bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic ablation of the Rho GTPase Rnd3 triggers developmental defects in internal capsule and the globus pallidus formation
Authors: Marfull‐Oromí Pau , Fleitas Catherine , Zammou Bahira , Rocandio Daniel , Ballester‐Lurbe Begoña , Terrado Jose , Perez‐Roger Ignacio , Espinet Carme , Egea Joaquim
Published: February 2021

The forebrain includes the cerebral cortex, the thalamus, and the striatum and globus pallidus (GP) in the subpallium. The formation of these structures and their interconnections by specific axonal tracts take place in a precise and orchestrated time and spatial‐dependent manner during development. However, the knowledge of the molecular and cellular mechanisms that are involved is rather limited. Moreover, while many extracellular cues and specific receptors have been shown to play a role in different aspects of nervous system development, including neuron migration and axon guidance, examples of intracellular signaling effectors involved in these processes are sparse. In the present work, we have shown that the atypical RhoGTPase, Rnd3, is expressed very early during brain development and keeps a dynamic expression in several brain regions including the cortex, the thalamus, and the subpallium. By using a gene‐trap allele (Rnd3gt) and immunological techniques, we have shown that Rnd3gt/gt embryos display severe defects in striatal and thalamocortical axonal projections (SAs and TCAs, respectively) and defects in GP formation already at early stages. Surprisingly, the corridor, an important intermediate target for TCAs is still present in these mutants. Mechanistically, a conditional genetic deletion approach revealed that Rnd3 is primarily required for the normal development of Medial Ganglionic Eminence‐derived structures, such as the GP, and therefore acts non‐cell autonomously in SAs and TCAs. In conclusion, we have demonstrated the important role of Rnd3 as an early regulator of subpallium development in vivo and revealed new insights about SAs and TCAs development.

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Age and gender differences in personality traits from early childhood through adolescence
Authors: Slobodskaya Helena R. , Kornienko Olga S.
Published: February 2021

Objective

Most research on personality development has employed self‐report questionnaires and concerned individuals older than 10 years. This is the first study to examine mean‐level age differences in personality traits from early childhood to late adolescence in the non‐Western cultural context.

Method

Personality was measured in two community samples of parent reports of 2–18‐year‐old children (N = 4,330) and self‐reports of 10–19‐year‐old adolescents (N = 4,663) from Russia by the Inventory of Child Individual Differences‐Short version (ICID‐S) at the three levels of the hierarchy, the two higher order traits, the Big Five, and lower order traits.

Results

Across childhood, the Agreeableness, Conscientiousness, and Neuroticism traits increased, and the Extraversion and Openness traits decreased. In adolescence, parent‐reported Conscientiousness traits increased and Neuroticism traits decreased, whereas youth‐rated Alpha and Agreeableness decreased in middle adolescence. There were small gender differences in trait levels and age trends. Parents and youths did not agree on gender differences in age trends for Neuroticism and Extraversion.

Conclusion

The findings support personality maturation from early childhood to late adolescence, with the exception of increasing Neuroticism across childhood, and provide some evidence for the disruption in personality maturation in adolescence. Parents and adolescents may have different perspectives on personality development.
What evolutionary processes maintain MHC IIꞵ diversity within and among populations of stickleback?
Authors: Peng Foen , Ballare Kimberly M. , Hollis Woodard S. , den Haan Stijn , Bolnick Daniel I.
Published: February 2021

Major Histocompatibility Complex (MHC) genes code for proteins that recognize foreign protein antigens to initiate T‐cell‐mediated adaptive immune responses. They are often the most polymorphic genes in vertebrate genomes. How evolution maintains this diversity remains of debate. Three main hypotheses seek to explain the maintenance of MHC diversity by invoking pathogen‐mediated selection: heterozygote advantage, frequency‐dependent selection, and fluctuating selection across landscapes or through time. Here, we use a large‐scale field parasite survey in a stickleback metapopulation to test predictions derived from each of these hypotheses. We identify over 1000 MHC IIβ variants (alleles spanning paralogous genes) and find that many of them covary positively or negatively with parasite load, suggesting that these genes contribute to resistance or susceptibility. However, despite our large sample‐size, we find no evidence for the widely cited stabilizing selection on MHC heterozygosity, in which individuals with an intermediate number of MHC variants have the lowest parasite burden. Nor do we observe a rare‐variant advantage, or widespread fluctuating selection across populations. In contrast, we find that MHC diversity is best predicted by neutral genome‐wide heterozygosity and between‐population genomic divergence, suggesting neutral processes are important in shaping the pattern of metapopulation MHC diversity. Thus, although MHC IIβ is highly diverse and relevant to the type and intensity of macroparasite infection in these populations of stickleback, the main models of MHC evolution still provide little explanatory power in this system.
Friends or enemies? The complicated relationship between Pseudomonas aeruginosa and Staphylococcus aureus
Authors: Yung Deborah Bow Yue , Sircombe Kathleen Jean , Pletzer Daniel
Published: February 2021

Pseudomonas aeruginosa (Pa) and Staphylococcus aureus (Sa) are opportunistic pathogens that are most commonly co‐isolated from chronic wounds and the sputum of cystic fibrosis patients. Over the last few years, there have been plenty of contrasting results from studies involving P. aeruginosa and S. aureus co‐cultures. The general concept that P. aeruginosa outcompetes S. aureus has been challenged and there is more evidence now that they can co‐exist. Nevertheless, it still remains difficult to mimic polymicrobial infections in vitro and in vivo. In this review, we discuss recent advances in regard to Pa‐Sa molecular interactions, their physical responses, and in vitro and in vivo models. We believe it is important to optimize growth conditions in the laboratory, determine appropriate bacterial starting ratios, and consider environmental factors to study the co‐existence of these two pathogens. Ideally, optimized growth media should reflect host‐mimicking conditions with or without host cells that allow both bacteria to co‐exist. To further identify mechanisms that could help to treat these complex infections, we propose to use relevant polymicrobial animal models. Ultimately, we briefly discuss how polymicrobial infections can increase antibiotic tolerance.
Cultural competence among nurses and its influencing factors: A cross‐sectional study
Authors: Cai Duanying , He Wei , Klug David
Published: February 2021

The purpose of this study was to investigate the level of cultural competence and its influencing factors among Chinese nurses by using a cross‐sectional design. Participants were recruited from four tertiary hospitals in Jiangsu, China, and 325 nurses completed the Cultural Competence Inventory for Nurses in China. Data were analyzed using stepwise multiple regression to identify factors influencing cultural competence. The results showed that Chinese nurses self‐rated cultural competence at a moderate level (mean value of 101.7 out of 145), which indicates that cultural training is necessary to improve their cultural competence. Nurses who were younger and had fewer years of working experience, had lower educational backgrounds, seldom learned about different cultures via mass media, and rarely resided in or visited places with different cultures tended to have lower cultural competence levels, and should be provided more opportunities for cultural training. By considering demographic characteristics that influence cultural competence among Chinese nurses, educators can specifically design cultural training content at an appropriate level, targeting trainees' needs and thereby enhance training effectiveness.
Optimization theory explains nighttime stomatal responses
Authors: Wang Yujie , Anderegg William R. L. , Venturas Martin D. , Trugman Anna T. , Yu Kailiang , Frankenberg Christian
Published: February 2021

Nocturnal transpiration is widely observed across species and biomes, and may significantly impact global water, carbon, and energy budgets. However, it remains elusive why plants lose water at night and how to model it at large scales.

We hypothesized that plants optimize nighttime leaf diffusive conductance (gwn) to balance potential daytime photosynthetic benefits and nocturnal transpiration benefits. We quantified nighttime benefits from respiratory reductions due to evaporative leaf cooling. We described nighttime costs in terms of a reduced carbon gain during the day because of water use at night. We measured nighttime stomatal responses and tested our model with water birch (Betula occidentalis) saplings grown in a glasshouse.

The gwn of water birch decreased with drier soil, higher atmospheric CO2, wetter air, lower leaf temperature, and lower leaf respiration rate. Our model predicted all these responses correctly, except for the response of gwn to air humidity. Our results also suggested that the slow decrease in gwn after sunset could be associated with decreasing leaf respiration.

The optimality‐based nocturnal transpiration model smoothly integrates with daytime stomatal optimization approaches, and thus has the potential to quantitatively predict nocturnal transpiration across space and time.
Chilled to be forced: the best dose to wake up buds from winter dormancy
Authors: Baumgarten Frederik , Zohner Constantin M. , Gessler Arthur , Vitasse Yann
Published: February 2021

Over the last decades, spring leaf‐out of temperate and boreal trees has substantially advanced in response to global warming, affecting terrestrial biogeochemical fluxes and the Earth's climate system. However, it remains unclear whether leaf‐out will continue to advance with further warming because species’ effective chilling temperatures, as well as the amount of chilling time required to break dormancy, are still largely unknown for most forest tree species.

Here, we assessed the progress of winter dormancy and quantified the efficiency of different chilling temperatures in six dominant temperate European tree species by exposing 1170 twig cuttings to a range of temperatures from −2°C to 10°C for 1, 3, 6 or 12 wk.

We found that freezing temperatures were most effective for half of the species or as effective as chilling temperatures up to 10°C, that is, leading to minimum thermal time to and maximum success of budburst. Interestingly, chilling duration had a much larger effect on dormancy release than absolute chilling temperature.

Our experimental results challenge the common assumption that optimal chilling temperatures range c. 4–6°C, instead revealing strong sensitivity to a large range of temperatures. These findings are valuable for improving phenological models and predicting future spring phenology in a warming world.
High night temperature effects on wheat and rice: Current status and way forward
Authors: Impa Somayanda M. , Raju Bheemanahalli , Hein Nathan T. , Sandhu Jaspreet , Prasad P.V. Vara , Walia Harkamal , Jagadish S.V. Krishna
Published: February 2021

Rapid increases in minimum night temperature than in maximum day temperature is predicted to continue, posing significant challenges to crop productivity. Rice and wheat are two major staples that are sensitive to high night‐temperature (HNT) stress. This review aims to (i) systematically compare the grain yield responses of rice and wheat exposed to HNT stress across scales, and (ii) understand the physiological and biochemical responses that affect grain yield and quality. To achieve this, we combined a synthesis of current literature on HNT effects on rice and wheat with information from a series of independent experiments we conducted across scales, using a common set of genetic materials to avoid confounding our findings with differences in genetic background. In addition, we explored HNT‐induced alterations in physiological mechanisms including carbon balance, source–sink metabolite changes and reactive oxygen species. Impacts of HNT on grain developmental dynamics focused on grain‐filling duration, post‐flowering senescence, changes in grain starch and protein composition, starch metabolism enzymes and chalk formation in rice grains are summarized. Finally, we highlight the need for high‐throughput field‐based phenotyping facilities for improved assessment of large‐diversity panels and mapping populations to aid breeding for increased resilience to HNT in crops.
Aspergillus niger, the causal agent of black mould disease in date fruits, infects and colonizes flowers and young fruitlets
Authors: Cohen Yuval , Shulhani Ran , Rot Yehuda , Zemach Hanita , Belausov Eduard , Grinberg‐Baran Maayan , Borenstein Menachem , Pivonia Shimon , Ezra David , Shtienberg Dani
Published: February 2021

Black mould, caused by Aspergillus niger, is the main fungal disease affecting date fruits. Symptoms develop inside the fruit, at the inner space between the pulp and the seed. This study focuses on the aetiology of black mould disease in Medjoul fruit. We followed symptom appearance naturally and after artificial A. niger inoculation at different development and maturity stages. Symptoms developed in only a short period during early fruit ripening. However, fruits were commonly colonized at earlier stages of development. Artificial inoculation of flowers and setting fruitlets increased the level of fruit colonization, while fungicide spraying at these stages decreased colonization. Several weeks following flower inoculation by A. niger, mycelium could be detected on degenerating stigmas and carpels as well as between the fruit and the calyx. Following inoculation with an A. niger strain expressing green fluorescent protein (A. nigerGFP), the pathogen was detected on stigmas of setting fruitlets but not within the stigmatic tissue or the transmitting tract of the carpel. The A. nigerGFP strain was detected during fruit development below the base of the large fruitlets and above the calyx surrounding the vascular bundle leading into the fruit. The results suggest that A. niger can infect and colonize flowers and setting fruitlets, grows on the degenerating carpels, and remains latent at a protected site at the base of the fruit until ripening. It then induces the typical black mould symptoms. The significance of these results for developing means to cope with the disease is discussed.
Mechanistic insights of CRISPR/Cas‐mediated genome editing towards enhancing abiotic stress tolerance in plants
Authors: Bhat Mujtaba Aamir , Mir Rakeeb Ahmad , Kumar Vijay , Shah Ali Asghar , Zargar Sajad Majeed , Rahman Safikur , Jan Arif Tasleem
Published: February 2021

Abiotic stresses such as temperature (high/low), drought, salinity, and others make the environment hostile to plants. Abiotic stressors adversely affect plant growth and development; and thereby makes a direct impact on overall plant productivity. Plants confront stress by developing an internal defense system orchestrated by compatible solutes, reactive oxygen species scavengers and phytohormones. However, routine exposure to unpredictable environmental stressors makes it essential to equip plants with a system that contributes to sustainable agricultural productivity, besides imparting multi‐stress tolerance. The sustainable approach against abiotic stress is accomplished through breeding of tolerant cultivars. Though eco‐friendly, tedious screening and crossing protocol limits its usage to overcome stress and in attaining the goal of global food security. Advancement on the technological front has enabled adoption of genomic engineering approaches to perform site‐specific modification in the plant genome for improving adaptability, increasing the yield and in attributing resilience against different stressors. Of the different genome editing approaches, CRISPR/Cas has revolutionized biological research with wider applicability to crop plants. CRISPR/Cas emerged as a versatile tool in editing genomes for desired traits in highly accurate and precise manner. The present study summarizes advancement of the CRISPR/Cas genome editing tool in its adoption to manipulate plant genomes for novel traits towards developing high‐yielding and climate‐resilient crop varieties.
Physical activity and sedentary time in children and adolescents with asthma: A systematic review and meta‐analysis
Authors: Mackintosh Kelly A. , McNarry Melitta A. , Berntsen Sveinung , Steele James , Sejersted Ellen , Westergren Thomas
Published: February 2021

The influence of asthma on physical activity (PA) in youth remains equivocal. This review synthesizes the evidence regarding the influence of asthma on PA and sedentary time and evaluates the role of key moderators for this relationship. In accordance with PRISMA guidelines, six electronic databases and gray literature were searched. Primary studies in English were included if they reported device‐assessed PA in youth with and without asthma. Random effects meta‐analyses examined the effect of asthma on PA and, separately, sedentary time. Mixed‐effect meta‐regression analyses were conducted using age and sex as moderators, with sub‐group comparisons for study quality and asthma diagnosis criteria. Overall, of 3944 citations retrieved, 2850 were screened after the removal of supplication and 2743 citations excluded. Of the 107 full‐text publications reviewed, 16 were included in data extraction and analysis, with 15 and five studies included in the PA and sedentary time meta‐analyses, respectively. The robust effect size estimate for the influence of asthma on PA and sedentary time was −0.04 [95% CI = −0.11, 0.03] and −0.09 [95% CI = −0.12, −0.06], indicating a non‐significant and significant trivial effect, respectively. The effect of asthma on PA levels or sedentary time was not associated with age or sex. Youth with controlled asthma are equally physically (in)active as their healthy peers, with asthma associated with less sedentary time. However, methodological limitations and a paucity of clear methodological reporting temper these conclusions. More rigorous device‐based assessments, with a particular focus on sedentary time, and more robust diagnoses of asthma, especially with regard to severity, are needed.
A protein kinase–major sperm protein gene hijacked by a necrotrophic fungal pathogen triggers disease susceptibility in wheat
Authors: Zhang Zengcui , Running Katherine L. D. , Seneviratne Sudeshi , Peters Haugrud Amanda R. , Szabo‐Hever Agnes , Shi Gongjun , Brueggeman Robert , Xu Steven S. , Friesen Timothy L. , Faris Justin D.
Published: February 2021

Septoria nodorum blotch (SNB), a disease caused by the necrotrophic fungal pathogen Parastagonospora nodorum, is a threat to wheat (Triticum aestivum) production worldwide. Multiple inverse gene‐for‐gene interactions involving the recognition of necrotrophic effectors (NEs) by wheat sensitivity genes play major roles in causing SNB. One interaction involves the wheat gene Snn3 and the P. nodorum NE SnTox3. Here, we used a map‐based strategy to clone the Snn3‐D1 gene from Aegilops tauschii, the D‐genome progenitor of common wheat. Snn3‐D1 contained protein kinase and major sperm protein domains, both of which were essential for function as confirmed by mutagenesis. As opposed to other characterized interactions in this pathosystem, a compatible Snn3‐D1–SnTox3 interaction was light‐independent, and Snn3‐D1 transcriptional expression was downregulated by light and upregulated by darkness. Snn3‐D1 likely emerged in Ae. tauschii due to an approximately 218‐kb insertion that occurred along the west bank of the Caspian Sea. The identification of this new class of NE sensitivity genes combined with the previously cloned sensitivity genes demonstrates that P. nodorum can take advantage of diverse host targets to trigger SNB susceptibility in wheat.
TECHNOLOGY, THEOLOGY, AND SPIRITUALITY IN THE DIGITAL AGE
Authors: Jackelén Antje
Published: February 2021

Digitalization and the development of Artificial Intelligence (AI) will bring about substantial changes in all aspects of life. This happens in a world marked by the poisonous synergy of five Ps, polarization, populism, protectionism, post‐truth, patriarchy, as well as an ambiguous interplay of secularization and new visibility of religion.

If development of AI is to be beneficial for people and planet a number of challenges must be met. In this regard, religion‐and‐science dialogue needs improvement in making things not only intellectually but also spiritually fit. Ethics should be involved from the beginning rather than being called upon first when problems arise. Faith communities have a prophetical, diaconal, ethical, and theological role.

Based on the characterization of life as a fourfold web of relationality, personal, social, political, as well as global issues are identified and discussed. These include mental health disorders, addiction, manipulation, and self‐exploitation. Reflections on leadership suggest resilience, coexistence, and hope as theological key components for navigating the uncharted realms of the digital age.
Teaching Modular Automation Concepts
Authors: Derby Stephen , Cooper Clay
Published: February 2021

Teaching a course on Modular Automation Concepts (MAC) for the automation field has been twice accomplished. In order to demonstrate the MAC strategies, the packaging automation industry is reviewed to find new opportunities for production machines. Student teams then designed new machines using MAC techniques. Samples of project results are summarized.
Constraint-Based Solid Modeling in a Virtual Reality Environment
Authors: Gao Shuming , Wan Huagen , Peng Qunsheng
Published: February 2021

With the rapid development of the virtual reality technology, the research on the integration of virtual reality with CAD system becomes more and more popular. The VR-based CAD system allows the designer to make design in a more intuitive and more convenient manner. But, on the negative side, it has difficulty in creating the precise geometric model of a product which is one of the most important part of the product model. This paper presents an approach for constraint based solid modeling in a virtual reality environment. The approach not only allows the designer to create, edit and visualize the design by direct 3D manipulations in a virtual environment, but also makes the created solid model precise by recognizing and solving the geometric constraints involved in the initial design. To effectively support direct 3D manipulations and fast change propagation, we adopt a new constraint based solid model which, besides the typical constituents, includes the Shape Control Point, Location Pattern, Explicit Shape Constraint, etc. Guided by the Location Pattern of each primitive, recognizing and solving of location constraints in our approach reaches real-time. The proposed approach has been implemented and a prototype system has been developed.
Real-Time Dynamic Balancing and Walking Control of a 7-Link Planar Biped
Authors: Troy James J.
Published: February 2021

Physically based modeling and feedback control techniques are used to simulate realistic motion for a planar 7-link biped. Multibody modeling, contact constraints, optimal balancing, and gait cycle generation will be discussed. Efficient multibody dynamics computation allows accurate motion to be simulated in real-time. A full state feedback linear-quadratic regulator control system is used to generate the joint actuator torques for balancing, and a state machine-PD controller is used for walking motion. The control system was designed to maintain stability on various surface environments and in the presence of external disturbances. Real-time interactive simulation software has been developed to allow the user to operate the biped system within a 3D virtual environment. Comparison of the 7-link biped simulation results to other planar biped models, as well as to human walking data, is presented.
A Visualization Model for Printed Woven Textiles
Authors: Hunting Brad , Derby Stephen , Puffer Raymond
Published: February 2021

This paper describes significant issues relating to the visual response modeling of on demand printed textiles. The visualization technique described comments on surface geometry, dye spread, substrate color, and color space conversion. The observations are based on experimental data and account for fiber properties, thread geometry, and weave geometry. This work is applicable to pre-press visualization of random access dot placement printed textiles. Software was developed to implement a model of printed textile visualization based on the issues presented here. The visualization process provides rapid evaluation of printing results to design parameter changes.
Development of Automated Fixture Planning Systems
Authors: Ma W. , Li J. , Rong Y.
Published: February 2021

Fixturing is an important manufacturing activity. Computer-aided fixture design technique is being rapidly developed to reduce the lead time involved in manufacturing planning. An automated fixture configuration design system has been developed to select automatically modular fixture components and place them into position with satisfactory assembly relationships. In this paper, an automated fixturing planning system is presented in which fixturing surfaces and points are automatically determined based on workpiece geometry and operational information. Fixturing surface accessibility, feature accuracy, and fixturing stability are the main concerns in the fixture planning. The system development, fixture planning decision procedure, and an implementation example are presented in the paper.
An Intelligent ES-ANNs System for Objective Evaluation of Leather Handle
Authors: Su Zhenwei , Su Daizhong
Published: February 2021

Basic problems and the bottleneck of current approaches for objective assessment of leather handle are discussed. As a solution, a new approach, an expert system (ES) based on artificial neural networks (ANNs) is proposed, in which the ES and ANNs co-operate in a superiority complementary way. The knowledge base of the system can be built in an effective way and the evaluation of leather handle can be conducted on-line. A case study has been conducted, and it has been demonstrated that the approach is capable of handling non-linear relationships among multiple measurement parameters of leather handle.
Agent-Based Collaborative Design of Parts in Assembly
Authors: Mori Toshiki , Cutkosky Mark R.
Published: February 2021

In this paper, we propose an architecture in which engineering design agents interact with each other, exchange design information and keep track of state information to assist with collaborative design. We present an example involving CAD agents, for which each state corresponds to a particular design model. If a designer publishes a new design, the operation is recorded as a state transition that triggers action. Focusing on the history of design states and operations, we present a coordination algorithm that corresponds to the tracking of Pareto optimality. A prototype implementation is described, using a commercial 3D CAD system and agent interfaces written in Java.
The Detection of Form Features in CAD Models Using Three Dimensional Discrete Wavelet Analysis
Authors: Qamhiyah Abir , Sun Lei
Published: February 2021

This paper reports on exploring the application of three-dimensional discrete Wavelet transform (DWT) to the recognition of form features in CAD models. The multi-resolution behavior of Wavelet transform (WT) and its proven pattern recognition capabilities enables the identification of form features of different scales. An example demonstrating the application of WTs to the recognition of form features is presented. The input to the WT is a digitized representation of the object, and the output is currently a digitized representation of the extracted form features.
Influence of Imperfections in Working Media on Diesel Engine Indicator Process: Part 1 — Theory
Authors: Danov Stanislav N. , Gupta Ashwani K.
Published: February 2021

Several improvements to the mathematical model of the indicator process, taking place in a diesel engine cylinder, are proposed. The thermodynamic behavior of working media is described by the equation of state, valid for real gases. Analytical mathematical dependencies between thermal parameters (pressure, temperature, volume) and caloric parameters (internal energy, enthalpy, specific heat capacities) have been obtained. These equations have been applied to the various products encountered during the burning of fuel and the gas mixture as a whole in the engine cylinder under conditions of high pressures and temperatures. An improved mathematical model, based on the first law of thermodynamics, has been developed by taking into account imperfections in the working media that appear under high pressures and temperatures. The numerical results show that there are significant differences between the values calculated using ideal gas behavior and the real gas, in particular at high pressure and high temperature conditions. The numerical experiments show that if the pressure is above 8 to 9 MPa, the imperfections in working medium must be taken into consideration. The results obtained from the mathematical dependency of the caloric parameters can also be used to model any energy conversion and combustion process, such as, advanced gas turbine engines which operate at high pressure ratios, rockets.
CAD Data Repair Based on Virtual Topology
Authors: Sheffer Alla , Blacker Ted , Bercovier Michel
Published: February 2021

Automatic and rapid transfer of CAD data among different CAD systems or engineering applications is of crucial importance for the acceleration of the product development processes. Geometric models generated by CAD systems often require multiple editing and adjustment within the receiving system. The major reason for this is that models generated by CAD systems often contain errors in their representation, such as cracks, duplication or overlaps. Such errors often hamper further processing like finite element analysis, rapid prototyping, etc.

In our previous work the concept of virtual topology was introduced which permits construction of valid topological models without prior geometrical correction. The virtual B-Rep provides a consistent geometric description of the model which is sufficient for many engineering applications. However providing an exact geometric description of the model if often desirable for further processing purposes.

In this work a new algorithm for repair of CAD models geometry is described. The algorithm is based on the model topology provided by the virtual B-Rep. The generated geometric description consists of the topological connectivity information on the model and of a triangular conformal faceting of the model faces envelope.
Modeling Noise in Approximation-Based Robust Design: A Comparison and Critical Discussion
Authors: Koch Patrick N. , Mavris Dimitri , Allen Janet K. , Mistree Farrokh
Published: February 2021

Robust design techniques are being developed that incorporate computational experimentation and approximation for efficient exploration of a preliminary design space. Critical to such approximation-based robust design approaches is the effective modeling of the effects of noise (uncontrollable factors) on performance (measuring and modeling performance variation). Given that approximations are sought for efficient exploration, the question addressed in this paper is the following: How can noise be modeled and incorporated effectively into the preliminary design of complex systems to effectively identify robust solutions?

Three approaches for modeling noise when approximate performance models are sought are tested and compared in this paper: statistical expected value and Taylor’s expansion, design of experiments (DOE)-based Monte Carlo simulation, and product arrays. The focus in this testing and comparison is on modeling and predicting performance variation. The example problem employed is the preliminary design of the thermodynamic cycle for a commercial turbofan turbine engine. The approximate models constructed for this example using each modeling approach are employed for exploring the preliminary design space and identifying robust solutions. The robust solutions obtained are compared and a discussion of the appropriate uses of each modeling approach is presented.
Vibration of the Rotor Shell in a Trochoidal-Type Machine Without Apex Seals
Authors: Li Shuangqing , Shung John B. , Barron Randall F.
Published: February 2021

The natural frequencies and dynamic response of a trochoidal cylindrical shell in a trochoidal-type machine are studied. Both analytical method and finite element method (FEM) solutions are obtained. The mode shapes obtained by the two approaches match quite well. The model established can be applied to control the running clearance between rotor and chamber in this type of machine, which is critical to the performance of the machine.
Topology Optimization Algorithm for Plates and Shells Subjected to Plastic Deformations
Authors: Yuge Kohei , Iwai Nobuhiro , Kikuchi Noboru
Published: February 2021

A topology optimization method for plates and shells subjected to plastic deformations is presented. The algorithms is based on the generalized layout optimization method invented by Bendsϕe and Kikuchi (1988), where an admissible design domain is assumed to be composed of microstructures with periodic cavities. The sizes of the cavities and the rotational angles of the microstructures are design variables which are optimized so as to minimize the applied work. The macroscopic material tensor for the porous material is numerically calculated by the homogenization method for the sensitivity analysis. In this paper, the method is applied to two-dimensional elasto-plastic problems. A database of the material tensor and its interpolation technique are presented. The algorithm is expanded into thin shells subjected to finite deformations. Several numerical examples are shown to demonstrate the effectiveness of these algorithms.
Exploiting Discrepancies in Function Computation Time Within Optimization Models
Authors: Nelson Sigurd A. , Papalambros Panos Y.
Published: February 2021

Computational models in engineering often use a range of analysis functions within the same optimization problem, from finite element models to analytical expressions. The computational expense of these models often differs by orders of magnitude, and practical optimization algorithms should address this discrepancy. In this article, in an effort to reduce the number of expensive analyses, a technique is discussed for modifying trust region algorithms to utilize the inexpensive functions directly when calculating iterates. The technique is applied to a trust region algorithm of Yuan, and two numerical examples are given.
On the Integration of Layered Manufacturing and Material Removal Processes
Authors: Kulkarni Prashant , Dutta Debasish
Published: February 2021

In this paper, we develop methodologies for the integration of Layered Manufacturing and traditional material removal processes into an integrated manufacturing setup. The scenarios under which this integration would be beneficial are identified and algorithms for the integration developed. As examples, we consider two current Layered Manufacturing technologies that use Material Removal operations as a part of their process. The benefits of our procedure are demonstrated by examples.
Multirate Integration in Hybrid Electric Vehicle Virtual Proving Grounds
Authors: Solis Dario , Schwarz Chris
Published: February 2021

In recent years technology development for the design of electric and hybrid-electric vehicle systems has reached a peak, due to ever increasing restrictions on fuel economy and reduced vehicle emissions. An international race among car manufacturers to bring production hybrid-electric vehicles to market has generated a great deal of interest in the scientific community. The design of these systems requires development of new simulation and optimization tools. In this paper, a description of a real-time numerical environment for Virtual Proving Grounds studies for hybrid-electric vehicles is presented. Within this environment, vehicle models are developed using a recursive multibody dynamics formulation that results in a set of Differential-Algebraic Equations (DAE), and vehicle subsystem models are created using Ordinary Differential Equations (ODE). Based on engineering knowledge of vehicle systems, two time scales are identified. The first time scale, referred to as slow time scale, contains generalized coordinates describing the mechanical vehicle system that includs the chassis, steering rack, and suspension assemblies. The second time scale, referred to as fast time scale, contains the hybrid-electric powertrain components and vehicle tires. Multirate techniques to integrate the combined set of DAE and ODE in two time scales are used to obtain computational gains that will allow solution of the system’s governing equations for state derivatives, and efficient numerical integration in real time.
Improving the Accuracy of Multi-Axis Machines Through On-Line Error Compensation Using Neural Networks
Authors: Ouafi Abderrazak El , Guillot Michel , Bedrouni Abdellah
Published: February 2021

This research is devoted to one of the most fundamental problems in precision engineering: multi-axis machines accuracy. The paper presents a new approach designed to support the implementation of software error compensation of geometric, thermal and dynamic errors for enhancing the accuracy of multi-axis machines. The accuracy of multi-axis machines can be significantly improved using an intelligent integration of sensor information to perform the compensation function. The compensation process consists of the following major steps carried out on-line: continuous monitoring of the machine conditions using position, force, speed and temperature sensors mounted on the machine structure. Error forecasting through sensor fusion. Volumetric error synthesis and software compensation. To improve the effectiveness of error modeling, an artificial neural network is extensively applied.

Implemented on a turning center, the compensation approach has enabled improvement of the machine accuracy by reducing the maximum dimensional error from 70 μm initially to less than 4 μm.
Multi-Objective Optimal Design of Automotive Engine Using Genetic Algorithm
Authors: Fujita Kikuo , Hirokawa Noriyasu , Akagi Shinsuke , Kitamura Shinji , Yokohata Hideaki
Published: February 2021

A genetic algorithm based optimization method is proposed for a multi-objective design problem of an automotive engine, that includes several difficulties in practical engineering optimization problems. While various optimization techniques have been applied to engineering design problems, a class of realistic engineering design problems face on a mixture of different optimization difficulties, such as the rugged nature of system response, the numbers of design variables and objectives, etc. In order to overcome such a situation, this paper proposes a genetic algorithm based multi-objective optimization method, that introduces Pareto-optimality based fitness function, similarity based selection and direct real number crossover. This optimization method is also applied to the design problem of an automotive engine with the design criteria on a total power train. The computational examples show the ability of the proposed method for finding a relevant set of Pareto optima.
Computation of Parametric Space Curves From Real Space Curves for the Data Exchange Between Heterogeneous CAD Systems
Authors: Lee Yong-Gu
Published: February 2021

There are many obstacles in exchanging model data between different CAD systems. One of them is that some CAD systems refuse to supply parametric space curves when sending a model data to other CAD systems. Parametric space curves are omitted because in many cases they are additional information to the real space curves.

Parametric space curves can be essential in many geometric computations such as surface triangulations. Thus a practical issue of computing parametric space curves from real space curves and the base surface is discussed.

The input geometric types are those that are defined in Part 42 of STEP. They are rich enough to cover most geometric types used in CAD systems. For the output geometric types, NURBS form is used since it is the most popular form for representing curves and surfaces.
Simultaneous Optimization of Product Family Sharing System Structure and Configuration
Authors: Fujita Kikuo , Akagi Shinsuke , Yoneda Tetsu , Ishikawa Makibi
Published: February 2021

This paper discusses the optimization problem of a family of products, where multiple products sharing system structure and configuration are simultaneously designed to be optimal. This kind of problems is a typical subproblem of product variety design. It requires the considerations on how to control the commonality of modules and attributes across products and on how design targets, such as requirements, production unit numbers, etc., affect the optimality. First, we classify design tactics into independent design, similar design and same design, and describe how to use these three methods over product representation that consists of systems, modules and attributes. After discussing typical optimization situation on design methods and influence of design target deviation to product family optimality, we develop the framework for assessing the optimality and sensitivity that includes cost model for design, development, production, use, etc. Then, we demonstrate the simultaneous optimization of multiple products with simple cases in aircraft design and planning.
An Intelligent Environment for Simulating Mechanical Assembly Operations
Authors: Gupta Satyandra K. , Paredis Christiaan J. J. , Sinha Rajarishi , Wang Cheng-Hua , Brown Peter F.
Published: February 2021

Rapid technical advances in many different areas of scientific computing provide the enabling technologies for creating a comprehensive simulation and visualization environment for assembly design and planning. We have built an intelligent environment in which simple simulations can be composed together to create complex simulations for detecting potential assembly problems. Our goal in this project is to develop high fidelity assembly simulation and visualization tools that can detect assembly related problems without going through physical mock-ups. In addition, these tools can be used to create easy-to-visualize instructions for performing assembly and service operations.
Coordinator: A Robust Setup Planner That Does Early Detection of Fixture-Feature Interactions
Authors: Faheem W. , Hayes C. C. , Gaines D. M. , Castaño J. F.
Published: February 2021

This paper presents Coordinator, a process planner that uses a blend of geometric and manufacturing information to detect a broad variety of manufacturing interactions to sequence setups plans. This system is designed to be used by experts to reduce the time and effort required to produce good plans. Coordinator’s contributions is early detection of fixture-feature interactions (interferences between manufacturing operations in which one destroys clamping surfaces required by another). The ability to detect them early (i.e. prior to setup sequencing) eliminates the need for many re-planning cycles. These interactions are usually addressed only after set-up sequencing because sequencing determines part shape in each setup, which in turn affects clamping options. Coordinator addresses this problem through a representational which considers multiple possible workpiece shapes and clamping surfaces prior to setup sequencing. This representation enables Coordinator to consider fixture-feature interactions to sequence setups well in the first iteration, greatly reducing the need for iterative adjustment.
A Geometric Algorithm for Hybrid Workpiece Localization/Envelopment Problem
Authors: Chu Y. X. , Gou J. B. , Li Z. X.
Published: February 2021

The problem of aligning the CAD model of a workpiece such that all points measured on the finished surfaces of the workpiece match closely to corresponding surfaces on the model while all unmachined surfaces lie outside the model to guarantee the presence of material to be machined at a later time is referred to as the hybrid localization/envelopment problem. The hybrid problem has important applications in setting up for machining of partially finished workpieces. This paper gives a formulation of the hybrid localization/envelopment problem and present a geometric algorithm for computing its solutions. First, we show that when the finished surfaces of a workpiece are inadequate to fully constrain the rigid motions of the workpiece, then the set of free motions remaining must form a subgroup G0 of the Euclidean group SE(3). This allows us to decompose the hybrid problem into a (symmetric) localization problem on the homogeneous space SE(3)/G0 and an envelopment problem on G0. While the symmetric localization problem is solved using the Fast Symmetric Localization (FSL) algorithm developed in one of our early papers, the envelopment problem is solved by computing the solutions of a sequence of linear programming (LP) problems. We derive explicitly the LP problems and apply standard linear programming techniques to solve the LP problems. We present simulation results to demonstrate efficiency of our method for the hybrid problem.
Representing Relationships in Hierarchical Assemblies
Authors: Heisserman Jeff , Mattikalli Raju
Published: February 2021

Computer aided design tools are gaining popularity in industry due to their ability to model the geometric aspects of products. This has shown substantial benefit for reducing the need and expense of building physical prototypes and allowing parts and tooling to be manufactured directly from these models. However, the current capabilities in existing CAD tools for modeling assemblies are quite limited.

In this paper we introduce a representation for describing interfaces between parts within hierarchical assemblies for capturing functional and physical mating relations. This representation is designed to support automated reasoning and automated generation and modification of assemblies. It is also designed for use with very large assemblies, compactly representing the interfaces of parts and assemblies that are reused within larger assemblies. We describe how this representation is used in our prototype design system, Genesis, for designing aircraft systems.
An Agent Mechanism for Version Support in Engineering Design
Authors: Florida-James Barry , Norman Peter , Hills Bill , Rossiter Nick , Chao Kuo-Ming
Published: February 2021

This paper presents a mechanism for complete product lifecycle version support in an engineering design environment. The mechanism addresses issues such as heterogeneity and interoperability through the use of co-operating agents. The version model is presented and the agents that implement this model. An industrial case study is presented with preliminary results to illustrate the mechanism.