gloria K. , Flugrad Donald R.
Published: February 2021

This paper demonstrates procedures implemented for the synthesis of a four-bar mechanism that produces large angular oscillations of the output member while maintaining effective transmission angles. The mechanisms are modeled as being driven by a force applied at the coupler link. Additionally this force’s line of action is constrained to occur along an approximate straight line. This research was conducted out of the need for a device that is capable of retraction of the horizontal tool bar housed on the back of a tractor. The tool bars accommodate the implements required to accomplish the numerous tasks of the farmer, i.e. row markers, sprayer arms, planters, etc. Upon retraction of the tool bar so that it is parallel to ground, the appropriate tools are lowered to their working position. As the length of these bars increases, a savings of time and increased productivity is realized. Kurt Hain makes the following observation regarding large oscillation mechanisms in [1]: “It would be very difficult to solve this problem with one four-bar linkage, because it is difficult to design a four-bar linkage having such a large oscillation of a crank without running into problems of poor transmission angle characteristics; it might be possible to use linkages in combinations with gears, but this would make the mechanism more expensive, less efficient, and probably noisier.” In this study simulated annealing, a genetic algorithm and the generalized reduced gradient method are used to produce mechanisms with large angular oscillations of the output member and transmission angles that vary by as little as 20° from 90°. A comparative analysis of each of the optimization procedures is presented with observations regarding the efficacy of each method in the solution of the large oscillation mechanism.
Fuzzy Heuristics for Sequential Linear Programming
Authors: Mulkay Eric L. , Rao Singiresu S.
Published: February 2021

Numerical implementations of optimization algorithms often use parameters whose values are not strictly determined by the derivation of the algorithm, but must fall in some appropriate range of values. This work describes how fuzzy logic can be used to “control” such parameters to improve algorithms performance. This concept is shown with the use of sequential linear programming (SLP) due to its simplicity in implementation. The algorithm presented in this paper implements heuristics to improve the behavior of SLP based on current iterate values of design constraints and changes in search direction. Fuzzy logic is used to implement the heuristics in a form similar to what a human observer would do. An efficient algorithm, known as the infeasible primal-dual path-following interior-point method, is used for solving the sequence of LP problems. Four numerical examples are presented to show that the proposed SLP algorithm consistently performs better than the standard SLP algorithm.
A Novel Finite Element Based Tool to Identify the Critical Parameters in Pavement Design
Authors: Bhattacharya Arun , Velinsky Steven A.
Published: February 2021

For many years, mathematical models have been employed to simulate pavement response to load, and these models have driven pavement design methods. However, based on the nature of the pavement’s constitutive materials and the complex interaction between the moving vehicle and the pavement, this formidable problem has been approached with many simplifying assumptions. Accordingly, these efforts have yet to result in a model capable of predicting damage accurately. This paper discusses work which implements a micromechanics based theory in an explicit finite element program to represent, for the first time, the response of pavement under cyclic loading. This micromechanics based approach is able to capture the complex nature of the pavement’s concrete material which includes such aspects as heterogeneity and nonlinear stress strain behavior. The Taguchi Method is then employed with this developed program to examine the critical design parameters, and the combination of these two methods provides a novel unified approach to pavement design capable of predicting pavement response under dynamic loading and identifying the sensitive design parameters.
NURBS-Based Variational Modeling As a Tool for the Analysis of Geometric Tolerances
Authors: Pierce Scott , Rosen David
Published: February 2021

The purpose of this research is to investigate a computer-aided approach to tolerance analysis for assemblies and mechanisms. A CAD system which can generate NURBS surfaces is used to produce imperfect-form, variant models. A method is developed for simulating the mating of these imperfect-form components by formulating surface mating relationships as a nonlinear programming problem. Using this approach, tolerance analysis can be performed by generating a series of typical component variants, simulating the positioning of these imperfect-form components then measuring geometric attributes of the assembly or mechanism which correspond to functionality.
A Fast Algorithm for Planning Collision-Free Paths With Rotations
Authors: Chen Shiang-Fong , Oliver James H. , Fernandez-Baca David
Published: February 2021

Motion planning is a major problem in robotics. The objective is to plan a collision-free path for a robot moving through a workspace populated with obstacles. In this paper, we present a fast and practical algorithm for moving a convex polygonal robot among a set of polygonal obstacles with translations and rotations. The running time is O(c((n + k)N + nlogn)), where c is a parameter controlling the precision of the results, n is the total number of obstacle vertices, k is the number of intersections of configuration space obstacles, and N is the number of obstacles, decomposed into convex objects. This work builds upon the slabbing method proposed by Ahrikencheikh et al. (1994), which finds an optimal motion for a point among a set of non-overlapping obstacles. Here, we extend the slabbing method to the motion planning of a convex polygonal robot with translations and rotations, which also allows overlapping configuration space obstacles. This algorithm has been fully implemented and the experimental results show that it is more robust and faster than other approaches.
A Framework for Representing and Computing Tool Accessibility
Authors: Stage Roger , Roberts Chell , Henderson Mark
Published: February 2021

One of the criteria used to assess whether a particular tool can be feasibly used to machine all or a portion of a part is that of accessibility. This paper is the result of research efforts to develop a comprehensive view of accessibility that supports manufacturability evaluation (ME). Accessibility is defined here as a descriptive characteristic that is applied to a region of the surface of a part. It indicates the orientations that a tool can have so that the cutting portion of the tool can reach the entire region while avoiding collision between the part and the tool. An Accessibility Framework is presented that defines four forms of accessibility for an entity-tool pair: full section accessibility (FSA), partial section accessibility (PSA), full tool accessibility (FTA), and partial tool accessibility (PTA). For entities possessing FSA or FTA relative to a particular tool, there are two possible types of accessibility: open and controlled. An A-cone (accessibility cone) represents the set of all directions from which a face is openly accessible. Controlled accessibility uses an implicit form of representation.

A computational approach that uses the framework to assess accessibility in support of ME is also presented. The approach is based on the idea of analyzing the compatibility of an entity-tool section pairs in broader and broader contexts. From the narrowest to the broadest the contexts are: local compatibility (LC), neighborhood compatibility (NC), and global compatibility (GC). The rationale for multiple contexts is that it enables a partitioning of the accessibility problem which can reduce computation time by quickly discarding cases of inaccessibility. The approach was implemented in a module as a part of an integrated ME system.
Manufacturing Simulations Based on Integrated Product/Process Models
Authors: Sands Benjamin , Stephens Debra , Laliberty Thomas J. , Raja Naresh
Published: February 2021

Integrated Product Process Development is essential to the development of competitive products, with manufacturing considerations such as cost, quality and cycle times well understood early in the design cycle. In order to rapidly design and develop new products, diverse organizations, often separated by hundreds of miles, must find new ways of sharing ideas and knowledge and working together towards common goals. New tools must be inserted into the process to enable and facilitate a different way of doing business. This paper summarizes work performed as part of the DARPA sponsored Rapid Design Exploration and Optimization (RaDEO) program, specifically the development of the Manufacturing Simulation Driver (MSD) system which demonstrates the automatic generation and execution of distributed manufacturing simulations. The MSD system enables Integrated Process Teams (IPT’s) to quickly create detailed manufacturing simulations of new products. MSD driven simulations include modeling the flow of a product through a particular factory early in the design cycle to provide the insight to modify designs in order to alleviate manufacturing bottlenecks. This capability enables emerging virtual enterprises conducting collaborative design and manufacturing to simulate and prove out the manufacturing cycle of a product prior to launching production ramp-up.

The Manufacturing Simulation Driver (MSD) system automatically populates simulatable manufacturing templates enabling manufacturability assessments of alternative candidate designs and processes to be conducted throughout the product development cycle. This capability provides design teams with early insight into aspects of the evolving design which compromises product manufacturability.
A Framework for Evaluating Risk in Innovative Product Development
Authors: Sarbacker Shawn D. , Ishii Kosuke
Published: February 2021

This paper presents a novel framework for evaluating risk in innovative product design and development, and a product development methodology for risk identification and management. We define “risk” as the exposure to the chance of an unsuccessful product development outcome due to ambiguity and uncertainty. We examine uncertainties in the company’s ability to identify, design, develop, manufacture, and market products that customers desire resulting in an acceptable return for the company. Based on a basic model of innovative product development, our framework identifies three dimensions of risk in product development: Envisioning Risk, Design Risk, and Execution Risk. The risk framework points out the criticality of the engineering design activity and of the interdependencies between all facets of the organization in executing innovative product development. This paper also presents a qualitative methodology, based on the risk framework, that may be used by development teams for identification of risk and eliciting risk management solutions.
The Definition and Use of the Process Flexibility Index
Authors: Kapoor Deepak , Kazmer David
Published: February 2021

This paper introduces an index for assessing the flexibility of candidate engineering designs and manufacturing processes at various stages during product realization. Once the process flexibility index (Cf) is defined, several examples of its use are provided in metal cutting, metal forming, and injection molding. The definition of the process flexibility index: resembles the process capability index, Cp; embraces Taguchi’s loss function; and provides a simple and quantitative basis for practicing the principles of axiomatic design. A high Cp indicates that the product can be consistently manufactured within precisely defined design specifications. A high Cf indicates that the product can be easily manufactured even with inaccurate design specifications.
An Objective Approach to Design Configuration Selection
Authors: Goodrich Mark D. , Rinderle James R.
Published: February 2021

Preliminary design is one of the most important stages of design but one of the least well understood. While complete designs can be analyzed in a number of ways, few methods exist to guide designers during the early stages of design. More objective, quantitative approaches to choosing from among configurational alternatives are preferable to current subjective methods of making preliminary design decisions. Design alternatives which are most worth investigating must be identified and then explored quickly and realistically.

Approaches to guiding configurational design are discussed, demonstrated, and evaluated in the context of the design of two-dimensional, pin-jointed, load-carrying truss structures. Specific methods used in the example problem illustrate the general need to select a representation which permits rapid screening and evaluation of design alternatives, to make use of reasonable approximations and estimates, to use information about the current design to guide design changes, and to take advantage of patterns found in the problem to update designs efficiently.

The proposed methods improve the initial design of a truss structure by a factor of 2.5 based on parametric optimization of the initial and final configurations. For large problems, the proposed methods involve fewer calculations than LU decomposition-based exhaustive evaluation methods of design by a factor in proportion to the number of vertices in the structure.
Evaluating Methodical Engineering Design Education
Authors: Rückert Carsten , Ahrens Gritt , Schroda Frauke , Gaedeke Oliver
Published: February 2021

At the Institute for Machine Design of the Technical University of Berlin, design methodology has been taught in industry-related engineering design projects for more than 20 years. In an interdisciplinary research study, different kinds of engineering design projects were evaluated. The aim was to identify factors which influence the acceptance and application of design methods, and thus optimize engineering design education and design methodology. The results suggest that the design work structure prescribed by design methodologies is a natural way to structure design work, at least for students. The separation of the basic machine elements education and the design methodology education seems to result in additional stress for the students.
A Method for the Evaluation of the Suitability of Specific Product Development Processes for Parallelization
Authors: Ahrens Gritt
Published: February 2021

A method for the parallelization of the working steps of an existing product development process is discribed. The procedure which is based on the design methodology as described by Pahl and Beitz provides a framework of rules and guidelines which enable the project leader to judge in which phase of a development and design process the introduction of Simultaneous Engineering is profitable.

In a case study of a German manufacturer of tubomachines and its subcontractor the developed method is validated by the example of the development and design process of a geared compressors. The reorganized process was tested using a commercially available 3D-CAD-System in order to simulate the design tasks and a commercially available PDM-System for the handling of the data produced.
Multi-Perspective Information Projection: Structuring Hypermedia Information in Engineering Development Projects
Authors: Kannapan Srikanth , Taylor Dean
Published: February 2021

Distributed enterprises are now collaborating closely with their suppliers and partners worldwide while continuously improving their response time to global markets. Such distributed enterprises demand greater levels of support for information sharing and collaborative workspaces among engineering development teams. While the use of Intranets for gathering and sharing information is expanding, the organization of the shared information is usually ad-hoc and is not designed to efficiently serve the diverse information needs of work-groups. Such ad-hoc organizations of information result information overload and hence information users have to resort to (syntactic) keyword search to access information. This paper proposes an Information Projection methodology that integrates the organization of the semantic content of shared information with the organization of syntactic content of documents in a way that is meaningful to specific work-groups so as to reduce information overload. The Information Projection methodology has been applied in three different engineering contexts to varied degrees of sophistication and has shown a significant degree of re-usability, although the information and document models that result are themselves very context specific. The information maps resulting from the context of a MEMS technology development project have also been implemented using basic Web technology (HTML, CGI scripts) and has provided several insights on the implications and limitations of such implementations.
A Neural Network Design Methodology for Structural Control
Authors: Yang S. M. , Lee G. S.
Published: February 2021

One of the major difficulties in neural network applications is the selection of the parameters in network configuration and the coefficients in learning rule for fast convergence as well as best system performance. This paper developed a network design methodology so that the optimal design parameters/coefficients can be determined in a systematic way thereby avoiding the lengthy trial-and-error. The methodology combines the Taguchi method of quality engineering and the back-propagation network with an adaptive learning rate for their advantages in implementation feasibility and performance robustness. Vibration suppression experiments of a composite smart structure with embedded piezoelectric sensor/actuator validate that the methodology provides an efficient neural controller design, including the plant order, the number of hidden layer neurons, the number of training patterns, and the coefficients of adaptive learning rate.
Revisiting Hrovat’s Semi-Active Tuned Mass Damper (SATMD)
Authors: Kuehn Jeffrey L. , Brock Gregory D. , Patten William N.
Published: February 2021

This paper examines the effects of actuator dynamics on the performance of a hydraulic semi-active tuned mass damper. The original semi-active tuned mass damper design proposed by Hrovat (1983) is recounted. A consistent model for the actuator dynamics is established. A practical bistate control strategy is then developed for the system. The performance of the SATMD is obtained using numerical simulations and compared to Hrovat’s results. While the work here suggests that a carefully designed semi-active tuned mass damper system can provide structural vibration mitigation for wind loads, seismic loads can saturate the tuned mass damper system.
Surface Topography and Noise Emission in Gearboxes
Authors: Amini Naser , Rosén B. G.
Published: February 2021

This paper, by the experimental investigation, deals with the effect of different surface topographies on noise generation in gears. Results from the noise assessment of one gear before and after honing are discussed. The honing operation was applied to the gear after the grinding. The gear was tested in an actual gearbox, operated in a test rig. Running conditions were systematically changed during the test; however, the same conditions were utilized for the gear before and after honing. The aim of the study was to identify the mechanism of the expected noise reduction, with surfaces being evaluated in 3D.

The following results have been obtained: The total energy in the noise decreases significantly. The magnitude of the tooth-mesh frequency dose not change, but the level of its higher harmonics decreases significantly. These reductions are especially significant, when running at higher rotational speeds or when the applied torque is increased.
Computational Issues in Damping Identification for Large Scale Problems
Authors: Pilkey Deborah F. , Roe Kevin P. , Inman Daniel J.
Published: February 2021

Damage detection and diagnostic techniques using vibration responses that depend on analytical models provide more information about a structure’s integrity than those that are not model based. The drawback of these approaches is that some form of a workable model is required. Typically, models of practical structures and their corresponding computational effort are very large. One method of detecting damage in a structure is to measure excess energy dissipation, which can be seen in damping matrices. Calculating damping matrices is important because there is a correspondence between a change in the damping matrix and the change in the health of a structure. The objective of this research is to investigate the numerical problems associated with computing damping matrices using inverse methods.

Two damping identification methods are tested for efficiency in large-scale applications. One is an iterative routine, and the other a least squares method. Numerical simulations have been performed on multiple degree-of-freedom models to test the effectiveness of the algorithm and the usefulness of parallel computation for the problems. High Performance Fortran is used to parallelize the algorithm.
Efficient Structural Acoustic Analysis Using Finite and Infinite Elements and Parallel Processing Architectures
Authors: Moore Stewart W. , Allik Henno
Published: February 2021

The analysis of three-dimensional shell structures submerged in an infinite fluid and subjected to arbitrary loadings is a computationally demanding problem regardless of the analytical technique used. Over the past several years, we have developed a combined finite/infinite element method of solving this class of problems that is more efficient than other available techniques, and have implemented it in a comprehensive set of computer programs called SARA.

This paper presents an overview of our work in parallizing this software. In the first part of the paper, we describe our method for solving the fluid-structure interaction equations including infinite element theory, and modeling practices that have evolved for solving cylindrical geometries.

The second part of the paper addresses parallalization of SARA-3D on both shared and distributed memory architectures. The SARA implementation of the method is described along with sample problems, and a comparison to a SARA-3D solution is provided.
Finite Element Methods for the Radiation of Ultrasonic Phased Arrays Into an Acoustic Medium
Authors: Grosh Karl , Dodson John M. , Lin Yuan
Published: February 2021

In this paper, the dynamic response of a piezoelectric transducer in contact with an acoustic media is formulated. This serves as a model problem for an ultrasonic phased array in contact with the human body. These arrays may be used for hyperthermia or ablation surgery; the focus of this paper, however, is the efficient numerical formulation for modeling the array problem. Efficient numerical methods will provide a useful design tool and allow for the investigation of structural–acoustic phenomena. A finite element formulation based on Galerkin and Galerkin Least Squares (GLS) methods is presented. The benefits of the GLS method over the standard Galerkin method are demonstrated through numerical experiments of the dynamic response of a multi–element array. The methods under development can be applied to any fluid structure interaction problem and point strongly to the advantage of GLS methods for mid– and high–frequency applications. The accuracy of approximate versus exact non–reflecting, truncation boundary conditions is discussed.