bluuebunny/crossref_metadata_2025 huggingface dataset:
Follicle‐stimulating hormone regulates glycolysis of water buffalo follicular granulosa cells through AMPK/SIRT1 signalling pathway
Authors: Pan Yu , Zhu Jianzong , Lv Qiao , Shi Deshun , Yang Sufang , Xing Qinghua , Zhang Ruimen , Cheng Juanru , Deng Yanfei
Published: November 2021

Glycolysis in follicular granulosa cells (GCs) is the primary source of energy metabolism substrate of oocytes and is closely related to follicular development in mammals. Many physiological functions of GCs are regulated by follicle‐stimulating hormone (FSH). In contrast, whether FSH regulates the glycolysis of GCs and its mechanism remains unclear. This study explored the correlation between FSH concentration and glycolysis level of GCs from different diameters of water buffalo follicles, and further explored the mechanism of FSH regulation in glycolysis in vitro cultured GCs. Results showed the variation trend of lactic acid concentration in follicular fluid and the expression level of glycolysis‐related genes in GCs were consistent with the variation trend of FSH concentration in follicular fluid from follicles with different diameters. When GCs were treated with FSH in vitro, the expression level of glycolysis‐related genes, lactate production and glucose uptake increased correspondingly (p < .05). Furthermore, we found that expression trend of AMPK/Sirtuin1 (SIRT1) pathway‐related genes in GCs was consistent with the expression trend of glycolysis‐related genes and was positively correlated with FSH concentrations in vivo or cultured in vitro. Activation of SIRT1 increased the expression level of glycolytic key proteins and lactic acid production in GCs, while inhibition of SIRT1 showed the opposite effect. In general, glycolysis in water buffalo GCs in vivo or cultured in vitro was positively correlated with FSH concentration. AMPK/SIRT1 pathway plays an important role in the regulation of FSH on glycolysis in GCs. Our findings will enrich the understanding of FSH regulating the development of water buffalo follicles.
Engaging local communities in restoration projects: reconsidering the role of traditional knowledge in Wadi Allaqi, Egypt
Authors: Kandal Hanaa A. , Swart Jac. A. A. , Yacoub Hoda A. , Gerkema Menno P.
Published: November 2021

Although there may be large differences between scientific and traditional knowledge (TK) traditions, the possible role of TK for natural management and ecological restoration is increasingly recognized and implies the engagement of local people in conservation and restoration projects. This article explores several forms of community engagement: public participation, citizen science, and responsible research and innovation and argues for an integrated approach as they cover different aspects with regard to the engagement of local people in the context of TK. We illustrate our approach with examples from Wadi Allaqi, a remote area in Southern Egypt. It is concluded that both scientists and local people could profit from such an interaction in ecological restoration and conservation, but that effective policy and management strategies are needed to improve and develop mutually fruitful relationships between scientists and local people.
Distress tolerance as a moderator of the dynamic associations between interpersonal needs and suicidal thoughts
Authors: Kyron Michael J. , Hooke Geoff R. , Bryan Craig J. , Page Andrew C.
Published: November 2021

Background

Identifying the interaction between dispositional and dynamic risk factors is necessary in understanding, predicting, and managing suicide risk. Interpersonal factors have consistently been linked to suicidal ideation over short‐term periods. Additionally, distress tolerance may be a relevant dispositional protective factor against stressful events.

Methods

Seven hundred and seventeen psychiatric inpatients (Male = 30.31%, Average Age = 40.71 years, Min = 14, Max = 82) self‐reported their distress tolerance at hospital admission, and interpersonal needs and suicidal ideation on a daily basis. Dynamic structural equation modelling was used to examine whether within‐level dynamics were moderated by distress tolerance.

Results

Both perceived burdensomeness and thwarted belongingness were significantly associated with same‐day suicidal ideation. Higher distress tolerance was associated with weaker daily associations between suicidal ideation and both perceived burdensomeness and thwarted belongingness. Distress tolerance was also associated with lower variability in suicidal ideation. Moderating effects were also evident when lifetime suicide attempts were added as a covariate, which was associated with stronger associations between interpersonal dysfunction and suicidal ideation, and higher variability in ideation.

Conclusions

Distress tolerance may be important to consider when examining the dynamic relationships between suicidal ideation and proximal factors. Psychotherapy that specifically targets distress tolerance may be effective in reducing reactivity to interpersonal stressors.
The Added Value of Configurational Meta‐analyses
Authors: Veri Francesco , Barrowman Hannah
Published: November 2021

This article discusses the challenges facing meta‐analyses considering multiple sources of heterogeneity in peer‐reviewed studies. While quantitative meta‐analysis can control or correct sources of heterogeneity, it focuses on the search for statistical consistency which limits the extent of causal inference and generalisation. In contrast, qualitative approaches for meta‐analysis tend to integrate various sources of heterogeneity through interpretive approaches. However, this integrative strategy leads to a constitutive or functional relationship between analysed constructs with limited capacity for theory testing. Comparative configurational meta‐analysis (CFG‐MA), a diversity‐oriented approach, has an overall advantage in managing heterogeneity as it recognises the uniqueness of the cases and their within‐case diversity by keeping the assumption of cross‐case causal complexity. CFG‐MA allows the integration of various sources of heterogeneity and the production of cross‐cases and within‐cases inference and generalisation.
Enhancing the sweat resistance of sunscreens
Authors: Keshavarzi Fatemeh , Knudsen Nina Østergaard , Komjani Niloufarsadat Mirmahdi , Ebbesen Morten F. , Brewer Jonathan R. , Jafarzadeh Shadi , Thormann Esben
Published: November 2021

Background

While sunbathing of performing outdoor sport activities, sunscreens are important for protection of uncovered skin against ultraviolet (UV) radiation. However, perspiration negatively affects the performance of a sunscreen film by weakening its substantivity and uniformity through the activation of two mechanisms, namely sunscreen wash‐off and sunscreen redistribution.

Material and methods

We used a perspiring skin simulator to investigate the effect of sunscreen formulation on its efficiency upon sweating. Specifically, we modified the sunscreen formulation by incorporating a hydrophobic film former and adding water‐absorbing particles. Sunscreen performance before and after perspiration is assessed by in vitro sun protection factor measurements, direct detection of changes in the sunscreen distribution using UV reflectance imaging, and by coherent anti‐Stokes Raman scattering (CARS) microscopy for microscopic characterization of the UV filter relocation.

Results

The results show that incorporating a hydrophobic film former can decrease sunscreen wash‐off due to sweating, while an excessive amount of film former might negatively affect the sunscreen distribution. The addition of water‐absorbing particles, on the other hand, had either a negative or positive impact on the sunscreen substantivity, depending on the particle properties. While the addition of large water‐absorbing particles appeared to increase sunscreen redistribution, smaller particles that could form a gel‐like structure upon contact with water, appeared to change sunscreen wetting and sweat droplet spreading, thereby decreasing sunscreen wash‐off and sunscreen redistribution.

Conclusions

We find that using a combination of hydrophobic film formers, which increase water resistance, and small water‐absorbing particles, which change the wetting behavior, can make sunscreen formulations more sweat‐resistant and less runny.
The Arabidopsis electron‐transfer flavoprotein:ubiquinone oxidoreductase is required during normal seed development and germination
Authors: da Fonseca‐Pereira Paula , Pham Phuong Anh , Cavalcanti João Henrique F. , Omena‐Garcia Rebeca P. , Barros Jessica A. S. , Rosado‐Souza Laise , Vallarino José G. , Mutwil Marek , Avin‐Wittenberg Tamar , Nunes‐Nesi Adriano , Fernie Alisdair R. , Araújo Wagner L.
Published: November 2021

The importance of the alternative donation of electrons to the ubiquinol pool via the electron‐transfer flavoprotein/electron‐transfer flavoprotein:ubiquinone oxidoreductase (ETF/ETFQO) complex has been demonstrated. However, the functional significance of this pathway during seed development and germination remains to be elucidated. To assess the function of this pathway, we performed a detailed metabolic and transcriptomic analysis of Arabidopsis mutants to test the molecular consequences of a dysfunctional ETF/ETFQO pathway. We demonstrate that the disruption of this pathway compromises seed germination in the absence of an external carbon source and also impacts seed size and yield. Total protein and storage protein content is reduced in dry seeds, whilst sucrose levels remain invariant. Seeds of ETFQO and related mutants were also characterized by an altered fatty acid composition. During seed development, lower levels of fatty acids and proteins accumulated in the etfqo‐1 mutant as well as in mutants in the alternative electron donors isovaleryl‐CoA dehydrogenase (ivdh‐1) and d‐2‐hydroxyglutarate dehydrogenase (d2hgdh1‐2). Furthermore, the content of several amino acids was increased in etfqo‐1 mutants during seed development, indicating that these mutants are not using such amino acids as alternative energy source for respiration. Transcriptome analysis revealed alterations in the expression levels of several genes involved in energy and hormonal metabolism. Our findings demonstrated that the alternative pathway of respiration mediated by the ETF/ETFQO complex affects seed germination and development by directly adjusting carbon storage during seed filling. These results indicate a role for the pathway in the normal plant life cycle to complement its previously defined roles in the response to abiotic stress.
Cell cycle checkpoint control in response to DNA damage by environmental stresses
Authors: Pedroza‐Garcia José Antonio , Xiang Yanli , De Veylder Lieven
Published: November 2021

Being sessile organisms, plants are ubiquitously exposed to stresses that can affect the DNA replication process or cause DNA damage. To cope with these problems, plants utilize DNA damage response (DDR) pathways, consisting of both highly conserved and plant‐specific elements. As a part of this DDR, cell cycle checkpoint control mechanisms either pause the cell cycle, to allow DNA repair, or lead cells into differentiation or programmed cell death, to prevent the transmission of DNA errors in the organism through mitosis or to its offspring via meiosis. The two major DDR cell cycle checkpoints control either the replication process or the G2/M transition. The latter is largely overseen by the plant‐specific SOG1 transcription factor, which drives the activity of cyclin‐dependent kinase inhibitors and MYB3R proteins, which are rate limiting for the G2/M transition. By contrast, the replication checkpoint is controlled by different players, including the conserved kinase WEE1 and likely the transcriptional repressor RBR1. These checkpoint mechanisms are called upon during developmental processes, in retrograde signaling pathways, and in response to biotic and abiotic stresses, including metal toxicity, cold, salinity, and phosphate deficiency. Additionally, the recent expansion of research from Arabidopsis to other model plants has revealed species‐specific aspects of the DDR. Overall, it is becoming evidently clear that the DNA damage checkpoint mechanisms represent an important aspect of the adaptation of plants to a changing environment, hence gaining more knowledge about this topic might be helpful to increase the resilience of plants to climate change.
Economic evaluations of interventions for the prevention and treatment of pressure ulcers: an umbrella review protocol
Authors: Klugarová Jitka , Pokorná Andrea , Hussain Salman , Vrbová Tereza , Slezáková Simona , Búřilová Petra , Saibertová Simona , Dolanová Dana , Klugar Miloslav
Published: November 2021

Objective:

The objective of this review is to synthesize the findings of economic evaluations of preventing or treating pressure ulcers.

Introduction:

Pressure ulcers are one of the most common preventable complications characterized by local tissue injury. Pressure ulcers increase mortality rates, impair quality of life, increase the length of hospital stay, and alter overall health outcomes. Published studies have found higher costs associated with treating pressure ulcers than preventing them, with treatment cost varying based on the pressure ulcer category (the greater the category, the higher the cost). We will systematically review the evidence on preventing or treating pressure ulcers from an economic perspective.

Inclusion criteria:

We will include systematic reviews that investigate both the cost and outcomes associated with the prevention or treatment of pressure ulcers. Systematic reviews dealing with economic evaluation of wound care or management will be excluded if they have not provided separate information for pressure ulcers.

Methods:

Epistemonikos, MEDLINE, NHS Economic Evaluation Database, and the Canadian Agency for Drugs and Technologies in Health (CADTH) website will be searched for relevant systematic reviews from inception and without any language restrictions. Titles and abstracts will be screened at the initial stage, followed by full-text screening. Quality assessment will be done using the standard JBI critical appraisal instrument for systematic reviews and research syntheses. Article screening, data extraction, and quality assessment will be performed by two reviewers independently. All economic health outcomes will be considered under the primary outcomes of the study.

Systematic review registration number:

Open Science Framework (https://osf.io/9y2a7/).
Geometrical Non-Linear Periodic Vibration of Plates
Authors: Petyt M. , Ribeiro P.
Published: November 2021

Periodic, geometrically non-linear free and steady-state forced vibrations of fully clamped plates are investigated. The hierarchical finite element method (HFEM) and the harmonic balance method are used to derive the equations of motion in the frequency domain, which are solved by a continuation method. It is demonstrated that the HFEM requires far fewer degrees of freedom than the h-version of the FEM. Internal resonances due to modal coupling between modes with resonance frequencies related by a rational number, are discovered. In free vibration, internal resonances cause a very significant variation of the mode shape during the period of vibration. A similar behaviour is observed in steady-state forced vibration. The stability of the steady-state solutions is studied by Floquet’s theory and it is shown that stable multi-modal solutions occur.
View Through the Door of the Sofia Project by a Reliability Engineer
Authors: Frank Michael V.
Published: November 2021

The National Aeronautics and Space Administration (NASA) and Deutsches Zentrum Für Luft- und Raumfahrt (DLR) e. V. are working together to create a Stratospheric Observatory for Infrared Astronomy (SOFIA). One of the key elements of the modification of the Boeing 747-SP aircraft to be used is a new door system that both protects the infrared telescope during flight by covering the aircraft cavity within which the telescope resides and following the telescopes motion to provided an unvignetted view of the sky. The intentions of this paper are: describe the value added by a productive interaction of reliability engineering with the integrated product design team at NASA Ames Research Center which is responsible for design of this “cavity door” system; to point out key reliability improvement strategies applied to the cavity door system; and to offer a few principles to guide interaction of reliability engineers with a design team.
Knowledge Transfer for Emerging Work Paradigms
Authors: Sturdivant Maggie , Carnes Earl
Published: November 2021

Department of Energy (DOE) missions include scientific research and development, nuclear weapons stockpile stewardship, and cleanup of the environmental legacy from weapons production. Since the cold war’s end, changes in mission focus have placed considerable attention on the standards for performing work. For activities where risk is understood, the work force’s collective experience is codified in standards. For activities with unconventional risks, good practices and individual experience communicate what is known at the edge of technology and consensus Standards. This paper describes the basis for a Procedures standard, a principles-based enterprise approach for knowledge transfer that supports the unique missions of DOE.
Web-Based Risk and Hazard Identification and Screening
Authors: Steele John L. , Bonano Evaristo J.
Published: November 2021

Organizations, both in the private and public sector, need to avoid to the extent practicable, workplace hazards and minimize the associated risks in order to comply with regulations. However, they have also recognized that this is a sound business practice that could result in significant cost savings by avoiding fines and penalties due to non-compliance and enhanced productivity. Consequently, many organizations have instituted safe work practices into their operations and those practices have become a major criterion in evaluating managers’ performance. This new philosophy is now commonly referred to as “Integrated Safety Management.”

Per the direction of the Secretary of Energy, all U. S. Department of Energy (“DOE”) facilities across the country have been instructed to implement an Integrated Safety Management System. Different DOE facilities have taken various approaches to the implementation of the system.

This paper describes the approach instituted at Sandia National Laboratories and a tool that was developed from lessons learned during that effort. The tool is the cornerstone for implementing an Integrated Safety Management System in a time and cost-effective manner. The tool is now commercially available and can be readily rendered applicable to any type of systematic assessment process.
Integration of Safety, Health, and Ergonomic Issues Into the Undergraduate Mechanical Engineering Curriculum
Authors: Bloswick Donald S. , Elliott Charles B. , Jones Kimberli
Published: November 2021

Course modules which include an introduction to safety, health and environmental issues and concerns are being developed for the undergraduate mechanical engineering curriculum. In addition a reference matrix is being prepared which includes list of available problem sets and case studies cross referenced to relevant undergraduate mechanical engineering courses. This information will be made available in electronic and web-based format for interested parties.
Semantic Knowledge for Manufacturing Systems
Authors: Tsourikov Val , Batchilo Leo , Devoino Igor
Published: November 2021

The process of extracting technical knowledge from the text of documents is considered. The results are represented as Subject-Action-Object (SAO) concepts. The SAOs are used for searching large databases and organizing relevant knowledge in problem-solution format (www.cobrain.com), for automatically building function models from documents, for revealing cause-effect relationships from the text and for other applications. As a result, the manufacturing processes can be improved and optimized.
RF-Switches in MEMS Technology for the Integration in Communication Applications
Authors: Michaelis Sven , Ploetz Florian , Aigner Robert , Timme Hans-Joerg , Binder Josef , Noe Reinhold
Published: November 2021

A new type of rf-switch for use in communication applications is presented in this paper. These switches can be used for purposes such as antenna selection (transmitter / receiver) or for the filter-path selection in multi-band communication systems.

The design of the switch is based on a torsion-type model with two switch contacts for a dual-mode switching operation. The mechanical operation is performed by electrostatic actuation with switching voltages in the range of 10V. The device is manufactured in a standard CMOS production line with a specialized micromachining process.

Initial samples of the switch have been tested successfully.
A Hybrid Pneumatic/Electrostatic Milli-Actuator
Authors: Chiang Kenneth H. , Fearing Ronald S.
Published: November 2021

In typical MEMS applications, actuation is accomplished directly by converting electrical input power to useful mechanical power. However, indirect schemes employing electrically driven primary and alternately driven secondary actuators can trade simplicity and bandwidth for lower forces and strokes in the primary actuator, hence reducing power consumption.

Because it is generally easier to build actuators with high force and low stroke, we propose a hybrid actuator with a pneumatic oscillator as the secondary and an electrostatic clamp as the primary. By clamping the oscillator at its extremes of travel, the hybrid actuator can be turned on and off.

In this paper, we report on progress towards fabricating such a hybrid actuator. We have demonstrated operation of a 40×40×30 mm3 oscillator at 6 Hz with a stroke of 2.5 mm and a peak force of 1.1 N, although fabrication of the electrostatic clamp has not been accomplished.
Residual Stress Effect on Performance of Diaphragm-Based MEMS Pressure Transducers
Authors: Niu Meng-Nian , Kim Eun Sok
Published: November 2021

We experimentally and theoretically confirm that residual stress within a diaphragm is critical in limiting the performance of diaphragm-based piezoelectric microphones even if the stress is low (around 50 MPa). We have fabricated and studied microphones with Al/parylene/ZnO/SiN2/poly-Si/SiN1 (from top to bottom) diaphragm. As the SiN1 supporting layer is removed layer by layer from the backside with CF4 plasma (in an RIE system), we measure both the sensitivity and center displacement of the microphone before and after each RIE etching of the SiN1 from the microphone diaphragm, and find the sensitivity increasing about 5–16 times with the best sensitivity reaching 11 μV/μbar from a mere 0.6 μV/μbar. The center displacement increases very moderately as the SiN1 layer thickness decreases from 0.8 to 0.2 μm. However, the center displacement starts to increase greatly as the SiN1 layer thickness goes below 0.2 μm, which compares with our theoretical analysis well. In the case of the SiN1 layer having compressive residual stress, the compressive stress can enhance the microphone sensitivity and center displacement to a certain extent.
Silicon Micromachined Fiber-Optic Pressure Sensor
Authors: Vujanic Aleksandar , Adamovic Nadja
Published: November 2021

In this paper, we present a fiber optic pressure sensor capable for operation in critical environments. Special attention is given to the sensor design, so that the sensor fabrication is as simple as possible and can be accomplished using standard micromachining processes (wet etching of silicon). Presented pressure sensor employs the principle of light intensity modulation induced by bending of a membrane with boss. Under the influence of pressure a sidewall of boss screens certain area of the fiber-end and modulates the reflected optical signal.

A number of design specialties and novel ideas for overcoming the limitations of standard wet etching of silicon are presented. The used fabrication procedure enables, with slight modification of the etching time, fabrication of sensors applicable for measuring various pressure ranges.
Design, Modeling, and Testing of Micromachined Piezoelectric Clamped-Clamped Beam Resonators
Authors: Piekarski Brett , DeVoe Don L. , Kaul Roger , Dubey Madan
Published: November 2021

The design, modeling, and performance of suspended piezoelectric clamped-clamped single-beam micro electro mechanical system (MEMS) resonators is reported. Resonators with frequencies between 171 kHz and 9.2 MHz have been fabricated, tested and compared to finite element and exact solution models. Resonator designs vary from 6- to 20-μm wide and 25- to 400-μm long. A model describing the electromechanical performance of the resonators is presented. Operation is demonstrated from a vacuum pressure of 20-mTorr to atmospheric with drive voltages as low as 2.5 mV and a dynamic range of greater than 40 dB. Devices exhibit loaded quality factors (Qs) greater than 1000 at a vacuum pressure of 20-mTorr.
Anodic Alumina MEMS: Applications and Devices
Authors: Govyadinov Alexander , Mardilovich Peter , Novogradecz Kathy , Hooker Stephanie , Routkevitch Dmitri
Published: November 2021

Hybrid micromachining of anodic alumina films was shown to be a promising technology for creating ceramic MEMS for harsh application environments. By combining features of both bulk and surface micromachining, this technology offers flexibility in design and tremendous application opportunities. This paper will overview the authors’ work on application development of micromachined anodic alumina, with the main focus on gas microsensors, vacuum microelectronics, and high aspect ratio MEMS.
Measurement and Modeling of the Flow Characteristics of Micro Disc Valves
Authors: Carretero J. A. , Breuer K. S.
Published: November 2021

The head losses in microfluidic systems such as micropumps are dominated by losses in microvalves, where microfabrication constraints limit significantly possible microvalve designs. This makes them quite different from conventional valves. In particular, flow characteristics in the laminar and low-Reynolds turbulent regimes are not understood clearly, and detailed information about the flow losses is lacking. This paper addresses this issue by using a scaled-up (10:1) valve experiment to measure pressure losses in typical microfabricated valve geometries. The macroscale model is fully instrumented and discharge coefficients and sensitivities to stroke, seat width and Reynolds number are presented.
A Study on the Interaction Force Between Two Small Bodies on a Liquid for Micro Self Assembly and Separation
Authors: Saif Taher
Published: November 2021

The paper presents a detailed study of the mechanism by which a MEMS plate forms a meniscus with a liquid, and the corresponding solid-liquid interaction force. The study is than extended to investigate the interaction force between two small thin plates forming meniscii with a liquid. It is shown that the force is attractive for similar meniscii and repulsive for opposite meniscii. If the meniscii are of the same type but not identical (e.g., one solid makes a steeper meniscus than the other) then the force is attractive at long distances, repulsive at shorter distances, with a stable equilibrium at a finite distance between the solids. The study reveals that MEMS (hydrophilic or phobic) can probe objects in a liquid without inundating themselves. Furthermore, capillary forces can be harnessed to self assemble or separate small solids (micro chips or living cells) on a liquid surface non-invasively.
Design and Analysis of a Preconcentrator for the μChemLab™
Authors: Wong C. Channy , Flemming Jeb H. , Manginell Ronald P. , Kottenstette Richard J. , Frye-Mason Gregory C.
Published: November 2021

Preconcentration is a critical analytical procedure when designing a microsystem for trace chemical detection, because it can purify a sample mixture and boost the small analyte concentration to a much higher level allowing a better analysis. This paper describes the development of a micro-fabricated planar preconcentrator for the μChemLab™ at Sandia. To guide the design, an analytical model to predict the analyte transport, adsorption and desorption process in the preconcentrator has been developed. Experiments have also been conducted to analyze the adsorption and desorption process and to validate the model. This combined effort of modeling, simulation, and testing has led us to build a reliable, efficient preconcentrator with good performance.
Atomistic and Continuum Computational Approaches at NRL for MEMS Device Analysis
Authors: Sandberg William C.
Published: November 2021

The computational approaches needed for analysis of the operation of MEMS devices can include quantum mechanical methods, atomistic molecular dynamics (MD) methods, molecular mechanics (MM), Direct Simulation Monte Carlo (DSMC), continuum fluid and solid mechanics, and on up to parametric representations. The length and time scales of the phenomena being studied dictates the selection of the appropriate computational approach, or, in some cases, the combination of approaches. A number of these computational approaches are being applied at the Naval Research Laboratory to analyze the performance of a variety of MEMS devices. Examples of a number of specific MEMS component analyses that have been carried out are discussed. Possible future applications for the MEMS computational technology are also presented.
Behavior of a MOEMS Package (TI DMD™) Under Mechanical and Thermal Loads
Authors: Variyam Manjula N.
Published: November 2021

The Digital Micromirror Device (DMD™), developed by Texas Instruments is a key player in the digital projection arena. The packaging requirements of this device are different from those of standard integrated circuits. The current paper focuses on understanding the DMD™ package structural behavior under thermal and mechanical loads through finite element modeling. Package stress conditions were quantified using a metric that accounted for both peel and shear stress. Analysis showed that the package was highly sensitive to mechanical load magnitude and distribution. The results identified dominant failure modes and provided direction for developing new design verification tests needed to qualify the package design.
Prototyping and Testing Methods for Electrostriction of Actuators for a Mesoscale Compressor
Authors: Trujillo R. , Mou J. , Phelan P. E. , Chau D. S.
Published: November 2021

A design of a prototype mesoscale compressor using electrostriction of polymers as a way of actuation is described. In this application, electrostrictive polymers (EP) are squeezed and stretched by electrostatic forces generated by a high voltage applied via thin-film Au electrodes. This paper compares the results of several experiments performed on silicone materials based on Dow Corning Sylgard 182 and 184. The silicone films are prepared by mixing Sylgard 182 or 184 with curing agents in a weight ratio of 10:1. Some samples are tested in a flat configuration, while others are rolled together to form a tube actuator. This actuator is placed inside a glass tube and sealed on one end to form a mesoscale compressor. The tests on electrode thickness show that the thinner the electrode, the greater the displacement. Greater strain can be achieved by making thinner silicone films. The pressure achieved is only on the order of 1 kPa, but significantly greater pressures are anticipated if sealing losses can be reduced.
A User’s Perspective: Packaging Achieves Test Affordability
Authors: Liu Wayne P.
Published: November 2021

Sensor performance and cost are typically the main features reviewed by potential users of MEMS sensor applications. However with more options becoming available, experienced users will begin to consider more than just performance and hardware cost and will seek packaging features which reduce the effort needed to set up, calibrate and successfully operate MEMS sensor systems. A reduction in the cost of effort needed to collect good data will impact test affordability. Data from MEMS shear stress testing on cylinder boundary layer and separation bubble features will be presented to show how packaging can affect both performance and affordability. Manufacturers should ask: What is remembered the most at the conclusion of a MEMS application, the cost of hardware or the cost of effort required to collect good data?
Program Assessment: Equivalency and Credentials for the Global Marketplace
Authors: Phillips Winfred M.
Published: November 2021

Great engineering achievements, from the Aqueducts of Rome and Hausman’s Sewer System for Paris to the Boeing 757 and the Space Shuttle, have always benefitted from international influence and content. The reliability of engineering structures and systems has always engendered the confidence of international users. U.S. citizens drive European automobiles with confidence and Europeans drive across U.S. bridges without pause. Today, international content is extensive, often formalized and regulated and a permanent part of tomorrow’s engineering. Engineers both participate in their profession worldwide and evaluate and accommodate international content at home. Multinational companies demand multinational engineering practice. “Credentials without borders” is desired. Accreditation is key to quality assurance.
Constitutive Modeling of Multiaxial Deformation and Induced Anisotropy in Superplastic Materials
Authors: Khraisheh Marwan K.
Published: November 2021

The multiaxial deformation of superplastic materials is modeled within a continuum theory of viscoplasticity using a generalized anisotropic dynamic yield function. The anisotropic dynamic yield function is capable of describing the evolution of the initial anisotropic state of the yield potential through the evolution of unit vectors defining the direction of anisotropy. The evolution of the direction of anisotropy is represented by a constitutive spin such that initially it is identical to the Eulerian spin and as deformation continues, it tends towards an orthotropic spin. Experiments on the model Pb-Sn alloy were conducted and used to calibrate and verify the constructed model. It is shown that the model in conjunction with the anisotropic dynamic yield function is capable of predicting the actual trend of the induced axial stresses recorded in fixed-end torsion experiments.
Using Modeling and Simulation to Evaluate Traction of Track Vehicles
Authors: Gunter David D. , Letherwood Michael D.
Published: November 2021

The US Army Tank-automotive and Armaments Command (TACOM) has the mission of procuring and managing the US Army’s fleet of wheeled and tracked vehicles. TACOM’s Tank Automotive Research, Development and Engineering Center (TARDEC) provides engineering and scientific support directed at maximizing the capability of all Department of Defense (DOD) ground vehicle systems and ensuring the safety of their personnel.

In order to reduce the time required to deploy troops and equipment, engineers and scientists at TARDEC have been investigating modifications to ground vehicles that lead to overall increases in performance, especially in the areas of off-road mobility, and on-road stability and handling. This paper describes an effort to assess the dynamic performance of a track laying (tracked) Recovery Vehicle towing a disabled tracked vehicle whose weight is approximately equal to that of the Recovery Vehicle. Specifically, this paper will describe techniques employed to develop a 3-dimensional dynamic model of the vehicle combination, and apply the model to evaluate towing performance of the recovery vehicle. It also describes measures aimed at minimizing incidences of jackknifing when braking on downhill slopes, as well as vehicle design modifications that were modeled and simulated in efforts to reduce the combination’s jackknife vulnerability. These modifications included tow bar schemes that locked-out inter-vehicle yaw, and external surge brakes mounted on the towed vehicle. Techniques used to model and simulate the tractive effort available to the Recovery Vehicle on varied soil types are described as are analyses used to determine the combination’s ability to climb grades. Vehicle modifications aimed at increasing the tractive effort available, such as tow bar pitch orientation and track shoe geometry changes are also described.
Twisting Moment of a Non-Rolling Tire
Authors: Gofron Marian
Published: November 2021

The steering system is a key element in the determination of vehicle performance. The steering force of a vehicle depends upon the steering system geometry and the interaction between the tires and the ground. Maximum steering force usually occurs when the vehicle is not moving and an attempt is made to steer the wheels lock to lock. During the process of designing a steering system, the steering force is often determined by laboratory experiments or simple calculations. This paper presents formulas that can be used to determine tire-twisting moment when the tire is not rotating. The formula considers the elastic and the frictional effect of the tire, the effect of steering direction, and footprint size on the tire twisting moment. A computer program utilizing these formulas can be written to determine the steering force for any steering linkage member for a stationary vehicle.
Modeling, Analysis, and Experimental Testing of ABS Systems With Load Shifting
Authors: Mills Val , Samuels Bernard , Wagner John , Smith James , Layton Richard
Published: November 2021

The steerability and stability of vehicles must be maintained during emergency stopping and evasive driving maneuvers on degraded roads. The introduction of antilock brake and traction control systems has expanded the envelope of safe vehicle operation. ABS development has traditionally depended on extensive in-vehicle testing, at proving grounds, which contribute to lengthy product development cycles. However, recent attention has focused on laboratory wheel testers and hardware-in-the-loop strategies to emulate test conditions in a controlled setting to shorten product design time and address critical safety issues. In this paper, the effect of transient load shifting due to cargo movement on ABS system performance will be studied. Analytical and empirical mathematical models are presented to describe the chassis, tire/road interface, wheel, and brake modulator dynamics. These models have been integrated into a simulation to allow the study of transient weight transfers on the vehicle’s overall stopping distance and steerability. Experimental test results will be gathered on a single wheel tester which has been fabricated. The analysis of the numerical and experimental results will allow the ABS system performance to be predicted for various loading conditions and establish an envelope for safety critical testing during the product development process.
Validation of a New Closure Model for Flow-Induced Alignment of Fibers
Authors: Imhoff A. , Parks S. , Petty C. , Bénard A.
Published: November 2021

A closure model for flow-induced orientation of short fibers is presented and discussed. The model retains all the six-fold symmetry and contraction properties of the fourth order tensor. A derivation of the model is presented and the conditions required for the model to be realizable are discussed. The model is validated against analytical and numerical solutions of the exact distribution function for the fiber orientation state for different flow fields. Variations of this model and its limitations are also discussed.
Higher Order Singularities and Their Energetics in Elastic-Plastic Fracture
Authors: Im Seyoung , Jeon Insu
Published: November 2021

The higher order singularities[1] are systematically examined, and discussed are their complementarity relation with the nonsingular eigenfunctions and their relations to the configurational forces like J-integral and M-integral. By use of the so-called two state conservation laws[2] or interaction energy, originally proposed by Eshelby[3] and later treated by Chen and Shield[4], the intensities of the higher order singularities are calculated, and their roles in elastic-plastic fracture are investigated. Numerical examples are presented for illustration.
Probabilistic Failure Analysis for Composite Laminates
Authors: Herrington Paul D. , Schilling Paul J.
Published: November 2021

Considering the increasing applications of composites as structural components, the reliability of these materials is an important issue. Given the inherent variability of the material properties of composites, a probabilistic approach to the design of these materials is required. In this paper, the first-order second-moment method, coupled with the Tsai-Wu interactive failure criterion, is used to determine the reliability of composite laminates under various plane stress conditions. Uncertainty in material and loading parameters are considered. The method considered requires only the first two moments of the basic variables as input. This factor, along with its ease of use, makes this technique attractive to designers. Numerical examples, along with plots of the effect of coefficient of variation on the safety index, are given for a typical glass/epoxy composite.
Advances in Air-Cooled Heat Exchanger Technology
Authors: Webb Ralph L.
Published: November 2021

This paper describes the author’s current and recent work on advanced technology concepts applied to air cooled heat exchangers. The concepts are applicable to: 1) Automotive heat exchangers (radiators, air-conditioning condensers and evaporators, and charge-air coolers), and 2) Residential air-conditioning.
Theoretical Modeling of Ice Formation Using Direct Contact Heat Exchange
Authors: Chau David S. , Phelan Patrick E. , Wood Byard D.
Published: November 2021

Theoretical modeling of a column type of direct contact heat exchanger was performed to predict the refrigerant evaporation and ice formation processes. There are a number of factors influencing the heat transfer rate-dependent evaporation of refrigerant and formation of ice. Among these are the size of the refrigerant droplets as injected, the local temperature and pressure, the heat transfer coefficient, and the temperature difference between the fluids. Differential equations are written for a general location in the flow, which express the conservation of energy and mass for the various species in the multiphase flow. The equations are solved stepwise from the initial injection location of the refrigerant to the location at which the entire refrigerant has become vapor. The theoretical modeling of the refrigerant evaporation and ice crystal growth processes is performed to determine the refrigerant bubble growth rate and the ice crystal growth rate in order to predict the refrigerant evaporation time and the size of the ice crystals.
Transient Modeling Results of a Methane-Steam Prereformer
Authors: Liese Eric A. , Gemmen Randall S.
Published: November 2021

A transient model for an external, counter-flow heat exchange, methane-steam reformer was presented previously (Liese et. al., 1999). In the present paper, a similar model is developed to simulate a simple tube geometry prereformer with no external heat addition. Model results are presented. First, a steady state analysis is shown for two prereformer geometries of equal catalyst volumes and residence time, but different superficial velocities. Second, common assumptions about the catalyst particle surface temperature are discussed, and a quasi-steady calculation of the particle surface temperature is presented. Startup and flow transients are shown for catalysts of low and high conductivites, and comparisons are made.
Discussion and Analysis of Flue Gas Utilization in a Phosphoric Acid Fuel Cell Engine During Idle Operation
Authors: Betts Daniel A. , Roan Vernon P. , Fletcher James H.
Published: November 2021

Fuel cell technology has in recent years won the favor of all major car manufacturers as a likely future replacement of the internal combustion engine. This has been driven by the potential for high efficiency and low emissions. Still, fuel cell engines must overcome major hurdles before being introduced into the market. One such hurdle is systems integration; in particular with fuel cell engines that do not use hydrogen as their primary fuel. In these engines, fuels, such as methanol, are employed instead of hydrogen because of their high energy density and ease of storage. However, these benefits are counterbalanced by the need to reform these fuels on-board the fuel cell vehicle, thus substantially increasing the complexity of the fuel cell engine.

Through the course of operating a 30ft methanol-fueled phosphoric acid fuel cell bus, repeated overheating of the steam-reformer catalyst bed at low engine power outputs was noted. For the purpose of better understanding these overheating events, relevant data was obtained from the bus. Bus operation at low power outputs was found to have low hydrogen consumption (∼40% to ∼60% of the stack’s incoming hydrogen) due to low electrical demands and reformate flow rate constraints. In the bus, the anode flue gas is burned in the reformer burner, which provides the heat required for the endothermic methanol steam reforming reaction (see fig.1). At low engine power, the flue gas is the reformer burner’s only fuel, but the energy carried by the flue gas is much greater than the energy required for the reforming reaction and consequently causes reformer overheating at low power.

This case serves as an example of how appropriate fuel cell system integration is crucial in order to harness fuel cell benefits. To study such system integration problems a steady state model of the fuel cell bus engine was developed. Using this model the bus reformer overheating problem was understood and several possible improvements for utilization of the flue gas were conceited.