bluuebunny/crossref_metadata_2025 huggingface dataset:
iucn_sim: a new program to simulate future extinctions based on IUCN threat status
Authors: Andermann Tobias , Faurby Søren , Cooke Robert , Silvestro Daniele , Antonelli Alexandre
Published: November 2020

The ongoing environmental crisis poses an urgent need to forecast the who, where and when of future species extinctions, as such information is crucial for targeting conservation efforts. Commonly, such forecasts are made based on conservation status assessments produced by the International Union for Conservation of Nature (IUCN). However, when researchers apply these IUCN conservation status data for predicting future extinctions, important information is often omitted, which can impact the accuracy of these predictions.

Here we present a new approach and a software for simulating future extinctions based on IUCN conservation status information, which incorporates generation length information of individual species when modeling extinction risks. Additionally, we explicitly model future changes in conservation status for each species, based on status transition rates that we estimate from the IUCN assessment history of the last decades. Finally, we apply a Markov chain Monte Carlo algorithm to estimate extinction rates for each species, based on the simulated future extinctions. These estimates inherently incorporate the chances of conservation status changes and the generation length for each given species and are specific to the simulated time frame.

We demonstrate the utility of our approach by estimating future extinction rates for all bird species. Our average extinction rate estimate for the next 100 yr across all birds is 6.98 × 10−4 extinctions per species‐year, and we predict an expected biodiversity loss of between 669 and 738 bird species within that time frame. Further, the rate estimates between species sharing the same IUCN status show larger variation than the rates estimated with alternative approaches, which reflects expected differences in extinction risk among taxa of the same conservation status. Our method demonstrates the utility of applying species‐specific information to the estimation of extinction rates, rather than assuming equal extinction risks for species assigned to the same conservation status.
Assessing functional redundancy in Eurasian small mammal assemblages across multiple traits and biogeographic extents
Authors: Moreno‐García Pablo , Baiser Benjamin
Published: November 2020

Functional redundancy (FR) is commonly invoked as one of the main mechanisms underlying ecological resilience. However, little is known about the extension of FR from single to multiple functions and its variation among ecological assemblages at biogeographic scales. We studied 51 assemblages of Eurasian small mammals (Mammalia: Rodentia and Mammalia: Soricomorpha), analyzing FR across and within assemblages. We quantified FR for trait sets related to five different functions: parasitic interactions, diet, habitat preferences, body mass and diel activity. We then evaluated the relationships between FR based on different functional trait sets across and within mammal assemblages, to determine whether small mammal assemblages and their species are redundant for single or multiple trait sets and thus, whether they are complementary or fully redundant when considering multiple functions. Further, we analyzed the influence of geography, climate, plant productivity and land use on FR. We found that FR based on mammal parasitic interactions, body mass and diel activity were positively correlated, whereas FR based on mammal body mass and habitat preferences were negatively related. These relationships were consistent across and within mammal assemblages. Additionally, FR mainly varied along geographic gradients (latitude and longitude). FR based on parasitic interactions, body mass and diel activity followed similar patterns, increasing at northern latitudes, possibly as a response to environmental filtering processes. FR for diet and habitat preferences increased at easterly longitudes, which may be due to landscape homogeneity in sites across central and eastern Asia. Despite redundancy across multiple functional trait sets, Eurasian small mammal assemblages were complementary when considering all five trait sets. Our results warn against conclusions drawn from the study of FR based on traits related to a single function.
Angel sharks (Squatinidae): A review of biological knowledge and exploitation
Authors: Ellis Jim R. , Barker Joanna , McCully Phillips Sophy R. , Meyers Eva K. M. , Heupel Michelle
Published: November 2020

Angel sharks (Squatinaspp.) are distributed in warm temperate to tropical waters around the world. Many species occur in shelf seas and exhibit seasonal inshore–offshore migrations, moving inshore to give birth. Consequently, there can be high spatial overlap of angel shark populations with fisheries and other human activities. Their dorso‐ventrally flattened body shape, large size (most species attain >100 cm total length,LT) and demersal nature means that they may be taken in a variety of demersal fishing gears from birth. Available data indicate that angel sharks typically have a biennial reproductive cycle, with litter sizes generally <20 and the young born atc. 20–30 cm. The biological characteristics of angel sharks render them susceptible to overexploitation, as exemplified by the decline ofSquatina squatinafrom many parts of its former range in the north‐east Atlantic and Mediterranean Sea. Currently, half of the 22 recognized extant species of angel shark are classed as Threatened on the International Union for Conservation of Nature (IUCN) Red List (with a further three classified as Data Deficient). Given the biological vulnerability of angel sharks, and that many species are data‐limited, the current paper provides a review of available biological information and fisheries data pertaining to this family.
Gateway to the North? Contingent Journeys at the Mexico‐Guatemala Border
Authors: Galemba Rebecca B. , Dingeman Katie , DeVries Kaelyn
Published: November 2020

As insecurity in Central America persists and avenues for asylum in the U.S. constrict, migrants are exploring options in Mexico—to seek humanitarian relief or to bide time as they consider whether to continue north, settle, or return. Based on interviews with migrants and shelter staff at the Mexico‐Guatemala border in the summer of 2017, this article applies contingency logics (Bledsoe 2002) to analyze how proximate social ties, accumulated experiences, and harsh ordeals inform how migrants make decisions, change their minds, and re‐envision destinations amid uncertainty. Complicating tensions between mobility/immobility and settlement/transit, we demonstrate how decisions to settle, seek protection, or wait in Mexico may be socially understood as fostering migrants’ larger goals to continue their journeys and pursue their migratory aspirations. However, given Mexico's expanding deportation apparatus and the unpredictability of options in Mexico, such forms of waiting also risk consigning migrants to indeterminate waiting, vulnerability, and entrapment.
Efficacy and safety of homologous autoinoculation in treatment of multiple recalcitrant warts of different types
Authors: Abdelmonaem Nsreen A , Shaheen M.A , Mohsen Mohamed Foad Tamer , El‐Husseiny Rania
Published: November 2020

Background

Homologous autoinoculation is a novel minimally invasive procedure that treats warts by stimulating specific immune response.

Aim

To evaluate the efficacy and safety of autoinoculation in treatment of multiple recalcitrant warts of different types in relation to patient's age, gender, type, number, size, and duration of warts.

Patients and Methods

Two hundred patients with multiple recalcitrant warts of different types were treated with one autoinoculation session. Each patient was subjected to history taking, general and dermatological examination, and photographic documentation before and after treatment. Patients were followed up after 1 week, 2, 12, and 16 weeks to assess possible side effects, treatment response, and recurrence rate, respectively. Evaluation of treatment response was done through physician assessment according to change in size or number of warts or both.

Results

After 12 weeks of procedure, 66% of patients showed complete clearance, 26% showed moderate clearance, and 4% showed mild clearance while only 1.5% of patients showed treatment failure, with negligible side effects and no recurrence. There was negative correlation between treatment response and wart duration (P < .001).

Conclusion

Autoinoculation is effective in treating multiple recalcitrant warts irrespective of their type, number or size, with minimal complications and no recurrence. The longer wart duration is, the less treatment response will be achieved.
Optimal make–take fees for market making regulation
Authors: Euch Omar El , Mastrolia Thibaut , Rosenbaum Mathieu , Touzi Nizar
Published: November 2020

We address the mechanism design problem of an exchange setting suitable make– take fees to attract liquidity on its platform. Using a principal–agent approach, we provide the optimal compensation scheme of a market maker in quasi‐explicit form. This contract depends essentially on the market maker inventory trajectory and on the volatility of the asset. We also provide the optimal quotes that should be displayed by the market maker. The simplicity of our formulas allows us to analyze in details the effects of optimal contracting with an exchange, compared to a situation without contract. We show in particular that it improves liquidity and reduces trading costs for investors. We extend our study to an oligopoly of symmetric exchanges and we study the impact of such common agency policy on the system.
A clinical perspective on adipose‐derived cell therapy for enhancing microvascular health and function: Implications and applications for reconstructive surgery
Authors: Jones V. Morgan , Suarez‐Martinez Ariana D. , Hodges Nicholas A. , Murfee Walter L. , Llull Ramon , Katz Adam J.
Published: November 2020

Restoration of form and function requires apposition of tissues in the form of flaps to reconstitute local perfusion. Successful reconstruction relies on flap survival and its integration with the recipient bed. The flap's precariously perfused hypoxic areas undergo adaptive microvascular changes both internally and in connection with the recipient bed. A cell‐mediated, coordinated response to hypoxia drives these adaptive processes, restoring a tissue's normoxic homeostasis via de novo vasculogenesis, sprouting angiogenesis, and stabilizing arterialization. As cells exert prolonged and coordinated effects on site, their use as biological agents merit translational consideration of sourcing angio‐competent cells and delivering them to territories enduring microcirculatory acclimatization. Angio‐competent cells abound in adipose tissue: a reliable, accessible, and expendable source of adipose‐derived cells (ADC). When subject to enzymatic digestion and centrifugation, adipose tissue separates its various ADC: A subset of buoyant oil‐dense adipocytes (the tissue's parenchymal component) accumulates on a supra‐natant layer, whereas the mesenchymal component remains in the infra‐natant sediment, containing the tissue's stromal vascular fraction (SVF), where angio‐component cells abound. The SVF can be further manipulated, selected, or culture expanded into more specific stromal subsets (herein defined as adipose stromal cells, ASC). While promising clinical applications for ADC await clinical proof and regulatory authorization, basic science investigation is needed to elucidate the specific ADC mechanisms that influence microvascular growth, remodeling, and function following flap surgery. The objective of this article is to share the clinical perspectives of reconstructive plastic surgeons regarding the use of ADC‐based therapies to help with flap tissue integration, revascularization, and wound healing. Specifically, the focus will be on considering the potential for ADC as therapeutic agents and how their clinical application motivates basic science opportunities.
The Anti‐photoaging Effects of Pre‐ and Post‐treatment of Platelet‐rich Plasma on UVB‐damaged HaCaT Keratinocytes
Authors: Cui Xiao , Ma Yongshi , Wang Hong , Huang Jianfang , Li Linlin , Tang Jianbing , Cheng Biao
Published: November 2020

Platelet‐rich plasma (PRP) has seen wide clinical use owing to its regenerative and repair abilities. Objective: To investigate the anti‐photoaging effects of pre‐ and post‐treatment of PRP on UVB‐damaged HaCaT cells. Methods: HaCaT cells were irradiated with 80 mJ/cm2 UVB, before or after PRP treatment (1000 × 107/L), and following measurements were taken: survival rate of UVB‐irradiated HaCaT cells, malondialdehyde (MDA) content and activities of glutathione peroxidase (GSH‐Px), superoxide dismutase (SOD) and catalase (CAT). Western blot was used to determine the effect of different PRP intervention on the expression of PI3K, AKT, ERK, MMP‐1, MMP‐9, TIMP‐1 and γ‐H2AX in the UVB‐irradiated HaCaT cells. Results: pre‐ and post‐PRP treatment reduced MDA content and increased the activities of GSH‐Px, SOD and CAT in photoaged HaCaT cells. These changes resulted in reduced cytotoxic effects. Besides, different PRP intervention promoted cell proliferation via PI3K/AKT pathway. Furthermore, PRP application suppressed the expression of γ‐H2AX. Also, PRP intervention alleviated photoaging effects by upregulating the expression level of tissue inhibitor of metalloproteinases‐1 (TIMP‐1) while downregulating matrix metalloproteinase (MMP) expression level in photoaged HaCaT cells. Conclusion: pre‐ and post‐PRP treatment play anti‐photoaging role through strengthening cellular oxidative defense capacity, mitigating MMP expression, alleviating DNA damages and promoting proliferation of UVB‐irradiated HaCaT cells.
Host density dependence and environmental factors affecting laurel wilt disease incidence
Authors: Choudhury Robin A. , Er Hong Ling , Hughes Marc A. , Smith Jason A. , Pruett Gretchen E. , Konkol Joshua , Ploetz Randy C. , Marois James J. , Garrett Karen A. , van Bruggen Ariena H. C.
Published: November 2020

Host size, density, and distribution, in addition to climate, can affect the likelihood a pathogen will invade and saturate landscapes. Laurel wilt, caused by the vector‐borne pathogen Raffaelea lauricola, has devastated populations of native Lauraceae in the south‐eastern USA, and continues to spread. We surveyed 87 plots in six coastal islands in South Carolina, Georgia, and north Florida, and one inland site (Archbold Biological Station) in south Florida for laurel wilt‐affected and unaffected individual plants belonging to the genus Persea. The coastal island sites were surveyed once in 2008 or 2009, and the inland site was surveyed eight times from 2011 to 2013. Disease incidence per plot ranged from 0% to 96%, with mean disease incidence 42% across all sites. Disease incidence was positively correlated with trunk diameter and with density of hosts with trunk diameter >5 cm, but negatively correlated with the degree of clustering, which was highest for small trees. A recursive partitioning model indicated that higher disease incidence was associated with moderate temperatures, wider trunk diameter, lower relative humidity, and lower wind speeds. Disease progress over time at Archbold followed a Gompertz curve, plateauing at 3% in 2 years. The dispersal kernel for disease incidence from a focus followed a negative exponential distribution. The number of plots with diseased trees at Archbold was similar for redbay (P. borbonia) and swampbay (P. palustris) but was lower for silkbay (P. humilis). Understanding how host density, size, and diversity interact with environmental effects will help guide future risk prediction efforts.
Metabolomic differences of seminal plasma between boars with high and low average conception rates after artificial insemination
Authors: Zhang Yu‐ting , Liu Yan , Liang Han‐lin , Xu Qian‐qian , Liu Zhong‐hua , Weng Xiao‐gang
Published: November 2020

Seminal plasma is a complex biological fluid containing many metabolites including amino acids, fructose, carbohydrates and lipids Metabolites play important roles in multiple biological processes, but details and significance of the seminal plasma metabolome related to boar fertility are unknown. The aim of the present study was to compare the comprehensive metabolome of seminal plasma from boars with different conception rate after artificial insemination and to identify the potential biomarkers. Semen samples were collected from boars which divided into two groups according to the conception rates in the offspring. Seminal plasma metabolites were isolated, purified, and then subjected to Ultra‐high Performance Liquid Chromatography‐Quadrupole Time‐of‐Flight Mass Spectrometry (UHPLC‐qTOF‐MS) procession. A total of 576 (Positive ion mode) and 377 (Negative ion mode) metabolites were identified in seminal plasma. Metabolites were identified and categorized according to their major chemical classes, including carboxylic acids and derivatives, organooxygen compounds, amino acids, peptides, and alogues, fatty amides, fatty acyls, benzene and substituted derivatives, purine nucleotides, pyrimidine nucleotides, glycosyl compounds, fatty acids and conjugates. The results showed that 4‐Aminobenzoate, Pro‐Asn, Ile‐Tyr, Homoveratric acid and D‐Biotin were higher in semen of boar with higher conception rate (HG) versus lower conception rate (LG) (p < .05), whereas L‐Serine, Butoxyacetic acid, S‐Methyl‐5'‐thioadenosine, Capsaicin and 1‐O‐(cis‐9‐Octadecenyl)‐2‐O‐acetyl‐sn‐glycero‐3‐phosphocholine (PAF) were lower in HG than in LG (p < .05). These metabolites may be considered as candidate biomarkers for different fertility in boars.
Interreligious dialogue, literacy and theologies of storytelling: Australian perspectives
Authors: Burritt Amanda Maree , Massam Katharine Therese
Published: November 2020

This article argues that interreligious dialogue, learning and literacy involve more than enabling the communication of information about diverse religious groups. Effective pedagogies in interreligious contexts equip learners with an awareness of and potentially the capacity to engage with the spiritual realities to which the traditions adhere. Approaches that incorporate rich stories are essential for genuine interreligious learning.
Two novel FUT1 alleles that cause para‐Bombay phenotype in a Chinese individual
Authors: Lin Feng‐Qiu , Zhang Kun‐Lian , Li Xiao‐Feng , Zhang Xu , Liu Ying , Li Jian‐Ping
Published: November 2020

Background

Bombay and para‐Bombay phenotypes, which arise from gene mutations of α‐1,2‐fucosyltransferase FUT1, are very rare in Chinese population. A para‐Bombay phenotype Chinese individual with two novel FUT1 mutations was reported here.

Study Design and Methods

The peripheral blood and saliva samples of the proband and her family members were collected after informed consent. ABO and H blood group phenotyping was performed by haemagglutination methods. ABO genotype was determined by PCR‐SSP kit. A, B, and H antigens in saliva were detected by a hemagglutination inhibition test. Fragments encompassing the full coding region of FUT1 and FUT2 genes were PCR amplified and sequenced. Allelic sequences were validated by cloning and sequencing individual colonies.

Results

The serologic reaction results of the proband revealed that A, B, and H antigen were absent on RBCs, but B and H antigen were presented in saliva, and the serum contains anti‐H. The proband was assigned as B/O1 by ABO genotyping. Two new heterozygous mutations of FUT1 gene, c.508dupT and c.787A>C, were identified through direct sequencing of PCR‐amplified products. TA cloning and sequencing confirmed that two novel mutations were on different alleles. FUT2 gene sequence of the proband is consistent with standard. The other family members of the proband showed normal phenotypes of ABO blood group and their genotypes are consistent with phenotypes.

Conclusion

Two novel FUT1 alleles, with the previously not reported mutations c.508dupT and c.787C, respectively, are responsible for the para‐Bombay phenotype detected in the sample from the proband.
Development of the STEP-to-DB Converter for the Web-Based PDM
Authors: Kim Sun-Ho , Jeong Yong-Mun
Published: November 2020

STEP data exchanged for collaborative engineering is usually used in CAD systems. However, it is not used so well in PDM systems due to differences in data scope and structure. In order to resolve this inefficiency, we developed the STEP file converter which can manipulate STEP data in web-based PDM systems. The translation scope is limited to AP203. The translator consists of two modules: 1) the viewer which displays STEP data in web environments and 2) mapping editor and translator between STEP schema and PDM database schema.
Information Sharing Within a Distributed, Collaborative Design Process: A Case Study
Authors: MacGregor Steven P. , Thomson Avril I. , Juster Neal P.
Published: November 2020

A current research project at the University of Strathclyde is introduced which aims to better understand the role of distributed engineering design in industry and address present problems. The first major industrial case study of the project, completed within a multinational in the oil and gas industry, is then described together with the main research questions. This multinational will be described in the text as company A. The findings are split into three areas depending on the data collection method employed. The main case study issues are investigated through interviews while a profile of current activities and perceptions comes from completed questionnaires. Sampling and analysis of distributed activity over time is served by the completion of daily diaries and direct observation. These combine to increase the understanding of information sharing and collaborative design in a distributed organization. Interviews show the importance of design reuse within the organization contrasting with the pressures of formalizing all parts of a design project. The preponderance of variant design activity is also highlighted along with concerns of continued practice. The questionnaires show that 34% of engineers’ time is spent sourcing relevant information and knowledge and that the most popular sources are company systems followed by personal contact. 18% of work is found to be distributed while colleagues from another location and another floor/department know more 51% and 57% of the time respectively. The detail design phase of a distributed design project is analysed over time which finds that most collaborative work consists of simple information exchange supplementary to the main design activity. Furthermore, concentrated periods of collaborative design are found to follow these information exchange cycles’. Distributed problems are also discussed in the paper, ranging from difficulties with unfamiliar terminology to a lack of visibility at worldwide sites.
Using the Abstract Prototyping Technique in the Development of Design Support Systems
Authors: Opiyo E. Z. , Horváth I. , Vergeest J. S. M.
Published: November 2020

In the process of development of Computer Aided Design (CAD) software tools, the expected functionality reappears in various different forms, for instance, as a collection of theories, methods, algorithms or as pilot implementations. Ensuring quality of these abstract software implementations can help assuring the acceptance of the functionality. The problem is that a formal methodology for assuring quality of all these abstract implementations is not available. As an attempt to deal with this challenge, we have developed a computer based pre-implementation testing methodology that has been named abstract prototyping. The exclusive feature of the abstract prototyping technique and the philosophy behind it is that it provides a framework for pre-implementation testing and for involving the representatives of various stakeholders in the development and testing of incidental implementations. We are using abstract prototyping as a framework for development and testing of abstract implementations of design support software tools, and it appears to be useful. It provides the developers with a methodology for exploring views of various stakeholders. It thus helps reduce the risk of developing poor design support software tools. In this paper we first review the problem and then briefly introduce the abstract prototyping concept and software tools. Afterwards, we focus on explaining how to use the abstract prototyping technique in the development and testing of design support software tools.
Integrated Genome-Like Product Database and Management System
Authors: Tan Ah-Kat , Bonollo Elivio
Published: November 2020

A novel approach in organizing product data and managing product information in collaborative product design and development environments is presented. Domains of product data and information are first discussed in the context of generic models of product development process and product design process. An approach called the Product Information Management System (PRIMAS) for organizing and managing product information is subsequently described. In the system, product data is organized in a genome-like relational database (PRIMAS-DB), comprising a matrix of two categories of factors, namely, the Information Fields and the Product Constituents. The Information Fields consist of four generic domains for organizing information for the various activities represented as Product Constituents. The operational model and architecture of PRIMAS are presented. Development of a prototype for PRIMAS and plan for further work are described.
Comparative Study of Representation Structures for Modeling Function and Behavior of Mechanical Devices
Authors: Summers Joshua D. , Vargas-Hernández Noé , Zhao Zuozhi , Shah Jami J. , Lacroix Zoé
Published: November 2020

Engineering design is focussed on the development of artifacts and systems to satisfy specified functions. Current CAD systems provide little support integrating the modeling of the function, behavior, and form of designed artifacts throughout the design process. The focus of this paper is to investigate four representations for use in function representation for conceptual design, embodiment design, and design for manufacturing. These four representations include: Graph Grammars, Exemplars, Bond Graphs, and Function Converters. It is shown that different representations are more suited for different phases of design depending upon required design tasks and for representing different types of function knowledge. Finally, an approach for integration of these representations is proposed, synthesizing a hybrid representation based upon the strengths of the four identified strategies.
Calibrating Virtual Environments for Engineering Applications
Authors: Jayaram Uma , Repp Roglenda
Published: November 2020

A major disadvantage of some tracking systems used in virtual reality environments is the degradation in accuracy due to the presence of metals and other electromagnetic distortions in the environment. Calibration of the virtual environment to account for these distortions is essential for VR applications in engineering where correlation between the virtual environment and the physical world is important. The goal of the calibration process is to map the distorted tracker space to the physical space as accurately as possible for real-time applications.

In this paper the authors present an integrated calibration system used with an electromagnetic tracking system. The components of this system are described in detail, including data collection, grid refinement, interpolation, and evaluation. The paper describes different alternatives for measuring systematic errors of magnetic trackers in a room, and for automatically correcting them using various techniques to interpolate between sets of measurements to achieve error estimates and corrections. Several key techniques and algorithms are presented in detail and evaluated in terms of accuracy and execution time over a range of cell densities. Among the interpolation methods considered are inverse distance weighting and affine transformation mappings, as well as variations and combinations of these. The calibration system, called COVE (Calibration of Virtual Environments), has been successful in allowing accurate tracking for several engineering applications.
Problem Formulation and Basic Elements for Automated Multi-Piece Mold Design
Authors: Chen Yong , Rosen David
Published: November 2020

Mold design can be a difficult, time-consuming process. Particularly for rapid tooling applications, delivering prototype parts with turn-around times of less than two weeks requires fast, proven mold design methods. We present a region-based approach to automated mold design that is suitable for simple two-piece molds (consisting of core and cavity), as well as molds with many additional moving sections. In our region-based approach, part faces are partitioned into regions, each of which can be formed by a single mold piece. The basic elements of our approach are concave regions (generalized pockets) and convex faces since these elements are central to the identification of regions. This paper focuses on the initial steps of automated mold design, including a problem formulation and methods for identifying the basic elements from part faces. By seeking to minimize the number of mold pieces, different partitions of faces into regions are explored until the smallest number of regions is found. During this process, faces may be split and allocated to different regions. The scope of this paper is limited to the initial steps of the region forming process. We present alternative region forming algorithms and analyze their computational complexity. Our approach is illustrated with two examples of industrial injection molded parts.
Timing Studies of Real-Time Linux for Control
Authors: Proctor Frederick M. , Shackleford William P.
Published: November 2020

Linux is being used increasingly for real-time control of industrial equipment. Versions of Linux adapted to support deterministic task execution are freely available. The resolution of task timing is much higher than for typical user-level processes, on the order of tens of microseconds. At this level, timing jitter due to hardware effects is visible.

This paper describes Linux and real-time Linux, its application for industrial control, and shows the results of some timing studies. Various timing techniques are presented and their advantages and disadvantages are discussed. A method for improving timing is presented.
Computer-Based Design of Disc Brakes by Multi-Objective Form Optimization
Authors: Metwalli Sayed M. , Hegazi Hesham A.
Published: November 2020

This paper is concerned with the application of CAD to design disc brakes using multi-objective form optimization. Temperature and disc (rotor) volume are two competing design objective functions used to obtain the optimum design parameters of disc brakes. The geometrical parameters affecting disk brake design such as the outer and inner disc diameters, disc thickness, pad thickness and pad angle are considered. The exponents of the two competing objective functions are to be optimized for better results. A sensitivity analysis of the two exponents (A and B) is used for this optimization procedure. The design vector for optimizing disc brakes includes the outer disc diameters, diameter ratio, disc thickness, and pad angle. The multi-objective formulation satisfies maximum attained torque; minimum actuating force; minimum thermal stresses; minimum temperature and minimum disc volume. A comparison with two previous optimization results indicates a marked improvement of the present design since previous results did not consider all design parameters or optimized objectives.
Relative Cooling With Liquid for Gas Turbines: Part I — A Solution for Exceeding 2000 K at Turbine Inlet
Authors: Constantin Sandu , Brasoveanu Dan
Published: November 2020

The thermal efficiency of gas turbines is critically dependent on the temperature of burnt gases at turbine inlet, the higher this temperature the higher the efficiency. Stochiometric combustion would provide maximum efficiency, but in the absence of an internal cooling system, turbine blades cannot tolerate gas temperatures that exceed 1300 K. Therefore, for this temperature, the thermal efficiency of turbine engine is 40% less than theoretical maximum. Conventional air-cooling techniques of turbine blades allow inlet temperatures of about 1500 K on current operating engines yielding thermal efficiency gains of about 6%. New designs, that incorporate advanced air-cooling methods allows inlet temperatures of 1750–1800 K, with a thermal efficiency gain of about 6% relative to current operating engines. This temperature is near the limit allowed by air-cooling systems. Turbine blades can be cooled with air taken from the compressor or with liquid. Cooling systems with air are easier to design but have a relatively low heat transfer capacity and reduce the efficiency of the engine. Some cooling systems with liquid rely on thermal gradients to promote re-circulation from the tip to the root of turbine blades. In this case, the flow and cooling of liquid are restricted. For best results, cooling systems with liquid should use a pump to re-circulate the coolant. In the past, designers tried to place this pump on the engine stator and therefore were unable to avoid high coolant losses because it is impossible to reliably seal the stator-rotor interface. Therefore it was assumed that cooling systems with liquid could not incorporate pumps. This is an unwarranted assumption as shown studying the system in a moving frame of reference that is linked to the rotor. Here is the crucial fact overlooked by previous designers. The relative motion of engine stator with respect to the rotor is sufficient to motivate a cooling pump. Both the pump and heat exchange system that is required to provide rapid cooling of liquid with cold ambient air, could be located within the rotor. Therefore, the entire cooling system can be encapsulated within the rotor and the sealing problem is circumvented. Compared to recent designs that use advanced air-cooling methods, such a liquid cooling system would increase the thermal efficiency by 8%–11% because the temperatures at turbine inlet can reach stoichiometric levels and most of the heat extracted from turbine during cooling is recuperated. The appreciated high reliability of the system will permit a large applicability in aerospace propulsion.
Reading Required Characters in Market of Products by Using Data Envelopment Analysis
Authors: Arakawa Masao , Nakayama Hirotaka , Yun Ye Boon , Ishikawa Hiroshi
Published: November 2020

In this paper, we will try to help decision making of very early design stage what the designers have to take into account to design competitive products. The proposed method is based on Data Envelopment Analysis (DEA) and through DEA; we will derive requirements of needs in the markets for the products. As for numerical example, we use 108 data from automobile and classify them into 11 categories and find out the character of each category and showed how the weights shift to gain competitive power in the market.
Product Line Design Selection Under Uncertainty and With Competitive Advantage
Authors: Li Hui , Azarm Shapour
Published: November 2020

An approach for product line design is presented in which a line of products is selected for launching into the market. In the approach, the product line design is viewed as a selection process with two main stages: design alternative generation and design alternative evaluation. The focus of this paper is on the design alternative evaluation stage. Issues considered include a large variety of customer preferences, market competitions, multiple business goals, uncertainty, and commonality among the alternatives in a product line. Because of the combinatorial nature of the problem, genetic algorithms are used in the design evaluation stage. Product line design selection of a cordless screwdriver is used as a demonstration example. However, the emphasis in the example is on the approach and not in the details per se.
Workspace-Based Design of Parallel Manipulators of Star Topology With a Genetic Algorithm
Authors: Baron Luc
Published: November 2020

This paper presents the results of the implementation of a genetic algorithm for the design of parallel manipulators of Star topology based on the characteristics of its workspace (W). The algorithm allows to propose new geometries of manipulators that maximize the weighted sum of the volume of W, the percentage of W having a dexterity index greater than a minimum threshold, and a shape ration of W. The algorithm has proven to be effective by proposing a new design that overcomes, by a factor of 3.636, the performances of the original Y Star design, after evaluating the performances of only 2000 alternative designs, which correspond to a traveling of only 2.02 × 10−16% through the search space of this design problem.
Computationally Inexpensive Metamodel Assessment Strategies
Authors: Meckesheimer Martin , Barton Russell R. , Simpson Timothy W. , Booker Andrew J.
Published: November 2020

In many scientific and engineering domains, it is common to analyze and simulate complex physical systems using mathematical models. Although computing resources continue to increase in power and speed, discipline-specific computer simulation modules continue to grow in complexity and remain computationally expensive, limiting their use in design optimization. The use of different approximation strategies as inexpensive metamodels of the discipline-specific simulation models has led to the development of various metamodel-based integration frameworks and associated research topics. In particular, integration of the discipline-specific metamodels requires an assessment of the overall system error based on the individual approximation errors. As a result, there is a need to develop efficient methods to assess metamodel fidelity at the system and subsystem level. In this paper, we investigate computationally inexpensive assessment methods for metamodel validation at the subsystem level and evaluate a two-stage validation approach on two classes of test problems:

1. Three response functions from a Boeing simulation model, and

2. two response functions from a set of problems for testing optimization codes.

Preliminary results indicate that the two stage-validation approach is promising, since it requires no additional computationally expensive disciplinary model evaluations and can provide a practical estimate of the true error measure.
Optimization for Minimum Weight of Ultralight Structures Under Axial Crush Loading
Authors: Chen Weigang
Published: November 2020

A methodology was proposed which combined the structural optimization technique with the recent achievements in crush mechanics of thin-walled members with ultralight metal filler. The optimization problems of foam-filled square, hexagonal, double-hat rectangular, double-hat hexagonal sections and double-walled sandwich sections were formulated and solved with crashworthiness and bending stiffness constraints. The proposed methodology requires relatively simple computations and is suitable for early stage design of crash members. The optimization results showed potentials of significant weight saving and volume reduction by utilizing ultralight metal filler. The double-walled sandwich sections appear to be the most weight efficient design with the highest specific energy absorption among all studied cross-sections.
Computational Performance of Wavelet-Based Meshless Methods in the Solution of Very Large Scale Elasticity Problems
Authors: Diaz Alejandro R. , Yamaura Kazuya
Published: November 2020

This paper discusses the computational performance of methods to solve very large scale, geometrically complex problems in elasticity using a voxelization of the domain and wavelet based discretizations. These methods are designed to avoid the complexities associated with the construction of standard finite element meshes. Results show that in very large scale problems these schemes converge more rapidly than a standard (finite element) method.
Packing Optimisation Using a Rubberband Analogy
Authors: Fadel Georges M. , Sinha Avijit , McKee Todd
Published: November 2020

Packing is a topic of interest in many fields. During our research on the underhood-packing problem, we observed that to bring components together — without switching their relative position — one could use the analogy of a rubber object stretched around the artifacts. In two-dimensional space, that object is a rubber band, and in three-dimensions, it is a balloon. Using this analogy, the convex hull can be used to determine the direction of forces applied to a single component, and a motion can result from the application of such forces. The objects can then be moved until contact occurs, at which point the forces become moments, and the objects can rotate with respect to each other. This technique can guarantee locally optimal packing, and displays a very intuitive behavior that might lead to further advances in optimization. This paper introduces the methodology for optimizing the packing of 2-dimensional geometric entities (polygons) in a plane and of 3-dimensional objects in space using the Rubber band Analogy.
Design of Multifunctional Compliant Mechanisms for Minimally Invasive Surgery
Authors: Dziedzic Ryan P. , Frecker Mary I.
Published: November 2020

This paper proposes incorporating compliant mechanisms into the design of minimally invasive surgical tools to help overcome current tool limitations — particularly to increase multifunctionality. To perform multiple unique functions, a compliant mechanism is designed with a single topology that allows multiple input forces to independently produce distinct output displacements. A multicriteria topology optimization procedure is developed for the design of compliant mechanisms, and the procedure is executed using Matlab. This method generates topologies displaying both sufficient compliance and stiffness for each load case by formulating the objective function as a ratio of mutual potential energy to strain energy. The total objective function is then assembled as the weighted sum of the objective functions for each load case. The optimization procedure is illustrated through the generation of topologies for a device based on a grasperscissors combination tool. Also addressed are factors which significantly influence the resulting solution, such as the weighting function value and starting point.
Finding and Removing Features From Polyhedra
Authors: Ribelles José , Heckbert Paul S. , Garland Michael , Stahovich Tom , Srivastava Vinit
Published: November 2020

Geometric models of solids often contain small features that we would like to isolate and remove. Examples include bumps, holes, tabs, notches, and decorations. Feature removal can be desirable for numerous reasons, including economical meshing and finite element simulation, analysis of feature purpose, and compact shape representation. In this work, an algorithm is presented that inputs a polyhedral solid, identifies and ranks its candidate features, and outputs solid models of the feature and the original object with the feature removed. Ranking permits a user or higher level software to quickly find the most desirable features for the task at hand. Features are defined in terms of portions of the surface that are classified differently from the rest of the solid’s surface with respect to one or more split planes. This approach to feature definition is more general than many previous methods, and generalizes naturally to quadric surfaces and other implicit surfaces.
Investigation of Compliant Centrifugal Clutch Designs
Authors: Crane Nathan B. , Weight Brent L. , Howell Larry L.
Published: November 2020

Compliant centrifugal clutches can make centrifugal clutches feasible in cost and weight sensitive applications. This paper introduces new configurations of compliant centrifugal clutches, proposes pseudo-rigid-body models for their analysis, and presents torque capacity results for several prototypes. The results are also compared to those obtained from compliant centrifugal clutch designs already commercially available. While all four new clutch designs compare favorably to commercially available clutch configurations, the floating opposing arm (FOA) clutch demonstrated the highest torque capacity of all the configurations.
Comparative Study of Seismic Analyses for Piping Systems
Authors: Jonsdottir Fjola , Jonsson Magnus Thor
Published: November 2020

In this paper different approaches in seismic design are investigated. Commonly used static analysis is compared with two different cases of harmonic analysis. The static analysis is based on a design response spectra. In the harmonic analysis, case 1, the loading is in the form of acceleration applied to the mass, for case 2, the loading is in the form of applied displacements to the supports. A typical expansion pipe unit is analysed with all three methods. It is shown that standard procedures can lead to a conservative design and prevent the optimization of the results. An optimum design can be obtained by using supports with adequate damping and stiffness, and hence, the loading on the piping system can be minimized.
Analytical Target Cascading in Automotive Vehicle Design
Authors: Kim Hyung Min , Rideout D. Geoff , Papalambros Panos Y. , Stein Jeffrey L.
Published: November 2020

Target cascading in product development is a systematic effort to propagate the desired top-level system design targets to appropriate specifications for subsystems and components in a consistent and efficient manner. If analysis models are available to represent the relevant design decisions, analytical target cascading can be formalized as a hierarchical multilevel optimization problem. The article demonstrates this complex modeling and solution process in the chassis design of a sport-utility vehicle. Ride quality and handling targets are cascaded down to systems and subsystems utilizing suspension, tire, and spring analysis models. Potential incompatibilities among targets and constraints throughout the entire system can be uncovered and the trade-offs involved in achieving system targets under different design scenarios can be quantified.
Large-Scale, Multidisciplinary Optimization of a Vehicle System in a Scalable, High Performance Computing Environment
Authors: Kodiyalam Srinivas , Yang R. J. , Gu Lei , Tho Cheng-Ho
Published: November 2020

The focus of this paper is on large-scale MDO of a vehicle system for Safety, NVH (noise, vibration and harshness) and Weight, in a scalable HPC environment. The computational complexity comes from addressing multiple safety modes including, frontal crash, offset crash, side impact and roof crush, in addition to the NVH discipline. A combination of high performance computing utilizing several hundred processors, Kriging metamodeling based design response approximation techniques, formal MDO strategies, and engineering judgement are effectively used to obtain superior design solutions with significantly reduced elapsed computing times. The reduction in large-scale MDO solution times through HPC is significant in that it now makes it possible for such technologies to impact the vehicle design cycle and improve the engineering productivity.
A Multi-Project Management Approach for Distributed Projects Management
Authors: Marie Franck , Bocquet Jean-Claude
Published: November 2020

As planning is the action undertaken before execution, it has a great importance as every investment. We identify some problematics in the planning process, and give some lightings about how to make it more efficient and reliable. We propose some methods for managing project at each detail level. We propose the extension of project manager’s concepts to all the people who are accountable for some objective or deliverable. So, there are in a single project a lot of people managing the part they are responsible for as an entire project. We propose a standard methodological kit for them, and we describe the consequences on skills and responsibilities of the project actors, and on the decisions they have to take and efforts they have to undertake to reach their objectives.