bluuebunny/crossref_metadata_2025 huggingface dataset:
Amorphous solid dispersions and the confounding effect of nanoparticles in in vitro dissolution and in vivo testing: Niclosamide as a case of study
Authors: Jara Miguel O , Warnken Zachary N , Williams Robert O
Published: December 2020

We developed an amorphous solid dispersion (ASD) of the poorly water soluble molecule niclosamide that achieved more than a 2 fold increase in bioavailability. Notably, this niclosamide ASD formulation increased the apparent drug solubility about 60 fold relative to the crystalline material due to the generation of nanoparticles. Niclosamide is a weakly acidic drug, BCS class II, and a poor glass former with low bioavailability in vivo. Hot melt extrusion is a high throughput manufacturing method commonly used in the development of ASDs for increasing the apparent solubility and bioavailability of poorly water-soluble compounds. We utilized the polymer polyvinylpyrrolidone vinyl acetate (PVPVA) to manufacture niclosamide ASDs by extrusion. Samples were analyzed based on their microscopic and macroscopic behavior and their intermolecular interactions, using DSC, XRD, NMR, FTIR, and DLS. The niclosamide ASD generated nanoparticles with a mean particle size of about 100 nm in FaSSIF media. In a side by side diffusion test, these nanoparticles produced a 4 fold increase in niclosamide diffusion. We successfully manufactured amorphous extrudates of the poor glass former niclosamide that showed remarkable in vitro dissolution and diffusion performance. These in vitro tests were translated to a rat model that also showed an increase in oral bioavailability.
Conversion between 100-million-year-old duplicated genes contributes to rice subspecies divergence
Authors: Wei Chendan , Wang Zhenyi , Wang Jianyu , Teng Jia , Shen Shaoqi , Xiao Qimeng , Bao Shoutong , Feng Yishan , Zhang Yan , Li Yuxian , Sun Sangrong , Yue Yuanshuai , Wu Chunyang , Wang Yanli , Zhou Tianning , Xu Wenbo , Yu Jigao , Wang Li , Wang Jinpeng
Published: December 2020

Extensive sequence similarity between duplicated gene pairs produced by paleo-polyploidization may result from illegitimate recombination between homologous chromosomes. The genomes of Asian cultivated rice Xian/indica(XI) and Geng/japonica(GJ) have recently been updated, providing new opportunities for investigating on-going gene conversion events. Using comparative genomics and phylogenetic analyses, we evaluated gene conversion rates between duplicated genes produced by polyploidization 100 million years ago (mya) in GJ and XI. At least 5.19%–5.77% of genes duplicated across three genomes were affected by whole-gene conversion after the divergence of GJ and XI at ~0.4 mya, with more (7.77%–9.53%) showing conversion of only gene portions. Independently converted duplicates surviving in genomes of different subspecies often used the same donor genes. On-going gene conversion frequency was higher near chromosome termini, with a single pair of homoeologous chromosomes 11 and 12 in each genome most affected. Notably, on-going gene conversion has maintained similarity between very ancient duplicates, provided opportunities for further gene conversion, and accelerated rice divergence. Chromosome rearrangement after polyploidization may result in gene loss, providing a basis for on-going gene conversion, and may have contributed directly to restricted recombination/conversion between homoeologous regions. Gene conversion affected biological functions associated with multiple genes, such as catalytic activity, implying opportunities for interaction among members of large gene families, such as NBS-LRR disease-resistance genes, resulting in gene conversion. Duplicated genes in rice subspecies generated by grass polyploidization ~100 mya remain affected by gene conversion at high frequency, with important implications for the divergence of rice subspecies.

One-sentence summary

On-going gene conversion between duplicated genes produced by 100 mya polyploidization contributes to rice subspecies divergence, often involving the same donor genes at chromosome termini.
Heterogeneity of Neuronal Populations Within Columns of Primate V1 Revealed by High-Density Recordings
Authors: Zhu Shude , Xia Ruobing , Chen Xiaomo , Moore Tirin
Published: December 2020

Primary visual cortex (V1) has been the focus of extensive neurophysiological investigation, and its laminar organization provides a key exemplar of the functional logic of neocortical microcircuits. Using newly developed high-density, linear array probes, we measured visual responses from large populations of simultaneously recorded neurons distributed across layers of macaque V1. In single recordings, myriad differences in the functional properties of neuronal subpopulations could be observed. In particular, we found that although standard measurements of orientation selectivity yielded only minor differences between laminar compartments, decoding of stimulus orientation from layer 4C responses was superior to that of both superficial and deep layers within the same cortical column. The superior orientation discrimination within layer 4C was associated with greater response reliability of individual neurons rather than lower correlated activity with neuronal populations. The results demonstrate the utility of high-density electrophysiology in revealing the functional organization and network properties of neocortical microcircuits in single experiments.
Repetitive mild traumatic brain injury causes synergistic effects on mortality
Authors: Willes Ashley M , Krcmarik Tori R , Daughtry Alexander E , Brusich Douglas J
Published: December 2020

Repetitive mild TBI (rmTBI) events are common in the U.S. However, rmTBI is challenging to study and this contributes to a poor understanding of mechanistic bases for disease following these injuries. We used fruit flies(D. melanogaster)and a modified version of the high-impact trauma (HIT) method of TBI to assess the pattern of mortality observed after rmTBI. We found that the pattern of mortality was synergistic after a critical number of injuries, similar to that observed previously at more moderate levels of TBI severity. The identity of cellular and molecular factors which contribute to the synergistic effect on mortality remain unknown, but this model offers a platform for investigation into such factors.
Environmental uncertainty and cross-buying in logistics outsourcing arrangements: a resource dependence perspective
Authors: Hofer Adriana Rossiter , Jin Yao Henry , Knemeyer A. Michael
Published: December 2020

Purpose

This study follows the tenets of the resource dependence theory (RDT) to investigate the effects of four dimensions of industry-level environmental uncertainty – munificence, dynamism, complexity and innovative intensity – on a shipper's cross-buying (i.e. outsourcing across multiple service categories) in logistics outsourcing arrangements.

Design/methodology/approach

Negative binomial regression was used to test the hypotheses with a sample of US manufacturers. Measures were developed through information acquired from a proprietary database of 3PL companies obtained through Armstrong and Associates, Inc. and publicly available industry measures from the US Manufacturing Census and Compustat.

Findings

The findings indicate that individual dimensions of environmental uncertainty exhibit distinct influences on shippers' cross-buying in their logistics outsourcing arrangements. Specifically, the growth and initial innovative intensity of shippers' industries lead to an increased number of logistics service categories outsourced to 3PLs, while industry dynamism and exceptionally high innovative intensity drive the opposite effect.

Practical implications

These findings provide valuable guidance to 3PLs with respect to decisions related to the acquisition of specialized transportation, storage, information systems and personnel assets to serve specific industries. The findings highlight industry conditions that are more likely to lead shippers to outsource across a wider array of logistics service categories and, as a result, potentially yield higher customer retention and profit margins.

Originality/value

While extant 3PL literature posits that shippers' individual strategic orientations and capabilities impact their outsourcing strategy, this study contributes to the literature by providing a theoretical-based empirical examination of the industry-level influencers of such behavior.
Dutch investment advisors’ perceptions towards the MiFID II directive
Authors: Loonen Tom
Published: December 2020

Purpose

The Markets in Financial Instruments Directive (MiFID) II directive was enforced in the EU in January 2018. While EU-member states implemented this directive in their national legislation, investment firms are still enforcing compliance. With the purpose of “investor protection”, the purpose of this study is to investigate the effectiveness of transparency, suitability, warning and information requirements. How do investment advisers view and embrace these MiFID II requirements? Are differences evident within this group of professionals?

Design/methodology/approach

In total, 267 Dutch investment advisors serving non-professional investors daily completed structured surveys on their opinion of the acceptance and effectiveness of the MiFID II requirements. The findings are compared with existing literature to examine similarities with other legislation.

Findings

The results demonstrated differences depending on the investment firms’ size and investment advisors’ seniority and gender. Professionals should be critical of new legislation and regulations, as it limits their autonomy. However, female investment advisors and those with up to ten years’ experience are less critical of the effectiveness of the MiFID II requirements, embracing them without discussion. Investment advisors in large investment firms believe that MiFID II contributes to investors’ interests, whereas those in small and medium-sized investment firms often do not share this opinion. For example, respondents considered cost transparency an effective requirement to achieve better investment services and protect investors’ interests.

Originality/value

The effectiveness and applicability of legislation are often viewed from a legal perspective, and enforcement is essential. However, this study explores legislation from the perspective of professionals under supervision.
Determinants of SMEs intention to adopt Islamic crowdfunding model in Northwestern Nigeria
Authors: Kazaure Mansur Ahmed , Abdullah Abdul Rashid , Zawawi Dahlia Binti , Hamzah Amer
Published: December 2020

Purpose

The study aims is to examine the determinant factors of small and medium enterprises’ (SMEs’) intention to adopt the Islamic crowdfunding model as alternative sources of finance.

Design/methodology/approach

Using a survey questionnaire, 385 responses were received from owners and managers of SMEs in three states (Kano, Kaduna and Katsina) of northwestern Nigeria and analyses using PLS-SEM 3.0 software.

Findings

All hypotheses were found to be significant.

Research limitations/implications

The research focused only on northwestern Nigeria; there is a need for further research to focus on other geographical zones in Nigeria.

Practical implications

Crowd funders and policymakers can use these findings to enable the adoption of the Islamic crowdfunding model.

Originality/value

The previous study has not examined the role of technology acceptance model in the adoption of the financial model; these findings contribute to the crowdfunding literature by filling this gap.
Characteristics of Aboriginal and Torres Strait Islander peoples attending Australian emergency departments
Authors: Lim Jolene CJ , Harrison Glenn , Raos Maximilian , Moore Katie
Published: December 2020

Objective

Aboriginal and Torres Strait Islander patients are overrepresented in Australian EDs. The present study aimed to assess their characteristics in utilising ED services at a national level.

Methods

This exploratory, quantitative study used 2016–2017 de‐identified data from the National Non‐admitted Patient Emergency Department Care Database to assess the proportions (with 95% confidence interval) of Indigenous and non‐Indigenous Australians across various aspects of ED presentations, including mode of arrival, triage scale, diagnosis information, episode end status and ED length of stay. Episode level ED data were compared by Indigenous status and geographical remoteness of EDs.

Results

Of 7.4 million presentations, 6.58% were Indigenous presentations, with over two‐thirds occurring in regional and remote EDs. Indigenous patients were more likely than non‐Indigenous patients to arrive to EDs by ambulance and police/correctional services vehicle across all remoteness areas. Additionally, they were more likely to present with respiratory system illness, illness of the skin/subcutaneous tissue/breast and mental/behavioural disorders. Indigenous Australians were more likely to leave EDs before being seen or care complete (odds ratio 1.73, 95% confidence interval 1.71–1.74), and this was observed for patients classified across all levels of triage scale.

Conclusions

This is the first national study looking at the characteristics of and reasons for presenting to Australian EDs for Indigenous and non‐Indigenous patients. Our findings provide important insight into the potential factors affecting Indigenous patient care, and an impetus for ongoing research and advocacy work to improve the quality of emergency care provided to Indigenous Australians.
Effective double‐digest RAD sequencing and genotyping despite large genome size
Authors: Gargiulo Roberta , Kull Tiiu , Fay Michael F.
Published: December 2020

Obtaining informative data is the ambition of any genomic project, but in nonmodel species with very large genomes, pursuing such a goal requires surmounting a series of analytical challenges. Double‐digest RAD sequencing is routinely used in nonmodel organisms and offers some control over the volume of data obtained. However, the volume of data recovered is not always an indication of the reliability of data sets, and quality checks are necessary to ensure that true and artefactual information is set apart. In the present study, we aim to fill the gap existing between the known applicability of RAD sequencing methods in plants with large genomes and the use of the retrieved loci for population genetic inference. By analysing two populations of Cypripedium calceolus, a nonmodel orchid species with a large genome size (1C ~ 31.6 Gbp), we provide a complete workflow from library preparation to bioinformatic filtering and inference of genetic diversity and differentiation. We show how filtering strategies to dismiss potentially misleading data need to be explored and adapted to data set‐specific features. Moreover, we suggest that the occurrence of organellar sequences in libraries should not be neglected when planning the experiment and analysing the results. Finally, we explain how, in the absence of prior information about the genome of the species, seeking high standards of quality during library preparation and sequencing can provide an insurance against unpredicted technical or biological constraints.
Prediction of photofading of N‐β‐hydroxyethylamino‐o‐nitrophenyl derivatives: a theoretical study
Authors: Wojciechowski Krzysztof , Szuster Lucjan
Published: December 2020

Until now, the lightfastness of hair dyes had not been investigated using all‐valence molecular orbital methods. The results of calculations are used to obtain the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) frontier electron density, which can reflect the propensity for electrophilic or nucleophilic attack at an atom in a molecule. Using semi‐empirical quantum chemical methods AM1 and PM3, we have calculated the reactivity rates , superdelocalisability and electron density distribution in the tested dyes. We have found that the photooxidation of hair dyes (photochemical decomposition of hair dyes) and derivatives of N‐β‐hydroxyethylamino‐o‐nitrobenzene occurs through the degradation of the N‐β‐hydroxyethylamine substituent and on C2 or C4 atom (C4–NO2) in the process of electrophilic reaction with singlet oxygen 1O2 or nucleophilic reaction on the C1 carbon atom of the aromatic ring, with the use of superoxide anion radical O2●. The structures of the dyes were optimised using MM+, DM and AM1 or PM3 until constant energy value was realised with a 0.01 kcal/mol convergence criterion.
Preliminary survey of nematodes associated with broadleaved trees in İzmit Forest Management Directorate, Turkey
Authors: Taşdemir Sinan , Akbulut Süleyman , Kanzaki Natsumi , Öztürk Nuray
Published: December 2020

A survey for Bursaphelenchus species was carried out in broadleaf forest sites of İzmit Forest Management Directorate. Nematodes were extracted from 128 wood samples, and 22 of them were cultured. Nematodes were identified using morphological characteristics and molecular analysis by amplifying D2‐D3 LSU with primers. Only one Bursaphelenchus species, Bursaphelenchus mucronatus kolymensis, was isolated from Quercus petraea representing the first report from broadleaved tree species in Turkey. Paraphelenchus acontioides and Aphelenchoides heidelbergi were identified and presented herein as the first reports of these two species from Turkey. In addition, five Aphelenchoides species were also found and reported as Aphelenchoides sp.
A delay in colonoscopy after positive fecal tests leads to higher incidence of colorectal cancer: A systematic review and meta‐analysis
Authors: Mutneja Hemant Raj , Bhurwal Abhishek , Arora Shilpa , Vohra Ishaan , Attar Bashar M
Published: December 2020

Background and Aim

A delay in performing colonoscopies after positive fecal tests in a screening program may risk neoplastic progression. Our objective is to conduct a systematic review and meta‐analysis to evaluate the effects of timing of a colonoscopy after a positive fecal test on the detection of colorectal cancer.

Methods

Cochrane guidelines and PRISMA statement were followed for this review. Digital dissertation databases were searched from inception to June 1, 2020, and all studies reporting the detection rates of colorectal cancer on the basis of different time intervals between a positive fecal test and the post‐test colonoscopy were included. We compared the detection rates of colorectal cancer (overall and advanced‐stage) and advanced adenoma based on different time intervals.

Results

A total of 361 637 patients from six observational studies were included for the analysis. The odds of detecting any colorectal cancer (odds ratio [OR] 1.58, 95% confidence interval [CI] 1.23–2.03, P < 0.001), advanced‐stage colorectal cancer (OR 2.16, 95% CI 1.47–3.16, P < 0.001), or advanced adenomas (OR 1.17, 95% CI 1.06–1.28, P = 0.001) are significantly higher if the colonoscopies are performed after 6 months from a positive fecal test, compared with within 6 months. There was no significant difference in the detection rates based on a 1‐month, a 2‐month, or a 3‐month cut‐off.

Conclusions

A delay of colonoscopies beyond 6 months after positive fecal tests is associated with a higher odds of detecting colorectal cancer. A timely follow up of patients with positive fecal tests is warranted.
Stochastic dominance and decomposable measures of inequality and poverty
Authors: Zheng Buhong
Published: December 2020

In this paper, we characterize some new links between stochastic dominance and the measurement of inequality and poverty. We show that: for second‐degree normalized stochastic dominance (NSD), the weighted area between the NSD curve of a distribution and that of the equalized distribution is a decomposable inequality measure; for first‐degree and second‐degree censored stochastic dominance (CSD), the weighted area between the CSD curve of a distribution and that of the zero‐poverty distribution is a decomposable poverty measure. These characterizations provide graphical representations for decomposable inequality and poverty measures in the same manner as Lorenz curve does for the Gini index. The extensions of the links to higher degrees of stochastic dominance are also investigated.
Crystallization histories of the group IIF iron meteorites and Eagle Station pallasites
Authors: Hilton Connor D. , Ash Richard D. , Walker Richard J.
Published: December 2020

The group IIF iron meteorites and Eagle Station pallasites (PES) have highly siderophile element abundances (HSE; Re, Os, Ir, Ru, Pt, and Pd) of metal that are consistent with formation in planetesimal cores by fractional crystallization with minor to major solid metal–liquid metal mixing. Modeling of HSE abundances of the IIF irons indicates a complex formation history that included the mixing of primitive and evolved solid and liquid metals. By contrast, modeling of HSE abundances of PES metal suggests these meteorites formed mainly as equilibrium solids from a common liquid. Abundances of some of the siderophile elements in the IIF irons and PES are permissive of a common core origin; however, the abundances of W and Ni indicate the PES ultimately formed on a more oxidized body. The PES most likely formed by the injection of olivine present at the core–mantle boundary into a metallic core liquid as a result of impact. The core then crystallized inward, trapping the olivine.
Nationalism and self‐determination in contemporary Ethiopia
Authors: Berhe Mulugeta Gebrehiwot , Gebresilassie Feseha Habtetsion
Published: December 2020

The 1995 Ethiopian Constitution envisions a multinational state with the right to self‐determination, including secession, given to the nations, nationalities, and peoples of the country. This remarkable document is a product of a unique combination of Ethiopia's history, Marxist‐Leninist debates of the 1974 revolution, and political circumstances of the time the Ethiopian People's Revolutionary Democratic Front (EPRDF) took power in 1991. The subsequent 20 years witnessed a concerted attempt to implement measures for federal decentralization alongside continued political centralization in the ruling party, with several intended and unintended consequences. Since 2016, a combination of the manipulation of constitutional provisions for personal and factional advantage, and polarized perspectives over the identity and future of the country, have unveiled a chapter of political crisis. The 1995 Constitution is hardly a cause of this crisis, yet the fate of the Constitution has become central to the dynamics of the crisis.
The effect of narrow‐band ultraviolet B radiation on sleep, happiness, and appetite: A prospective cohort study
Authors: Vashurin Ilan , Barzilai Aviv , Baum Sharon , Ohana Orly , Pavlotsky Felix , Greenberger Shoshana
Published: December 2020

Background

The health benefits of sunlight are well documented, including the effects on happiness and sleep. However, only a few studies have investigated the benefits of artificial narrow‐band ultraviolet B (NB‐UVB) radiation.

Objectives

To investigate the effect of NB‐UVB on sleep quality, happiness, and appetite.

Methods

Patients from a single phototherapy unit were selected, and their epidemiological characteristics were documented. Subjects were asked to complete questionnaires including the Pittsburg Sleep Quality Index (PSQI), Subjective Happiness Scale (SHS), and the Simplified Nutritional Appetite Questionnaire (SNAQ) 4 weeks before and after the initiation of the NB‐UVB therapy. The sample consisted of 52 patients.

Results

Four weeks after the initiation of NB‐UVB sessions, sleep quality was significantly improved (the PSQI decreased from 6.5 to 5.23 (t = −3.52, P < .01). In contrast, subjective happiness did not improve (the SHS decreased from baseline 5.5 to 5.2, P > .05). Similarly, appetite did not change (the SNAQ score increased from baseline 14.75 to 15.05, P > .05) and body mass index was not affected by phototherapy. In general, men were found to have better sleep quality before and after UV light therapy.

Conclusion

Our data suggest that NB‐UVB exposure over 4 weeks improves sleep quality; however, it does not influence happiness or appetite.
Evaluation of Quantiferon®‐Monitor as a biomarker of immunosuppression and predictor of infection in lung transplant recipients
Authors: Gardiner Bradley J. , Lee Sue J. , Cristiano Yvonne , Levvey Bronwyn J. , Sullivan Lucy C. , Snell Gregory I. , Peleg Anton Y. , Westall Glen P.
Published: December 2020

Background

Optimizing immunosuppression in lung transplant recipients (LTR) is crucially important in minimizing the risk of infection and rejection. Quantiferon®‐Monitor (QFM) is a candidate immune function biomarker which has not yet been rigorously evaluated in the lung transplant setting. The aim of this prospective cohort study was to explore relationships between QFM results, immunosuppression, and infection/rejection in LTR.

Methods

QFM, which measures interferon‐γ after stimulation with innate and adaptive immune antigens, was tested before and at 2, 6, 12, 24 and 52 weeks post‐transplant. Immunosuppression relationships were assessed with linear mixed effects models. Clinical outcomes were analyzed based on the preceding QFM result.

Results

Eighty LTR were included. Median pre‐transplant QFM levels were 171 IU/mL (IQR 45‐461), decreasing to 3 IU/mL (IQR 1‐8) at 2 weeks post‐transplant then progressively recovering toward baseline with time from transplant. Prednisolone was strongly inversely associated with QFM level (0.1 mg/kg dose increase correlating with 88 IU/mL QFM decrease, 95% CI 61‐114,P < .001). Patients with QFM values <10 and <60 IU/mL were more likely to develop a serious opportunistic infection between 3 and 6 months (HR 6.38, 95% CI 1.37‐29.66,P = .02) and 6‐12 months (HR 3.25, 95% CI 1.11‐9.49,P = .03) post‐transplant, respectively.

Conclusions

QFM values declined significantly post‐transplant, with patients recovering at different rates. Prednisolone dose significantly impacted QFM results. Low levels were associated with infection beyond 3 months post‐transplant, suggesting that QFM may be able to identify overly immunosuppressed patients who could be targeted for dose reduction. Larger prospective studies are needed to further evaluate this promising assay.
Haptic Display of Interaction Forces in MEMS Assembly Processes
Authors: Evans Daniel J. , Jayaram Sankar , Feddema John T. , Jayaram Uma , Johnson William A. , Seywald Hans
Published: December 2020

In recent years, the world economy has seen expansive market growth in the area of Micro-Electro Mechanical Systems (MEMS). It is predicted that the MEMS market could reach more than $34 billion by the year 2002. Today, commercially available MEMS products include accelerometers for airbags and inkjet printer heads. These products require little or no assembly because a monolithic integrated circuit process is used to develop the devices. However, future MEMS will be more elaborate. Monolithic integration is not feasible when incompatible processes, complex geometry, or different materials are involved. For these cases, new and extremely precise micro-manipulation capabilities will be required for successful product realization. This paper outlines the design and implementation of a computer aided simulation of Micro Electro Mechanical Systems (MEMS) assembly utilizing force feedback devices for display of forces of interaction. The system described in this paper solves boundary element equations for electrostatic forces between MEMS components and then displays this solution in near real time with the help of the PHANToM force feedback device. Issues discussed in this paper include: boundary element solutions of electrostatic forces, interpolation of a six degree of freedom solution grid, scaling up of electrostatic forces to human scale, and use of the PHANToM device for haptic display of electrostatic and contact forces.
Predicting Product Cosmetic Quality Using Virtual Environments
Authors: Maxfield John , Juster Neal P. , Dew Peter M. , Taylor Stephen , Fitchie Martin , Ion William J. , Zhao Jeff , Thompson Martin
Published: December 2020

This paper describes a previously unreported application of virtual environments — the prediction of product cosmetic quality. Successful prediction of cosmetic quality without the production of a physical prototype requires the integration of a number of ‘software’ models. The models include an assembly model representing the manner in which the product is put together; an environment model providing a real world graphical context for the product; a behaviour model representing how the product moves and deforms under use conditions; a tolerance model representing the allowable variation in the product due to manufacturing and assembly variation; and an interaction model enabling the user to interact with the system. This paper presents interim results of a research project that has combined these models and implemented them within an automotive design and manufacturing process during the development of a new automobile. The paper contains the results of initial user evaluation and issues for future research.
Using the Palm Computer to Augment the Design of Machine Elements
Authors: Shoup Terry E.
Published: December 2020

This paper discusses the utility of the palm sized computers for augmenting the design of machine elements. Two palm computer programs are presented for handling frequently occurring problems in stress analysis in order to demonstrate the utility of the palm computer in this environment. One of these programs handles the manipulation of a three dimensional state of stress and the other program handles stress concentration factors. These modules facilitate computational processes that would not be possible with a traditional hand-held calculator. These programs are useful for students of machine design and practitioners as well.
Dichromatic Graphs: A Tool for the Algorithmic Education of Mechanical Engineers
Authors: Escanaverino Jose Martinez , Toll Alejandra Garcia , Cardenas Tania Ortiz
Published: December 2020

Computational problems, that is, those whose solution is given by numerical quantities, are a central theme in every field of science and technology. The present paper shows that the learning of mechanical engineering subjects where posing and solution of computational problems is important can be simplified if the structures of mathematical models, computational problems and algorithms are represented by means of dichromatic graphs. Playing the role of unusual route maps, these graphs allow the student to understand at a glance what a computational problem is, and the flow of information in the algorithms that solve the same problem. Even more important, these graphs are both guide and record of the algorithm synthesis process. The results of practical classroom experiences at graduate and undergraduate levels are given. Theoretical concepts on the paper are illustrated by means of an example taken from real-life mechanical engineering education.
Software Tools for Abstract Prototyping of Design Support Tools
Authors: Opiyo Eliab Z. , Horváth Imre , Vergeest Joris S. M.
Published: December 2020

Systematic design, user centered implementation and testing to requirements can contribute significantly to assuring quality of design support tools. The problem is that disorganized requirements elicitation and testing is generally time consuming and can sometimes lead to formulation of incomplete specification requirements. Furthermore, current software testing techniques involve usage of partially or fully implemented prototypes and thus provide feedback for the developers too late. These problems can be avoided through the application of a novel computer based pre-implementation testing technique, called abstract prototyping. It comprises structured multistage design and evaluation cycles, involving both the developers and the potential end-users as the evaluation subjects. This technique introduces quality improvement cycles early in the development process, well before the implementation of prototypes, and provides a structured framework for defining requirements and testing of design support tools.

In this paper we first introduce the abstract prototyping technique. Then we describe the architecture and functionality of the software developed for abstract prototyping. We also give an example on the application of this software tool for evaluation of the particle system theory for vague modeling of shapes in conceptual design. This software tool facilitated definition of requirements and testing to the formulated requirements. In this case the particle system theory represented the highest level of abstraction of the vague modeling software tool. The same procedure can be used in the subsequent levels of abstraction of methods, algorithms and pilot implementations. We can argue that the abstract prototyping technique helps to achieve the kinds of improvement and quality gains that are expected in the development of new design support tools and in upgrading the existing tools.
Sliced Geometry Representation Based on Implicit Curves
Authors: Park Seok-Min , Crawford Richard H. , Beaman Joseph J.
Published: December 2020

Current solid freeform fabrication data exchange practice supports only discretized approximations of part geometry. For producing accurate patterns and functional parts, the adequacy of linear approximations is suspect. The most efficient way of minimizing the degradation of geometric entities is to eliminate this intermediate format and directly exchange the source geometry. However, each commercial CAD vendor has its own representation, and choosing a single format has proven somewhat problematic. As an alternative, we have developed a method to approximate a contour from a set of discrete points using high order polynomials and to efficiently generate scan vectors from the high order contour. Our method exploits the so-called algebraic spline (A-spline) curve. Data fitting using A-splines gives a set of implicit curve segments with C3 local continuity, compared to the C0 continuous collection of line segments that is common in SFF practice. The A-spline approximation is capable of representing sliced geometry generated from various types of surfaces, including parametric, implicit, and mixed surface forms. The A-spline approximation method was tested by fabricating a curved object by Selective Laser Sintering. The resulting part showed higher surface quality with none of the tessellation artifacts inherent in part generation from polygonal contours. The run-time efficiency of the method is comparable to that of linear contour processing.
Integration of Commercial CAD With Commercial NC Programming Packages
Authors: Miao Huikang K. , Sridharan Nandakumar , Shah Jami J.
Published: December 2020

This paper focuses on the issues in automating the various tasks in process planning and on the issues in integrating the process-planning task with commercial CAD/CAM software. Automated process planning involves two important tasks; machining feature extraction and feature-based process planning. The integration of CAD and NC may be done by two alternative approaches: external or internal. This study uses the external approach. The CAD model of the part and the stock is exported to a format compatible with the external geometry engine. The machining feature recognition system communicates with the external geometry engine through APIs to obtain geometric and topological information required for feature recognition. The machining knowledge embedded in the recognized features is used by the process-planner to chalk out a process plan for the part. The machining features are classified into three broad categories each with machining significance specific to NC machining, so that when extracted they are useful in making process-planning decisions. Setup Planning, Operation Sequencing and Tool Selection is performed automatically based on criteria such as feature shapes, feature locations, tool access directions and feasibility of workpiece locating and clamping. The detailed process planning is based on a commercial CAD/CAM/CAE package, I-DEAS.
Features As an Abstraction for Designer Convenience in the Design of Complex Products
Authors: Summers Joshua D. , Maxwell Douglas , Camp Christopher , Butler Alley C.
Published: December 2020

This paper reports on a research effort involving design of a class of significantly complex products — nuclear submarines. It focuses on the use of features as a means of design abstraction, and it is found that a principal motivation for the use of features in this design environment is the convenience of the early stage submarine designer. To support this argument, a review of feature research is presented. Experiments in the development of feature catalogs are described, and implementation through two generations of feature based submarine CAD systems are discussed. The architecture of the feature based submarine CAD systems includes the use of Microsoft Foundation Classes (MFC), the ACIS geometric modeler, and user interfaces which store/recall hierarchical submarine feature information easily. Strong connections to object-oriented programming and object-oriented databases are recognized. Conclusions are drawn regarding the use of features for designer convenience and regarding support provided by hierarchical, parameterized features for other means of design automation.
Use of Rapid Prototyping Methods for Production
Authors: Markowski Andrzej , Petersen Harry
Published: December 2020

Rapid Prototyping and Rapid Tooling (RP/RT) can reduce time-to-market by creating physical parts and tooling from computer files. These can be used for verification of designs, tests and marketing, and also as final products or tools for short run production. Education is critical, because effective use of RP/RT technology requires preparation and training of all parties, including designers, engineers, manufacturing technologists, and business people. This paper reviews advances in RP/RT along with research, education, and a case study conducted at Minnesota State University, Mankato.
Turbulent Dispersed Particulate Flow in a Zigzag Channel
Authors: Akbar Muhammad K. , Sharif Muhammad A. R. , Bradt Richard C.
Published: December 2020

A Lagrangian simulation technique to predict the trajectories of solid particles in turbulent flow of a liquid continuous phase is presented. The method assumes one-way coupling, i.e., influence of particle on the flow is neglected. Mass loading ratio is as low as the order of 1 × 10−5. Drag, Magnus lift, Saffman lift across the flow direction, and gravitational forces are considered. Particle-particle and particle-wall interactions have been counted. On the other hand, turbulent fluctuation effects are neglected. Particle trajectories in a zigzag channel are computed. Effects of particle size, particle drop position, zigzag angle of the channel and inlet flow Reynolds number have been investigated. Particle size and/or density and initial particle placement position have been found to have significant effect on the trajectories.
Enhanced Methane-Air Mixing Using Shock and Expansion Waves
Authors: Brasoveanu Dan , Gupta Ashwani K.
Published: December 2020

A unified model of gaseous fuel-air mixing is applied here to study the effect of shock waves on enhanced methane-air mixing. The model uses the fuel mass fraction within infinitesimal fluid elements and the total derivative of this fraction with respect to time to measure the degree and rate of mixing, respectively. The model is strictly accurate only for low-pressure combustors because of the ideal gas law assumption incorporated in the model. The model is also limited to gaseous fuels that contain single chemical specie, or behave like single specie. The model can be applied to any operational conditions or combustor geometry. Results show that mixing can be completed within the narrow region of the shock wave and therefore in a negligibly short time, if pressure, temperature and velocity distributions within this region are optimized. Furthermore, combining the effects of air preheat and shock waves can enhance both mixing with air penetration into fuel and fuel dispersion into the surrounding air. These results provide important guidelines for the design of supersonic combustors to achieve high efficiency and high intensity, while maintaining a low level of pollutants emission.
Problems and Sample Calculations Related to Fire Development
Authors: Kim Hyeong-Jin , Lilley David G.
Published: December 2020

Release of toxic, flammable and/or explosive materials into the atmosphere is extremely dangerous. If an ignition source is found, the resulting fire can often be devastating. Information, analysis and calculations of fire dynamic phenomena can assist in understanding and applying scientific information to real-world fire situations. Fire dynamicists can develop an appreciation for technical/scientific understanding of the phenomena and its applicability to real-world practical down-to-earth situations. Some sample calculations are exhibited to illustrate several aspects of fire behavior.
On Turbulent Secondary Flows by Using Linear and Nonlinear k–ω Model
Authors: Song B. , Amano R. S.
Published: December 2020

In the present study, the fully developed turbulent secondary flows inside rotating and non-rotating square duct are numerically simulated using the linear and nonlinear k–ω models. For non-rotating duct, an eight-vortex structure is well captured by the nonlinear k–ω model. For rotating duct, it is interesting to notice that the two vortices are generated when Ro = 0.05, four vortices are presented when Ro = 0.15, and two vortices appeared when the rotational speed is increased up to Ro = 0.35. Although the linear and nonlinear models all produce reasonable results, the different results are also exhibited with these models. For example, the nonlinear model produces a stable effect in the pressure side and predicts less distortion region than the linear model. In the suction side, the linear k–ω model produces greater gradients than the linear model which seems to be realistic.
Design Rules for Selecting and Designing Compliant Mechanisms for Rigid-Body Replacement Synthesis
Authors: Berglund Michael D. , Magleby Spencer P. , Howell Larry L.
Published: December 2020

There exists a need for methodologies on designing mechanical devices with flexible elements (compliant mechanisms). Many engineers currently have little direction in their designing efforts and have difficulty improving the performance of devices with flexible members. This paper presents a step towards a process and a set of rules for designing compliant mechanisms which aid engineers in selecting the best design concept among a set of alternatives. The approach is a more rational method for selecting and improving designs than the existing intuitive approach engineers now take. The general design rules aid the engineer in identifying good and bad design features and practices for devices containing flexible elements. The design rules help engineers avoid oversights and/or overlooked factors in design problems. Since many equivalent compliant mechanisms can be made from a single rigid-body solution, the rules can help engineers select between the compliant alternative designs.
Optimal Layout of Irregularly Shaped Objects
Authors: Yu Chan , Manoochehri Souran
Published: December 2020

A new method is being developed to automatically generate an optimal solution of the two-dimensional layout problem. Finding the optimal solution of a layout design problem, especially that of irregular shapes, is quite difficult and requires an extensive amount of computation mainly due to the combinatorial nature of the problem. In this work, each object is categorized into either a mating or a non-mating group based on its concavity features. Each mating object is then decomposed into sets of convex objects and its mating conditions are then checked with other mating objects. Based on mating conditions, two or more objects are mated to form a mating pair. After the mating pool of possible candidate mating pairs is generated, the genetic algorithm generates an optimal packing sequence of the mating group as well as the non-mating group. Then, local positional arrangement of each object in the sequence is determined to get a final solution.
Method and Code for the Visualization of Multivariate Solids
Authors: Abdel-Malek Karim , Yang Jingzhou
Published: December 2020

This paper is devoted to a method and computer code for the automatic visualization of multivariate solids. Example of a multivariate solids arise in computer aided geometric design when a geometric entity is swept in space, where the totality of points touched by the entity is called the swept volume and is characterized by an equation of many parameters. The method and code are presented in an integrated manner and are aimed at providing the reader with a replicable computer algorithm. The formulation for is based on the implicit function theorem; is applicable to the visualization of solids of any number of parameters; and produces the exact boundary representation. Considering the solid as a manifold (possibly with boundaries), it is shown that further stratification of the various submanifolds yields varieties that can be depicted in R3. A measure of the computational complexity is presented to give the reader a sense of robustness of the method. The code is developed using a symbolic manipulator and is presented with a number of examples.
Closed-Form Swept Volume of Implicit Surfaces
Authors: Abdel-Malek Karim , Yang Jingzhou , Blackmore Denis
Published: December 2020

Recent developments in formulations for generating swept volumes have made a significant impact on the efficiency of employing such algorithms and on the extent to which formulations can be used in representing complex shapes. In this paper, we outline a method for employing the representation of implicit surfaces using the Jacobian rank deficiency condition presented earlier for the sweep of parametric surfaces. A numerical and broadly applicable analytic formulation is developed that yields the exact swept volume.
Metrics for Quality Assessment of a Multiobjective Design Optimization Solution Set
Authors: Wu Jin , Azarm Shapour
Published: December 2020

In this paper, several new set quality metrics are introduced that can be used to evaluate the ‘goodness’ of an observed Pareto solution set. These metrics, which are formulated in closed-form and geometrically illustrated, include coverage difference, Pareto spread, accuracy of an observed Pareto frontier, number of distinct choices and cluster. The metrics should enable a designer either monitor the quality of an observed Pareto solution set as obtained by a multiobjective optimization method, or compare the quality of observed Pareto solution sets as reported by different multiobjective optimization methods. A vibrating platform example is used to demonstrate the calculation of these metrics for an observed Pareto solution set.
Improved Side Impact Protection: A Search for Systems Modeling Priorities
Authors: Gabler Hampton C. , Fildes Brian N. , Fitzharris Michael
Published: December 2020

Systems Modeling evaluates the fleetwide crashworthiness of a vehicle design across the full range of potential impact speeds, angles, collision partners, occupant seating locations, and occupant restraints. Although this approach provides a more thorough assessment of crash protection than provided by a single crash test or simulation, the development of a complete Systems Model requires exhaustive simulation of every potential crash mode — a computationally prohibitive approach. This paper presents a methodology in which real world highway accident data is used to systematically develop Systems Modeling strategies that fully expose the tradeoffs between computational expense and model fidelity as measured by Harm. Using Australian side impact accident data, the paper illustrates the methodology by developing two computationally efficient strategies for developing a Systems Model for the evaluation and optimization of Side Impact protection.