bluuebunny/crossref_metadata_2025 huggingface dataset:
Free ad(vice): internet influencers and disclosure regulation
Authors: Mitchell Matthew
Published: February 2021

Consumers rely on intermediaries (“influencers”) such as social media recommendations to provide information about products. The advice may be mixed with endorsement in a way that is unobservable to the follower, creating a trade‐off for influencers between the best advice and the most revenue. This article models the dynamic relationship between an influencer and a follower. The relationship evolves between periods of less and more revenue. The model can provide insight into policies such as the Federal Trade Commission's mandatory disclosure rules. An opt‐in policy may be superior: it deregulates influencers who are reaping the rewards of past good advice.
Are Asian least developed countries sidelined in advanced manufacturing production networks?
Authors: Suvannaphakdy Sithanonxay , DiCaprio Alisa
Published: February 2021

The production of parts for high‐technology final products can play an important role in advancing economic development. This appears a particularly attractive outcome for least developed countries (LDCs). But due to data constraints, analysis has been based largely on middle‐income economies. We seek to address this gap by using proxy data to explore the position of Asian LDCs in electronics and automotive production. Our analysis shows that there has been a surprising amount of LDC trade activity in these sectors over the past decade. In addition, a group of LDCs has succeeded in what appears to be successful engagement with these production networks. We discuss the forms of participation we observe and ask whether they might enable countries to attain development outcomes that might otherwise be out of reach.
Variations in Long‐term Opioid Therapy Definitions: A Systematic Review of Observational Studies Using Routinely Collected Data (2000‐2019)
Authors: de Oliveira Costa Juliana , Bruno Claudia , Baranwal Navya , Gisev Natasa , Dobbins Timothy A. , Degenhardt Louisa , Pearson Sallie‐Anne
Published: February 2021

Routinely collected data have been increasingly used to assess long‐term opioid therapy (LTOT) patterns, with very little guidance on how to measure LTOT from these data sources. We conducted a systematic review of studies published between January 2000 and July 2019 to catalogue LTOT definitions, the rationale for definitions and LTOT rates in observational research using routinely collected data in nonsurgical settings. We screened 4056 abstracts, 210 full‐text manuscripts and included 128 studies, mostly from the United States (81%) and published between 2015 and 2019 (69%). We identified 78 definitions of LTOT, commonly operationalised as 90 days of use within a year (23%). Studies often used multiple criteria to derive definitions (60%), mostly based on measures of duration, such as supply days/days of use (66%), episode length (21%) or prescription fills within specified time periods (12%). Definitions were based on previous publications (63%), clinical judgment (16%) or empirical data (3%); 10% of studies applied more than one definition. LTOT definition was not provided with enough details for replication in 14 studies and 38 studies did not specify the opioids evaluated. Rates of LTOT within study populations ranged from 0.2% to 57% according to study design and definition used. We observed a substantial rise in the last 5 years in studies evaluating LTOT with large variability in the definitions used and poor reporting of the rationale and implementation of definitions. This variation impacts on research reproducibility, comparability of findings and the development of strategies aiming to curb therapy that is not guideline‐recommended.
Epidemiology of drug‐related deaths in European hospitals: A systematic review and meta‐analysis of observational studies
Authors: Montané Eva , Castells Xavier
Published: February 2021

Aims

To perform a systematic review of observational studies on the epidemiology of drug‐related death (DRD) in patients requiring hospitalisation or while hospitalised (hospital‐acquired DRD).

Methods

We conducted a systematic review of observational studies investigating the occurrence rate of DRD episodes among deceased inpatients. Two independent researchers assessed eligibility criteria, extracted data and evaluated the risk of bias. Both quality assessment and meta‐analysis were performed.

Results

From 1351 identified potential studies, 6 retrospective studies were included. DRD occurrences rates were 7.3% (95% confidence interval [CI] 4.1–12.5) among deceased inpatients and 0.13% (95% CI 0.04–0.40) among hospitalised patients. During hospitalisation, acquired‐DRD represented 2.7% (95% CI 1.0–6.9) of inpatient deaths and occurred in 0.05% (95% CI 0.01–0.23) of hospitalised patients. However, these estimates have to be viewed with caution because there was significant heterogeneity (I2 > 97%). None of the studies were considered to be at high risk of bias according to the criteria of the NIH Quality Assessment Tool. The most common adverse drug reactions related to death were haemorrhages due to antithrombotic drugs (39%, 95% CI 26.5–53.2) and infections in drug‐immunosuppressed patients (27.5%, 95% CI 16.7–41.7).

Conclusion

We found that the DRD occurrence rate of deceased hospital inpatients has been infrequently studied in Europe. Our findings suggest that drugs are an important cause of death in hospitals. The limited number of studies in European countries stresses the need for more research in this area.
Thermal exposure of implant osteotomies and its impact on osseointegration—A preclinical in vivo study
Authors: Heuzeroth Raphael , Pippenger Benjamin E. , Sandgren Rebecca , Bellón Benjamin , Kühl Sebastian
Published: February 2021

Objectives

Thermal and mechanical stresses during osteotomy preparation can impair implant osseointegration. This study investigated implant osseointegration following the measurement of temperature exposure during osteotomy drilling, varying drill design, sequence, and drill wear.

Materials and methods

36 tapered implants were placed in a mandibular minipig model after guided drilling of implant osteotomies using 4 different groups: (1) control drills with a conservative, sequential drilling sequence, (2) control drills using a shortened drill sequence (PF), (3) novel test drill displaying an optimized drill design and surface treatment, PF, and (4) aged test drill, PF. Intraosseous temperatures during drilling were measured using a temperature probe. BIC, fBIC, and tissue reactions were histomorphometrically derived after 2 and 8 weeks of healing.

Results

Compared to control drills (1) or (2), test drills (3) resulted in significantly lower maximum temperatures ((35.4 (CI 30.2–40.5)°C vs. (46.5 (CI 41.0–52.0)°C, p = .0021)) and shorter drill times ((4.5 (CI 1.6–7.3)sec vs. 10.3 (7.3–13.4)sec). Lower osteotomy temperature values and shorter drill times corroborated with significantly higher BIC after 2 and 8 weeks healing for the test (3) compared to control groups (2) (2 weeks: (44.9 (CI 34.1–55. 7)% vs. (31.3 (CI 20.5–42.2)%, p = <.0001 and 8 weeks: (73.7 ( CI 64.2–83.2)% vs. (66.2 (CI 57.0–75.4)%, p = <.0455).

Conclusion

The improved osseointegration of implants placed after osteotomy preparation with novel test drills using a shortened drill sequence compared to standard drills and conventional drill protocols might be attributed to more favorable thermal profiles and less mechanical stress exerted on the bone surrounding the implant osteotomy.
Seating accuracy of implant immediate provisional prostheses fabricated by digital workflow prior to implant placement by fully guided static computer‐assisted implant surgery: An in vitro study
Authors: Abduo Jaafar , Lau Douglas
Published: February 2021

Objectives

Evaluation of seating accuracy of implant immediate provisional prostheses fabricated prior to fully guided static computer‐assisted implant surgery (sCAIS).

Materials and Methods

Two maxillary training models were used to plan for single anterior (S‐Ant) and single posterior (S‐Post) implant prostheses, and a bridge (B) spanning from an anterior implant (B‐Ant) to a posterior implant (B‐Post). A commercial software was used to plan the implant location, design the surgical guides and design the provisional prostheses. The master models with the provisional prostheses were scanned to generate virtual master models. For each maxillary model, a total of 10 guides and 10 surgical models were produced. Following implant placements in each surgical model, the provisional prostheses were attached to the implants and were scanned to produce virtual surgical models. The virtual master and surgical models were superimposed to measure the vertical error, the proximal contact error and the proximal contact quality.

Results

The vertical error was greatest for the S‐Post (0.41 mm), followed by B‐Post (0.29 mm), B‐Ant (0.26 mm) and S‐Ant (0.21 mm). There was no significant difference in vertical errors among the prostheses. For the proximal contact, the S‐Ant had significantly greater error (0.45 mm ‐ 0.46 mm) than S‐Post (0.15 mm) and B (0.09 mm ‐ 0.15 mm). A similar pattern was observed for proximal contact quality.

Conclusions

All prostheses were associated with errors vertically and at the proximal contacts. Therefore, the clinicians who plan to use this workflow should be prepared to adjust the prosthesis after implant insertion.
A sparse observation model to quantify species distributions and their overlap in space and time
Authors: Ait Kaci Azzou Sadoune , Singer Liam , Aebischer Thierry , Caduff Madleina , Wolf Beat , Wegmann Daniel
Published: February 2021

Camera traps and acoustic recording devices are essential tools to quantify the distribution, abundance and behavior of mobile species. Varying detection probabilities among device locations must be accounted for when analyzing such data, which is generally done using occupancy models. We introduce a Bayesian time‐dependent observation model for camera trap data (Tomcat), suited to estimate relative event densities in space and time. Tomcat allows to learn about the environmental requirements and daily activity patterns of species while accounting for imperfect detection. It further implements a sparse model that deals well will a large number of potentially highly correlated environmental variables. By integrating both spatial and temporal information, we extend the notation of overlap coefficient between species to time and space to study niche partitioning. We illustrate the power of Tomcat through an application to camera trap data of eight sympatrically occurring duikerCephalophinaespecies in the savanna – rainforest ecotone in the Central African Republic and show that most species pairs show little overlap. Exceptions are those for which one species is very rare, likely as a result of direct competition.
The origination and distribution of money market instruments: sterling bills of exchange during the first globalization†
Authors: Accominotti Olivier , Lucena‐Piquero Delio , Ugolini Stefano
Published: February 2021

This article presents a detailed analysis of how liquid money market instruments—sterling bills of exchange—were produced during the first globalization. We rely on a unique dataset that reports systematic information on all 23,493 bills re‐discounted by the Bank of England in the year 1906. Using descriptive statistics and network analysis, we reconstruct the complete network of linkages between agents involved in the origination and distribution of these bills. Our analysis reveals the truly global nature of the London bill market before the First World War and underscores the crucial role played by London intermediaries (acceptors and discounters) in overcoming information asymmetries between borrowers and lenders on this market. The complex industrial organization of the London money market ensured that risky private debts could be transformed into extremely liquid and safe monetary instruments traded throughout the global financial system.
Evaluation of patient engagement in medicine development: A multi‐stakeholder framework with metrics
Authors: Vat Lidewij Eva , Finlay Teresa , Robinson Paul , Barbareschi Giorgio , Boudes Mathieu , Diaz Ponce Ana Maria , Dinboeck Michaela , Eichmann Lukas , Ferrer Elisa , Fruytier Sevgi E. , Hey Claudia , Broerse Jacqueline E. W. , Schuitmaker‐Warnaar Tjerk Jan
Published: February 2021

Background

Patient engagement is becoming more customary in medicine development. However, embedding it in organizational decision‐making remains challenging, partly due to lack of agreement on its value and the means to evaluate it. The objective of this project was to develop a monitoring and evaluation framework, with metrics, to demonstrate impact and enhance learning.

Methods

A consortium of five patient groups, 15 biopharmaceutical companies and two academic groups iteratively created a framework in a multi‐phase participatory process, including analysis of its application in 24 cases.

Results

The framework includes six components, with 87 metrics and 15 context factors distributed among (sub)components: (a) Input: expectations, preparations, resources, representativeness of stakeholders; (b) Activities/process: structure, management, interactions, satisfaction; (c) Learnings and changes; (d) Impacts: research relevance, study ethics and inclusiveness, study quality and efficiency, quality of evidence and uptake of products, empowerment, reputation and trust, embedding of patient engagement; (e) Context: policy, institutional, community, decision‐making contextual factors. Case study findings show a wide variation in use of metrics. There is no ‘one size fits all’ set of metrics appropriate for every initiative or organization. Presented sample sets of metrics can be tailored to individual situations.

Conclusion

Introducing change into any process is best done when the value of that change is clear. This framework allows participants to select what metrics they value and assess to what extent patient engagement has contributed.

Patient contribution

Five patient groups were involved in all phases of the study (design, conduct, interpretation of data) and in writing the manuscript.
Dysplasia and carcinoma of the gallbladder: pathological evaluation, sampling, differential diagnosis and clinical implications
Authors: Roa Juan C , Basturk Olca , Adsay Volkan
Published: February 2021

Pathological evaluation of gallbladder neoplasia remains a challenge. A significant proportion of cases presents as clinically and grossly inapparent lesions, and grossing protocols are not well established. Among epithelial alterations, pseudo‐pyloric gland metaplasia is ubiquitous and of no apparent consequence, whereas goblet cell metaplasia and a foveolar change in surface cells require closer attention. Low‐grade dysplasia is difficult to objectively define and appears to be clinically inconsequential by itself; however, extra sampling is required to exclude the possibility of accompanying more significant lesions. For high‐grade dysplasia (‘high‐grade BilIN’, also known as ‘carcinoma in situ’), a complete sampling is necessary to rule out invasion. Designating in‐situ or minimally invasive carcinomas limited to muscularis or above as early gallbladder carcinoma (EGBC) helps to alleviate the major geographical differences (West/East) in the criteria for ‘invasiveness’ to assign a case to pTis or pT1. Total sampling is crucial in proper diagnosis of such cases. A subset of invasive GBCs (5–10%) arise from the intracholecystic neoplasm (ICN, ‘adenoma‐carcinoma sequence’) category. Approximately two‐thirds of ICNs have invasive carcinoma. However, this propensity differs by subtype. True ‘pyloric gland adenomas’ (> 1 cm) are uncommon and scarcely associated with invasive carcinoma. A distinct subtype of ICN composed of tubular, non‐mucinous MUC6+ glands [intracholecystic tubular non‐mucinous neoplasm (ICTN)] forms a localised pedunculated polyp. Although it is morphologically complex and high‐grade, it appears to be invasion‐resistant. Some of the invasive carcinoma types in the gallbladder have been better characterised recently with adenosquamous, neuroendocrine, poorly cohesive and mucinous carcinomas often being more advanced and aggressive.
It's a little bit like prison, but not that much: Aboriginal women's experiences of an acute mental health inpatient unit.
Authors: Bradley Patricia , Lowell Anne , Daiyi Cherise , Macklin Karen , Nagel Tricia , Dunn Sandra
Published: February 2021

This research aimed to gain an understanding of the acute mental health inpatient experience as described by Aboriginal women during admission. It recorded for the first time the words of Aboriginal women within the inpatient unit, including their perceptions of factors which may promote or impede a culturally safe environment. Eleven Aboriginal women inpatients gave interviews before discharge from the inpatient unit. Five Aboriginal Reference Group (ARG) members with experience of the inpatient unit also gave interviews, adding ‘insider–outsider’ perspectives. Interviews were recorded, transcribed, entered into NVivo software, and analysed inductively to raise codes and develop themes. Five interconnecting themes emerged: Social Context: life experience preceding, shaping, and following admission; Connection: with kin, community, and culture. Control: self‐determination, legally and physically curtailed; Caring: actions promoting reconnection and self‐determination; Communication: conveying caring and supporting agency, reconnection, and return to community. Findings reflected inpatient issues reported in previous studies, adding insights into the cultural concerns of Aboriginal women and offering practical clinical implications for culturally secure service delivery in an inpatient setting. Existing literature offered a basis for developing the model offered here for transcultural interaction for recovery in an inpatient setting. Attention to these findings can enhance Aboriginal women's inpatient experience and promote further research. The article complies with the COREQ‐32 checklist for describing qualitative studies.
Does cross‐border acquisition reduce earnings management of emerging market acquirers? Evidence from India
Authors: Valiya Purayil Priyesh , Lukose P. J. Jijo
Published: February 2021

Cross‐border acquisitions by emerging market firms have been increasing at an accelerated pace. The present study examines the impact of cross‐border acquisition on the earnings manipulation of emerging market firms by analyzing the cross‐border deals from India during the period 2000–2015. Using two proxies for earnings management, we find that cross‐border acquisition reduces the incentive to manipulate earnings by way of accruals, but not via real economic transactions. Further, cross‐sectional tests reveal that the incentive to reduce accrual earnings manipulation is more pronounced when the acquisition is made in countries with a strong corporate governance structure. Additional analysis indicates that acquisition results in increased earnings response coefficient for the acquirer firms relative to the control firms. Our finding is robust even after controlling for cross‐listing and endogeneity associated with cross‐border acquisition decision. The results have implications for the literature on the spillover of financial reporting practices across countries due to cross‐border business activities, especially in the context of emerging markets, which are known for their weak investor protection and underdeveloped institutional environment.
Editorial: Standardizing methods and measures in randomized controlled trials: a necessary catalyst for clinical translation
Authors: Luby Joan L.
Published: February 2021

The pressing need for more randomized controlled trials (RCTs) of treatments for childhood mental disorders has been emphasized by researchers and clinicians as well as in recent commentaries in JCPP (e.g. Stringaris, 2014). Despite the significant increase in research on aetiology, course and antecedents of developmental psychopathology more generally, and the numerous important discoveries that have been made in this domain in the last two decades, the translation of these findings into clinical practice has lagged behind (Insel and Gotay, 2014). Currently, based on limitations in the extant literature, treatment decisions by child mental health clinicians are still made largely based on personal anecdotal experience. Consistent with this, wide variation in prescribing practices have been found by region internationally (Steinhausen, 2015). When it comes to psychotherapeutic interventions, these clinical strategies are often driven by the limited availability of empirically supported treatments in any given community. In the case of psychopharmacologic treatments, while some clinical guidelines are now available, much more definitive data are needed to inform indications, optimal dosing and duration of treatment, uses of polypharmacy, as well as more nuanced information about differential developmental effects. Therefore, a significant gap still exists between clinical practice and the empirical database in the treatment of child mental disorders. Further, the available database is also limited by small sample sizes and mixed findings, making it much less straightforward to coherently guide clinical treatment of childhood psychopathology.
Toward More Accurate Measures of Family Structure: Accounting for Sibling Complexity
Authors: Sanner Caroline , Jensen Todd M.
Published: February 2021

In this article, we argue that accounting for sibling complexity is a necessary step toward more accurate assessments of family structure. First, we argue that current conceptualizations of family structure are rooted in (and reinforce) Eurocentric definitions of family, and we highlight contradictions between family theory and measurements of family structure. Second, we discuss the prevalence of diverse sibling compositions in families and show the informative value of accounting for sibling complexity. Third, we explore the barriers to accounting for sibling structure by evaluating the extent to which complex sibling compositions are captured in publicly available secondary datasets recently used to study families. Finally, we consider both theoretical and methodological implications of failing to account for sibling complexity in family research and offer recommendations for future data collection efforts.
Mesophyll photosynthetic sensitivity to leaf water potential in Eucalyptus: a new dimension of plant adaptation to native moisture supply
Authors: Salvi Amanda M. , Smith Duncan D. , Adams Mark A. , McCulloh Katherine A. , Givnish Thomas J.
Published: February 2021

Photosynthetic sensitivity to drought is a fundamental constraint on land‐plant evolution and ecosystem function. However, little is known about how the sensitivity of photosynthesis to nonstomatal limitations varies among species in the context of phylogenetic relationships.

Using saplings of 10 Eucalyptus species, we measured maximum CO2‐saturated photosynthesis using A–ci curves at several different leaf water potentials (ψleaf) to quantify mesophyll photosynthetic sensitivity to ψleaf (MPS), a measure of how rapidly nonstomatal limitations to carbon uptake increase with declining ψleaf. MPS was compared to the macroclimatic moisture availability of the species’ native habitats, while accounting for phylogenetic relationships.

We found that species native to mesic habitats have greater MPS but higher maximum photosynthetic rates during non‐water‐stressed conditions, revealing a trade‐off between maximum photosynthesis and drought sensitivity. Species with lower turgor loss points have lower MPS, indicating coordination among photosynthetic and water‐relations traits.

By accounting for phylogenetic relationships among closely related species, we provide the first compelling evidence that MPS in Eucalyptus evolved in an adaptive fashion with climatically determined moisture availability, opening the way for further study of this poorly explored dimension of plant adaptation to drought.
Veritism and the normativity of logic
Authors: Shoaibi Nader
Published: February 2021

The idea that logic is in some sense normative for thought and reasoning is a familiar one. Some of the most prominent figures in the history of philosophy including Kant and Frege have been among its defenders. The most natural way of spelling out this idea is to formulate wide‐scope deductive requirements on belief which rule out certain states as irrational. But what can account for the truth of such deductive requirements of rationality? By far, the most prominent responses draw in one way or another on the idea that belief aims at the truth. In this paper, I consider two ways of making this line of thought more precise and I argue that they both fail. In particular, I examine a recent attempt by Epistemic Utility Theory to give a veritist account of deductive coherence requirements. I argue that despite its proponents’ best efforts, Epistemic Utility Theory cannot vindicate such requirements.
Uncertainty Quantification with Experts: Present Status and Research Needs
Authors: Hanea Anca M. , Hemming Victoria , Nane Gabriela F.
Published: February 2021

Expert elicitation is deployed when data are absent or uninformative and critical decisions must be made. In designing an expert elicitation, most practitioners seek to achieve best practice while balancing practical constraints. The choices made influence the required time and effort investment, the quality of the elicited data, experts’ engagement, the defensibility of results, and the acceptability of resulting decisions. This piece outlines some of the common choices practitioners encounter when designing and conducting an elicitation. We discuss the evidence supporting these decisions and identify research gaps. This will hopefully allow practitioners to better navigate the literature, and will inspire the expert judgment research community to conduct well powered, replicable experiments that properly address the research gaps identified.
Survey of newborn direct antiglobulin testing practice in United States and Canadian transfusion services
Authors: Crowe Elizabeth P. , Goel Ruchika , Andrews Jennifer , Meyer Erin K. , Wong Trisha E. , Sloan Steven R. , Delaney Meghan , Lieberman Lani , Cushing Melissa M.
Published: February 2021

Background

We hypothesized that variability in practice exists for newborn immunohematology testing due to lack of consensus guidelines. We report the results of a survey assessing that variability at hospitals in the United States and Canada.

Study Design and Methods

An AABB Pediatric Subsection working party developed and validated a survey of newborn immunohematology testing practice. The survey was sent electronically to transfusion service leadership at teaching institutions.

Results

The response rate was 67% (61/91); 56 surveys meeting inclusion criteria were analyzed. Approximately 90% (50/56) were from birth hospitals and 16.1% (9/56) were from pediatric hospitals. Newborn immunohematology testing is ordered as a panel by 66.0% (33/50) of birth hospitals. ABO group and DAT is mandated before discharge in 14/56 (25.0%) and 13/56 (23.2%), respectively. About 76.8% (43/56) selectively perform a DAT according to blood blank or clinical parameters. The most common DAT practices include anti‐IgG only testing by 73.2% (41/56) and use of umbilical cord specimen type by 67.9% (38/56). A positive DAT is a critical value for 26.8% (15/56) and followed with eluate testing when a maternal antibody screen is positive for 48.2% (27/56). In the setting of a non‐ABO maternal red cell antibody, 55.4% (31/56), phenotype neonatal red cells when the DAT is positive. Group O RBC are transfused irrespective of the DAT result for 82.1%, (46/56).

Conclusion

There is variability in newborn immunohematology testing and transfusion practice and potential overutilization of the DAT. Evidence‐based consensus guidelines should be developed to standardize practice and to improve safety.
Impact on Beams
Authors: Mason H. L.
Published: February 2021

This paper deals with transverse impact on beams the mass of which is of importance. Experimental results are presented for comparison with theory. Impacts which appear single to the eye are shown to consist in reality of several blows in quick succession.

Section 1 of the paper traces the historical development of this subject by discussing the investigations of Young, Hodgkinson, Cox, Saint Venant, and Timoshenko. Section 2 treats a simplified system in which a concentrated mass strikes a smaller concentrated mass having a “soft” spring restraint. For elastic impact, theory predicts for the struck mass a path composed of sinusoidal elements separated by instantaneous blows. For inelastic impact it predicts a joint harmonic motion. Records of the paths of both masses were obtained experimentally.

Section 3 of the paper uses Timoshenko’s method of combining local deformation of the contact region with lateral vibration of the beam. An experimental investigation of maximum contact pressure and of blow duration gives what is believed to be the first confirmation of this theory.

Section 4 describes an experimental determination of flexural stresses in elastic and inelastic impact on a 3-in. I-beam by the use of a Westinghouse magnetic strain gage. The indication is that stresses may be higher than those calculated by the usual approximations.
The Use of Rubber in Vibration Isolation: Including the Case of Six Degree of Freedom Systems
Authors: Hull E. H.
Published: February 2021

The desirable properties of an elastic material applicable to many types of vibration-isolation problems are outlined. Of those materials at present available, rubber appears most suitable for this type of work. The general elastic properties of rubber are discussed and data given for determining the stiffness of pads made from one particular compound. Equations are developed for the six natural frequencies and associated modes of vibration of a mass supported on elastic pads and examples of vibration isolation worked out using this theory.
The Load-Deflection Characteristics of Initially Curved Flexural Springs
Authors: Johnson W. E.
Published: February 2021

The problem considered in this paper is that of determining the relation between the load and the deflection of a curved flexural member which is permitted to take large deflections, so that its action may be considered to be that of a spring. Four primary types of springs are considered, in each of which the line of action of the load is either perpendicular or parallel to the tangent to the neutral axis at the point of clamping, as shown in Fig. 1. In addition to these, the equations for the initial curve of a piston ring with a large gap are given.

The results for the four primary types may be used for any spring which is a combination of several springs of one type, and also for combinations of different types. Thus a spring consisting of any portion of a circular arc may be analyzed. Also, the relations of load, deflection, and stress may be obtained for a spring consisting of several convolutions (corrugated), and subjected to either a compressive or extending force.

For each of the primary types, two sets of curves are given, one set showing the relation between the load and the deflection in the direction of the load, while the other shows the relation between the load and the greatest moment arm which is used to determine the stress. Each set of curves is plotted for several values of the initial curvature, including limiting cases of the column and straight cantilever. Curves are in suitable form for design work.

Methods of computing these relations are summarized so that cases not included in the plotted results may readily be computed. The method of analysis, and discussion of related incidental problems are given in appendixes.
Simultaneous Effects of Corrosion and Abrupt Changes in Section on the Fatigue Strength of Steel
Authors: Dolan Thomas J.
Published: February 2021

This paper gives the results of a series of tests of the torsional and flexural fatigue strength of specimens of S.A.E. 3140 steel which were tested in air and under a stream of tap water.

Comparative results are given showing the effects of abrupt changes in section with the steel in the hot-rolled condition and also after heat-treatment. The effect of the corrosive action of the stream of water on the fatigue strength of the specimens of various shapes is determined in addition to the effects due to abrupt changes in section and to heat-treatment.
The Calculation of Steam-Turbine Reheat Factors
Authors: Smith Ronald B.
Published: February 2021

This paper approaches the problem of reheat from the analytical standpoint. Relations are derived for the reheat gain in the saturated- and superheated-steam regions, which show the influence of pressure ratio, temperature, efficiency and number of expansions. A comparison between the calculated reheat and the reheat computed graphically from the Keenan-Keyes properties of steam indicates good agreement over a wide range of conditions.
Thermo-Fluid Design Simulation of Nd3+ POCl3 Transverse Flow Liquid Laser Cavity
Authors: Singh Vinod Kumar , Singhal Gaurav , Talukdar Prabal
Published: February 2021

Computational fluid dynamics (CFD) based thermal design of a transverse flow optical cavity is carried out for 1 kW Nd3+ POCl3 liquid laser source to investigate temperature and velocity distribution in the optical pumping region of the cavity. Temperature gradient and turbulence both affect the refractive index of the liquid gain medium, which results in optical path difference (OPD), divergence and hence, poorer quality of the laser beam. The main purpose of this design is to achieve uniform flow and least temperature gradient in the optical pumping region so that the optical path difference can be minimized and a good beam quality can be achieved. CFD model has been developed for carrying out thermo-fluid simulations for this thermal system and based on these simulations, an optimum geometry of inlet ports along with their position from optical pumping region have been proposed. A user defined function (UDF) is incorporated for the input of spatially varying heat source term in each cell of the optical pumping region of the cavity. Variations in refractive index and optical path difference are estimated from the temperature data using another UDF. Simulation reveals that mass flowrate between 1.5 kg/s and 2.0 kg/s maintains the optical homogeneity of gain medium. Preliminary experiments have been carried out to demonstrate the effect of flowrate on the beam divergence and thereby exhibiting the importance of present simulation work.
Integrating Solids-Based Machining With Feature Recognition
Authors: Tuttle R. , Sormaz N. , Clark D. E. R. , Corney J.
Published: February 2021

The paper describes a system for automatically generating machinable volumes from solid models of single-sided, 2.5D, components and their stock. The resulting bodies are used to support the generation of CNC code from a commercial solids-based machining package. Unlike much of the reported work in this area the authors’ goal has not been an entirely automated system, but rather an intelligent assistant, capable of increasing the part programmer’s productivity. The methodology demonstrates one way in which the twin problems of feature interaction and multiple interpretations can be side-stepped. The authors’ system generates machinable feature volumes bounded by planar and cylindrical faces using algorithms which have been developed and extended from previously reported work. Because the system is closely coupled to a commercial package it has been possible to produce estimates of the time savings (or productivity gains) delivered by the current system which suggested this approach could be of real benefit to practicing engineers.
Creation and Manipulation of Complex Displacement Features During the Conceptual Phase of Design
Authors: van Elsas P. A. , Vergeest J. S. M.
Published: February 2021

Surface feature design is not well supported by contemporary free form surface modelers. For one type of surface feature, the displacement feature, it is shown that intuitive controls can be defined for its design.

A method is described that, given a surface model, allows a designer to create and manipulate displacement features. The method uses numerically stable calculations, and feedback can be obtained within tenths of a second, allowing the designer to employ the different controls with unprecedented flexibility.

The algorithm does not use refinement techniques, that generally lead to data explosion. The transition geometry, connecting a base surface to a displaced region, is found explicitly. Cross-boundary smoothness is dealt with automatically, leaving the designer to concentrate on the design, instead of having to deal with mathematical boundary conditions.

Early test results indicate that interactive support is possible, thus making this a useful tool for conceptual shape design.
Feature-Based Assembly Mating Reasoning
Authors: Wang Eric , Kim Yong Se
Published: February 2021

It is desirable to provide computer-based tools to assist designers and manufacturing engineers in the difficult task of geometric reasoning to achieve fast product development and flexible manufacturing. In the domain of assembly reasoning and planning, numerous methods have been developed to analyze a user-specified assembly configuration of parts. Fewer efforts have been made to systematically obtain the assembly configuration itself from underlying information. As a step in this direction, we present an assembly mating reasoning method that determines feasible assembly configurations directly from part geometry. Our method recognizes form features from the boundary representations of the components, then treats the form features as assembly features and identifies mating relations between them. Assembly configurations are constructed by using Boolean operations on the components to simulate the assembly process. A heuristic backtracking search is used to traverse the space of feasible component assembly operations. The result of the search is an enumeration of feasible assembly configurations.
A Potential Field Algorithm for Fixture Synthesis in 2D
Authors: Penev Kamen , Requicha Aristides A. G.
Published: February 2021

A fixture is an arrangement of fixturing modules that locate and hold a workpart during a manufacturing operation. In this work we address the fixturing problem in the plane. We consider fixtures with frictionless point contacts. The focus is on contact point placement and its integration with fixture analysis. A novel method for planar fixture synthesis has been developed. It is a non-deterministic, potential field algorithm for contact point placement. The method provides a basic framework for the integration of heterogeneous high-level fixturing agents through an interface based on zones of attraction and repulsion on the workpart boundary. The algorithm may produce redundant fixtures, and can augment partial solutions to complete form closure fixtures.
Removal of Submicron Particles Using High Frequency Ultrasonics
Authors: Busnaina Ahmed A. , Dai Fen
Published: February 2021

High-frequency ultrasonic cleaning is widely used in the semiconductor and other industries affected by contamination for the removal of particulate contamination. High frequency (near 1 MHz) ultrasonic cleaning (known as megasonic cleaning) is specially used in semiconductor manufacturing [1]. Many studies concerning submicron particle removal using megasonic and ultrasonic cleaning has been conducted recently [2–7]. The megsonic cleaning process proved to be the essential processes in cleaning silicon wafers after processes such as CMP, RIE, CVD, Sputter, etc. This paper introduces recent results that involve new techniques for introducing the ultrasonic energy in the cleaning bath.
Thermal Aspects of a Novel Micropumping Device
Authors: Sharatchandra M. C. , Sen Mihir , Gad-el-Hak Mohamed
Published: February 2021

Heat transfer and attendant temperature rises in a novel micropumping device, are studied numerically. The full two-dimensional Navier-Stokes and energy equations, the latter with viscous dissipation terms retained, are solved using a finite-volume methodology. The effects of Prandtl number and pump size are explored. In addition, an approximate one-dimensional thermal model is developed and the comparisons with the more precise numerical model yielded close agreement in the computed bulk temperature distributions along the pump. For large Eckert numbers, the results indicate that enhancements in the hydrodynamics of pumping could be accompanied by extremely high temperature gradients. Finally, the system transients were found to be restricted to rather large times from startup for some proposed micropumping applications, suggesting the possibility of designing pump operating cycles to circumvent the problem of heat build-up due to viscous dissipation.
The Development of Nomographs Into Mathematical Functions
Authors: Clark William H.
Published: February 2021

This study was initiated to develop a quick, accurate evaluation of the energy usage and demand of hospitals. The computer programs that were available to facilitate such energy studies required more time, accuracy and data than was available in the project scope (i.e. an industrial type of overall energy audit) to perform a long-term energy analysis. The thoroughness required of a comprehensive study of such a complex facility could not, however, be sacrificed for the sake of a quick, expedient solution.

A compromise solution that is both accurate and quick was found in the series of nomographs produced by an exhaustive study by the Federal Programs Office of the U.S. Department of Energy. This report, dated June 1, 1979, is entitled, “Architects and Engineers Guide to Energy Conservation in Existing Buildings.”

Pertinent nomographs from this report were converted into mathematical functions. These, in turn, were assimilated into a seamless stand alone database application, complete with data entry screens, pull down menus, help messages and data entry screening. The result is an effective, user friendly software program that is simple enough to be used by contractors, but with the accuracy and input variability required of professional energy auditors. The weather data bases includes over four hundred U.S. stations and several hundred international locations, to include bin analysis capabilities at each.

The cumulative result of the equations itemized herein, when used for a building analysis, is a consistent match to actual metered energy usage data. This was proven on a dozen comprehensive hospital energy audits, for which over $10 million in actual energy conservation projects were proved. These were done for the Texas Loan Star program using oil overcharge money.

There is strong confidence by users of this software that the values this application of nomographs produces are accurate and trustworthy. The calculations are performed quickly and easily enough that many iterations can be done — in the time taken to do a single run on competing software — to evaluation many interrelated project costs and paybacks.
Computer Prediction of Anthropometric Frame Size in Children
Authors: Sanchez L. A. , Shoup T. E.
Published: February 2021

In the design and improvement of medical equipment and consumer products, it is often important to be able to make predictions of anthropometric measurements of the human frame in order to size devices for optimum use. Properly sized equipment and products are easier to use, have far more functional utility and present improved market opportunities. The prediction process for anthropometric size is especially difficult when the human frame is that of a child, since for this segment of the human population, the size varies greatly with time. The most frequently used independent variable used in the prediction of frame size for children is the chronological age in years. It is the purpose of this paper to discuss the most often used prediction formulas for human growth and to present a new formulation for anthropometric size made possible by the use of an optimization algorithm using the digital computer. It is believed that this is the first time this particular formulation has been presented.
Computerized Data Acquisition and Model Prototype Testing
Authors: Khosrowjerdi M. , Presz Walter M. , Reynolds Gary
Published: February 2021

Exact, analytical solutions for practical, fluid flow problems are almost impossible to obtain. Also, because most practical fluid problems are turbulent, and at high Reynolds number, even approximate solutions are limited. Thus, scale model prototyping, and testing are a critical part of any product development program in the aerospace industry. This paper presents state of the art computer procedures which greatly increase the ability to conduct detail model tests more effectively. Computer aided design and data acquisition in conjunction with stereolithography fabrication are shown to allow prototype modifications quickly, and at low costs. Stereolithography techniques are also shown to provide the ability to integrate pressure tap instrumentation into the model fabrication. Computer controlled test facilities, and traverse systems are shown to enhance the gathering, and analysis of large amount of test data.

Sample models, test facilities and data are presented for a jet engine exhaust ejector. Details of the data collection software and analysis procedures are presented. Computer jet traverse data analysis and results are presented for the ejector. Experimental ejector pumping, thrust augmentation and jet mixing results are presented and compared to analytical predictions. The model tests do not include compressibility effects, shock waves, or the non uniform temperature and velocity profiles associated with the actual engine exhaust flow. Furthermore, the model flowfield is at a much lower Reynolds number than the actual flowfield. Even so, computerized data acquisition and model prototype testing of this type can be very helpful in providing insight to the controlling physics, and in generating relative trends needed in the product optimization process.
Fuzzy Logic and Cell to Cell Mapping
Authors: Edwards D. , Choi H. T. , Canning J.
Published: February 2021

Nonlinear systems are important in many fields of science, mathematics, and engineering. In recent years, simple cell mapping (SCM) and generalized cell mapping (GCM) methods have been proposed and successfully used to analyze nonlinear systems. The GCM method requires the determination of a transition probability matrix. In a manner similar to GCM, we use fuzzy logic to calculate a transition possibility matrix for a nonlinear system. This matrix can then be used to establish the statistical properties of strange attractors associated with a chaotic system. We analyze a chaotic system using fuzzy logic to demonstrate this approach and then compare our result with the GCM method.
The Design and Manufacture of Wobble “Stones” As a Project in a Rapid Design Prototyping Course
Authors: Biswas Arunava , Kinzel Gary L. , Cheng Yuan-Pu
Published: February 2021

Celts1, wobble stones, or rattlebacks possess the interesting property of having a preferred direction of rotation. This property occurs because of the distribution of the mass of the body and the geometry at the contact point. This paper presents the design equations for wobble stones in general and describes a project in the Rapid Design Prototyping Class at Ohio State to design and manufacture wobble “stones” using CAD/CAM and an injection molding machine.