bluuebunny/crossref_metadata_2025 huggingface dataset:
Reconciling estimates of global spread and infection fatality rates of COVID‐19: An overview of systematic evaluations
Authors: Ioannidis John P. A.
Published: March 2021

Background

Estimates of community spread and infection fatality rate (IFR) of COVID‐19 have varied across studies. Efforts to synthesize the evidence reach seemingly discrepant conclusions.

Methods

Systematic evaluations of seroprevalence studies that had no restrictions based on country and which estimated either total number of people infected and/or aggregate IFRs were identified. Information was extracted and compared on eligibility criteria, searches, amount of evidence included, corrections/adjustments of seroprevalence and death counts, quantitative syntheses and handling of heterogeneity, main estimates and global representativeness.

Results

Six systematic evaluations were eligible. Each combined data from 10 to 338 studies (9‐50 countries), because of different eligibility criteria. Two evaluations had some overt flaws in data, violations of stated eligibility criteria and biased eligibility criteria (eg excluding studies with few deaths) that consistently inflated IFR estimates. Perusal of quantitative synthesis methods also exhibited several challenges and biases. Global representativeness was low with 78%‐100% of the evidence coming from Europe or the Americas; the two most problematic evaluations considered only one study from other continents. Allowing for these caveats, four evaluations largely agreed in their main final estimates for global spread of the pandemic and the other two evaluations would also agree after correcting overt flaws and biases.

Conclusions

All systematic evaluations of seroprevalence data converge that SARS‐CoV‐2 infection is widely spread globally. Acknowledging residual uncertainties, the available evidence suggests average global IFR of ~0.15% and ~1.5‐2.0 billion infections by February 2021 with substantial differences in IFR and in infection spread across continents, countries and locations.
Analysis of cytokine levels, T regulatory cells and serotonin content in patients with depression
Authors: Obermanns Jasmin , Krawczyk Elena , Juckel Georg , Emons Barbara
Published: March 2021

Alterations in peripheral serotonin concentrations and an imbalanced immune system have been reported in patients with depression. Cytokines and T regulatory (Treg) cells may play an important role in the development of depression. This study investigates the levels of cytokines and Treg cells, as well as the concentration of serotonin (5‐HT) in the blood of 89 patients suffering from depression and 89 healthy participants between two acquisitions. We investigated the state of health before (T1) and after (T2) psychological and pharmacological therapy. Both cytokine (IL‐6, IL‐10, TNF‐α, and INF‐γ) and 5‐HT levels in the blood were measured by enzyme‐linked immunosorbent assays. The levels of CD4+CD25+ Treg cells were determined by flow cytometric analysis. Patients with depression showed significantly higher serum levels of IL‐6 and INF‐γ, no altered serum levels of IL‐10 and TNF‐α, and decreased platelet and serum 5‐HT levels compared with healthy participants at the first acquisition. In addition, the symptoms of depression and anxiety, the TNF‐α level, and the amount of CD4+CD25+ cells in the blood were decreased from the first to the second acquisition. Further, a correlation between IL‐6 and platelet 5‐HT has been observed in patients. An imbalance of the immune system in patients with depression and an association of the serotonergic system and cytokines were observed. These results indicate that the development of depression might be related to several interacting proteins, including cytokines and 5‐HT, and the treatment affects imbalances of these factors.
Ranking range models under incomplete attribute weight information in the selected six MADM methods
Authors: Liu Yating , Tang Huali , Liang Haiming , Zhang Hengjie , Li Cong‐Cong , Dong Yucheng
Published: March 2021

Multiple attribute decision making (MADM) is used to rank the alternatives according to evaluation information based on multiple attributes, and many MADM methods have been studied to deal with the MADM problems. In existing MADM methods, when setting different attribute weights, the ranking of alternatives are different. And ranking range can be used to measure a lower bound and an upper bound of rankings of alternatives with the change of the attribute weights. Also, in some real MADM problems, the information on attribute weights may be unknown or partially known, which is called incomplete attribute weight information. Then, this study investigates the ranking range models (RRMs) under incomplete attribute weight information in the selected six MADM methods: Weighted geometric averaging (WGA), Ordered weighted geometric averaging (OWGA), TOPSIS, VIKOR, PROMETHEE and ELECTRE. Particularly, we can construct several 0‐1 mathematical programming models to compute the ranking range of alternatives under incomplete attribute weight information for the selected six MADM methods. Then, two case studies on project investment and Academic Ranking of World Universities (ARWU) are used to justify the validity of the RRMs under incomplete attribute weight information in the selected six MADM methods.
Cell shape‐based chemical screening reveals an epigenetic network mediated by focal adhesions
Authors: Kanazawa Tomomi , Michida Hiroki , Uchino Yuki , Ishihara Akari , Zhang Suxiang , Tabata Sho , Suzuki Yutaka , Imamoto Akira , Okada Mariko
Published: March 2021

Adapter proteins CRK and CRKL participate in a variety of signaling pathways, including cell adhesion, and fate regulation of mammalian cells. However, the molecular functions of CRK/CRKL in epigenetic regulation remain largely unknown. Here, we developed a pipeline to evaluate cell morphology using high‐content image analysis combined with chemical screening of kinase and epigenetic modulators. We found that CRK/CRKL modulates gene regulatory networks associated with cell morphology through epigenetic alteration in mouse embryonic fibroblasts. Integrated epigenome and transcriptome analyses revealed that CRK/CRKL is involved in super‐enhancer activity and upregulation of Cdt1, Rin1, and Spp1 expression for the regulation of cell morphology. Screening of a library of 80 epigenetic inhibitors showed that histone H3 modifiers, euchromatic histone methyltransferase 2 and mitogen‐ and stress‐activated kinase 1, may be important for CRK/CRKL‐mediated morphological changes. Taken together, our results indicate that CRK/CRKL plays a critical role in gene regulatory networks through epigenetic modification.

Databases

Chromatin immunoprecipitation sequencing and RNA sequencing data were deposited in the DNA Data Bank of Japan under DRA011080 and DRA011081 accession numbers, respectively.
Decolonial feminist theory: Embracing the gendered colonial difference in management and organisation studies
Authors: Manning Jennifer
Published: March 2021

Feminist theories in management and organization studies, each with their own ontological and epistemological assumptions, offer critical perspectives of the status quo to challenge our idea of progress in the discipline, yet there is limited engagement with ideas, theories, or practices from the lived experiences of Global South women. Decolonial feminism engages with debates pertaining to coloniality/modernity and indigenous identity and gender in Latin America, while providing a space for the voices and lived experiences of marginalized, non‐Western(ised) women. Positioned in the context of Guatemalan Maya women and deploying critical insights from decolonial feminists, I unpack how the discourse about Global South women silences their voices and agency. Integrating decolonial feminist theory allows us to rethink management and organizationorganization studies as a Western gendered system. Interrupting mainstream narratives to bring a new geopolitics of knowledge and knowing from the perspective of the gendered colonial difference.
Mechanical properties of borothermally synthesized zirconium diboride at elevated temperatures
Authors: Murchie Alec C. , Watts Jeremy L. , Fahrenholtz William G. , Hilmas Gregory E.
Published: March 2021

The mechanical properties of a nominally phase pure ZrB2 ceramic were measured up to 2300°C in an argon atmosphere. ZrB2 was hot pressed at 2000°C utilizing borothermally synthesized powder from high purity ZrO2 and B raw materials. The relative density of the ceramics was about 95% with an average ZrB2 grain size of 8.8 µm. The room temperature flexural strength was 447 MPa, with strength decreasing to 196 MPa at 1800°C, and then increasing to 360 MPa at 2300°C. The strength up to 1800°C was likely controlled by a combination of effects: surface damage from oxidation of the specimens, stress relaxation, and decreases in the elastic modulus. The strength above 1800°C was controlled by flaws in the range consistent with sizes of the maximum ZrB2 grain size and the largest pores. Fracture toughness was 2.3 MPa·m1/2 at room temperature, increasing to 3.1 MPa·m1/2 at 2200°C. The use of higher purity starting materials improved the mechanical behavior in the ultra‐high temperature regime compared to previous studies.
Strategic justifications of the TAL family of rules for bankruptcy problems
Authors: Moreno‐Ternero Juan D. , Tsay Min‐Hung , Yeh Chun‐Hsien
Published: March 2021

We follow the Nash program to provide strategic justifications of the TAL family of rules for bankruptcy problems. The design of our game is inspired by an axiomatization of the TAL family of rules exploiting the properties of consistency together with certain degrees of lower and upper bounds to all creditors. Bilateral negotiations of our game follow the spirit of those bounds. By means of consistency, we then extend the bilateral negotiations to an arbitrary number of creditors.
Development of a nomogram for screening the risk of left ventricular hypertrophy in Chinese hypertensive patients
Authors: Ye Chaoyi , Wang Tingjun , Gong Jin , Cai Xiaoqi , Lian Guili , Luo Li , Wang Huajun , Xie Liangdi
Published: March 2021

Left ventricular hypertrophy (LVH) is an important risk factor for cardiovascular morbidity and mortality in hypertensives. Therefore, early identification of at‐risk patients is necessary. The objective of this study was to estimate the risk of LVH among Chinese hypertensives by designing a nomogram. 832 hypertensives were divided into two groups based on the presence of LVH. The least absolute shrinkage and selection operator (LASSO) regression and multivariable logistic regression were successively applied for optimal variable selection and nomogram construction. Discrimination power, calibration, and clinical usefulness were evaluated using the receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis. Internal validation was performed using the bootstrap method. The nomogram included five predictors, namely gender, duration of hypertension, age, body mass index (BMI), and systolic blood pressure. The area under the ROC curve (AUC) was 0.724 (95% CI: 0.687‐0.761), indicating moderate discrimination. The calibration curve showed an excellent agreement between the predicted LVH and the actual LVH probability. The risk threshold between 5% and 72% according to the decision curve analysis, and the nomogram is clinically beneficial. Internal validation by bootstrapping with 1000 samples showed a good C‐index of 0.715, which suggested that the predictive abilities for the training set and testing set were in consistency. Our study proposed a nomogram that can be utilized to assess the LVH risk rapidly for Chinese hypertensives. This tool could be useful in identifying patients at high risk for LVH. Further studies are required to ascertain the stability and applicability of this nomogram.
Priming of mesenchymal stem cells with a hydrosoluble form of curcumin allows keeping their mesenchymal properties for cell‐based therapy development
Authors: Colin Margaux , Dechêne Lola , Ceusters Justine , Niesten Ariane , Demazy Catherine , Lagneaux Laurence , Zouaoui Boudjeltia Karim , Franck Thierry , Van Antwerpen Pierre , Renard Patricia , Mathieu Véronique , Serteyn Didier
Published: March 2021

Mesenchymal stem cells are increasingly studied for their use as drug‐carrier in addition to their intrinsic potential for regenerative medicine. They could be used to transport molecules with a poor bioavailability such as curcumin in order to improve their clinical usage. This natural polyphenol, well‐known for its antioxidant and anti‐inflammatory properties, has a poor solubility that limits its clinical potential. For this purpose, the use of NDS27, a curcumin salt complexed with hydroxypropyl‐beta‐cyclodextrin (HPβCD), displaying an increased solubility in aqueous solution, is preferred. This study aims to evaluate the uptake of NDS27 into skeletal muscle‐derived mesenchymal stem cells (mdMSCs) and the effects of such uptake onto their mesenchymal properties. It appeared that the uptake of NDS27 into mdMSCs is concentration‐dependent and not time‐dependent. The use of a concentration of 7 µmol/L which does not affect the viability and proliferation also allows preservation of their adhesion, invasion and T cell immunomodulatory abilities.
Chicago Classification update (V4.0): Technical review on diagnostic criteria for ineffective esophageal motility and absent contractility
Authors: Gyawali C. Prakash , Zerbib Frank , Bhatia Shobna , Cisternas Daniel , Coss‐Adame Enrique , Lazarescu Adriana , Pohl Daniel , Yadlapati Rena , Penagini Roberto , Pandolfino John
Published: March 2021

Esophageal hypomotility disorders manifest with abnormal esophageal body contraction vigor, breaks in peristaltic integrity, or failure of peristalsis in the context of normal lower esophageal sphincter relaxation on esophageal high‐resolution manometry (HRM). The Chicago Classification version 4.0 recognizes two hypomotility disorders, ineffective esophageal motility (IEM) and absent contractility, while fragmented peristalsis has been incorporated into the IEM definition. Updated criteria for ineffective swallows consist of weak esophageal body contraction vigor measured using distal contractile integral (DCI, 100–450 mmHg·cm·s), transition zone defects >5 cm measured using a 20 mmHg isobaric contour, or failure of peristalsis (DCI < 100 mmHg·cm·s). More than 70% ineffective swallows and/or ≥50% failed swallows are required for a conclusive diagnosis of IEM. When the diagnosis is inconclusive (50%–70% ineffective swallows), supplementary evidence from multiple rapid swallows (absence of contraction reserve), barium radiography (abnormal bolus clearance), or HRM with impedance (abnormal bolus clearance) could support a diagnosis of IEM. Absent contractility requires 100% failed peristalsis, consistent with previous versions of the classification. Consideration needs to be given for the possibility of achalasia in absent contractility with dysphagia despite normal IRP, and alternate complementary tests (including timed upright barium esophagram and functional lumen imaging probe) are recommended to confirm or refute the presence of achalasia. Future research to quantify esophageal bolus retention on stationary HRM with impedance and to understand contraction vigor thresholds that predict bolus clearance will provide further refinement to diagnostic criteria for esophageal hypomotility disorders in future iterations of the Chicago Classification.
Histopathological comparison of pleomorphic adenomas of the parotid and submandibular gland
Authors: Mantsopoulos Konstantinos , Sievert Matti , Iro Ann‐Kristin , Müller Sarina Katrin , Koch Michael , Schapher Mirco , Agaimy Abbas , Iro Heinrich
Published: March 2021

Objective

The aim of this study was to investigate and compare the histopathological findings in pleomorphic adenomas (PA) of the parotid and submandibular gland with emphasis on the histological subtype and capsular characteristics.

Materials and Methods

The histopathological specimens of all patients with PAs of the parotid and submandibular gland between 2000 and 2020 were re‐examined by an experienced head and neck pathologist. Patients without representative slides allowing evaluation of the whole periphery of the PA were excluded from our study sample.

Results

Nine hundred and thirty‐four patients formed our study sample (327 men, 607 women, male‐to‐female ratio: 0.53:1). Eight hundred and forty‐four cases had a PA in the parotid gland and the remaining 90 in the submandibular gland. Our comparative analysis showed that submandibular PAs are characterized by the consistent presence of an intact anatomical capsule, infrequent occurrence of pseudopodia and satellite nodules, and a low proportion of the high‐risk myxoid subtype.

Conclusion

Our study highlights significant differences between PAs of the parotid and submandibular glands in their histopathological characteristics. Their differences likely underlie the favorable surgical outcome observed in PAs of the submandibular glands and may explain the propensity of PAs of the parotid glands for local recurrences.
The chromosome‐scale reference genome of safflower (Carthamus tinctorius) provides insights into linoleic acid and flavonoid biosynthesis
Authors: Wu Zhihua , Liu Hong , Zhan Wei , Yu Zhichao , Qin Erdai , Liu Shuo , Yang Tiange , Xiang Niyan , Kudrna Dave , Chen Yan , Lee Seunghee , Li Gang , Wing Rod A. , Liu Jiao , Xiong Hairong , Xia Chunjiao , Xing Yongzhong , Zhang Jianwei , Qin Rui
Published: March 2021

Safflower (Carthamus tinctorius L.), a member of the Asteraceae, is a popular crop due to its high linoleic acid (LA) and flavonoid (such as hydroxysafflor yellow A) contents. Here, we report the first high‐quality genome assembly (contig N50 of 21.23 Mb) for the 12 pseudochromosomes of safflower using single‐molecule real‐time sequencing, Hi‐C mapping technologies and a genetic linkage map. Phyloge

nomic analysis showed that safflower diverged from artichoke (Cynara cardunculus) and sunflower (Helianthus annuus) approximately 30.7 and 60.5 million years ago, respectively. Comparative genomic analyses revealed that uniquely expanded gene families in safflower were enriched for those predicted to be involved in lipid metabolism and transport and abscisic acid signalling. Notably, the fatty acid desaturase 2 (FAD2) and chalcone synthase (CHS) families, which function in the LA and flavonoid biosynthesis pathways, respectively, were expanded via tandem duplications in safflower. CarFAD2‐12 was specifically expressed in seeds and was vital for high‐LA content in seeds, while tandemly duplicated CarFAD2 genes were up‐regulated in ovaries compared to CarFAD2‐12, which indicates regulatory divergence of FAD2 in seeds and ovaries. CarCHS1, CarCHS4 and tandem‐duplicated CarCHS5˜CarCHS6, which were up‐regulated compared to other CarCHS members at early stages, contribute to the accumulation of major flavonoids in flowers. In addition, our data reveal multiple alternative splicing events in gene families related to fatty acid and flavonoid biosynthesis. Together, these results provide a high‐quality reference genome and evolutionary insights into the molecular basis of fatty acid and flavonoid biosynthesis in safflower.
Investigating the relationship between emotional granularity and cardiorespiratory physiological activity in daily life
Authors: Hoemann Katie , Khan Zulqarnain , Kamona Nada , Dy Jennifer , Barrett Lisa Feldman , Quigley Karen S.
Published: March 2021

Emotional granularity describes the ability to create emotional experiences that are precise and context‐specific. Despite growing evidence of a link between emotional granularity and mental health, the physiological correlates of granularity have been under‐investigated. This study explored the relationship between granularity and cardiorespiratory physiological activity in everyday life, with particular reference to the role of respiratory sinus arrhythmia (RSA), an estimate of vagal influence on the heart often associated with positive mental and physical health outcomes. Participants completed a physiologically triggered experience‐sampling protocol including ambulatory recording of electrocardiogram, impedance cardiogram, movement, and posture. At each prompt, participants generated emotion labels to describe their current experience. In an end‐of‐day survey, participants elaborated on each prompt by rating the intensity of their experience on a standard set of emotion adjectives. Consistent with our hypotheses, individuals with higher granularity exhibited a larger number of distinct patterns of physiological activity during seated rest, and more situationally precise patterns of activity during emotional events: granularity was positively correlated with the number of clusters of cardiorespiratory physiological activity discovered in seated rest data, as well as with the performance of classifiers trained on event‐related changes in physiological activity. Granularity was also positively associated with RSA during seated rest periods, although this relationship did not reach significance in this sample. These findings are consistent with constructionist accounts of emotion that propose concepts as a key mechanism underlying individual differences in emotional experience, physiological regulation, and physical health.
Social Norms and Expectations about Student Loans and Family Formation
Authors: Kuperberg Arielle , Mazelis Joan Maya
Published: March 2021

Social norms and expectations regarding marriage or childbearing while in debt—or with an indebted partner—may explain links between student loans and lower family formation rates. This study analyzes an original survey of college students (N = 2,990) at two universities examining how student loans will, would, or should affect romantic relationship and family formation decisions. A significant minority believed marriage should be delayed and nearly half believed childbearing should be delayed when people have student loan debt. Many reported they would hesitate to marry someone with high student debt, their loans would delay family formation, and they would form families earlier if their debt were forgiven. Those with loan debt and higher debt were more willing to partner with those who had high student debt. Women were less likely to believe people should delay childbearing and marriage because of loans, but more hesitant to marry a partner with high student debt. Findings suggest social norms underlie childbearing and marriage delays among those with loans, and student loan debt creates a class divide among the highly educated.
Donor‐derived human herpesvirus 8 infection with Kaposi sarcoma and Kaposi sarcoma inflammatory cytokine syndrome in a heart transplant recipient: A case report
Authors: Antonio Russo , Laura Giovannini , Nicolina Conti , Elena Sabattini , Luca Vizioli , Tiziana Lazzarotto , Luciano Potena , Davide Pacini , Nazzareno Galie’
Published: March 2021

Human herpesvirus‐8 (HHV‐8) infection is associated with neoplastic and non‐neoplastic diseases in immunocompromised patients. Kaposi sarcoma (KS) is a common malignancy reported in solid organ transplant recipients (SOTR). Kaposi sarcoma inflammatory cytokine syndrome (KICS), initially described in HIV patients, is characterized by high viral loads, elevated levels of cytokines, cytopenia, high fever, organ failure, and poor outcome. We report the case of a 54‐year‐old patient who developed simultaneous occurrence of KS of lymph nodes and KICS as a complication of primary donor‐transmitted HHV‐8 infection, after heart transplantation (HT). The diagnosis, management, and prognosis of this condition are unclear and needs a multidisciplinary approach.
Fast A‐type currents shape a rapidly adapting form of delayed short latency firing of excitatory superficial dorsal horn neurons that express the neuropeptide Y Y1 receptor
Authors: Sinha Ghanshyam P. , Prasoon Pranav , Smith Bret N. , Taylor Bradley K.
Published: March 2021

Key points

Neuropeptide Y Y1 receptor‐expressing neurons in the dorsal horn of the spinal cord contribute to chronic pain.

For the first time, we characterized the firing patterns of Y1‐expressing neurons in Y1eGFP reporter mice.

Under hyperpolarized conditions, most Y1eGFP neurons exhibited fast A‐type potassium currents and delayed, short‐latency firing (DSLF).

Y1eGFP DSLF neurons were almost always rapidly adapting and often exhibited rebound spiking, characteristics of spinal pain neurons under the control of T‐type calcium channels.

These results will inspire future studies to determine whether tissue or nerve injury downregulates the channels that underlie A‐currents, thus unmasking membrane hyperexcitability in Y1‐expressing dorsal horn neurons, leading to persistent pain.

Neuroanatomical and behavioural evidence indicates that neuropeptide Y Y1 receptor‐expressing interneurons (Y1‐INs) in the superficial dorsal horn (SDH) are predominantly excitatory and contribute to chronic pain. Using an adult ex vivo spinal cord slice preparation from Y1eGFP reporter mice, we characterized firing patterns in response to steady state depolarizing current injection of GFP‐positive cells in lamina II, the great majority of which expressed Y1 mRNA (88%). Randomly sampled (RS) and Y1eGFP neurons exhibited five firing patterns: tonic, initial burst, phasic, delayed short‐latency <180 ms (DSLF) and delayed long‐latency >180 ms (DLLF). When studied at resting membrane potential, most RS neurons exhibited delayed firing, while most Y1eGFP neurons exhibited phasic firing. A preconditioning membrane hyperpolarization produced only subtle changes in the firing patterns of RS neurons, but dramatically shifted Y1eGFP neurons to DSLF (46%) and DLLF (24%). In contrast to RS DSLF neurons, which rarely exhibited spike frequency adaptation, Y1eGFP DSLF neurons were almost always rapidly adapting, a characteristic of nociceptive‐responsive SDH neurons. Rebound spiking was more prevalent in Y1eGFP neurons (6% RS vs. 32% Y1eGFP), indicating enrichment of T‐type calcium currents. Y1eGFP DSLF neurons exhibited fast A‐type potassium currents that are known to delay or limit action potential firing and exhibited smaller current density as compared to RS DSLF neurons. Our results will inspire future studies to determine whether tissue or nerve injury downregulates channels that contribute to A‐currents, thus potentially unmasking T‐type calcium channel activity and membrane hyperexcitability in Y1‐INs, leading to persistent pain.
Incorporating End-Users’ Attitudes Towards Uncertainty Into an Expert System
Authors: Tian Yun Qi , Thurston Deborah L. , Carnahan James V.
Published: March 2021

Uncertainty is a real and unavoidable part of the design process. Uncertainty in the area of manufacturing cost estimation can have a negative impact on the desirability of design alternatives, and some might be deemed “too risky” for further consideration in spite of potential benefits. Expert designers obtain a sense of what level of risk is acceptable for different types of applications. Expert systems for design thus might include a set of necessary and reasonable assumptions which reflect a particular expert’s attitude towards risk and uncertainty. These assumptions may not be applicable for all users. In this paper we present an expert system for design which explicitly addresses the individual user’s attitude towards uncertainty. We have developed a spreadsheet user-interface for assessing this attitude through a utility function, and for linking those results to a heuristic rule base. The heuristic rule base contains only technical expertise used to determine a set of feasible alternatives, while the process of evaluating and ranking these feasible alternatives is driven by the user’s individual preferences and risk-taking profile.
Simplification of Feature Based Models for Tolerance Analysis
Authors: Martino Peter
Published: March 2021

This paper presents a method for eliminating unnecessary parts, features, and dimensions from feature based models in computer aided tolerance analysis systems.

A typical tolerance analysis involves a dozen or so parts, or subassemblies. Each part may have dozens of features, and hundreds of dimensions. Many of these subassemblies, parts, features, and dimensions do not effect the tolerance analysis, and therefore are not needed. Computational effort can be reduced by eliminating the unnecessary items from the model.

Currently, tolerance analysis models are implicitly simplified by the user. The user examines the problem, and determines which parts, features, and dimensions can be ignored. The user then constructs his model, leaving out the unneeded items. This is true whether the analysis is accomplished with a computer aided tool, or with paper and pencil. Simplification of the model is essential. Practical tolerance analysis problems become overwhelmingly complex if every detail is included.

The method discussed in this paper is intended for use in computer aided tolerance analysis systems that use feature based, and dimension driven, solid modeling. It uses a combined tree and graph data structure. The tree structure represents the hierarchy of assemblies, parts, and features in the model. The graphs represent the dependence between features in a part, or parts in an assembly. An algorithm has been developed that searches this tree/graph model, locating the parts and features needed to accomplish the tolerance analysis.
A Logic-Based Integrated Manufacturing Planning System
Authors: Fuh Jerry Y.-H. , Chang Chao-Hwa , Melkanoff Michel A.
Published: March 2021

The purpose of this research is to develop a methodology and a prototype system that allows the integration of product design and manufacturing planning. The task is achieved through an integrated CAD-CAPP-CAFP# environment. The system consists of three major modules, namely, Feature Analyzer, Process Planner and Fixture Planner. The manufacturing information of a part required for process and fixture planning is extracted from the 3-D geometric model and the 2-D engineering drawing, thereby both geometric and non-geometric attributes of a part can be obtained. An integrated approach to process and fixture planning is adopted to ensure that the process plan for a part is generated on the basis of a workable fixture plan. The approaches to feature analysis and to integrating process and fixture planning are introduced.
Efficient Modeling Method of Sheet Objects
Authors: Lee Kunwoo , Kwon Byung Wook
Published: March 2021

The paper describes a new modeling method by which an object of a thin thickness can be modeled in an efficient way. In this study, a thin object, considered as a sheet model, is modeled by adding, cutting, and bending each sheet created interactively in the two dimensional working plane. Then the straight edges can be changed into curved ones for complicated shapes. Once a sheet model is completed, the corresponding solid is created automatically for a given thickness.

Compared to other solid modeling systems, the modeling method suggested in this study has the advantage of easy usage and short modeling time for sheet-like objects such as most plastic products.
Computational Analysis of Spin-Up From Rest of a Stably-Stratified Fluid in a Cylinder
Authors: Valentine Daniel T.
Published: March 2021

This paper presents applications of a control-volume finite-difference method to flow problems in cylindrical geometries. The method is an extension of the method known as ETUDE, which is an Euler-explicit in time, transportive-upwind convection, second-order diffusion, finite-difference estimate. The primary purpose of this paper is to present an interesting new method that comes about from control-volume considerations, i.e., from a proper extension of ETUDE, to solve problems in cylindrical coordinates. One- and two-dimensional test problems are computed to illustrate the properties of this new method. The predicted results of the two-dimensional test problem are compared with similar calculations of the spin-up of homogeneous fluids reported in the literature. With the properties of the method established, it was applied to investigate the spin-up of a two-layered, stably stratified fluid initially at rest in a cylindrical container. The effect of the stable, density structure on spin-up is discussed.
Frontal Offset Pole Impact Simulation of Automotive Vehicles
Authors: Saha N. K. , Wang H. C. , El-Achkar R.
Published: March 2021

A finite element model has been developed to simulate 25 percent offset impact of a vehicle to a rigid pole. The finite element model uses large displacement formulation and elastic-plastic material models. Techniques for crashworthiness simulation such as contact and sliding interfaces to prevent penetration of surfaces and hourglass control of mesh instability are also used. In a pole impact, vehicle front end members undergo large localized plastic deformation and usually fracture. In this study, the fracture process is simulated using effective plastic strain limit derived from component tests. The finite element model contains about 20,000 elements. It predicts overall vehicle deformation, acceleration, and velocity histories at key vehicle locations. Model predictions are compared with prototype test data.
High Speed Constructional Method of Stiffness Matrix Based on Object Orientation
Authors: Takahashi H. , Nagasawa S. , Sakuta H.
Published: March 2021

The paper deals with a method of high speed construction of stiffness matrix in FEM. The stiffness matrices of each element becomes to equal in following conditions. 1) Components of the B and D matrices are independent of global coordinate. 2) Elements have the same material properties and the same local coordinates respectively. This equality gives possibility of associable calculation to us. Hence, we can generate the global stiffness matrix at high speed by use of this feature. In this paper, a method of associable calculation by using equality of object ELEMENT based on object oriented concept is proposed. Futhermore, in comparison between conventional method and proposed one, relationship between accelerative rate and ratio of equal object and result of numerical experiment are described.
A Comparison of Analytical Predictions With Experimental Measurements of Transmission Error of Misaligned Loaded Gears
Authors: Vinayak Harsh , Houser Donald R.
Published: March 2021

This paper deals with the experimental study of dynamic transmission error of a gear pair. Two aspects of the experiment are discussed : 1) design of the test facility and data acquisition system and 2) comparison of transmission error and load distribution with experimental data. Several gears were tested under varying misalignments. A prediction program LDP (Load distribution Program) was used for theoretical calculations of dynamic transmission error.
Computational Issues Associated With Gear Rattle Analysis: Part I — Problem Formulation
Authors: Padmanabhan C. , Rook T. E. , Singh Rajendra
Published: March 2021

This paper proposes a new procedure for formulating the gear rattle type problem analytically before attempting a numerical solution. This step is necessary due to the nature of the mathematical formulation with vibro-impacts, which is non-analytical and hence causes numerical “stiffness”. The procedure is essentially an “intelligent” pre-processing stage and is based on our vast experience in simulating such systems. Important concepts such as order reduction, gear contact ratio, appropriate choice of non-dimensionalization parameters are illustrated through several examples.
A Discrete Analysis of Metal-V Belt Drive
Authors: Karam A. , Play D.
Published: March 2021

The metal-V belt drive includes a large number of parts which interact between them to transmit power from the input to the output pulleys. A compression belt composed of a great number of struts is maintained by a tension flat belt. Power is them shared into the two belts that moves generally in opposite directions. Due to the particular geometry of the elements and to the great number of parts, a numerical approach achieves the global equilibrium of the mechanism from the elementary part equilibrium. Sliding arc on each pulley can be thus defined both for the compression and tension belts. Finally, power sharing can be calculated as differential motion between the belts, is defined. The first part of the paper will present the different steps of the quasi-static mechanical analysis and their numerical implementations. Load distributions, speed profiles and sliding angle values will be discussed. The second part of the paper will deal to a systematic use of the computer software. Speed ratio, transmitted torque, strut geometry and friction coefficients effect will be analysed in relation with the output parameter variations. Finally, the effect pulley deformable flanges will be discussed.
A Group Theory for Composite Gear Trains Employing Three-Shafts
Authors: Siva Prasad V. , Dukkipati R. V. , Osman M. O. M.
Published: March 2021

The paper presents four generalized expressions for obtaining the gear sizes compared to nine required in the earlier proposed general theory. The analysis facilitates group_wise visualization of various parameters and their inter-dependency. The theory saves considerable time and labour in the synthesis and design work, and enables easy computerization.
Research on Gear Cutter Tooth Profile for Semi-Topping: A Case of a Helical Gear
Authors: Ariga Y. , Nagata Shiyeyoshi
Published: March 2021

Gear tooth tips are frequently chamfered to prevent nicks or scuffing on the tooth surface. Some of the hob cutters and pinion cutters can be chamfered but many types of cutters should be used for a particular range of tooth numbers since the amount chamfering largely varies depending on the tooth number. However, intensive efforts in the design have made it possible to produce cutters with little variation of chamfering amount for a wide range of tooth numbers.

The error in the amount of chamfering by a single cutter designed by the above method can be maintained within ±10 % for gears with tooth numbers ranging from 16 to 94. It was found that three cutters of the conventional design are required for keeping the error within the same range for cutting gears within a given range of tooth numbers.

The paper describes the tooth design method of the hob cutter with little variation of chamfering amount along changes in number of teeth to be machined and demonstrates that chamfering errors are maintained within practically allowable ranges for profile shift cutting or helical gear cutting with the use of this cutter.
Silent Gear Design for Mass-Produced Gears With Scatters in Tooth Form Accuracy
Authors: Nonaka T. , Kubo A. , Kato S. , Ohmori T.
Published: March 2021

As the shape of tooth flank form has a great influence on the running noise of gears, a computer aided gear design system has been developed to evaluate this effect. The design and the improvement of power transmission gears have used this system successfully for various machines, especially for the noise reduction of automobile transmission gears. However it becomes difficult to apply this system to mass production gears, as their geometrical shape of tooth flanks of a gear are often different each other. A statistical approach is then proposed to estimate vibrational excitation force. The analysis also incorporated the effects of the alignment errors on gear noise. Then the results show a good correlation between the calculated vibrational excitation and the measured gear noise for an actual automotive gear set. The shape of tooth flank form usually affects gear noise greatly, especially under light load conditions. This effect becomes complicated when there exist alignment errors of gear shafts. The results of the study indicate that the optimum shape of tooth flank form can be different depending on the ability to control the quality of the gears in the production line.
Modeling a Flexible-Link Power Transmission System
Authors: Murray Maureen J. , Canfield Thomas R.
Published: March 2021

The flexible link and sprocket system of a tracked vehicle was modeled as part of a supercomputing pilot project on a Cray X-MP supercomputer. This computer simulation model utilizes the ADAMS 3-dimensional rigid body dynamics code. Using this ADAMS model of the track system, engineers can simulate the complex action of this three dimensional mechanism, and, through the use of graphics, can illustrate the behavior of the interaction of the components in this track system.
A New Method to Reduce the Polygon Effect of Chain Drives With Tensioner
Authors: Li Shu-Min
Published: March 2021

It is known to all that there is the polygon effect in chain drives, it causes that the velocity ratio transmitted changes periodically, and the velocity of driven sprocket is variational, while the velocity of driving sprocket is constant in chain drives.

For reducing the effect a new method simple in construction is developed in this paper — with a tensioner which is mounted in the proper position at the tight side, the variation of velocity ratio transmitted and the velocity of driven sprocket can be reduced evidently.

In this paper it has been discussed how to determine the position and the teeth number of the tensioner in order to reduce the variation of transmition ratio in the chain drives. In addition, an example is presented here, it can be indicated that the variation of velocity ratio transmitted can be reduced evidently by use of the method with a tensioner at the tight side.
Automated Shape Generation of Components in Mechanical Assemblies
Authors: Shimada Kenji , Gossard David
Published: March 2021

Detailed shape design using current CAD systems is labor-intensive and requires little creativity. It is therefore a strong candidate for automation. Our research goal is to develop a method of automated shape generation in mechanical component design. As a preliminary step, we have developed a system for the generation of mechanical components of constant cross-section, i.e. “2.5D solids”. After functionally-important partial geometries and skeletal structures are defined by designers, the system automatically generates “skinning” shapes that encompass these partial geometries and skeletons by using FEM-based deformable curves.
A Milling Machining Automation Scheme for B-Rep-2.5D Solid Objects
Authors: Ho Won , Davis John H. , Adcock Willis A.
Published: March 2021

A Milling machining automation scheme is presented. A splitting operation for solid modeling techniques is applied repeatedly for a 2.5D boundary represented object. Every plane parallel to the x-y plane is extracted, the z coordinate values are used to split the object, and 2D representations are generated for each plane. A geometric segmentation, a tool selection, and a merging process are applied in sequence. Finally, the tool paths are generated for each unit of milling area.
Contact Analysis and Optimization of a Poppet Valve With Seat Deformation and Friction
Authors: Manicka Yatheendhar D. , Belegundu Ashok D.
Published: March 2021

The contact pressure between a poppet valve and its seat is an important consideration for valve performance. The geometry of the contacting surfaces is optimized to acheive maximum uniformity in the contact pressure distribution. A general contact algorithm for point-to-cubic sliding contact is presented and verified. It is then used to optimize the valve geometry. The poppet valve and seat are modeled as axisymmetric components.
A Decision-Analytic Method for Competitive Design for Quality
Authors: Vasseur Hubert , Kurfess Thomas R. , Cagan Jonathan
Published: March 2021

We consider the design issues of characterizing and appropriately choosing the quality of a product for maximum customer satisfaction and maximum corporate profit. We assume that the basic design configuration of a product is determined and that the designer must select the product quality by imposing statistical tolerances (manufacturing accuracy specifications) and choosing appropriate manufacturing processes. We claim that these design considerations, although often neglected, impact the behavior, cost, and even marketability of the product. A design concept without these specifications is incomplete because i) its feasibility is questionable ii) its cost of production is undetermined iii) its performance is unknown. The design process is seen here as an exploratory activity constrained by the manufacturing systems available. In particular, we provide a decision-analytic methodology to reason about the quality of product and the influences on profit resulting in a specification of manufacturing process and machine accuracy to match customer requests. The method is illustrated by the study of a simple three component assembly.
Computer Aided Modeling of Families and Family Members of Designed Parts
Authors: Johannesson H. L.
Published: March 2021

In the present paper a computer based method for modeling of families and family members of designend parts is suggested and presented. The product models that are built, contain “rules” for generating geometric models of part members plus nongeometric information to be used when manufacturing the parts. The geometric design “rules”, that are stored in the part family data base, consist of normalized line and are defining data to be used when generating geometry defining cross section part contours. These geometry defining data are generated automatically by the user when drawing contours in a CAD-system that is able to record the users actions, and generate the corresponding macro code. This code is interpreted by a part family storage program that stores both the interpreted geometric information, and user entered nongeometric information in the part family data base.

When creating a part family member, the stored part family data, plus data defining interacting standard components, are retrieved from data bases. The nongeometric data are written on document files, and a 3-D solid geometric model of the part member is created in the used CAD-system by extruding and/or rotating part member and standard component interface geometry contours.
Inverse Kinematics of Manipulators With 3 Revolute and 3 Parallelogram Joints
Authors: Dietmaier P.
Published: March 2021

This paper introduces the use of planar parallelogram linkages as generalized joints in a robot manipulator. The inverse kinematics for all possible manipulators formed from 3 parallelogram and 3 revolute joints are derived from the closure equations of an equivalent closed loop linkage. The internal displacement coordinates of the manipulator are obtained by solving a quadratic and an 8th degree polynomial equation, which results in up to 16 different configurations of the manipulator arm.
Motion Kinematics of Series-Parallel Robots Using a Virtual Link Concept
Authors: Shukla Deepak , Paul Frank W.
Published: March 2021

This paper presents a generic and systematic approach to solve the kinematics of series-parallel (hybrid) robot manipulators. The virtual link concept is a theoretical development to solve the kinematics of hybrid robots using the Denavit-Hartenberg notations. These notations have so far been applicable only to series robots. The virtual link concept employs fictitious serial links, termed “virtual links”, to transform a series-parallel manipulator into an equivalent series manipulator. The kinematics of this transformed series manipulator is solved using Denavit-Hartenberg notations. The results are mapped back to the actual manipulator using kinematic relations between fictitious serial links and the replaced parallel structure of the actual manipulator. This approach appears to be generic and systematic for analyzing the kinematics of series-parallel robot manipulators.