bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of sexuality in religious responses to problematic drug use in Argentina
Authors: Jones Daniel Eduardo , Dulbecco Paloma , Cunial Santiago L.
Published: February 2021

Purpose

The purpose of this paper is to inquire into the role that sexuality plays in faith-based programs for the prevention and care of problematic drug use.

Design/methodology/approach

This paper conducts 25 semi-structured interviews with institutional staff and another 31 with people undergoing treatment in spiritual and religious drug rehabilitation programs in Argentina.

Findings

First, within these therapeutic devices, different sexual experiences are considered initial catalysts for drug use. Also, within these institutions, certain morally condemned sexual behaviors are seen as associated with consumption. Second, these institutions establish diverse rules and recommendations about intimate relationships for people in recovery to improve the outcome of treatments. Third, therapeutic institutions produce gender stereotypes related to the sexuality of drug users. Fourth, institutions assume heterosexuality within their target populations, thereby reinforcing the heteronormative frameworks of these therapeutic interventions.

Research limitations/implications

This is a small qualitative study conducted in Argentina. Although its results cannot be generalized, they serve as a preliminary empirical input to analyze drug treatment programs in the country and other regions of the world.

Originality/value

This study addresses the relationships between problematic drug use, rehabilitation and sexuality from the perspectives of both professionals and men and women who consume drugs. This paper adopts a critical perspective on gender and sexual diversity to analyze how therapeutic institutions reproduce certain gender stereotypes and heteronormativity. In doing so, the research intends to contribute to discussions that can lead to more comprehensive policies regarding problematic drug use.
Foster employability and fight social exclusion through the development of lifelong learning (LLL) key-competences: reviewing twenty years of LLL policies
Authors: Ceschi Andrea , Perini Marco , Scalco Andrea , Pentassuglia Monica , Righetti Elisa , Caputo Beniamino
Published: February 2021

Purpose

This study aims to provide an overview of the past two decades of lifelong learning (LLL) policies for enhancing employability and reduce social exclusion in young people of European countries through the development of the so-called LLL key-competences.

Design/methodology/approach

Built on a quasi-systematic review, this contribution explores traditional and new methods for promoting the LLL transition, and then employability, in young adults (e.g. apprenticeship, vocational training, e-learning, etc.).

Findings

It argues the need to identify all the possible approaches able to support policymakers, as they can differently impact key-competence development.

Originality/value

Finally, based on the consolidated EU policy experience, we propose a strategy of implementation of the LLL programmes that facilitates the institutions’ decision processes for policy-making through the use of decisional support system.
Evaluating the health promoting schools in Iran: across-sectional study
Authors: Sartipizadeh Mehrangiz , Yazdi-Feyzabadi Vahid , Alipouri Sakha Minoo , Zarrin Aein , Bazyar Mohammad , Zahirian Moghadam Telma , Zandian Hamed
Published: February 2021

Purpose

Health-promoting schools have been associated with improvements in the health status of students globally. This study is a secondary analysis study assessing Iranian HPSs.

Design/methodology/approach

This was a cross-sectional study on routinely collected data using an external audit 63-item checklist, which was utilized to evaluate 440 HPSs between 2014 and 2017. The mean score for each of the checklists' components was calculated. Nonparametric tests were conducted to investigate the association between the presence of a school caregiver, students' educational level and the school's score.

Findings

While the number of five- and four-star schools increased significantly, one- to three-star schools declined. Providing clinical and counseling services had negative growth. Despite the steady growth of the staff's health, this category still had the lowest score among; on the contrary, physical activity had the highest score in 2017. The presence of a full-time school caregiver and middle schools were both significantly correlated with achieving higher scores (p < 0.005).

Originality/value

It seems that in addition to developing school facilities to promote physical activities, measures should be taken to promote access to counseling services, considering health issues of students and staff and finally increasing the number of full-time school caregiver
From Sèvres to Melbourne: Art and education museums in 19th-century Victoria
Authors: Griffith Anna , Carroll Mary Brigit , Farrell Oliver
Published: February 2021

Purpose

This paper focuses on the donation in 1888 of a Sèvres Vase to the Education Department of Victoria after the International Exhibition in Melbourne. Using the vase as its focus the paper reflects on what this donation may be able to tell us about the impact, primarily on education, of a series of International Exhibitions held both in Australia and internationally between 1851 and 1900. The life of the Sèvres vase highlights the potential of the Exhibitions for the exchange of ideas internationally, the influence of the International Exhibition movement on education and the links between a 19th-century gift and the teaching of Art in 1930s Melbourne.

Design/methodology/approach

The paper examines one object in relation to education in its wider historical context through a reading of the archival records relating to the Melbourne Teacher’s Training College and Melbourne High School.

Findings

The influence of the educational exhibits of the 1888 Centennial International Exhibition held in Melbourne are shown to have had an impact on the design of the Melbourne Teachers Training College.

Originality/value

This paper provides a new and original perspective on the Melbourne Teachers Training College and its foundation through its library and museum collections.
Threat of hostile takeover and the cost of seasoned equity offerings
Authors: Sheikhbahaei Ali , Shams Syed
Published: February 2021

Purpose

This paper investigates the relationship between a firm's susceptibility to a hostile takeover and investors' reactions to a seasoned equity offering (SEO).

Design/methodology/approach

The study applies ordinary least squares (OLS) with fixed effects regression analyses to a sample of 2,517 observations from US listed companies. Event study methodology was employed to capture market reactions to the announcement of newly issued stocks. To achieve cross-sectional analyses, time variations in takeover laws allowed us to perform the desired tests across two decades of data.

Findings

The results suggest that investors react positively to the announcement of an equity offering when the threat of hostile takeover is higher. The magnitude of positive stock market reactions varies over two decades due to time series variations in takeover laws. Furthermore, the findings show that a higher hostile takeover index (HTI) score reduces investors' concerns about the inefficient usage of proceeds in acquisitions.

Practical implications

The results demonstrate that the corporate takeover legal environment provides an important external governance mechanism through which investors' confidence increases during an SEO event. The study's empirical evidence implies that the extent of external disciplinary mechanism plays a significant role in reducing investors' uncertainty about the misuse of raised capital.

Originality/value

The exogenous fast-evolving legal environment surrounding the takeover market in the United Status allowed our study to bypass the endogeneity concerns in measuring governance strength. From the review of prior literature, this paper appears to be the first to use HTI scores to examine investors' reactions to a corporate announcement.
Inventory classification system in space mission component replenishment using multi-attribute fuzzy ABC classification
Authors: Yung Kai Leung , Ho George To Sum , Tang Yuk Ming , Ip Wai Hung
Published: February 2021

Purpose

This project attempts to present a space component inventory classification system for space inventory replenishment and management. The authors propose to adopt a classification system that can incorporate all the different variables in a multi-criteria configuration. Fuzzy logic is applied as an effective way for formulating classification problems in space inventory replenishment.

Design/methodology/approach

A fuzzy-based approach with ABC classification is proposed to incorporate all the different variables in a multi-criteria configuration. Fuzzy logic is applied as an effective way for formulating classification problems in space inventory replenishment of the soil preparation system (SOPSYS) which is used in grinding and sifting Phobos rocks to sub-millimeter size in the Phobos-Grunt space mission. An information system was developed using the existing platform and was used to support the key aspects in performing inventory classification and purchasing optimization.

Findings

The proposed classification system was found to be able to classify the inventory and optimize the purchasing decision efficiency. Based on the information provided from the system, implementation plans for the SOPSYS project and related space projects can be proposed.

Research limitations/implications

The paper addresses one of the main difficulties in handling qualitative or quantitative classification criteria. The model can be implemented using mathematical calculation tools and integrated into the existing inventory management system. The proposed model has important implications in optimizing the purchasing decisions to shorten the research and development of other space instruments in space missions.

Originality/value

Inventory management in the manufacture of space instruments is one of the major problems due to the complexity of the manufacturing process and the large variety of items. The classification system can optimize purchasing decision-making in the inventory management process. It is also designed to be flexible and can be implemented for the manufacture of other space mission instruments.
Identifying the required infrastructure to improve the jack-up maintenance process based on effective criteria in the Persian Gulf
Authors: Farizhendy Mojgan Mortezaei , Golabchi Mahmood , Noorzai Esmatullah
Published: February 2021

Purpose

The purpose of this research is to identify the effective criteria and determine the required infrastructure for the repair of drilling rigs.

Design/methodology/approach

The research was carried out through questionnaires and interviews with experts, including consultants, contractors and operators. A long list of the required infrastructure, dividing into three groups of vital, necessary and support, was prepared and compared with the productivity criteria.

Findings

The results show that it is better to prepare and upgrade the vital, necessary and supportive equipment in the shipyards, including refrigeration workshop, cofferdam for repairing spudcans and residential and educational places.

Practical implications

These results are helpful for the industries working on jack-ups and the countries having similar conditions to enable them to use their assets in an optimum way.

Originality/value

Oil drilling rigs' repair and maintenance (R&M) services are essential because of affecting the economy. Furthermore, about 25% of Iran’s oil drilling rigs are jack-up, needing overhauls every five years. Other research has investigated how to repair jack-ups, their incidents, their R&M industry market and, only in some cases mentioned, cost and time criteria. Therefore, it is necessary to identify the criteria and study the infrastructures in the shipyards.
Does ownership structure and market sentiment affect the performance of IPOs in India in short run? A dynamic panel data analysis
Authors: Singla Harish Kumar
Published: February 2021

Purpose

This study aims to compare the short-run performance of construction and non-construction initial public offerings (IPOs) that are offered in India during 2006–2015. The study also attempts to investigate the impact of ownership structure (i.e. concentrated ownership in the hand of promoters and institutional ownership) and market sentiment on the performance of construction sector IPOs in short run.

Design/methodology/approach

A total of 281 IPOs were listed at National Stock Exchange, India, during the study period, and 44 of those were from construction sector. The short-run performance of these construction and non-construction IPOs was compared using two indicators, i.e. monthly stock return (SR) and excess return over market benchmark (MAR). To examine the effect of concentrated ownership in the hand of promoters, institutional ownership and market sentiment on IPO performance, systematic dynamic panel regression model was developed.

Findings

The IPOs of construction firms perform significantly better than the non-construction firms. The performance of construction IPOs is significantly driven by the lag effect. This suggests a significant informational inefficiency, which results in a delayed reaction by investors. The market sentiment has a positive influence on the performance of construction sector IPOs, whereas the institutional holding has a negative influence.

Originality/value

To the best of the author’s knowledge, this study is the first attempt to examine the performance of construction sector IPOs in short run. The study uses systematic dynamic panel data regression, which provides better and reliable estimates.
Sharing of tacit knowledge in volunteer Portuguese firefighters – paths to diagnosis
Authors: Oliveira Márcio José Sol Pereira , Pinheiro Paulo
Published: February 2021

Purpose

Focusing on the study of tacit knowledge sharing in nonprofit organizations (NPOs) in Portugal and taking as a case study the Portuguese voluntary firefighters, this study aims to identify the most relevant factors for sharing tacit knowledge and identify the types of barriers most prevalent to such sharing in these organizations.

Design/methodology/approach

A literature review on tacit knowledge sharing allowed the identification of indicators and barriers to the sharing of this knowledge. This was followed by a mixed methodology that combines qualitative and quantitative techniques through questionnaires and interviews, whose treatment allowed to determine the indicators that influence each of these factors and which types of barriers.

Findings

Three factors have been identified that lead to the sharing of tacit knowledge within these organizations: organizational culture, individual characteristics and organizational structure. Four typologies of barriers were identified: communicational, technological, personal and resource or infrastructure.

Research limitations/implications

The present research focuses exclusively on the sharing of tacit knowledge, not considering other forms of knowledge. As a case study, although with heterogeneous organizations, the same cannot be replicated to different realities.

Practical implications

The investigation of the main factors and the main types of barriers that arise to the sharing of tacit knowledge in these organizations may serve as a basis for the creation of diagnostic and intervention tools.

Originality/value

Studies in this area targeting NPOs are scarce, as opposed to what is happening in the private and public sectors. The option of a case study of organizations such as the Portuguese fire brigades, unique in their action and identity, accompanies the need increasingly recognized by society, in enabling these organizations of competencies for the best possible performance, in the face of tragic events that have occurred in recent years in Portugal.
Cordate-shaped UWB-MIMO antenna with notch band characteristic and high isolation
Authors: Pannu Preeti , Sharma Devendra Kumar
Published: February 2021

Purpose

This paper aims to design a most demanding low profile and compact ultra-wide band (UWB) antenna system for various wireless applications. The performance (in terms of data rate) of UWB system is improved by using multiple-input-multiple-output (MIMO) technology with it. Owing to the overlap of other existing licensed bands with that of UWB, electromagnetic signals can interfere. So, notched band UWB MIMO antenna system reported here which is highly compact, bandwidth efficient, superior data rate and high inter-element isolation comparatively to other reported designs.

Design/methodology/approach

A 49 × 49 × 1.6 mm3 quad-port UWB MIMO antenna with specific bandwidth elimination property is designed. The proposed planar MIMO configuration comprises unique four identical “Cordate-shaped” monopole radiators fed by 2.3-mm thick microstrip-lines. The radiators are located right-angled to each other to enhance inter-element isolation. Further, a different approach of slitted-substrate is applied to minimize the overall size and mutual coupling of the MIMO antenna, as a substitute of decoupling and matching structures. The defected ground structure is used to obtain −10 dB impedance bandwidth in entire UWB band, without compromising with the lower cut-off frequency response. Further, to eliminate the undesired resonant band (WLAN at 5.5 GHz) from UWB, a rounded split ring resonator is introduced in monopole patch.

Findings

In the entire operating band of 2.8 to 11 GHz, isolation among elements is more than 24 dB, envelope correlation coefficient less than 0.002, diversity gain greater than 9.99 dB and TARC less than −7 dB are obtained at all 4-ports.

Research limitations/implications

The measured parameters of the fabricated prototype antenna on FR4 substrate are found in good agreement with the simulated results. The small variation in software results and hardware results are observed due to hardware design limitations.

Practical implications

The proposed design may be used for any wireless application following in the range of UWB.

Originality/value

It can be shown from graphs of measured parameters of the fabricated prototype antenna. They found to be in good agreement with the simulated results.
The Political Economy of the Differential Regional Effects of Monetary Policy: Evidence From China
Authors: Liao Changjun , Wang Shengquan
Published: February 2021

Previous studies have argued that heterogeneities across regions in economic and/or financial variables drive the differential regional effects of monetary policy. In this study, we conduct a political economy analysis of the regional effects of China's monetary policy (i.e., economic competition between local governments) as Chinese‐style fiscal decentralization and China's promotion tournament for officials produce regional effects. Furthermore, we use a threshold model and provincial‐level data from 2005 to 2018 to test our hypotheses and estimate exogenous monetary policy shocks. We find that (1) economic competition between regions is a key driver of the asymmetric regional effects of monetary policy and (2) the fiercer the competition a province faces, the less effective the monetary policy is in shaping economic growth there. Our conclusion remains unchanged when we change the threshold variable and divide the sample into three subregions.
Cognitive decline among individuals with history of mild symptomatic SARS‐CoV‐2 infection: A longitudinal prospective study nested to a population cohort
Authors: Del Brutto Oscar H. , Wu Shasha , Mera Robertino M. , Costa Aldo F. , Recalde Bettsy Y. , Issa Naoum P.
Published: February 2021

Background and purpose

Neurological complications of SARS‐CoV‐2 infection are noticed among critically ill patients soon after disease onset. Information on delayed neurological sequelae of SARS‐CoV‐2 infection is nil. Following a longitudinal study design, the occurrence of cognitive decline among individuals with a history of mild symptomatic SARS‐CoV‐2 infection was assessed.

Methods

Stroke‐ and seizure‐free Atahualpa residents aged ≥40 years, who had pre‐pandemic cognitive assessments as well as normal brain magnetic resonance imaging and electroencephalogram recordings, underwent repeated evaluations 6 months after a SARS‐CoV‐2 outbreak infection in Atahualpa. Patients requiring oxygen therapy, hospitalization, and those who had initial neurological manifestations were excluded. Cognitive decline was defined as a reduction in the Montreal Cognitive Assessment (MoCA) score between the post‐pandemic and pre‐pandemic assessments that was ≥4 points greater than the reduction observed between two pre‐pandemic MoCAs. The relationship between SARS‐CoV‐2 infection and cognitive decline was assessed by fitting logistic mixed models for longitudinal data as well as exposure‐effect models.

Results

Of 93 included individuals (mean age 62.6 ± 11 years), 52 (56%) had a history of mild symptomatic SARS‐CoV‐2 infection. Post‐pandemic MoCA decay was worse in seropositive individuals. Cognitive decline was recognized in 11/52 (21%) seropositive and 1/41 (2%) seronegative individuals. In multivariate analyses, the odds for developing cognitive decline were 18.1 times higher among SARS‐CoV‐2 seropositive individuals (95% confidence interval 1.75–188; p = 0.015). Exposure‐effect models confirmed this association (β = 0.24; 95% confidence interval 0.07–0.41; p = 0.006).

Conclusions

This study provides evidence of cognitive decline among individuals with mild symptomatic SARS‐CoV‐2 infection. The pathogenesis of this complication remains unknown.
Increasing climatic sensitivity of global grassland vegetation biomass and species diversity correlates with water availability
Authors: Liu Daijun , Zhang Chao , Ogaya Romà , Fernández‐Martínez Marcos , Pugh Thomas A. M. , Peñuelas Josep
Published: February 2021

Grasslands are key repositories of biodiversity and carbon storage and are heavily impacted by effects of global warming and changes in precipitation regimes. Patterns of grassland dynamics associated with variability in future climate conditions across spatiotemporal scales are yet to be adequately quantified. Here, we performed a global meta‐analysis of year and growing season sensitivities of vegetation aboveground biomass (AGB), aboveground net primary productivity (ANPP), and species richness (SR) and diversity (Shannon index, H) to experimental climate warming and precipitation shifts. All four variables were sensitive to climate change. Their sensitivities to shifts in precipitation were correlated with local background water availability, such as mean annual precipitation (MAP) and aridity, and AGB and ANPP sensitivities were greater in dry habitats than in nonwater‐limited habitats. There was no effect of duration of experiment (short vs long term) on sensitivities. Temporal trends in ANPP and SR sensitivity depended on local water availability; ANPP sensitivity to warming increased over time and SR sensitivity to irrigation decreased over time. Our results provide a global overview of the sensitivities of grassland function and diversity to climate change that will improve the understanding of ecological responses across spatiotemporal scales and inform policies for conservation in dry climates.
Design for Complexity Reduction of Fuel Sender Assembly
Authors: Greer James , Chen Li , Rao S. S. , Cipra R. J.
Published: February 2021

This work presents a design methodology to address the complexity reduction of fuel-sender assembly. The current fuel-sender design is reviewed first by considering the present assembly, and then the complexity involved in the design and manufacturing processes are discussed. Using the current situation as the baseline, the proposed design is deployed for each subassembly of the fuel sender, along with parts manufacturability, assembly, and cost analyses, focusing on reducing the complexity of the fuel sender assembly. The group technology concepts are applied to the fuel level sensor, in which a shape factor and corresponding design control charts are defined and proposed for grouping particular fuel tank configurations with individual sensors. The optimum robust design techniques are considered for portions of the design proposed. Two goals are simultaneously targeted while satisfying the behavior constraints in the design phase. These goals are to reduce component cost, and to minimize the uncertainties associated with the manufacturing process. The results of the optimization analysis are used to produce the design drawings. The design proposed is intended as a first iteration, and will certainly be modified to become even more efficient in future iterations.
Design Optimization of Rigid-Body Mechanisms via Multidimensional CSG
Authors: Wise Kevin D. , Eisenthal David C. R. , Bowyer Adrian
Published: February 2021

In this paper we describe a new multidimensional constructive solid geometry technique for creating a configuration-space map for a group of objects of almost arbitrary geometry. We then outline our plans for a design optimization system for mechanisms which exploits the ability of our technique to handle objects which are defined parametrically.
Computation of Geometric Properties of Cross Sections With Holes and/or Inserts Based on Scanned Binary Data
Authors: Pao Y. C. , Ritman E. L.
Published: February 2021

Formulas have been derived for computation of the cross sectional area, location of the centroid, and moments of inertia making direct use of the binary-data which are to be collected from computer-tomographical scanning of porous materials. Bone data are applied to demonstrate the developed computational procedure and interactive operation of QuickBASIC programs.
Modeling and Simulation of an Asymmetric Mine-Soil-Structure Interaction Problem
Authors: Gupta Aaron D.
Published: February 2021

An asymmetric mine-soil-structure interaction problem with two competing plate thicknesses was modeled using a hydrodynamic code. The plate acts as a momentum trap for a vertical impulse test facility proposed at the Aberdeen Proving Ground. The model allows simulation of complex asymmetric explosive-soil-structure interaction effects and generates loading and response of the plate due to varying center line offset, stand-off, depth of soil overburden and explosive contents. The objective is to select a minimally thick plate which must survive the interaction without any significant residual permanent deformation.
Analysis of Multiple Stage Hydroforming of Sheet Metal With Intermediate Annealing
Authors: Gandikota Varadaraju A. , Madhavan Viswanathan , Hooper Steven J.
Published: February 2021

This paper presents the development of a finite element simulation of multistage hydroforming of sheet metal parts with annealing between forming stages, implemented using the commercial explicit dynamic code LS-DYNA. In each of the hydroforming stages, the sheet is formed to the shape of the die used in that stage by the application of fluid pressure on the top surface of the sheet. At the end of each stage, the stresses in the part are relieved and changes in material properties due to various heat treatments are accommodated while maintaining the deformed geometry of the part, including sheet thickness variations. In this manner the forming of an aircraft engine nacelle inlet lip in three stages with annealing between the stages has been simulated. In addition, single stage hydroforming to the final shape and three stage forming without intermediate annealing have been simulated. The results are used to compare the effectiveness of intermediate die shapes to the effectiveness of intermediate heat treatments in extending sheet metal formability. It is found that intermediate heat treatments enhance the ability of intermediate die shapes to promote uniform deformation of the sheet.
Web-Based Cad Tools for a Networked Manufacturing Service
Authors: Wang Fu-Chung F. , Wright Paul K.
Published: February 2021

New techniques in Information Technology are now changing not only our daily life, but also the professional practice of product design and manufacturing for new product development. Internet technology in particular opens up another domain for building future CAD/CAM environments. This environment will be a global, network-centric environment with various members providing different software tools, manufacturing facilities, and analysis services for distributed design and fabrication. In this paper, we first briefly describe a vision and current development in a distributed design and manufacturing environment. The paper then emphasizes how current CAD tools will evolve to facilitate the distributed design and fabrication process. In particular, the development of a set of Web-based design tools for fabricating parts using a machining process via the Internet is presented. Experiments on machining 2-1/2 D and freeform parts through this Java-based design tool have shown the feasibility for a networked machining service via the Internet.
Embedded PC Control System for a Highway Crack Sealing Machine
Authors: Feng X. , Bennett D. A. , Velinsky S. A.
Published: February 2021

This paper presents the hardware and software design of the embedded control system for a highway crack sealing machine. A long-reach robotic manipulator has been specially designed for this application. In order to ensure the reliability and performance of the system, a unique distributed and multiprocessor architecture is used. The architecture is designed to employ the reliability of Windows NT and a graphical user interface while concurrently allowing real-time operation. By implementing embedded PC technologies, the software development process has benefited from the widely available off-the-shelf 32-bit software and programming tools. This paper discusses the use of both Visual C++ (MFC) and Visual Basic to realize a modern mechanical-electronic engineering system with minimum programming efforts. The communication between applications and over the network is also described with an emphasis on building an Internet-aware embedded system that has tremendous application potential.
Feature-Based Machining Precedence Reasoning and Sequence Planning
Authors: Kim Yong Se , Wang Eric , Lee Choong Soo , Rho Hyung Min
Published: February 2021

This paper presents a feature-based method to support machining sequence planning. Precedence relations among machining operations are systematically generated based on geometric information, tolerance specifications, and machining expertise. The feature recognition method using Alternating Sum of Volumes With Partitioning (ASVP) Decomposition is applied to obtain a Form Feature Decomposition (FFD) of a part model. Form features are classified into a taxonomy of atomic machining features, to which machining process information has been associated. Geometry-based precedence relations between features are systematically generated using the face dependency information obtained by ASVP Decomposition and the features’ associated machining process information. Multiple sets of precedence relations are generated as alternative precedence trees, based on the feature types and machining process considerations. These precedence trees are further enhanced with precedence relations from tolerance specifications and machining expertise. Machining sequence planning is performed for each of these precedence trees, applying a matrix-based method to reduce the search space while minimizing the number of tool changes. The precedence trees may then be evaluated based on machining cost and other criteria. The precedence reasoning module and operation sequence planning module are currently being implemented within a comprehensive Computer-Aided Process Planning system.
Enhancing a Commercial 3D CAD System by CSCW Functionality for Enabling Co-Operative Modelling via WAN
Authors: Stork André , von Lukas Uwe , Schultz Ralph
Published: February 2021

This paper presents results from a joint project with the aim to introduce advanced Computer Supported Co-operative Work (CSCW) technology to a mid-size supplier for the automotive industry by enhancing the 3D CAD system in use by CSCW functionality and enabling distributed, synchronous, co-operative modelling over a wide area network. Beside the realization of the CSCW extension we present first experience from practical use and a cost assessment discussing the rentability of our approach.
Elementary Computer Modeling Applied to TWA800 Fuel Tank Forensic Issues
Authors: Wyczalek Floyd A.
Published: February 2021

The specific mission was to identify the conditions of atmospheric pressure and ambient temperature under which a so-called empty-Boeing model 747-131 fixed wing jet aircraft center wing tank (CWT), containing a residual fuel loading of about 3 kg/m3, less than 100 gallons of aviation kerosene (JetA Athens refinery commercial jet fuel), could form hazardous air/fuel mixtures. The issues are limited to explosion safety concerns relating to certificated fixed wing jet aircraft in regularly scheduled commercial passenger service. It is certain that a combustible mixture does not exist in a fuel tank containing Jet-A type fuel at ambient temperatures below 38°C (100°F), which is the lean limit flash point (LFP) for commercial jet fuel at sea level. Never the less, although not included in this paper, the original study reported by Wyczalek and Suh (1997), identified six highly unlikely, but rationally possible critical conditions which can occur in a combination which may permit a combustible mixture to exist within a jet aircraft fuel tank and pose a potential hazard.

The scope of this paper is limited to mathematical modeling concerns related to fixed wing jet aircraft fuel tanks and commercial jet fuels combustible air-fuel mixture ratios. It was further limited to a historical review of the scientific literature in the public domain from 1950 to the present time, which defined the thermodynamic and minimum ignition energy properties of aviation gasoline and commercial jet fuels; and, to comparisons with new thermodynamic data for JetA Athens flight test samples, released by the National Transportation Safety Board (NTSB) during public hearings on the TWA800 event in Baltimore, Maryland in December 1997. The original work reported by Wyczalek and Suh (1997) conclusively demonstrated that the USAF Wright Air Development Center and the US Bureau of Mines conducted and published comprehensive evaluations of the potential hazards relating to jet aircraft fuel tanks as early as 1952. This historical scientific data and the mathematical models for the new jetA and Athens refinery jetA in this paper, are relevant to pending TWA800 related litigation, and to the future implementation of NTSB recommendations resulting from the TWA800 event.
Steam Turbine Airfoil Design Optimization
Authors: Wang K. D. , Amano R. S. , Hong Chi-An
Published: February 2021

In designing steam turbine airfoil, a continuous slope (second derivative) is desirable to prevent local flow circulation and a minimum curvature is necessary to decrease turbulence. To meet this requirement, the design program uses fifth and sixth order. Berstein polynomials to define for both the pressure-side and the suction-side profile curves. Two sets of data are required to the design program. The first set of data is relevant to the geometric parameters that include radius of nose and tail, inlet and exit metal angles, length and orientation of chord, throat and pitch, bend angle, and wedge angle. The second set of data consists of five control variables to determine the suction-side profile and three control variables to determine the pressure-side profile. The program was successfully applied to modify an existing airfoil. Geometric parameters were obtained by direct measurement. Trial and error procedures were employed to determine the value of those eight control variables so that the airfoil can be curve-fitted by running the design program. The airfoil reproduced by the design program were continuous smooth, which were utilized in a subsequent computational fluid dynamics performance analysis. A close examination of reproduced airfoil reveals that the curve-fitting result is satisfactory as it eliminates certain discontinuities in the measured data. A more efficient airfoil could then be made by adjusting geometrical parameters and control variables. Results obtained by using this program indicate that it can not only effectively optimize airfoil shape to achieve better aerodynamic performance but also preserve original design intents. Through-flow calculations were also made to determine an optimum flow path of the entire turbine. A viscous flow program was used to aerodynamically analyze the original and the new designs.
The Necessity for Product Knowledge Reuse and Sharing Within Knowledge-Based Engineering Systems
Authors: Sainter P. , Oldham K. , Kneebone S.
Published: February 2021

The deployment of knowledge-based engineering systems is on the increase within engineering industries and, as such, there will be an ever-increasing demand to share a common product representation, which includes design and manufacturing knowledge. At the moment, each commercial knowledge-based engineering system has its own development language and therefore representation language for design and manufacturing knowledge. To date, no work has fully addressed the need to exchange product knowledge as well as product data. It is, therefore, the main aim of this paper to demonstrate the need for a standard product knowledge representation language and how it could be developed by using existing standards, thereby providing the ability to exchange product knowledge as well as product data.
Tolerance Analysis of Deformable Assemblies
Authors: Sellem Eric , Rivière Alain
Published: February 2021

This article describes the use of a mechanical approach taking deformation into account in the computation of tolerances for welded, riveted, bolted or glued assemblies of sheetmetal parts. Integration of the FEM to model the elastic deformability in the assembly process results in a finer and more realistic simulation. Both analysis and synthesis tools can be based on this approach.
Life Estimation of a Spur Gear With a Tooth Cracked at Fillet Region
Authors: Arıkan M. A. Sahir , Tarhan A. Ismail , Yahşi O. Selçuk
Published: February 2021

A computer program is developed to find the dynamic tooth load variation, make growth analysis of the crack at tooth fillet region, and determine the life of a spur gear in terms of load cycles. Variable amplitude-variable position cyclic load on the tooth is found by using a model based on torsional vibrations of gears. Stress intensity factor is determined by assuming small, through face width cracks. Paris-Erdogan crack growth rate equation is used for crack growth analysis. Load interaction effects are taken into consideration by using Willenborg retardation model. Stress intensity factor variation is arranged by using range-pair range cycle counting method. Rack cutter tip fillet radius and rack cutter geometry are taken into consideration in tooth modeling and rack cutters standardized by ISO are used for the analysis. Finite element method is used to find tooth stifnesses. Bending deformations of gear bodies and supporting shafts, bearing deformations, torsional deformations of gear bodies, and contact deformations of teeth are included in stiffness calculations.
Optimal CMM Measurement Locations for Manufactured Part Modeling
Authors: Wang Yu (Michael) , Gupta Shailendra
Published: February 2021

The focus of this paper is to address the problem of optimal measurement location for manufactured part modeling (MPM) with CMM coordinate data. In the manufactured part modeling approach, a shape deviation model parameterized to represent the part’s actual geometric attributes is determined from the measured data. The resulting model parameters are then used to make decisions regarding part acceptability and/or manufacturing process control. The goal of optimal measurement is to ensure the accurate and robust estimation of model parameters. A sensitivity measure that reflects the confidence associated with the estimated values of the parameters and their robustness against singularity is developed as a criterion for choosing measurement point locations.
B2: An Interactive Quality Visualization and Improvement Technique for B-Spline Surfaces
Authors: Chen Yifan , Beier Klaus-Peter
Published: February 2021

A new interactive technique for B-spline surface quality visualization and improvement, called the B2 method, is presented. This method interpolates the control points of a given B-spline surface using a second B-spline surface. If small irregularities exist in the control points of the original surface, they will be magnified through the second B-spline and demonstrated as large distortions in its control points. This facilitates the detection of small surface irregularities. Subsequently, the surface may be improved through direct and interactive adjustment of the second B-spline’s control polyhedron.
Constraint Reordering for Multi-Objective Configuration Design
Authors: Adams Nathan J. , Fadel Georges M.
Published: February 2021

Configuration design is the process of placing components, without altering their shape or connectivity, into an available space, while satisfying various spatial constraints, such as no component overlap. Minimizing the volume occupied by the components and or maximizing the accessibility of the components are just two examples of the many objectives that can drive a configuration design problem.

For complex configuration designs, there can be many objectives, which can impose spatial constraints among the components and increase the design complexity, cycle cost, and time. An iterative procedure becomes necessary to reconcile these spatial constraints. To reach solutions that are optimal, these constraints must be reordered else combinatorial methods such as Genetic Algorithms that are used for such problems do not converge. Successful reordering can make complex configuration design problems easier to solve by minimizing the iterations necessary to reach an acceptable solution. Minimizing iterations translates into faster convergence and thus savings on time and money.

This paper presents a methodology that can manage the propagation of spatial constraints in complex configuration design problems. Representative examples are shown and results and conclusions are drawn.
An Interactive Multistage ε-Inequality Constraint Method for Multiple Objectives Decision Making
Authors: Palli N. , McCluskey P. , Azarm S. , Sundararajan R.
Published: February 2021

Multiple objectives decision making (MODM) in engineering design involves obtaining a preferred optimal solution in the context of conflicting design objectives. Problems with multiple objectives do not have a unique optimal solution but a set of Pareto optimal solutions. This paper presents a new interactive multistage MODM method which captures a decision maker’s preference structure in order to obtain a preferred Pareto solution even for non-convex problems. Representative subsets of an entire Pareto optimal set are generated and expanded based on the decision maker’s preference. The ε-constraint method is used to constrain the multiple objectives problem based on the decision maker’s feedback. In addition, ideas from an interactive weighted Tchebycheff approach are applied to reduce the feasible region at each stage, ensuring that the process eventually converges to a preferred solution. The method is demonstrated with two examples: (i) a simple two-bar truss design, and (ii) a more complicated problem of power electronic module design.
A Case Retrieving System for Machining Processes of Axisymmetric Parts Based on Geometric Indexing and Process Hierarchical Structure
Authors: Chang Hsin-chi , Lu Wen F. , Liu Xiaoqing Frank
Published: February 2021

To develop a new machining process plan in the competitive global market, one effective way is to retrieve a relevant case similar to the new desired case and then adapt it to meet the new situations. This paper proposes a retrieving system for process planning cases from two aspects — the representation and manufacturing processes of a part. The core of the retrieving system contains 1) the feature-based representation of a part, 2) indexing of a part based on two-dimensional peripheral indexing and feature indexing, 3) a hierarchical structure of cutting processes from part cutting history, 4) a similarity metric. The similarity metric is used to measure the similarity between the new desired part and one old case based on the indexes of the parts. The application domain here is the process planning for axisymmetric parts. The proposed retrieving system is implemented in a Sun workstation using ACIS 3D-Toolkit and C++.
Crossover Strategy for Improved Solution Space Exploration With Genetic Algorithms
Authors: Anderson Kurt S. , Hsu YuHung
Published: February 2021

The following paper presents a modified crossover operator to extend the exploration capability in Genetic Algorithms for high dimensional optimization problems. Traditional strategies apply crossover once on a pair of selected chromosomes to generate two offspring by randomly selecting a single crossover location within the chromosomal length. The proposed method applies crossover once on each separate gene (variable) instead of on the entire chromosome. To further accelerate exploration of the Genetic Algorithm, nonuniform distribution of the respective crossover position on each gene has also been studied. The empirical results show that Genetic Algorithms with the proposed crossover strategies can find optimal or near optimal solutions within fewer generations than traditional single point crossover.
Approximate-Cooperative Design Formulations for Enterprise Design and Integration
Authors: Hernandez Gabriel , Allen Janet K. , Mistree Farrokh
Published: February 2021

Enterprise design is embodied by the notion of integrating the processes of product design, manufacturing process design, and organization design to enhance manufacturing competitiveness. However, because of cognitive and computational limitations, the integration of the enterprise design activities based on large and complex enterprise models is not efficacious. In this paper, we show how to achieve an efficacious integration by promoting a common decision support model across the enterprise and using approximate-cooperative formulations of individual design decisions. The preliminary embodiment of a flywheel produced in a forging process is used to illustrate this perspective.
Topology Design of Truss Structures by Shape Annealing
Authors: Shea Kristina , Cagan Jonathan
Published: February 2021

Shape annealing is a design technique that combines grammatical transformation with simulated annealing to generate optimally directed discrete structures. The primary advantage of shape annealing over other discrete methods is the introduction of new joints and members, using a shape grammar, to enable simultaneous optimization of topology, shape, and sizing. This approach makes the exploration of truss topologies that are not constrained to a pre-defined grid possible. While details of the method have been presented (Reddy and Cagan, 1995; Shea et al., 1997), this paper provides an overview of the current implementation and validation through a comparison of results for least-weight design problems to both grid-based solutions and previously reported shape annealing solutions. These comparisons illustrate the capability of shape annealing in generating optimal designs and the advantages of not restricting topology optimization to a grid-based design universe. Comparing new results to those previously reported shows improvement in solution quality and extensions for practical multiobjective design. Finally, solutions to a dome problem illustrate the inherent ease in extending the method to three-dimensional design and multiple loading conditions. These examples demonstrate that shape annealing is effective for exploring topology design of truss structures for both least-weight and multiobjective design problems.