bluuebunny/crossref_metadata_2025 huggingface dataset:
Parsimony vs predictive and functional performance of three stomatal optimization principles in a big‐leaf framework
Authors: Bassiouni Maoya , Vico Giulia
Published: April 2021

Stomatal optimization models can improve estimates of water and carbon fluxes with relatively low complexity, yet there is no consensus on which formulations are most appropriate for ecosystem‐scale applications. We implemented three existing analytical equations for stomatal conductance, based on different water penalty functions, in a big‐leaf comparison framework, and determined which optimization principles were most consistent with flux tower observations from different biomes.

We used information theory to dissect controls of soil water supply and atmospheric demand on evapotranspiration in wet to dry conditions and to quantify missing or inadequate information in model variants. We ranked stomatal optimization principles based on parameter uncertainty, parsimony, predictive accuracy, and functional accuracy of the interactions between soil moisture, vapor pressure deficit, and evapotranspiration.

Performance was high for all model variants. Water penalty functions with explicit representation of plant hydraulics did not substantially improve predictive or functional accuracy of ecosystem‐scale evapotranspiration estimates, and parameterizations were more uncertain, despite having physiological underpinnings at the plant level.

Stomatal optimization based on water use efficiency thus provided more information about ecosystem‐scale evapotranspiration compared to those based on xylem vulnerability and proved more useful in improving ecosystem‐scale models with less complexity.
Apoplastic lipid barriers regulated by conserved homeobox transcription factors extend seed longevity in multiple plant species
Authors: Renard Joan , Martínez‐Almonacid Irene , Queralta Castillo Indira , Sonntag Annika , Hashim Aseel , Bissoli Gaetano , Campos Laura , Muñoz‐Bertomeu Jesús , Niñoles Regina , Roach Thomas , Sánchez‐León Susana , Ozuna Carmen V. , Gadea José , Lisón Purificación , Kranner Ilse , Barro Francisco , Serrano Ramón , Molina Isabel , Bueso Eduardo
Published: April 2021

Cutin and suberin are lipid polyesters deposited in specific apoplastic compartments. Their fundamental roles in plant biology include controlling the movement of gases, water and solutes, and conferring pathogen resistance. Both cutin and suberin have been shown to be present in the Arabidopsis seed coat where they regulate seed dormancy and longevity.

In this study, we use accelerated and natural ageing seed assays, glutathione redox potential measures, optical and transmission electron microscopy and gas chromatography‐mass spectrometry to demonstrate that increasing the accumulation of lipid polyesters in the seed coat is the mechanism by which the AtHB25 transcription factor regulates seed permeability and longevity.

Chromatin immunoprecipitation during seed maturation revealed that the lipid polyester biosynthetic gene long‐chain acyl‐CoA synthetase 2 (LACS2) is a direct AtHB25 binding target. Gene transfer of this transcription factor to wheat and tomato demonstrated the importance of apoplastic lipid polyesters for the maintenance of seed viability.

Our work establishes AtHB25 as a trans‐species regulator of seed longevity and has identified the deposition of apoplastic lipid barriers as a key parameter to improve seed longevity in multiple plant species.
Spread of self‐compatibility constrained by an intrapopulation crossing barrier
Authors: Broz Amanda K. , Simpson‐Van Dam Armeda , Tovar‐Méndez Alejandro , Hahn Matthew W. , McClure Bruce , Bedinger Patricia A.
Published: April 2021

Mating system transitions from self‐incompatibility (SI) to self‐compatibility (SC) are common in plants. In the absence of high levels of inbreeding depression, SC alleles are predicted to spread due to transmission advantage and reproductive assurance.

We characterized mating system and pistil‐expressed SI factors in 20 populations of the wild tomato species Solanum habrochaites from the southern half of the species range.

We found that a single SI to SC transition is fixed in populations south of the Rio Chillon valley in central Peru. In these populations, SC correlated with the presence of the hab‐6 S‐haplotype that encodes a low activity S‐RNase protein. We identified a single population segregating for SI/SC and hab‐6. Intrapopulation crosses showed that hab‐6 typically acts in the expected codominant fashion to confer SC. However, we found one specific S‐haplotype (hab‐10) that consistently rejects pollen of the hab‐6 haplotype, and results in SI hab‐6/hab‐10 heterozygotes.

We suggest that the hab‐10 haplotype could act as a genetic mechanism to stabilize mixed mating in this population by presenting a disadvantage for the hab‐6 haplotype. This barrier may represent a mechanism allowing for the persistence of SI when an SC haplotype appears in or invades a population.
Who loves input controls? What happened to “outputs not inputs” in UK Public Financial Management, and why?
Authors: Hood Christopher , Piotrowska Barbara Maria
Published: April 2021

Why do frequently criticized input controls survive in the management of public spending while apparently more enlightened output/outcome controls come and go? The question matters, because output/outcome controls are often assumed in public financial management and related literature to lead to superior policy performance as compared with input‐focused approaches. We tackle the question by applying qualitative push–pull analysis to compare one key type of input controls (administration cost [AC] controls) with one much‐discussed form of output/outcome controls (performance targets linked to spending allocations) in one major country case, the United Kingdom, over two decades. Drawing on documents and in‐depth interviews with 120 key political and bureaucratic players, we conclude that bureaucratic inertia at most only partially explains the survival of input AC controls in this case. The push/pull factors associated with the politics of blame and credit made the political players fair‐weather output controllers but all‐weather input controllers.
Death, Deprivation, and a Sartrean Account of Horror
Authors: Kaufman Frederik
Published: April 2021

Deprivation offers a plausible explanation for the badness of death, so fear is not unreasonable. But horror at the prospect of one's death is not just extreme fear because horror is structurally different than fear. Horror requires a different explanation. For Sartre, horror is possible only in unique circumstances. I argue that Sartre's view, when combined with the subjective incomprehensibility of one's annihilation, can explain horror and other negative emotions that are not contingent on deprivation. Further, I argue that while fear can be reasonable if one's death will deprive, Lucretius's Symmetry Argument shows that horror is unreasonable.
Impaired error‐related processing in patients with first‐episode psychosis and subjects at clinical high risk for psychosis: An event‐related potential study
Authors: Park Jihye , Lho Silvia Kyungjin , Hwang Wu Jeong , Moon Sun‐Young , Oh Sanghoon , Kim Minah , Kwon Jun Soo
Published: April 2021

Aim

Impaired event‐related potential (ERP) indices reflecting performance‐monitoring systems have been consistently reported in patients with schizophrenia. However, whether these impairments exist from the beginning of the early phase of psychosis, such as in first‐episode psychosis (FEP) patients and individuals at clinical high risk (CHR) for psychosis, has not yet been clearly ascertained.

Methods

Thirty‐seven FEP patients, 22 CHR subjects, and 22 healthy controls (HC) performed a visual go/no‐go task so that three ERP components associated with performance monitoring—error‐related negativity (ERN), correct response negativity (CRN), and error positivity (Pe) —could be assessed. Repeated‐measures analysis of variance (ANOVA) with age and sex as covariates was used to compare ERN, CRN, and Pe across the groups.

Results

Repeated‐measures ANOVA with age and sex as covariates revealed that compared with HC, FEP patients and CHR subjects showed significantly smaller ERN amplitudes at the Fz (F = 4.980, P = 0.009) and FCz (F = 3.453, P = 0.037) electrode sites. Neither CRN nor Pe amplitudes showed significant differences across the FEP, CHR, and HC groups.

Conclusion

These findings suggest that performance monitoring is already compromised during the early course of psychotic disorders, evident in FEP patients and CHR subjects, as reflected in the reduced ERN amplitude. Considering these findings, ERN could serve as a potential indicator of early‐stage psychosis.
Health screening system to ensure children's health and development in Japan
Authors: Tomokawa Sachi , Miyake Kimihiro , Takahashi Kenzo , Tomokawa Aya , Kokudo Shohei , Ueno Marie , Kigawa Mika , Asakura Takashi
Published: April 2021

Background

The establishment of health screening systems for children is important, however, such systems are not always well‐established in developing countries. This study aimed to improve child health screening systems in developing countries by analyzing the factors that contribute to enabling continuous and proper screenings at various governmental levels in Japan.

Methods

We reviewed the history of child health and development screening systems in Japan and examined factors that enabled their regular and nationwide implementation.

Results

We identified the six enabling factors: (i) the existence of relevant laws and regulations in health and education systems for health checkups, (ii) mandated and detailed conditions for health checkups within both school and community health, (iii) the provision of guidelines and manuals for health checkups, (iv) a sufficient number of professionals to carry out the health checkups, (v) clear criteria for evaluating and interpreting the checkup results, and (vi) understanding among teachers, children, and guardians of the importance of health checkups.

Conclusion

We proposed the following six requirements to the governments in developing countries for establishing their own health screening programs: (i) a clear description of the need for regular and continuous health checkups in the relevant laws, regulations, and policies, (ii) mandate as essential activity and detailed requirements of the screening activities, (iii) provision of relevant manuals for health workers and teachers, (iv) provision of enough well‐trained professionals and a training system, (v) studying growth and development curves for children, and (vi) promoting understanding among stakeholders about the importance of health checkups.
Seeing you, seeing me: Links between perceived commitment, metaperceptions, and relationship well‐being
Authors: Tissera Hasagani , Lydon John E.
Published: April 2021

Are perceiver's impressions of target's commitment associated with the target's relationship experience? Could target's metaperceptions (i.e., target's beliefs about the perceiver's impressions of the target) help explain why? In the present dyadic study (N = 206; Ncouples = 103), we found that perceiver's impressions of target's commitment was positively related to target's relationship well‐being, and target's metaperceptions helped to account for this link. Additional analyses disentangled the roles of accuracy and bias of metaperceptions. On average, people underestimated their partners' impressions of commitment, and this negative mean‐level bias was related to lower relationship well‐being. Overall, the present results shed light on the potential implications of metaperceptions for relational well‐being.
The qualitative exploration of social competencies and incompetencies on mobile dating applications
Authors: Dredge Rebecca , Anderson Joel
Published: April 2021

Romantic and sexual relationships are increasingly initiated using mobile dating applications rather than in face‐to‐face contexts. There is subsequently a need to understand socially competent and incompetent behaviors during this pre‐interaction relationship development stage. One‐on‐one in‐depth interviews were conducted with 22 emerging adults from Australia and Belgium. Data were analyzed inductively based on thematic analysis. Participants reported 11 superordinate social competencies represented by 85 competent and 67 incompetent behavioral norms that varied across four stages of online relationship formation (profile, matching, discovery, and evaluation stages). Findings provide a unique contribution to the literature as online social competence has yet to be conceptualized. Comparisons between online and face‐to‐face relational processes are also discussed.
Photoautotrophic production of renewable ethylene by engineered cyanobacteria: Steering the cell metabolism towards biotechnological use
Authors: Kallio Pauli , Kugler Amit , Pyytövaara Samuli , Stensjö Karin , Allahverdiyeva Yagut , Gao Xiang , Lindblad Peter , Lindberg Pia
Published: April 2021

Ethylene is a volatile hydrocarbon with a massive global market in the plastic industry. The ethylene now used for commercial applications is produced exclusively from nonrenewable petroleum sources, while competitive biotechnological production systems do not yet exist. This review focuses on the currently developed photoautotrophic bioproduction strategies that enable direct solar‐driven conversion of CO2 into ethylene, based on the use of genetically engineered photosynthetic cyanobacteria expressing heterologous ethylene forming enzyme (EFE) from Pseudomonas syringae. The emphasis is on the different engineering strategies to express EFE and to direct the cellular carbon flux towards the primary metabolite 2‐oxoglutarate, highlighting associated metabolic constraints, and technical considerations on cultivation strategies and conditional parameters. While the research field has progressed towards more robust strains with better production profiles, and deeper understanding of the associated metabolic limitations, it is clear that there is room for significant improvement to reach industrial relevance. At the same time, existing information and the development of synthetic biology tools for engineering cyanobacteria open new possibilities for improving the prospects for the sustainable production of renewable ethylene.
Accelerating Bayesian Estimation for Network Poisson Models Using Frequentist Variational Estimates
Authors: Donnet Sophie , Robin Stéphane
Published: April 2021

This work is motivated by the analysis of ecological interaction networks. Poisson stochastic block models are widely used in this field to decipher the structure that underlies a weighted network, while accounting for covariate effects. Efficient algorithms based on variational approximations exist for frequentist inference, but without statistical guaranties as for the resulting estimates. In the absence of variational Bayes estimates, we show that a good proxy of the posterior distribution can be straightforwardly derived from the frequentist variational estimation procedure, using a Laplace approximation. We use this proxy to sample from the true posterior distribution via a sequential Monte Carlo algorithm. As shown in the simulation study, the efficiency of the posterior sampling is greatly improved by the accuracy of the approximate posterior distribution. The proposed procedure can be easily extended to other latent variable models. We use this methodology to assess the influence of available covariates on the organization of several ecological networks, as well as the existence of a residual interaction structure.
Green's functions, linear second‐order differential equations, and one‐dimensional diffusion advection models
Authors: Yu Xiao , Lan Kunquan , Wu Jianhong
Published: April 2021

Green's functions to linear second‐order ordinary differential equations with general separated boundary conditions (BCs) are derived, where the parameters used in the BCs are allowed to take negative values. Previous results only considered the nonnegative parameters and such separated BCs arise in the usual Thomas–Fermi BCs. Properties of the Green's functions with possibly negative parameters are obtained and are new. As applications, we study the steady‐state solutions of the one‐dimensional diffusion advection models arising in chemical reactor theory and mathematical biology. We exhibit that the BCs arising from the one‐ dimensional diffusion advection models contain negative parameters.
Maximum dorsiflexion increases Achilles tendon force during exercise for midportion Achilles tendinopathy
Authors: Yeh Chia‐Han , Calder James D. , Antflick Jarrod , Bull Anthony M.J. , Kedgley Angela E.
Published: April 2021

Rehabilitation is an important treatment for non‐insertional Achilles tendinopathy. To date, eccentric loading exercises (ECC) have been the predominant choice; however, mechanical evidence underlying their use remains unclear. Other protocols, such as heavy slow resistance loading (HSR), have shown comparable outcomes, but with less training time. This study aims to identify the effect of external loading and other variables that influence Achilles tendon (AT) force in ECC and HSR. Ground reaction force and kinematic data during ECC and HSR were collected from 18 healthy participants for four loading conditions. The moment arms of the AT were estimated from MRIs of each participant. AT force then was calculated using the ankle torque obtained from inverse dynamics. In the eccentric phase, the AT force was not larger than in the concentric phase in both ECC and HSR. Under the same external load, the force through the AT was larger in ECC with the knee bent than in HSR with the knee straight due to increased dorsiflexion angle of the ankle. Multivariate regression analysis showed that external load and maximum dorsiflexion angle were significant predictors of peak AT force in both standing and seated positions. Therefore, to increase the effectiveness of loading the AT, exercises should apply adequate external load and reach maximum dorsiflexion during the movement. Peak dorsiflexion angle affected the AT force in a standing position at twice the rate of a seated position, suggesting standing could prove more effective for the same external loading and peak dorsiflexion angle.
Contested theories of prison labor practice
Authors: DelSesto Matthew
Published: April 2021

In recent years, prison strikes and controversies have brought public attention to the systemic problems with prison labor in the United States. Such labor often exploits people who are imprisoned to do work that is vital to society—including firefighting, farming, or manufacturing consumer goods—with wages that can be less than a dollar per hour in highly coercive working conditions. Although there is call to end prison labor today, theories of prison labor have historically been contested, even among activists and progressive reformers. Accordingly, this review offers a short sociological history of labor in correctional environments, highlights contemporary controversies, and argues for a more fine‐grained approach to the relationships among labor, prisons, and reentry. It traces the field of reformers and scholars that have made arguments for punitive, rehabilitative, restorative, and transformative approaches to work. The contested theories of prison labor across time and space suggest that a better understanding is needed of what makes labor exploitative and what forms of labor have the potential to transform the root causes of crime, within and beyond prison walls. Overall, this review has implications for those who study prison and reentry programs, relationships between crime and community, and the political economy of incarceration.
Detection of the HLA‐A*02:191 allele in a Taiwanese individual
Authors: Yang Kuo‐Liang , Li Chi‐Cheng , Lin Py‐Yu
Published: April 2021

One nucleotide substitution in codon 156 of HLA‐A*02:07:01:01 results in a novel allele, HLA‐A*02:191.
Coronavirus seroprevalence among villagers exposed to bats in Thailand
Authors: Suwannarong Kanokwan , Janetanakit Taveesak , Kanthawee Phitsanuruk , Suwannarong Kangsadal , Theamboonlers Apiradee , Poovorawan Yong , Tun Hein M. , Chanabun Sutin , Amonsin Alongkorn
Published: April 2021

A serological survey of human coronavirus antibodies among villagers in 10 provinces of Thailand was conducted during 2016–2018. Serum samples (n = 364) were collected from participants from the villages and tested for coronavirus antibodies using a human coronavirus IgG ELISA kit. Our results showed that 10.44% (38/364; 21 males and 17 females) of the villagers had antibodies against human coronaviruses. The odds ratio for coronavirus positivity in the villagers in the central region who were exposed to bats was 4.75, 95% CI 1.04–21.70, when compared to that in the non‐exposed villagers. The sociodemographics, knowledge, attitudes and practices (KAP) of the villagers were also recorded and analysed by using a quantitative structured questionnaire. Our results showed that 62.36% (227/364) of the villagers had been exposed to bats at least once in the past six months. Low monthly family income was statistically significant in increasing the risk for coronavirus seropositivity among the villagers (OR 2.91, 95% CI 1.13–7.49). In‐depth interviews among the coronavirus‐positive participants (n = 30) showed that cultural context, local norms and beliefs could influence to bat exposure activities. In conclusion, our results provide baseline information on human coronavirus antibodies and KAP regarding to bat exposure among villagers in Thailand.
Species diversity in Friesea (Neanuridae) reveals similar biogeographic patterns among Antarctic Collembola
Authors: Stevens Mark I. , Greenslade Penelope , D’Haese Cyrille A.
Published: April 2021

The pan‐Antarctic distributions of several collembolan species have been supported by morphology for over 120 years. However, for most species where molecular data are available, these are now known to belong instead to several species, and most classified as short‐range endemics. One such species, Friesea grisea, had a pan‐Antarctic distribution that has been in question, but until recently, specimens of F. grisea from the type locality on South Georgia have not been included in any molecular appraisal. Here, we compare the molecular identity of specimens of F. grisea, from South Georgia, with other Antarctic and sub‐Antarctic species using the mitochondrial COI gene. A Bayesian phylogenetic analysis for 14 species of Friesea from southern regions, including F. grisea sensu stricto with species previously identified as ‘F. grisea’ (F. antarctica, F. gretae and F. propria) confirms the distinctness of the South Georgian specimens based on molecular data, and these results are confirmed morphologically. The genus Friesea is one of the most speciose genera of Collembola known in the Antarctic region, and we provide an annotated key (dichotomous and interactive versions) to all Friesea species in the sub‐Antarctic and Antarctica. We compare the biogeography of Friesea to other Collembola from the region to highlight our current understanding of species boundaries and island linkages.
Vibration Control of Flexible Joint Robots Using a Discrete-Time Two-Stage Controller Based on Time-Varying Input Shaping and Delay Compensation
Authors: Pham Minh-Nha , Hazel Bruce , Hamelin Philippe , Liu Zhaoheng
Published: April 2021

Most industrial serial robots use decentralized joint controllers assuming rigid body dynamics. To prevent exciting the flexible mode, gains are kept low, resulting in poor control bandwidth and disturbance rejection. In this paper, a two-stage flexible joint discrete controller is presented, in which the decentralized approach is extended with a stiffness to take into account the dominant coupling mode. In the first-stage, an input shaping feedforward shapes the rigid closed-loop dynamics into desired dynamics that does not produce link vibrations. Robotic dynamic computation based on a recursive Newton–Euler algorithm is conducted to update the feedforward link inertia parameter during robot motion. A second-stage is added to increase disturbance rejection. A generalized Smith predictor (GSP) is developed to compensate for delay and feedback sensor filtering. An effective methodology is presented to optimize the control loop gains. Numerical simulations and experiments on a six-joint robot manipulator confirm that the proposed controller improves control performances in terms of bandwidth, vibration attenuation, and disturbance rejection.
An Automated Layout Design System for Industrial Plant Piping
Authors: Narikawa N. , Fujimoto S. , Sasaki N. , Azuma S.
Published: April 2021

This paper describes a new approach to an automated layout design system for industrial plant piping. The routing system, which is the main part of this layout system, is composed of three steps, according to the practical layout design process. By dividing the layout design into the optimal routing phase (Step 1, Step 2) and the arrangement phase (Step 3), it is possible to design without depending on the routing order, and with small computer memory storage capacities. The optimal route is obtained by using the routing algorithm and heuristic search, based on expert knowledge. The arrangements are made by applying the enumeration method, taking the strong and weak constraints into account.
Development of an Automated Testing System
Authors: Kelso Frank M. , Riley Donald R.
Published: April 2021

Design is an iterative, model-based process in which both analytical and experimental testing play an important role. Research in the area of automating the design process hopes to both reduce the iterative design cycle time and improve the quality of the resulting design. Automating the design process, however, suggests automating the testing process as well. Considering the iterative nature of design, testing plays an important role not only in suggesting improvements in successive design iterations, but also in validating the modeling assumptions and simplifications made during the design process.

This paper discusses the role of testing in the design process, and proposes a computational model which can be used to facilitate automation of the mechanical testing process. The proposed computational model represents the materials test in terms of the operational definition of the material property, and attempts to adequately abstract and represent the important elements of an actual system: the applied service conditions, the physical response of the material, and the empirical relationships which exist between the two. Specifically, deterministic finite state machines (DFSM’s) are proposed to represent the process control knowledge necessary in executing a test and controlling the servohydraulic testing system.
Knowledge-Based Diagnostics and Design Systems
Authors: Wang Sherman S.
Published: April 2021

Substantial literature using knowledge-based system techniques has been accumulated over the past few years in the fields of diagnostics, modeling and design. Many of these techniques have been successfully used by a wide variety of industrial companies. The purpose of this paper is to present a summary of these new techniques, and an examination of their advantages and limitations for industrial applications. These techniques will help to insure the integrity of future concurrent design and manufacturing development. The purpose of our survey study is to show that the design and modeling of product functions and their associated diagnostic processes should be tightly coupled. The design and diagnostic tasks should be supported by integrated and intelligent software. Many examples of knowledge-based systems for disk drive diagnostics and design will also be included.
Integration of CAD to CAM Through Optimum Process Planning and Expert System Approach: A Comparison
Authors: Jha Nand K.
Published: April 2021

Integration of CAD to CAM has emerged as most important tool of automation in manufacturing. This integration can be achieved by various means. In this paper two different approaches have been studied. These are optimum process planning and expert system process planning. A comparison of both approaches has been presented thorough an example.
Design for Injection Molding and Die Casting: A Knowledge-Based Approach
Authors: Poli Corrado , Rajagopalan Swaminath
Published: April 2021

This paper describes an IBM-pc compatible knowledge based system developed for the evaluation of injection molded and die cast parts. The system directs the designers’ attention to the part’s various costly to produce features, thus, guiding them into designing more economical to produce parts. The software is such that it can be used at both the very early configurational stage of part design and at the later parametric design stage. Unlike other design for injection molding systems, this system can be used without a detailed knowledge of the process. The use of the software is illustrated by analyzing an injection molded part.
Form Feature Recognition by Convex Decomposition
Authors: Kim Yong Se
Published: April 2021

A convex decomposition method, called Alternating Sum of Volumes (ASV), uses convex hulls and set difference operations. ASV decomposition may not converge, which severely limits the domain of geometric objects that can be handled. By combining ASV decomposition and remedial partitioning for the non-convergence, we have proposed a convergent convex decomposition called Alternating Sum of Volumes with Partitioning (ASVP). In this article, we describe how ASVP decomposition is used for recognition of form features. ASVP decomposition can be viewed as a hierarchical volumetric representation of form features. Adjacency and interaction between form features are inherently represented in the decomposition in a hierarchical way. Several methods to enhance the feature information obtained by ASVP decomposition are also discussed.
Hyperq/Plastics: An Expert System for Plastic Material and Process Selection
Authors: Beiter Kurt , Krizan Steven , Ishii Kosuke , Hornberger Lee
Published: April 2021

The selection of material and processing techniques for plastic parts is a challenging task for design engineers. This paper describes the development of an intelligent program that helps engineers perform this task. An extensive survey of practicing engineers, product designers and material specialist revealed that these experts used both qualitative and quantitative selection methodologies. The program described, HyperQ/Plastics, is a HyperCard program that uses Prolog to combine these two types of selection methodologies. The current version of this program is undergoing tests at several industrial sites.
A Meta Knowledge Base for Machining Process Selection
Authors: Shah Jami J. , Hsiao David W.-C.
Published: April 2021

The work reported here is part of a larger project aimed at developing a system for concurrent design and manufacturing. One of the manufacturing applications is manufacturability evaluation performed on design models based on features. The model is not restricted to a limited set of predefined features, but can contain user-defined features that the application program, such as the Manufacturability Evaluator, has no prior knowledge of. A methodolgy was developed whereby the manufacturability evaluator could understand design features from a manufacturing viewpoint and automonously generate feasible machining process sequences for undocumented features. This requires that the system decompose design features into some generic fundamental terms and compare this representation to the capabilities of common machining operations. Therefore, the system needs deeper knowledge about machining processes than that afforded by production rules. In our method, undocumented features are partially evaluated to derive the faces intersecting at concave edges. An algorithm is developed to organize these faces into manufacturing features. The meta knowledge base captures the fundamental characteristics of a machining process by its elementary producible volume and the limitations of tool motions. This representation enables the manufactuability evaluator to create alternative machining sequences for undocumented features.
PWBMA: An Object-Oriented Knowledge-Based System for Manufacturability of Printed Circuit Boards
Authors: Padhy Sisir K. , Dwivedi S. N.
Published: April 2021

Cooperative or concurrent product development is gaining popularity and will become norms of the Industry of the Future. To avoid problem created by designs not amenable to manufacturing, the designer should be aware of manufacturing constraints. Electronics manufacturing is one of the fastest growing segment of manufacturing domain today. The rapid change in the manufacturing of printed wiring boards with the induction of surface mounted components makes the system design more complex. To capture the manufacturability constraints of the manufacturing of printed wiring boards (printed wiring board is another name of printed circuit boards), a knowledge-base is developed to assist the designer. Rules and guidelines pertaining to manufacturability are formulated and incorporated into the knowledge-base. The implementation of the meta-level knowledge to increase the efficiency of the system is also presented. The system is developed using an object-oriented paradigm and capable of suggesting design modification to the designer at the early stage of design to eliminate the manufacturing problems in the later phase of board production. The broad user interface makes the system very user friendly.
An Intelligent CAD Environment for Routine Mechanical Design
Authors: Shah Jami J. , Sen Somnath , Ghosh Sutanu
Published: April 2021

This paper presents the functional requirements and architecture design of a system for supporting routine mechanical design of parts, assemblies, or systems. The majority of activity in routine design involves the use of heuristic rules, procedures, and analysis techniques that are well understood and widely accepted. Taking advantage of the common features in routine design, which are domain independent, it is possible to construct a domain independent shell. The shell, named “The Design Machine®” commands a feature-based assembly modeler, a feature-based part modeler, and a solid modeler, in that order. The system includes abstract sketching facility, icon compiler, a knowledge base building facility, inferencing capabilities (The Design Engine®), and intelligent data management.
An Extensible Computer Environment for Modeling and Analysis in Mechanical Design
Authors: Mashburn T. A. , Anderson D. C.
Published: April 2021

This paper investigates a computer environment approach for the exploration of design behavior in the mechanical design process. Generic component types and behavior modelers are developed based on the needs of mechanical designers and are represented in a computer environment. Built-in component types and physical behaviors are also developed. Extension can then occur as needed during design refinement. The resulting system can support exploration and knowledge refinement during design.
Automated Model Generation Using the KIF Declarative Language
Authors: Hurst Terril N.
Published: April 2021

Logic-based artificial intelligence researchers propound the declarative programming paradigm as a solution to problems arising from conventional procedural programming methods. A formal language possessing a declarative semantics, called Knowledge Interchange Format (or KIF), has been used for interchanging information between disparate programs, each containing specialized internal representations to support specific requirements. A simple system has been developed to evaluate the utility of KIF and declarative programming. The domain chosen for this evaluation was lumped-parameter dynamic systems analysis, due to its well-established vocabulary and concepts. In particular, bond graph theory formed the basis of the knowledge representation which was written in KIF.

Models were generated to analyze the physical dynamics of a servomechanism used in a compact disc player. Fully automated model construction and solution was achieved, beginning with a set of library elements written in KIF and ending with solution of a set of first-order differential equations which characterize dynamic behavior. Work has begun to include assembly as well as bond graph information in order to evaluate the system’s utility for managing constraints in multiple domains.

Based on demonstrated success in the dynamics and assembly domains, the next step will be to apply declarative programming to more-open domains, such as functional tolerancing, for which a comprehensive vocabulary and conceptual framework is still lacking. The hope is that the declarative paradigm will contribute to the formalization of several domains which can then be more easily integrated within a concurrent engineering environment, thus fostering conceptual product designs which are more robust with respect to manufacturability constraints.
Towards a Logical Theory of Engineering Design Information
Authors: Salustri F. A. , Venter R. D.
Published: April 2021

Recent research in Design Theory and Methodology has sought to formalize the engineering design process without particular concern for the paradigm used to model design information. The authors propose that no correct formalization of the design process can be achieved without first formalizing the semantics of the information used in the process. To this end, the authors present a new theory meant to formalize the semantics of design information that is independent of its use in a design process. Using symbolic logic, the theory is presented as a set of axioms, and draws from the object orientation and hypertext paradigms. Design entities are modeled by formal units called objects, and are related by formal structures called links. Abstraction mechanisms relevant to design are formalized and the role of constraints is explored. The hybrid model is meant not only to aid in the study of the design process itself, but also to improve communications between designers, assist standardization of design specifications, and develop new, powerful software tools to aid the designer in his work.
Design of Cellular Manufacturing Systems: A Heuristic Approach
Authors: Gu Peihua
Published: April 2021

Clustering based algorithms have been used for machine cells grouping for years and have been considered as a feasible approach because the algorithms are flexible and easy to implement on computers. However, two major deficiencies have been identified for clustering algorithms in this research; they are inconsistency and possible mis-clustering. Inconsistency is usually caused by arbitrary determination of initial cluster centres and mis-clustering, from the manufacturing point of view, is due to pattern similarity as the unique criterion for the cluster-seeking process.

A new heuristic clustering algorithm has been developed and applied to formation of machine cells. The algorithm not only overcomes common drawbacks of clustering methods, but also minimizes bottleneck machines required. The algorithm consists of three parts: 1) determination of initial clustering centres, 2) cluster-seeking process, and 3) minimization of number of bottleneck machines. The initial clustering centres are determined by finding a set of components which require the most different machine operations, then the cluster-seeking process is carried out based on manufacturing similarity. The final step is to minimize the number of bottleneck machines required for forming independent cells. Another advantage of the algorithm is that it can generate alternate cells configurations by simply changing input parameters. This provides an opportunity to resolve conflict between formed cells and some physical constraints such as plant space, machine location, cranes available and the like. Examples are provided to illustrate the approach.
Robotic Grip Determination From Solid Models
Authors: Gabriele Gary A.
Published: April 2021

Design for Assembly (DFA) can have a significant influence on the cost of a product. DFA is especially beneficial for products that are robotically assembled, due to the limitations placed on the product design by the automated assembly equipment. Automated assembly analysis systems have been developed to assess the assemblability of a product but, many lack an interface to the product CAD database. The lack of a CAD interface requires the user to examine every part in the assembly to determine the characteristics and features that promote efficient assembly. This is a time consuming and tedious process.

An automated assembly analysis system is described that will automatically analyze a product design to determine if it can be assembled on a particular assembly system and suggest improvements in the design. Three main stages of the system are identified. The first stage determines if the individual parts of the assembly can be presented to the work station. The second stage determines if the individual parts of the assembly can be grasped and manipulated by the end effectors. The third stage determines if every part in the assembly can be positioned and inserted into the assembly to complete the assembly process.

A prototype system was developed that addresses the second stage of the proposed automated assembly analysis system and is described herein. The Robotic Grip Determining (RGD) program examines a B-Rep solid model of a part to determine if it can be grasped by a modeled end effector. If the RGD program determines that the part can be grasped, a list of gripping positions are generated that describe how the end effector can grasp the part. These gripping positions can then be passed to the third stage of the proposed automated assembly-system.
An Algorithm to Slice 3-D Shapes for Reconstruction in Prototyping Systems
Authors: Chalasani K. L. , Grogan B. , Bagchi A. , Jara-Almonte C. C. , Ogale A. A. , Dooley R. L.
Published: April 2021

Rapid Prototyping (RP) processes reduce the time consumed in the manufacture of a prototype by producing parts directly from a CAD representation, without tooling. The StereoLithography Apparatus (SLA), and most other recent RP processes build a 3-D object from 2.5-D layers. Slicing is the process of defining layers to be built by the system. In this paper a framework is proposed for the development of algorithms for the representation and definition of layers for use in the SLA, with a view to determine if the slicing algorithms will affect surface finish in any significant manner. Currently, it is not possible to automatically vary slice thicknesses within the same object, using the existent algorithm. Also, it would be useful to use a dense grid for hatching or skin filling any given layer, or to change the hatch-pattern if desired. In addition, simulation of the layered building process would be helpful, so that the user can prespecify parameters that need to be varied during the process. The proposed framework incorporates these and other features. Two approaches for determining contours on each slice are suggested and their implementation is discussed. In the first, the layers are defined by the intersections of a plane with the surfaces defining the object. The plane is moved up from the base of the object as it is being built in increments. All intersections found are stored in a data structure, and sorted in head to tail fashion to define a contour for all closed areas on a layer. The second approach uses a scanline-type search to look for an intersection that will trigger a contour-tracing procedure. The contour-tracer is invoked whenever an unused edge is found in the search. This saves storage and sorting times, because the contour is determined as a chain of edges, in cyclic order. It is envisaged that results of this work on the SLA can be applied to other RP processes entailing layered building.
Transputer Based Parallel Processing Applied to Machine Vision Inspection
Authors: Carey Richard A. , Daley Wayne D. R. , Lindberg Jon S.
Published: April 2021

The use of Machine vision systems has become more widespread in manufacturing processes for the purposes of quality control inspection, and product identification and sorting. Typical Machine Vision applications need to run in real time (30 frames per second), and as a result most of the existing systems are built from hardware to meet this speed requirement. There is currently no single processor that is reasonably priced and fast enough to provide real time performance on Machine Vision applications. This paper describes a Transputer based system that employs different architectures and algorithms to achieve real time processing speeds for some Machine Vision applications. The paper discusses the differences between sequential and parallel architectures, and the way the unique abilities of the Transputers are utilized to create a flexible system that provides the best performance for a variety of applications. The areas of Machine Vision discussed are Image Acquisition, Image Enhancement, Feature Extraction and Image Interpretation. Image Acquisition and interpretation are discussed briefly, with an in depth discussion of the algorithms and architecture needed to optimize Image Enhancement and Feature Extraction on a Transputer based system.
Computer-Aided Testimg for Compression of Cylinders: A Model for Control of Open-Die Upset Forging
Authors: Ettouney Osama M.
Published: April 2021

A computer-aided testing system for compression of cylinders is developed. The system utilizes force and shape information taken in real-time from the workpiece to calculate process parameters and variables in compression: material properties, foldover, strain, friction, forming-limit diagrams, and fracture. In this way, the system will eliminate the need for other separate tests, such as the ring test used to determine friction. This system is comprised of three functions: a computer-controlled press, models and identification algorithms, and the finite-element analysis. The system is designed to be used as a model for control strategies of the open-die upset forging process. Here, the goal is to control the process so that the final shape is reached without fracture. If fracture is likely to occur at any moment several corrective actions can be taken to allow more deformation, such as modifying lubrication. When tested, the system proved to be accurate in conducting experiments in a well-defined repeatable conditions.
Generation of Offset Curves for NC Machine Tool Path
Authors: Umezaki Eisaku , Watanabe Hiroshi
Published: April 2021

This paper proposes a new method which generates offset curves used to obtain NC machine tool paths. A basic idea of the method is to utilize a called offset curve zone where the offset curves of each side constituting the profile of workpieces are generated. Using this method, we can generate the offset curves without being conscious of unnecessary offset curves often appeared in use of other methods and efficient tool paths because there are almost no overlaps of tool paths. For example, this method is applied to workpiece profiles consisted of the segments of straight line and circular arcs to generate the offset curves for tool paths in a two-and-a-half dimensional pocket cutting.