bluuebunny/crossref_metadata_2025 huggingface dataset:
Intergenerational cardiovascular disease risks among Hispanics living in the United States
Authors: Kobayashi Marissa A. , Lee Tae K. , St. George Sara M. , Lebron Cynthia , Dorcius David , Prado Guillermo , Messiah Sarah E.
Published: November 2021

Background

Few studies have assessed intergenerational associations of obesity and cardiovascular disease risks from parents to their children among Hispanic Americans.

Objectives

To assess intergenerational cardiovascular associations among Hispanic families.

Methods

Using baseline data from an obesity‐focused efficacy trial targeting Hispanic adolescents (n = 280) and their parents, we conducted a series of logistic regression analyses to investigate the effects of parental BMI and blood pressure on adolescents' BMI and blood pressure, respectively.

Results

After adjusting for significant socio‐demographic variables and adolescents' lifestyle behaviours, adolescents were more than twice as likely to be in the severely obese versus overweight range when their parents had obesity (vs. non‐obese; OR = 2.55, 95% CI = 1.20, 5.39) and more than twice as likely to be in the severely obese versus obese weight range (OR = 2.44, 95% CI = 1.22, 4.87) when their parents had obesity. When compared to those with normal blood pressure, adolescents who had parents with elevated blood pressure/hypertension were more than twice as likely to have elevated blood pressure (OR = 2.05, 95% CI = 1.04, 4.00) or be classified as hypertensive stage 1/2 (OR = 2.81, 95% CI = 1.31, 6.01).

Conclusions

Both severe obesity and elevated blood pressure are highly associated among Hispanic parent–child dyads. Findings underscore the potential benefits of intervening with the family system.
Trends in seroprevalence of SARS‐CoV‐2 and infection fatality rate in the Norwegian population through the first year of the COVID‐19 pandemic
Authors: Tunheim Gro , Rø Gunnar Øyvind Isaksson , Tran Trung , Kran Anne‐Marte Bakken , Andersen Jan Terje , Vaage Eline Benno , Kolderup Anette , Vaage John Torgils , Lund‐Johansen Fridtjof , Hungnes Olav
Published: November 2021

Background

Infection with the novel coronavirus SARS‐CoV‐2 induces antibodies that can be used as a proxy for COVID‐19. We present a repeated nationwide cross‐sectional study assessing the seroprevalence of SARS‐CoV‐2, the infection fatality rate (IFR), and infection hospitalization rate (IHR) during the first year of the pandemic in Norway.

Methods

Residual serum samples were solicited in April/May 2020 (Round 1), in July/August 2020 (Round 2) and in January 2021 (Round 3). Antibodies against SARS‐CoV‐2 were measured using a flow cytometer‐based assay. Aggregate data on confirmed cases, COVID‐19‐associated deaths and hospitalizations were obtained from the Emergency preparedness registry for COVID‐19 (Beredt C19), and the seroprevalence estimates were used to estimate IFR and IHR.

Results

Antibodies against SARS‐CoV‐2 were measured in 4840 samples. The estimated seroprevalence increased from 0.8% (95% credible interval [CrI] 0.4%–1.3%) after the first wave of the pandemic (Rounds 1 and 2 combined) to 3.2% (95% CrI 2.3%–4.2%) (Round 3). The IFR and IHR were higher in the first wave than in the second wave and increased with age. The IFR was 0.2% (95% CrI 0.1%–0.3%), and IHR was 0.9% (95% CrI 0.6%–1.5%) for the second wave.

Conclusions

The seroprevalence estimates show a cumulative increase of SARS‐CoV‐2 infections over time in the Norwegian population and suggest some under‐recording of confirmed cases. The IFR and IHR were low, corresponding to the relatively low number of COVID‐19‐associated deaths and hospitalizations in Norway. Most of the Norwegian population was still susceptible to SARS‐CoV‐2 infection after the first year of the pandemic.
Hardness and toughness improvement of SiC‐based ceramics with the addition of (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2
Authors: Yuan Jin‐Hao , Guo Wei‐Ming , Liu Yang , Sun Shi‐Kuan , Duan Xiao‐Ming , Jia De‐Chang , Lin Hua‐Tay
Published: November 2021

The influences of different contents ranging 0–15 wt% of high‐entropy boride (HEB) (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2 on the mechanical properties of SiC‐based ceramics using Al2O3‐Y2O3 sintering additives sintered by spark plasma sintering process were investigated in this study. The results showed that the introduction of 5 and 10 wt% (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2 could facilitate the densification and the grain growth of SiC‐based ceramics via the mechanism of liquid phase sintering. However, the grain growth of SiC‐based ceramics was inhibited by the grain boundary pinning effect with the addition of 15 wt% (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2. The SiC‐based ceramics with 15 wt% (Hf0.2Mo0.2Ta0.2Nb0.2Ti0.2)B2 showed the enhanced hardness (21.9±0.7 GPa) and high toughness (4.88±0.88 MPa·m1/2) as compared with high‐entropy phase‐free SiC‐based ceramics, which exhibited a hardness of 16.6 GPa and toughness of 3.10 MPa·m1/2. The enhancement in mechanical properties was attributed to the addition of higher hardness of HEB phase, crack deflection toughening mechanism, and presence of residual stress due to the mismatch of coefficient of thermal expansion.
In‐flash immersion‐and‐quench of yttria‐stabilized zirconia into liquid nitrogen yields an electronic conductor
Authors: Kathiria Rushi K. , Jo Seohyeon , Raj Rishi , Yadav Devinder
Published: November 2021

It is known that once flash has been triggered with furnace heating, specimens can be held in the state of constant flash, or Stage III, outside the furnace at ambient temperature. The flash is maintained by the current flowing through the specimen. We show that this in‐flash state is further preserved when the specimen is immersed into liquid nitrogen. Furthermore, we show that the nature of the material existing in Stage III can be quenched by turning off the power to the specimen while it is still in immersion. Normally, during furnace cool, the specimens revert to their original state when the flash is turned off. However, yttria‐stabilized zirconia retrieved from in‐flash immersion‐and‐quench is discovered to be electronically conductive at room temperature, at approximately 11 S/m. The conductivity declines somewhat when the specimen is heated slightly above room temperature, suggesting metal‐like behavior. These in‐flash immersed specimens, with their Stage III structure frozen in place, will enable ex‐situ characterization of changes in the crystallographic, chemical, defect and electronic structure induced by flash activation.
Flood susceptibility assessment for ungauged sites in urban areas using spatial modeling
Authors: Masoumi Zohreh
Published: November 2021

In urban areas, flood susceptibility assessment is of special importance because of the high settlement population, properties, and infrastructures. Geospatial information science (GIS) provides a tool for investigating flood susceptibility based on several aspects including economic damages and critical infrastructures in cities. This study aims to provide a tool based on GIS analyses to support decision‐makers in identifying flood hazards in urban areas, in which previous flood data, flood causative factors, and urban infrastructure data are not adequately available. To assess flood susceptibility in the study area, the related spatial high‐resolution data were produced. Then, flood zones were estimated for different recurrence intervals using meteorological data. Finally, susceptibility was assessed in urban areas for different urban infrastructures using GIS modeling. The model was designed based on the assumption that any critical urban infrastructure, such as power towers, was affected by flood zones and, in addition to flooding, could cause hazards by itself. Moreover, five scenarios were defined to calculate susceptibility when in the problematic locations of the floodway. DoAsb Floodway was chosen as a case study located in Zanjan city, northwest of Iran. The results indicated the high‐susceptible areas around the floodway. Moreover, the flood susceptibility level for each urban infrastructure in the study area was calculated and classified into five classes from low susceptible to very high susceptible. Also, the results of the five scenarios showed if some parts of the floodway had problems, the susceptibility rate would be high. The generated flood susceptibility maps of this model can be used to plan suitable programs in order to avoid flood damage and ensure public safety.
Interprofessional geriatric and palliative care intervention associated with fewer hospital days
Authors: Min Lillian , Saul D'Anna , Firn Janice , Chang Robert , Wiggins Jocelyn , Khateeb Rafina
Published: November 2021

Background

With increasing complexity of our aging inpatient population, we implemented an interprofessional geriatric and palliative care intervention on a hospitalist service. This study aimed to measure the intervention's impact on length of stay (LOS), 30‐day readmission, and the daily intensity of inpatient services utilization.

Methods

Using a nonrandomized controlled intervention at a 1000‐bed U.S. academic quaternary medical center, we studied 13,941 individuals admitted to a general medicine hospitalist service (of which 5644 were age > =65 years); 1483 were on intervention teams (576 age > =65 years), 5413 concurrent controls, and 7045 historical controls. On 2 of 11 hospitalist teams, a geriatrician, palliative care physician and social worker attended multidisciplinary discharge rounds twice weekly, to recommend inpatient geriatric or palliative care consult (GPCC), postacute nursing or home care, versus postdischarge outpatient consultation. We measured the difference in improvement over time between intervention and control team patients for the following: (1) LOS adjusted for case‐mix index, (2) 30‐day readmissions, and (3) intensity of hospital service utilization (mean services provided per patient per day).

Results

Adjusted LOS (in hospital days) was decreased by 0.36 days (p = 0.039) for the 1483 patients in the intervention teams, with greater LOS reduction of 0.55 days per admission (p = 0.022) on average among the subset of 576 older patient admissions. Readmissions were unchanged (−1.17%, p = 0.48 for all patients; 1.91%, p = 0.46 for older patients). However, the daily relative value unit (RVU) utilization was modestly increased for both the overall and older subgroup, 0.35 RVUs (p = 0.041) and 0.74 RVUs (p < 0.001) per patient‐day on average across the intervention teams, respectively.

Conclusion

An interprofessional intervention of geriatric and palliative care consultation in collaboration with a hospitalist service may reduce LOS, especially for geriatric patients, without an increase in readmissions. This model may have broader implications for hospital care and should be further studied.
Lubrication study of representative fluid foods between mimicked oral surfaces
Authors: Xu Wenhu , Xu Qixiang , Zhong Min
Published: November 2021

The lubricities of glycerol solutions with different viscosities were investigated at various frictional pairs, speeds, and loads to explore the lubrication regulations of diverse foods in mouths of different people. The friction pairs were characterized in terms of mechanical properties, surface morphology, and hydrophobicity. The results showed that the partial or complete Stribeck curves occurred with different speeds and viscosities. Various friction pairs had great influences on the boundary lubrication zone, but little influences on the elastohydrodynamic lubrication (EHL) zone. Increasing loads caused the friction coefficient decreasing in boundary lubrication zone; however, the friction coefficient changed a little in the mixed lubrication and EHL zones.
Advances in the diagnosis of acute pancreatitis in dogs
Authors: Cridge Harry , Twedt David C. , Marolf Angela J. , Sharkey Leslie C. , Steiner Jörg M.
Published: November 2021

In the last 20 years, the diagnosis of pancreatitis has become more frequent as a result of improved diagnostic modalities such as abdominal ultrasound examination, advanced imaging, and immunoassays for the measurement of pancreatic lipase. Our aim is to provide a state‐of‐the‐art overview of the clinical diagnosis of acute pancreatitis (AP) in dogs with a particular focus on pancreatic lipase assay validation and clinical performance, in addition to advanced imaging modalities. We also discuss the potential indications for cytology and histopathology in dogs with suspected AP.
Monetary rewards in employee referral programs
Authors: Ekinci Emre
Published: November 2021

This paper examines the conditions under which employee referrals serve as a screening function when there is a conflict of interest between the firm and the current employees concerning referral recruitment. In particular, I consider two potential mechanisms that lead to a conflict of interest: the employee’s social connection with the applicant and her promotion prospects. Specifically, I posit that the employee will have an incentive to refer low‐ability applicants if she has a strong social connection with them or if she faces the possibility of competing against her own referral to earn a promotion at the firm. Taking these potential sources for conflicting interests, I investigate the extent to which the firm can make use of financial incentives (fixed fees and bonuses) to align incentives of the employee with those of the firm.
Anterior Cervical Discectomy and Fusion Combined with Foraminotomy Assisted by High‐Definition 3‐Dimensional Exoscope in the Treatment of Cervical Spondylotic Radiculopathy Secondary to Bony Foraminal Stenosis
Authors: Bai Lu Lu , Wang Wen Tao , Wang Jian Feng , Du Jin Peng , Xue Xu Kai , Hao Ding Jun
Published: November 2021

Objective

To evaluate the outcomes of cervical spondylotic radiculopathy secondary to bony foraminal stenosis treated with anterior cervical discectomy and fusion (ACDF) combined with anterior cervical foraminotomy (ACF) assisted by High‐Definition 3‐Dimensional Exoscope.

Methods

In this retrospective study, a total of 19 consecutive patients (12 males and seven females, with an average of 49.2 years, range from 40 to 59 years) with spondylotic radiculopathy caused by bony foraminal stenosis underwent ACDF combined with ACF assisted by High‐Definition 3‐Dimensional Exoscope in our hospital between January 2019 and December 2019 were included in this study. All patients signed the consent form before the surgery. The patient baseline information such as gender, age, body mass index (BMI), surgery time, blood loss, hospital stay, lesion segment, side, follow‐up time and postoperative complications were recorded. The Japanese Orthopedic Association (JOA), Neck Disability Index (NDI), and Visual Analogue Scale (VAS) were measured and compared before surgery, 1 months and final follow‐up after surgery. The radiographic outcomes were evaluated using the C2‐C7 angel, disc height, foraminal height, superior diagonal distance, inferior diagonal distance, and foraminal area.

Results

The involved levels included C4‐C5 (six cases), C5‐C6 (10 cases), C6‐C7 (three cases). The mean duration of the surgery, mean blood loss, mean hospital stay, and mean follow‐up were 100 ± 11.10 min, 19.4 ± 7.05 mL, 7.1 ± 0.99 days, and 12.1 ± 2.25 months, respectively. The average preoperative JOA score was 11.9 ± 1.31, then improved to 15.7 ± 0.73 (t = −13.45, P < 0.001) and 16.2 ± 0.74 (t = −14.39, P < 0.001) at 1 month after operation and at last follow‐up, respectively. The average preoperative NDI score was 27.3 ± 3.36, then decreased to 5.1 ± 1.79 (t = 20.63, P < 0.001) and 4.5 ± 1.21 (t = 25.53, P < 0.001) 1 month after operation and at last follow‐up, respectively. The average preoperative VAS score was 6.7 ± 0.93, then decreased to 2.4 ± 0.69 (t = 15.05, P < 0.001) and 1.9 ± 0.78 (t = 16.40, P < 0.001) 1 month after operation and at last follow‐up, respectively. As compared with the condition before surgery, there was a significant improvement in the C2‐C7 angel, disc height, foraminal height, and foraminal area (P < 0.05). None of the patients developed postoperative vascular injury, nerve injury, loosening and rupture of the internal fixation, displacement of interbody fusion cage, and pseudarthrosis.

Conclusion

ACDF combined with ACF assisted by High‐Definition 3‐Dimensional Exoscope is effective and safe for the treatment of CSR caused by secondary to bony foraminal stenosis.
Evaluating the Efficacy of Combined P188 Treatment and Surgical Intervention in Preventing Post-Traumatic Osteoarthritis Following a Traumatic Knee Injury
Authors: Narez Gerardo E. , Brown Gabriel , Herrick Ashley , Ek Ryan J. , Dejardin Loic , Wei Feng , Haut Roger C. , Haut Donahue Tammy L.
Published: November 2021

Previous studies have shown that reconstructive surgery alone following injury to the anterior cruciate ligament (ACL) does not prevent the development of post-traumatic osteoarthritis (PTOA). Poloxamer 188 (P188) has been shown to prevent cell death following trauma in both articular cartilage and meniscal tissue. This study aims to test the efficacy of single or multiple administrations of P188 in conjunction with reconstructive surgery to help prevent or delay the onset of the disease. Thirty skeletally mature rabbits underwent closed-joint trauma that resulted in ACL rupture and meniscal damage and were randomly assigned to one of four treatment groups with varying doses of P188. ACL reconstruction was then performed using an autograft from the semitendinosus tendon. Animals were euthanized 1-month following trauma, meniscal tissue was assessed for changes in morphology, mechanical properties, and proteoglycan content. Femurs and tibias were scanned using microcomputed tomography to determine changes in bone quality, architecture, and osteophyte formation. The medial meniscus experienced more damage and a decrease in the instantaneous modulus regardless of treatment group, while P188 treatment tended to limit degenerative changes in the lateral meniscus. Both lateral and medial menisci had documented decreases in the equilibrium modulus and inconsistent changes in proteoglycan content. Minimal changes were documented in the tibias and femurs, with the only significant change being the formation of osteophytes in both bones regardless of treatment group. The data suggest that P188 was able to limit some degenerative changes in the meniscus associated with PTOA and may warrant future studies.
Simulated Environmental Tests for Selected Advanced Technology Fuel Cladding Solutions
Authors: Penttilä Sami , Autio Juha-Matti , Lydman Jari , Toivonen Aki , Peltonen Seppo , Lukin Johanna
Published: November 2021

Current development on advanced technology fuel (ATF) claddings is aiming at improved high temperature integrity of new candidate materials designed on existing zirconium cladding materials. To assess their performance in commercial use, characterization of newly proposed materials is essential. The primary requirement for the cladding materials is the ability to tolerate loss of cooling for a significant period without failing. The tests in this work were performed on different types of coated Zr-alloys in a high temperature steam furnace in flowing steam conditions at 1100 °C for 500 s, 1200 °C for 1800s, and 1300 °C for 300 s. In addition, autoclave exposures were performed in simulated pressurized water reactor (PWR) water chemistry to confirm the material viability in normal light water reactor (LWR) operating conditions. After autoclave and steam furnace tests, exposed specimens were characterized using a Zeiss Crossbeam 540 field emission gun-scanning electron microscope (FEG-SEM) equipped with a semiquantitative energy dispersive X-ray spectrometer (EDS). Oxide and coating layers were imaged using secondary electrons and elemental composition of the layers were determined using selected area (SA) and point analyses. In addition, elemental maps were collected from specific areas of interest. Most of the tested specimens indicated detached coating layer. Varying amounts of cracking in the coating materials were present. Some of the cracks extended even into the base material. Based on this study, further developments of ATF cladding solutions are needed through international collaboration.
Buckling and Post-Buckling of Thin Elastoplastic Cylindrical Shells With Finite Rotations
Authors: Le Grognec Philippe , Le Van Anh
Published: November 2021

An elastoplastic thin shell model is presented in this work in order to compute the buckling and post-buckling behavior of cylindrical shell-type structures. Standard assumptions in the shell kinematics allow us to develop a large deformation and finite rotation model for thin shells from the three-dimensional continuum.

An elastoplastic constitutive model for thin shells is derived from the three-dimensional framework, assuming the plane stress condition. The von Mises yield criterion is adopted including non-linear isotropic and linear kinematic hardening.

The resulting non-linear system is solved by a Newton-Raphson solution procedure, including the consistent linearization of the shell kinematics and the elastoplastic material model.

The high non-linearities due to the buckling-type instabilities, especially those occuring in the neighbourhood of critical points, necessitate the use of an appropriate step-length control. An arc-length method has been successfully implemented for passing through limit points (load or displacement peaks) where pure load or displacement controls fail. The proposed method is effective in handling both sharp snap-throughs and snap-backs.

Two numerical examples are presented in view of the assessment of the proposed approach and a particular attention is devoted to the post-buckling of hollow cylinders under axial compression. We identify several types of buckling mode for these structures, among which the axisymmetric mode, the “diamond” mode and the “elephant foot” mode, depending on geometry and boundary conditions.
Problems of Nonlinear Multiple-Mode Vibrations of Thin Elastic Shells of Revolution
Authors: Kubenko Veniamin D. , Kovalchuk Piotr S.
Published: November 2021

A method is suggested for the calculation of nonlinear free and forced vibrations of thin elastic shells of revolution, which are modeled as dynamic systems of multiple degrees of freedom. Cases are investigated in which the shells are characterized by two or more closely-spaced eigenfrequencies. Based on an analysis of averaged equations, obtained by making use of asymptotic methods of nonlinear mechanics, a number of new first integrals is obtained, which state a regular energy exchange among various modes of cylindrical shells under conditions of nonlinear resonance. Amplitude-frequency characteristics of multiple-mode vibrations are obtained for shells subjected to radial oscillating pressure.
Risk Analysis and Jurisprudence: A Recent Example
Authors: Cooke Roger , Kraaikamp Cor
Published: November 2021

We discuss a recent incident in which risk analysts appeared as expert witnesses in a civil tort case. The problems which this generated illustrate how the role of expert witness has drifted away from its traditional mooring. Unclarities on both sides of the bench with regard to the difference between subjective and objective probability combined with fallacies of probabilistic reasoning give pause to those who might expect a rapid entry of risk analysis into tort law and jurisprudence.
A Web-Based Process/Material Advisory System
Authors: Chen Yusheng , Gupta Satyandra K. , Feng Shaw
Published: November 2021

This paper describes a web-based process/material advisory system that can be used during conceptual design. Given a set of design requirements for a part during conceptual design stage, our system produces process sequences that can meet the design requirements. Quite often during conceptual design stage, design requirements are not precisely defined. Therefore, we allow users to describe design requirements in terms of parameter ranges. Parameter ranges are used to capture uncertainties in design requirements. Our system accounts for uncertainties in design requirements in generating and evaluating process/material combinations. Our system uses a two step algorithm. During the first step, we generate a material/process option tree. This tree represents various process/material options that can be used to meet the given set of design requirements. During the second step, we evaluate various alternative process/material options using a depth first branch and bound algorithm to identify and recommend the least expensive process/material combination to the designer. Our system can be accessed on the World Wide Web using a standard browser. Our system allows designs to consider a wide variety of process/material options during the conceptual design stage and allows them to find the most cost-effective combination. By selecting the process/material combination during the early design stages, designers can ensure that the detailed design is compatible with all of the process constraints for the selected process.
Information Modeling of Conceptual Design Integrated With Process Planning
Authors: Feng Shaw C. , Song Eugene Y.
Published: November 2021

Information modeling is critical to the integration of conceptual design and process planning. An information model for conceptual design is provided in this paper. Conceptual design is a key activity in early product development. It determines product functions, form, and the basic structure. Major manufacturing cost is committed in early conceptual design process. The model presented in this paper includes an activity model for the conceptual design process and an object model for classes used in conceptual design. The activity model sets the context in which the objects are defined and used. The object model describes the data and functions used in conceptual design and integration with process planning. The main purpose of the model development is to initiate standard interface specifications that are necessary for design and process planning integration.
A Method for Measuring Deformation Rates in Hydrogel Structures: Multi-Plane Imaging and Measurement Limitations
Authors: Bauer Joseph M. , Beebe David J.
Published: November 2021

A technique for determining the three dimensional motions of hydrogel structures in microchannels is introduced. In developing this technique, we have adapted microscopic particle image velocimetry (μPIV), a method for measuring velocity fields in microfluidic devices. The motions of 1 μm fluorescent seed particles that are incorporated into a hydrogel microstructure (200 μm tall × 400 μm diameter) are tracked over several expansion cycles using microscopy. Combining measurements taken in different planes produces a three-dimensional representation of the motions present during volume changes can be reconstructed. By providing cross sections of the local deformation rates in hydrogel microstructures, this technique allows for the optimization of device designs as well as providing a better understanding of the processes by which hydrogels change volume under mechanical constraints.
An Optical Cross-Connect Switch Based on Micro-Bubbles
Authors: Chen D. , Close S. , Fouquet J. , Haven R. , Reynolds H. , Schiaffino S. , Schroeder D. , Troll M. , Venkatesh S.
Published: November 2021

An all optical cross-connect for communications networks is presented here. Optical switching is accomplished in a planar silica lightwave circuit where the switching array matrix is defined by a system of intersecting waveguides. Small microchannels are fabricated at the waveguide intersection and are filled with an index matched liquid. Microbubbles are thermally manipulated to allow light to be either transmitted or reflected by total internal reflection. The physics associated with the bubble behavior and the requirements of a reliable package present a slew of challenges for the mechanical engineer.
Development of a MEMS-Based Active Control System for Flow Separation in the Transonic Regime
Authors: Tung Steve , Maines Brant , Jiang Fukang , Tsao Tom
Published: November 2021

A MEMS-based active system is currently under development for flow separation control in the transonic regime. The system consists of micro shear stress sensors for flow sensing and micro balloon actuators for separation control. We have successfully completed the first phase of the program in which the micro sensors and actuators were fabricated and tested in a wind tunnel facility. In the test, the sensors and actuators were flush mounted on a 3D model, which is representative of the upper surface of a wing with a deflected trailing edge flap. The model was installed in the wind tunnel and tested at a series of Mach numbers between 0.2 and 0.6. For all Mach numbers, the sensor output indicates that flow separates over the trailing edge when the micro balloons are in the ‘down’ position. When the micro balloons are inflated, the shear stress level on the trailing edge increases substantially, indicating an improvement of the separation characteristics. This result demonstrates the feasibility of using MEMS sensors and actuators to control flow separation. It is the first step toward the development of a revolutionary closed loop flow control system applicable to existing and future aircraft to enhance aerodynamic performance.
MEMS Impinging-Jet Cooling
Authors: Lin Qiao , Wu Shuyun , Yuen Yin , Tai Yu-Chong , Ho Chin-Ming
Published: November 2021

This paper presents an experimental investigation on MEMS impinging jets as applied to micro heat exchangers. We have fabricated MEMS single and array jet nozzles using DRIE technology, as well as a MEMS quartz chip providing a simulated hot surface for jet impingement. The quartz chip, with an integrated polysilicon thin-film heater and distributed temperature sensors, offers high spatial resolution in temperature measurement due to the low thermal conductivity of quartz. From measured temperature distributions, heat transfer coefficients are computed for single and array micro impinging jets using finite element analysis. The results from this study for the first time provide extensive data on spatial distributions of micro impinging-jet heat transfer coefficients, and demonstrate the viability of MEMS heat exchangers that use micro impinging jets.
Design of Piezoresistive Cantilevers for Low Force Electrical Contact Measurements
Authors: Pruitt Beth , Partridge Aaron , Bartsch Michael , Liang Yiching , Kenny Thomas , Wenzel Stuart , Reynolds Carl
Published: November 2021

Micromachined piezoresistive cantilevers were fabricated to measure contact resistance and force for low force and small area electrical contacts. The intended application is the evaluation of contact tip geometries and metal films manufactured using standard semiconductor processing techniques. Prototype cantilevers are evaluated for force sensitivity, range, and noise as well as for feasibility of 4 wire contact resistance measurements at the end of the cantilever. The piezoresistors have a gage factor of about 35 and noise of about 1mV/Hz at 1Hz (the lowest frequency of intended measurements). Initial measurements of one cantilever design tested indicate sensitivity of 0.24mV/μN and force resolution of about 0.41mN for a piezoresistor drive voltage of about 9V and 100X gain on the bridge output. Force measurements are noise limited at the 5 Hz sampling rates used. 4-wire contact resistance measurements were made synchronously with piezoresistor bridge output voltage measurements.
High Amplitude Secondary Mass Drive
Authors: Dyck Christopher W. , Allen James J. , Huber Robert J. , Sniegowski Jeffry J.
Published: November 2021

In this paper we describe a high amplitude electrostatic drive for surface micromachined mechanical oscillators that may be suitable for vibratory gyroscopes. It is an advanced design of a previously reported dual mass oscillator (Dyck, et. al., 1999). The structure is a 2 degree-of-freedom, parallel-plate driven motion amplifier, termed the secondary mass drive oscillator (SMD oscillator). During each cycle the device contacts the drive plates, generating large electrostatic forces. Peak-to-peak amplitudes of 54 μm have been obtained by operating the structure in air with an applied voltage of 11 V. We describe the structure, present the analysis and design equations, and show recent results that have been obtained, including frequency response data, power dissipation, and out-of-plane motion.
Fabrication and Test of an Electromagnetic Micro Actuator With a Planar Coil on a Parylene Diaphragm
Authors: Kim Ki Hoon , Yang Sang Sik
Published: November 2021

This paper presents the fabrication and test results of an electromagnetic micro actuator for peristaltic micropumps. The actuator consists of a parylene diaphragm, spiral Cu coils and magnets. Parylene is waterproof and the Young’s modulus of it is small compared with metals or silicon and its compounds. So, it is adequate for the actuator diaphragm of a micropump. The deflection of the fabricated actuator diaphragm is measured using a laser displacement meter. The deflections of the flat and corrugated diaphragms are 20 μm and 30 μm at 1 Hz, respectively, when input current amplitude is 100 mA and duty ratio is 50%.
Two-Dimensional Arrays of Out-of-Plane Needles
Authors: Stoeber Boris , Liepmann Dorian
Published: November 2021

In order to make frequent injections of insulin and other therapeutic agents more efficient, a new painless way to inject drug subcutaneously is investigated. Injecting such agents just under the stratum corneum is a painless and very effective way of drug delivery, since the nerve endings occur deeper under the skin, and the presence of a large number of capillaries help to absorb the drugs efficiently into the body. The critical component for the successful development of this methodology is an array of robust, sharp, hollow microneedles. Arrays of needles that fulfill these requirements have been fabricated using a new fabrication process based on a combination of isotropic and anisotropic etching. Prototypes of these type of single crystal needles have been successfully tested by injection of fluid into chicken thighs. The flow characteristics of these needles have been modeled using the modified Bernoulli equation. This model has been validated through experimental results.
Three-Dimensional Imaging of Microfluidic Mixing Surfaces Using Dual-Channel Confocal Microscopy
Authors: Peach John P. , Hitt Darren L. , Dunlap Christopher T.
Published: November 2021

In the present study, we report on an experimental technique which enables the three-dimensional imaging and reconstruction of the microfluidic mixing surface — and the entire flow volume — at a 90° flow branch formed between converging Newtonian fluids of differing flow rate and viscosity. Only steady-state flows are examined. The technique involves the use of dual-channel laser scanning confocal microscopy (LSCM) and represents a significant extension of the technique previously introduced by Hitt & Lowe [1].
Energy Optimized Valve With Low Leakage Rates
Authors: Strobelt T. , Willmann M. , Kohnle J. , Waibel G. , Sandmaier H. , Zengerle R.
Published: November 2021

In our paper we report on piezo actuated valves with low leakage rates (<10 nl/min). The valves are made by silicon/glass and plastics. They are adapted to real, battery driven applications in medical systems and consumer products. Therefore the valves have to be optimized to extremely low energy consumption.
Development of Particle Methods for Computing MEMS Gas Flows
Authors: Sun Quanhua , Boyd Iain D. , Fan Jing
Published: November 2021

The development of particle methods to simulate flows related to micro-electro-mechanical systems is described. This effort is aimed at increasing our understanding of rarefied gas behavior to facilitate the design and optimization of micro-devices. The proposed information preservation method preserves macroscopic information of the flow as the particles move and interact with each other and the domain boundaries. The results exhibit very low levels of statistical scatter, which helps apply the method to low speed MEMS flows. In the implementation, specific consideration is needed for flows with large temperature variation.
Micro Protein Arrays Prepared by Microfabricated Stamps
Authors: Tseng F. G. , Huang H. M. , Liu C. S. , Huang C. Y. , Lin S. C. , Chieng C. C.
Published: November 2021

A novel protein arraying method is proposed by utilizing micro stamps to spot proteins on a bio-absorption surface. The method can pick up various protein solutions to spot onto a desired substrate for protein immobilization. The fabrication process of the micro stamp combines surface micromachining and molding process. Successful transfer of BSA protein solution onto a PVDF (Polyvinylidene difluoride) surface has been demonstrated by using the micro fabricated stamps. The size of stamped protein spot in this stage is about 20–50% larger than that of the stamp. To quickly verify the protein binding ability to two different substrates: PVDF and PhastGel® Pad, a chopstick system is used to pickup protein solution for stamping. Result shows that appreciable amount protein retention is achieved for at least 6 hours on both substrates. Improved spotting size and position control on micro stamping process has also been carried out by stamp surface coating with aluminum/aluminum oxide and stamp picking up protein-solutions from a protein-solution pre-wetted clean room tissue.
Trends and New Paradigms in Electronics Cooling Market and Industry
Authors: Copeland David
Published: November 2021

Cooling technology for modern servers, workstations and desktop computers has just begun a period of rapid change. As processor powers approach 100 watts, longstanding limits on air cooling are being challenged. The most recent changes are in the heatsinks themselves, as the longstanding manufacturing process of extruding is no longer capable of meeting new performance requirements.

This study focuses on the history of creating an effective organization for bringing the skive heatsink to market, concentrating on development of a start-up unit within the company and a host of relationships, both technical and business, outside the company. Metals companies in Japan have long been accustomed to the necessity of constant innovation. Heatsinks fall into the vague category of a semi-custom product — each customer has almost the same requirements, with slightly different exceptions to a standard part. Additionally, a product lifetime may be measured in months rather than years.

In heatsinks, the high thermal conductivity, low density and low material cost of aluminum preclued serious competition from other materials. The computer market is dominated by large players but the size distribution tails off very slowly. 51% of the market is held by 6 companies, the largest with 14%. The remaining 49% features a wide distribution of market share and technical capabilities. This results in some customers with large staffs specializing in cooling technology, others with a small number (sometimes 1) of multidisciplinary mechanical/thermal engineers, and others with no engineering staff other than system integrators.

The presence of other materials is increasing, as heatsinks for the highest power processors will soon need copper bases and, ultimately, two-dimensional heatpipes known as vapor chambers. This integration of components represents a significant departure from the previous norm of attaching a one-dimensional tube heatpipe to an all-aluminum heatsink. In some cases ownership of development and production is the responsibility of the heatsink maker, in other cases the heatpipe or, in the case of an integrated cooling fan, the fan maker.

In order to address this wide and rapidly moving market, we have made alliances with makers of other electronics cooling components (fans, plastic housings, thermal interface materials), jointly developed products with computer and processor makers, and co-sponsored university research. This year (2000) saw a large-scale entry into the Gigahertz processor cooling market, with a focus on high level visibility at technical conferences and trade shows. As thermal concerns move from a final step in the design cycle to a initial consideration, educating customers about the potential contributions of the skive heatsink has become a major effort in our technical marketing campaign.
Assessment of Damage in Heterogeneous Concrete Composites
Authors: Smolarkiewicz Pawel P. , Willam Kaspar J.
Published: November 2021

Ultrasonic testing provides non-destructive measurements, which are widely used to evaluate stiffness degradation in materials and structures. In a recent study, a computational simulation method was developed for modeling ultrasonic pulse propagation in heterogeneous concrete materials. This method is based on a two-phase finite element model of the particle composite consisting of linearly elastic aggregate inclusions and a cement matrix, the damage of which is assessed via dynamic wave transmission analogous to ultrasonic testing. The advantage of this approach is its ability to examine the heterogeneous meso-structure and the progressive degradation of the elastic stiffness properties of the cement matrix. Although it proved very informative to simulate the ultrasonic response in coarse concrete mixes, it is unfortunately computationally very demanding because of the high mesh resolution necessary in space and time. The question arises, whether a simpler, less expensive method based on homogenized effective stiffness properties can provide comparable results. It is the objective of this paper to show, that, in fact, the resolution of the heterogeneities is necessary, and that the use of homogenized concrete properties cannot provide the information when progressive degradation is considered in the cement matrix which magnifies the contrast of the heterogeneous meso-structure.
PEDSS: A Product Engineering Decision Support System
Authors: Wang Nanxin , Becker Beverly , Kaepp Greg
Published: November 2021

Automotive vehicle body structure design is a long and complex design process. It involves iterations of design modifications, analysis, validation, and confirmation. It is time consuming and costly. In order to bring better and more affordable vehicles to the consumers, the auto-industry is seeking ways to reduce the vehicle cycle time and, at the same time, improve vehicle quality. One approach is to maximize the reuse of the engineering knowledge and make smart engineering decisions early. To assist engineers making decisions in the early design cycle, a Ford team has been working on the development of an intelligent vehicle Product Engineering Decision Support System called PEDSS. PEDSS is a knowledge based design tool that performs trade-off studies among various performance requirements, design specifications, package and manufacturing constraints, serviceability, and cost. It is developed using JAVA, JESS — a Java AI shell, and CORBA. It has been integrated with the company’s CAD system: IDEAS and applied to a small vehicle segment platform design.
Study of Dynamic Properties of Automotive Hydrobushing
Authors: Lu Min , Ari-Gur Judah
Published: November 2021

The objective of this research is to understand the dynamic properties of the hydrobushing. By means of a proposed mathematical model, it is found that the dynamic stiffness and loss angle of a hydrobushing are related to the rubber property and the effectiveness of the fluid in the inertia track. At high frequencies, however, the fluid in the inertia track becomes inefficient so that it may be ignored. It is also concluded that the rubber damping has minimal effect on the hydrobushing dynamic properties and may be neglected. The maximum loss angle of a hydrobushing, which corresponds to the maximum damping coefficient, occurs at a frequency close to the fluid resonant frequency. The degree of its closeness depends on the damping ratio and dynamic stiffness ratio.
Neural Network Based Automotive Clutch Model for Dynamic Engagement Analysis With Variable Time Steps
Authors: Cao M. , Wang K. W. , Fujii Y. , Tobler W. E.
Published: November 2021

The lubricated clutch in an automatic transmission plays an important role in the performance and comfort of passenger vehicles. Therefore, an accurate and easy-to-implement dynamic clutch model is necessary for powertrain system design and performance studies. A neural network approach recently developed by Parvataneni et al. [1999] for clutch modeling has illustrated some very promising results. However, this model has complex architecture that may cause slow training and testing. Also, due to the lack of time information, the network cannot adapt to time step variations. Therefore, it cannot be easily integrated with powertrain system models, which in general require variable time steps for a superior numerical integration performance. In this paper, a new first-principle-based hybrid network clutch model is derived for dynamic engagement analysis with variable time steps. With improvement over the previous work by Parvataneni et al. [1999], the time pattern information is added to the inputs and a simpler architecture is developed through more explicit utilization of the physical laws. A second order training algorithm with dynamic derivatives is also used to improve the training efficiency and accuracy. With these new features, this model can significantly outperform the previous approach in terms of accuracy and efficiency. The network is trained and tested using experimental data as well as analytical results. It is shown that this new model can compensate for time step variations and can predict the clutch torque accurately for a wide range of operating conditions.
Regulating Filling Pattern for Optimum Design of Resin Transfer Molding
Authors: Chen Y. F. , Minaie B. , Mescher A. M.
Published: November 2021

During resin transfer molding (RTM), dry spot formation and air entrapment during the filling stage often lead to inferior parts and high scrap rate. These problems are usually caused by improper design of inlet conditions and vent locations that prevent the Last Point to Fill (LPF) location from coinciding with the preset vent location. This paper presents a methodology to design the RTM process with a desired filling pattern free of dry spots. Unlike the traditional filling simulation that predicts the filling pattern using prescribed inlet conditions and the specification of the preform permeability field, this methodology calculates the optimum inlet conditions based on the specification of the desired filling pattern and the prescription of preform permeability. The use of this algorithm greatly enhances the process design capability by reducing trial-and-error procedures that use traditional direct filling simulation as a primary process design tool. The numerical algorithm is described along with RTM design example showing that use of the proposed methodology results in the LPF location coinciding with the preset vent location.