bluuebunny/crossref_metadata_2025 huggingface dataset:
Bacterial infection in dogs with aspiration pneumonia at 2 tertiary referral practices
Authors: Howard Jennifer , Reinero Carol R. , Almond Greg , Vientos‐Plotts Aida , Cohn Leah A. , Grobman Megan
Published: November 2021

Background

In dogs, antimicrobial drugs are widely prescribed for aspiration pneumonia (AP) despite poor documentation of bacterial infection in AP (b‐AP) using bronchoalveolar lavage fluid (BALF) analysis. Interpretating discordant cytology and culture results is challenging, contributing to lack of a criterion standard, and highlighting differences between veterinary and human medical criteria for b‐AP.

Objectives

Determine how many dogs with AP had BALF collection and differences in diagnosis of b‐AP using veterinary vs human medical criteria. Report findings of noninvasive markers (e.g. fever, band neutrophilia, radiographic severity score) in dogs with and without b‐AP.

Animals

Retrospective cohort study of client‐owned dogs (n = 429) with AP at 2 university veterinary hospitals. Twenty‐four dogs met enrollment criteria.

Methods

Inclusion criteria were radiographic diagnosis of AP, ≥1 risk factor, CBC findings, and BALF cytology and culture results. Veterinary medical b‐AP criteria were cytology findings compatible with sepsis with or without positive culture, or cytology findings not consistent with sepsis and positive culture (≥1.7 × 103 cfu/mL). Human medical b‐AP criteria required culture with ≥104 cfu/mL or > 7% cells with intracellular bacteria on cytology.

Results

Only 24/429 dogs met all enrollment criteria; 379/429 dogs lacked BALF collection. Diagnosis of b‐AP differed using veterinary (79%) vs human (29%) medical criteria. Fever, band neutrophils and high radiographic scores were noted in dogs with and without b‐AP.

Conclusions and Clinical Importance

Lack of routine BALF collection hampers definitive recognition of bacterial infection in AP. Differences in dogs meeting veterinary vs human medical definitions for b‐AP and usefulness of noninvasive markers warrant further study to improve understanding of the role of bacteria in AP.
Does the interference phenomenon affect strength development during same‐session combined rehabilitation program in hemodialysis patients?
Authors: Pavlin Laura , Rodriguez Annie , Ohresser Isabelle , Larivière Martin , Portal Cyril , Cristol Jean‐Paul , Bernardi Henri , Turc‐Baron Cécile , Candau Robin
Published: November 2021

Introduction

This study aimed to assess if an interference effect could blunt the neuromuscular gains induced by a same‐session combined rehabilitation in hemodialysis (HD) patients.

Methods

Patients exercised twice a week, for 16 weeks, over their HD sessions. They were either always trained with resistance and endurance exercises (continuous training, “CONT”) or alternatively with 1 week of resistance alternated with 1 week of endurance (discontinuous training, “DISC”). Adherence and workload were continuously recorded. Short Physical Performance Battery (SPPB) score, one‐leg balance test, and handgrip and quadriceps strength were evaluated before and after training intervention.

Results

Adherence to both programs was high (>90%). SPPB score had significantly improved (CONT: +1.5 point, DISC: +1.2 pt, p < 0.001), like one‐leg balance test (CONT: +3.7 s, DISC: +5.5 s, p < 0.05), handgrip strength of exercised (CONT: +5.5 kg, DISC: +5.6 kg, p < 0.001) and of nonexercised arm (CONT: +4.4 kg, DISC: +2.8 kg, p < 0.01) as well as maximal quadriceps strength (+22 N·m for dominant and +29 N·m for nondominant leg in both groups, p < 0.001) bearing no difference between the trainings.

Conclusion

Same‐session combined training does not induce an interference effect in HD patients and temporal separation of exercises does not optimize strength gains. These practical data may be relevant for clinicians and practitioners to alternate endurance and resistance exercises.
A case of dermatofibrosarcoma protuberans and reflectance confocal microscopy of a post‐surgical skin graft
Authors: Nawrocki Shiri , Rubin Alexandra , Srivastava Radhika , Chamorro Paola , Rao Babar K. , Wassef Cindy M.
Published: November 2021

Dermatofibrosarcoma protuberans (DFSP) is an overall rare malignancy yet is one of the most common cutaneous sarcomas. The diagnosis of DFSP is typically made following histopathologic examination of the lesion, classically revealing a storiform pattern of spindle cells with elongated nuclei infiltrating the dermis and subcutis. Surgical excision is the standard treatment. Local recurrence is estimated to occur in 20−50% of cases, thus frequent postsurgical monitoring is required. Noninvasive imaging modalities offer a potential alternative to multiple repeat biopsies. We report the first case where reflectance confocal microscopy accompanied clinical examination in monitoring for DFSP recurrence postsurgical excision.
Strength in numbers: The forces of constituency size, legislator identity, and institutional position on veterans’ representation
Authors: Cormack Lindsey
Published: November 2021

Objective

Veterans are overrepresented in Congress, yet few studies focus on how veteran‐related outcomes are related to the veteran status of individual legislators and the size of veterans within a district.

Methods

Using a novel data set spanning from 2005 to 2017, I assess three measures of substantive representation: placement on a relevant committee, legislative effort, and communication efforts.

Results

Veterans in Congress are not more likely to get a seat on the Veterans Affairs Committee than non‐veterans, but the share of veterans in a constituency is related to committee placement. Though veterans tend to introduce more bills and talk about veterans’ issues more often, the share of veterans within a constituency is also positively related to efforts focused on veterans.

Conclusion

Veterans in Congress and size of veterans’ constituencies impact different features of representational politics. Legislators from areas with greater shares of veterans, regardless of their own veteran status tend to get sets on the Veteran Affairs Committee, introduce more veterans’ legislation, and talk about veterans in communications.
Parametrically Excited Vibrations and Auto-Parametric Resonance in Cylindrical Shells
Authors: Popov A. A. , Thompson J. M. T. , McRobie F. A.
Published: November 2021

Vibrations of cylindrical shells parametrically excited by external axial forcing or by internal auto-parametric resonances are considered. A Rayleigh-Ritz discretization of the von Kármán-Donnell equations through symbolic computations leads to low dimensional models of shell vibration. After applying methods and ideas of modern dynamical systems theory, complete bifurcation diagrams are constructed and analyzed with an emphasis on modal interactions and their relevance to structural behaviour. In the case of free shell vibrations, the Hamiltonian and a transformation into action-angle coordinates followed by averaging provides readily a geometric description of the interaction between concertina and chequerboard modes. It was established that the interaction should be most pronounced when there are slightly less than 2 N square chequerboard panels circumferentially, where N is the ratio of shell radius to thickness. The two mode interaction leads to preferred vibration patterns with larger deflection inwards than outwards, and at internal resonance, significant energy transfer occurs between the modes. The regular and chaotic features of this interaction are studied analytically and numerically.
Can Faster-Better-Cheaper Work? Challenges and Recommendations for the Management of Future Space Missions
Authors: Paté-Cornell M. Elisabeth , Dillon Robin L.
Published: November 2021

Several years ago, NASA shifted its unmanned space program to a faster-better-cheaper (FBC) management style. As opposed to complex spacecraft that cost billions of dollars and required a decade of development, FBC projects have reduced scopes and are developed in approximately three years for about $200 million. In order to examine the successful attributes and potential weaknesses of this new management style, we performed in 1997 and 1998, several case studies of such missions at NASA’s Jet Propulsion Laboratory (JPL). We examined in detail three FBC missions, Mars Global Surveyor (MGS), Mars Pathfinder (MPF), and Deep Space 1 (DS1), recognizing that MGS and to some extent MPF were of intermediate type because they had inherited either parts or staff training from previous missions. We also studied Cassini, the “last” of the flagship missions, as a base case for comparison. This study was performed before a few recent failures (e.g., Lewis, Mars Climate Orbiter and Mars Polar Lander) that have attracted the attention of the public (and Congress) on the potential downsides and the management difficulties of the faster-better-cheaper mode of operation. We identified and describe in this paper, several management features of earlier FBC missions that seem to have contributed to their success. Yet, at that time already, we had cautioned NASA that our results were based on a very small sample. We pointed out that most of these features had potential downsides and we expressed some concerns about the long-term viability of some of these same features. Based on these case studies and on NASA’s recent experience, we provide here a set of recommendations that should be helpful for the management of current and future FBC programs.
The Development of a Hardware Oriented Tool for Risk Assessment and Modelling
Authors: Kara-Zaitri Chakib , Alsahli Obaida
Published: November 2021

This paper describes the development of a “hardware-oriented” tool capable of handling the qualitative analysis of Integrated FMEA and FTA i.e. Failure Modes and Effects Tree Analysis (FMETA). The Boolean reduction required for the determination of MCSs is inherently dealt with the hardware system. The work carried takes advantage of the significant development made in Application Specific Integrated Circuits (ASICs). The new idea here is that a hardware design can, in fact, mimic the failure logic of a given system and can therefore encapsulate the underlying FMETA knowledge base. In this research, an algorithm based on the new idea has been successfully implemented on a Programmable Logic Device (PLD) using simulation software. The prototype system developed is a small unit consisting of a chip containing the “wired-in” failure knowledge base, in terms of FMETA, and a simple input / output device for interrogation purposes. The intrinsic PLD simulation algorithm is shown to successfully model the relationships existing between repeated failure causes, modes and effects and generate the list of associated MCSs in a truly integrated FMEA/FTA context.
Safety Hazards Associated With the Failure of Safety Barriers Under the Control of Microprocessors
Authors: Dickson Richard L. , McQuiston William C.
Published: November 2021

Microprocessor-based control systems have become increasingly popular in the work place because of their versatility and functionality. As a result, microprocessors are being used to monitor and control safety barriers associated with fire protection systems, radiation interlock systems, robotics systems, and manufacturing equipment. These systems tend to be complex and subject to single-point and common-cause failures. Failures occur when the control system can not perform its intended function for any of a number of reasons such as microprocessor malfunction or failure, loss of electrical power, power surge, software logic error, design error, or installation error. Failures of microprocessor-based control systems have the potential to adversely impact the safety of workers, the public and the environment, especially when the microprocessor is exclusively responsible for maintaining or monitoring a safety barrier or safety system. Unfortunately, individuals responsible for system design, design review, system operation and safety oversight may not recognize or appreciate the safety consequences of placing a safety barrier under the exclusive control of a microprocessor-based system. Five examples of microprocessor-based control system failures are discussed to illustrate potential problems that have occurred.
Take a Fresh Look at Existing Hazard Analysis Data to Assess Safety Instrumented System Needs
Authors: Chadwell G. Bradley
Published: November 2021

Many traditional methods for assessing Safety Instrumented Systems (SISs) focus on controlling individual hazards on a scenario-by-scenario basis. In these existing approaches, engineers use a hazard analysis, or other form of risk assessment, to evaluate each potential accident scenario to determine the need for a SIS. While comprehensive, such methods can result in more SISs being defined than are necessary.

This paper describes an approach for SISs using existing hazard analysis data from a new perspective. The approach goes beyond traditional scenario-by-scenario methods by explicitly considering the process as a whole. A major benefit is the potential to optimize resources by identifying the minimum set of SISs required to address all the hazards present in the process. Hence, this method can reduce capital expenditures, as well as testing and inspection requirements. This paper discusses the practicalities of taking a global perspective of a process in defining SIS requirements. Additionally, the concept of Importance Measures, used for prioritizing efforts to control and reduce risk, is extended to prioritizing and optimizing SIS selection from a risk-based perspective.
Risk Based Inspection (RBI) Within a Mechanical Integrity System: Leveraging Your Mechanical Integrity System
Authors: Boult Mark , de Regt Cees
Published: November 2021

Implementing a Mechanical Integrity (MI) system provides immediate benefits. This paper identifies some of those benefits, and looks at ways you can leverage your MI system by using its information and data. Means for gaining greater benefit include Risk Based Inspection (RBI), Reliability Centered Maintenance (RCM) studies, Root Cause Analysis, plus other assessments. This paper discusses where these assessments fit into the MI system and their effectiveness. An RBI study description is included that demonstrates the effectiveness of using MI data and information to reap additional benefits. The outcome of the study was an immediate financial improvement of $1,600,000 by canceling an internal inspection and they by avoiding a one-day facility shutdown. This equated to an immediate return on investment of 16:1. Additional other savings were also identified. The project team estimated that the computerized MI records halved the effort to complete the study, providing an additional saving to the company of $100,000.
Computer Program PRAISE: Uncertainty Analysis of Heat Exchanger Three-Dimensional Flow Speed Model
Authors: Islamov Rustam , Ustinov Vasily
Published: November 2021

The main thrust of the Probabilistic Risk Assessment (PRA) model is to assess the spectrum possible scenarios (sequences of events) that can lead undesirable consequences. However, there is no guarantee that all possible scenarios have been identified and properly assessed. This lack of completeness introduces an uncertainty in the results and conclusions of the analysis. Even for scenarios, which have been identified, the event sequence and system logic models do not precisely represent reality. There are uncertainties introduced by the relative inadequacy of the conceptual models, the mathematical models, the numerical approximations, the coding errors and the computational limits.
Design, Fabrication and Characterization of a New Magnetic Microsensor Using Plasma Hall Effect
Authors: Seo Young Ho , Han Ki-Ho , Cho Young-Ho
Published: November 2021

This paper is the first attempt to use the plasma Hall effect for magnetic field detection. The plasma Hall microsensor measures the Hall voltage induced by AC plasma electrons. In a theoretical analysis, we develop an analytical model of the plasma Hall sensor in order to express the plasma Hall voltage as a function of electrode geometry, magnetic field, plasma discharge field and chamber pressure. On this basis, we have designed and fabricated a new class of magnetic microsensors using AC neon plasma. In the experimental study, we have measured the plasma Hall voltage for varying five different conditions, including the frequency and magnitude of magnetic field, the frequency and magnitude of plasma discharge voltage, and the neon pressure. The plasma Hall microsensors show a magnetic field sensitivity of 8.87±0.18mvV/G with 4.48% nonlinearity. The experimental results agree well with those estimated from the theoretical analysis, thus verifying the feasibility of the plasma Hall device for a new class of magnetic microsensor.
Design, Fabrication and Testing of Laterally Driven Electrostatic Motors Employing Walking Motion and Mechanical Leverage
Authors: Tas N. R. , Molenaar R. , Sonnenberg T. , Baartman J. P. , Koster M. P. , Elwenspoek M.
Published: November 2021

This paper describes the design, fabrication and testing of laterally driven linear electrostatic micromotors. The motors employ mechanical leverage with the aim to increase the force from the order of 1 μN up to the order of 0.1 mN, in combination with walking motion to increase the stroke to virtually unlimited. Three designs have been made and tested. Although walking motion has been shown to be feasible in MEMS technology, improvement of the clamping is needed to benefit from the use of levers to increase the generated force.
Bulk Silicon Machined Micro-Electro-Mechanical (MEM) Devices Movable in Optic Immersion Fluids
Authors: Madanagopal K. V. , Tien Norman C.
Published: November 2021

We report on the fabrication, testing and modeling of spring suspended, bulk-silicon micromachined devices that are movable by electrostatic actuation in optic immersion liquids. The devices are designed to have smooth sidewall surfaces that can serve as optical reflecting elements. The devices are found to move about 23 1μm under 25V DC excitation.
A Nonlinear Dynamics Model of a Microelectromechanical Vibrating Wheel Gyroscope
Authors: Feng Z. C.
Published: November 2021

Microelectromechanical gyroscopes (micro gyros) sense the rotational input to the device by measuring the mechanical deformation on a vibrating structure caused by Coriolis forces. To utilize the magnification factor at mechanical resonances, the frequency of the electrostatic excitation and the natural frequencies of the structure are closely matched. Recently, it has been reported that as the mismatch decreases, the device operation becomes more and more unstable. This paper presents a nonlinear dynamics model of a microelectromechanical vibrating wheel gyroscope to obtain quantitative prediction on the instability related to the mismatch. Under the assumption of small motions, weakly nonlinearity is incorporated into the model. The nonlinear terms introduce coupling between two linearly independent modes, namely the drive mode and the sense mode. The method of averaging is applied to further reduce the coupled equations of motion. In the averaged equations, the periodic motions become fixed points in the amplitude and phase variables. Stability analysis of the fixed points leads to the criterion for the mismatch in terms of the gyro geometric design. Since current micro gyros are designed to maximize the sensitivity by utilizing the mechanical magnification effect at the resonances, the occurence of modal coupling is a very likely event. Our analysis indicates that such occurences can lead to the energy transfer from the drive mode to the sense mode. Consequently, the sensor will give non-zero output even when there is no rotational input to the sensor.
A New Al2O3/GaAs Deformable Mirrors for Tunable Optoelectronic Devices
Authors: Lin Chien-chung , Martin Wayne A. , Harris James S. , Chan Edward Keat Leem
Published: November 2021

A new Al2O3/GaAs distributed Bragg reflector is demonstrated using surface micromachining technology. This new type of structure can be integrated into vertical cavity tunable optoelectronic devices which will have a major impact on future wavelength division multiplexing communication systems. Numerical analysis of the top structure is performed and comparison between different structures is made. A new post-growth tuning voltage adjustment is also developed. This type of movable mirror with adjustable mechanical properties will be very important for adaptive optics and optoelectronic devices.
The Moving Liquid Mirror (MLM) Spatial Light Modulator: Simulation and Measurement of the Optical Performance
Authors: Wolter Alexander , Kunze Detlef , Doleschal Wolfgang , Lakner Hubert , Zimmer Günter
Published: November 2021

Spatial light modulators (SLM) are electro-optical devices employed as optical pattern generators in applications like projection displays, direct-writing systems for photolithographic patterning, adaptive optics or optical signal processing.

Here we report on the “moving liquid mirror” (MLM) as a new micromechanical actuator technology based on a deformable oil film on an aluminum mirror with electrode structure. The actuator is suitable for integration on a silicon backplane as CMOS-addressing circuit. Thus production in standard CMOS-technology is possible.

A theoretical analysis of the device behavior is given, and the results of simulations are presented. Measurements on passive devices show good agreement with the simulations.

Finally, active MLM-devices have been fabricated. Images can be programmed into the devices and observed under a microscope (figure 1).
The Kinematics of Bend-Induced Stirring in Micro-Conduits
Authors: Yi Mingqiang , Bau Haim H.
Published: November 2021

The absence of turbulence and the difficulty associated with introducing moving stirrers into microfluidic systems make the mixing problem in microdevices challenging. We studied theoretically steady, laminar, incompressible flow through a sequence of conduits with rectangular cross-sections aligned to form 90° with each other. The feasibility of taking advantage of bend-induced vortices to stir the fluid and enhance the mixing process was evaluated. Since at very low Reynolds numbers the bend-induced vortices decay rapidly, it was necessary to utilize a large number of bends to achieve the desired effects. Since it is not practical to directly simulate the flow through a large number of bends, we borrowed Jones et. al.’s (1989) idea of constructing a two-dimensional map to project fluid particles from a cross-section upstream of the bend to a cross-section downstream of the bend. This map was then applied repetitively to trace particle trajectories in various bend arrangements. Under certain conditions, chaotic advection was observed.
Diagnosis of MEMS Packages Using Speckle Correlation Method: An Application in Pressure Sensor Packaging
Authors: Yan Xiantao
Published: November 2021

Cracked glass beads embedded in the plastic housing material of fuel vapor pressure sensors have been observed after a few hundreds of cycles of thermal shock test. In order to diagnose the root cause of the cracked glass bead, the speckle correlation method is used to in-situ measure the thermal deformation field on the surface of the glass bead. Measurements are taken at 130°C, 26°C and −40°C. The speckle patterns at different temperature are recorded digitally by a CCD camera with a resolution of 1024×1024 pixels. Every two sequential speckle patterns are compared to yield the displacement field of the sample. Then the strain fields are calculated by a finite deformation formulation. Results reveal that the material made of the glass bead is highly non-uniform, and there exists a highly tensile strain zone on the surface of the glass bead. This is correlated with the location of cracking in the bead. Moreover, there is a sliding zone along the boundary of the glass bead, which may result in leakage. As a replacement for glass bead, a metal bead embedded in housing material is examined. Experimental results show that strain level in the metal bead is lower than that in the glass bead, which will reduce disturbance on the sensor part. In addition to that, there are no potential cracking and leakage problems in the pressure sensor applications. Therefore, the metal bead is recommended for future pressure sensor applications.
MEMS Post-Packaging by Localized Heating
Authors: Lin Liwei
Published: November 2021

This work addresses important post-packaging issues for microelectromechanical systems (MEMS) and introduces specific research directions by means of localized heating and bonding. MEMS packaging has become a major research subject due to the stringent packaging requirements in the emerging filed of MEMS. Establishing a versatile post-packaging process not only advances the field scientifically but also helps product commercialization in industry. An innovative post-packaging approach by localized heating and bonding is proposed and presented in this paper. Various post-packaging processes are demonstrated, including an integrated LPCVD (Low Pressure Chemical Vapor Deposition) sealing process, localized silicon-gold eutectic bonding, localized silicon-glass fusion bonding, localized solder bonding and localized CVD bonding processes.
Complex Biological Fluid Flow Through Microfabricated Polysilicon Microneedles
Authors: Zahn Jeffrey D. , Liepmann Dorian
Published: November 2021

Microneedles can be used for sample extraction or injection for biomedical applications. It is important to understand how complex biological fluids behave within the needles because non-newtonian effects are associated with fluid flow of concentrated biological solutions.

Different concentrations of sheep blood diluted with phosphate buffered saline (PBS) were investigated in different planar needle geometries. Only slight shear thinning behavior was observed, and only slight changes in apparent viscosity were recorded even at higher hematocrit levels. This is hypothesized to be a result of the Fahraeus effect in which cells are excluded from the wall regions in small channels. Microneedles with complex features clogged easily whereas needles with larger hydraulic radii allowed higher concentrations of blood to flow through them. However, at higher hematocrit levels (>25%) even the lower resistance needle clogged. Further investigations are needed to correlate how geometry affects flow of complex cellular suspensions.
Non-Silicon Mass Production of Micromachined Biosensors
Authors: Lu Yumin , Madou Marc , Crumly William , Jensen Eric
Published: November 2021

Sophisticated integrated circuit processing of silicon materials has been promoted as the optimum methodology for miniaturized mechanical and chemical sensors for over two decades. However, in micro biomedical applications, advantages of using Si are often not as clear as in mechanical sensors. The high cost of Si, difficulties in packaging, need for modularity and biocompatibility all encourage investigation of non-silicon materials and semi-continuous processing. Metal/polymer hybrid structures are preferred as the substrate materials in this application.

The two manufacturing techniques demonstrated here involve non-silicon materials and a modular methodology. They are based on robust printed circuit board and flexible printed circuit [FPC] high volume fabrication techniques using polyimide base films for millimeter scale devices and photoreactive dry film resists for sub-millimeter devices. The core concept shared between the designs is a structure having sensor sites and their electrical contacts on opposing sides of the substrate. This separation of fluid chemistry on one side and dry electrical contact on the other improves reliability, ultimate packaging simplicity, and ease of use. Chemical sensors fabricated by each of these processes as well as the corresponding sensor performance are presented.

The two-sided paradigm improves upon single-sided devices by allowing simpler, smaller and higher-yield fabrication of multi-purpose sensor arrays. Finished product yield is additionally enhanced by modularity. That is, each sensor type is created on it’s own sheet, independent of the other sensor types. At final assembly, many sensors of different types can be cut from different sheets and combined into any desired array configuration using contemporary pick and place equipment. A schematic of the two-sided sensor structure is shown in Figure 1.

The first approach by Packard-Hughes Interconnect, OSU and Microbionics Inc. for creating these structures is shown in Figure 2. In this case a method of fabricating high volume FPC with integrated contacts (Gold Dot Technology) is leveraged to create a biosensor that can be produced in volumes of greater than a quarter million per batch and at a low assembled cost.

A second approach explored by OSU, and Microbionics Inc. has been demonstrated to reduce the sensor size to below 100 μm at similar costs. This is accomplished as shown in Figure 3 by defining the sensor geometry in dry photoresist sheets using a simplified two-layer alignment technique that requires exposure from only one side.

Selection of the appropriate technique is application dependent. Preliminary results of potassium ion and chloride sensors are presented.
What Is Needed for Teamworking in the 21st Century
Authors: Fukuda Shuichi
Published: November 2021

How teamworking would play an important role in the 21st century and what are needed to realize it are discussed in this paper. It is pointed out that for teamworking in the 21st century, the identification and coordination of a strategic goal between different people with different background are the prerequisite for realizing true collaboration. And to share a strategic goal, images will play very important roles so that a methodology toward image based design must be developed and established.
Multiscale Analysis of Trabecular Bone
Authors: Bouyge Frederic , Jasiuk Iwona
Published: November 2021

Bone has a complex hierarchical structure. We study trabecular bone as a multi-scale material. In particular, we distinguish the following scales: nanostructural (collagen fibrils and apatite crystals), microscale (single laminae and laminated structure), mesoscale (random network of struts), and macroscale. We first present experimental observations and an overview of existing theoretical models of bone. Then, we construct a hierarchical model to predict elastic properties of trabecular bone.
Performance Predictor for Thin-Wall Plastic Parts Produced by Injection Molding
Authors: Wang H. P. , Ramaswamy Sreeganesh , Dris Irene , Perry Erin M. , Gao Dominic
Published: November 2021

The objective of this work was to develop a numerical simulation tool that is able to predict the processing window for thin-wall plastic parts made by the injection molding process. This performance predictor links the processing conditions (filling time, resin inlet melt temperature, and so on) to the mechanical properties and failure mechanisms of the part, using empirical data developed for the thermal and shear degradation behavior of the resin. Usage of such a performance predictor will help to expedite the long process development cycle time and to reduce the potentially expensive tooling costs associated with the thin-wall segment of the plastics business.
Process Stability in Multilayer Sheet Extrusion
Authors: Upadhyay R. K. , Tryson Glen
Published: November 2021

Calendering of multi-layer sheets is an excellent process for production of sheets and films for thermoformable feedstocks. The quality of the sheet surface and throughput rate are strongly affected by thermal and adhesive properties of constituent materials and temperatures of individual layers and nip-rolls. We conducted a set of experiments that allows us to relate process conditions to sheet quality and develop mathematical functions for process optimization. In addition, we have developed a physics-based model to calculate transient thermal distribution in the sheet and adhesive strength between rolls and sheet surface. Model predictions of temperature are in good agreement with actual surface temperature measurement. The model can be used to relate quality characteristics to thermal gradients and adhesive strength and can become a useful tool for development the of optimum process envelope for highest throughput.
Modeling and Vibration Feedback Control of Rotating Tapered Beams Incorporating Adaptive Capabilities
Authors: Na Sungsoo , Librescu Liviu
Published: November 2021

This paper addresses the problem of the modeling and vibration control of tapered rotating blades modeled as thin-walled beams and incorporating adaptive capabilities. The blade model incorporates non-classical features such as anisotropy, transverse shear, secondary warping and includes the centrifugal and Coriolis force fields.

For the non-adaptive system, a thorough validation and assessment of a number of nonclassical features including the taper characteristics is accomplished. The adaptive capabilities are provided by a system of piezoactuators bonded or embedded into the structure and spread over the entire span of the beam.

Based on the converse piezoelectric effect, the piezoactuators produce a localized strain field in response to a voltage and consequently, a change of the dynamic response characteristics is induced. A combined feedback control law relating the piezoelectrically induced transversal bending moment at the beam tip with the kinematical response quantities appropriately selected is used and the beneficial effects upon the closed-loop dynamic characteristics of the blade are highlighted.
Comparative Study of S2 Glass Plain and Twill Woven Composites Under Fatigue Loading
Authors: Kelkar Ajit D. , Shenoy Sunil S.
Published: November 2021

Woven composites have good properties in mutually orthogonal directions, more balanced properties than unidirectional laminates and have better impact resistance. The use of these composites for primary structural applications in place of conventional laminated composites has been increased considerably in the recent years. They are being manufactured by using new processes such as Resin Infusion (VARIM) and Resin Transfer Molding (RTM). These new processes are low cost, affordable and suitable for high volume manufacturing environment. One of the popular plain woven composites is fabricated using S2-Glass and SC-15 resin system components by using Resin Infusion (VARIM) process. These woven composites are being evaluated for Integral Armor applications. These components are expected to be under fatigue loading. To assess the feasibility of this material manufactured through Resin Infusion (VARIM), it is very important to understand the fatigue behavior of these composite materials. The present study provides comparison of the performance evaluation of plain and twill woven composite material for Integral Armor applications. Tension-Compression (R = −1) fatigue experiments were performed. All the fatigue tests are performed at 1 Hz frequency. S-N diagram and stiffness degradation over the fatigue life of the specimens were obtained.
Redesign of Spherical Acrylic Submersible for Manned Operation to 3000 ft (914.4 m) Ocean Depth
Authors: Das Partha S.
Published: November 2021

Harbor Branch Oceanographic Institution (HBOI) is using its spherical acrylic manned submersible for ocean exploration for last 3 decades. However, the development of tiny shear cracks at the interface areas of these submersibles following only few hundred dives require frequent, expensive repairs. To overcome this crack generation problem, a two-Phase research program is initiated at HBOI. In the Phase I of this study, a detailed nonlinear 3-D Finite Element Analysis (FEA) is performed at first to increase the understanding of the mechanical behavior at the interface of this submersible and then various analyses are carried out to develop a guidelines for redesigning the spherical acrylic submersible. Complete redesigning of the bottom of acrylic submersible is only presented here in details, as the discussion on the top of acrylic submersible is presented earlier.

Based on the new design guidelines, in the Phase II of this study, a new spherical acrylic submersible is fabricated at HBOI. Brief discussion of the experimental results on the new submersible is also presented here. A significant reduction in peak stresses and a very small relative displacement at the gasket/acrylic interface which are believed to be two of the main causes for crack development at the interface areas clearly indicate a major improvement in the new design of the acrylic submersible, as they are also suggested by the extensive FEA results. This improvement in design is expected to extend the crack free cyclic fatigue life of the acrylic submersible at 3000 ft (914.4 m) ocean depth significantly.
Predicting the Large Deflection Path of End-Loaded Tapered Cantilever Beams
Authors: Parkinson Matthew B. , Roach Gregory M. , Howell Larry L.
Published: November 2021

A simple (quadratic) mathematical model for predicting the deflection path of both non-tapered and continuously tapered cantilever beams loaded with a vertical end force is presented. It is based on the proposition that the path is a function of the ratio of the endpoints’ moments of inertia. The model is valid for both small and large (the tip makes a 70 degree angle with the horizontal) deflections. This was verified through physical testing, comparison to solution of the Bernoulli-Euler equation, and results obtained through nonlinear finite element analysis. Predicted endpoint deflections were found to be accurate within 1.8% of the actual deflection path for moment of inertia ratios varying from 1:1 to 1000:1.
Effect of Electric Field on Flow Pattern in Flow Boiling of R-134a: A Visualization Study
Authors: Salehi Mohsen , Molki Majid , Ohadi Michael
Published: November 2021

An experimental study was performed to qualitatively investigate the effect of an applied electric field on two-phase flow patterns in convective flow boiling of R-134a inside a channel. The experiments were performed in a horizontal channel with 3 mm hydraulic diameter. Inlet vapor qualities of 5%, 40%, and 80% at a flow Reynolds number of 1000 and heat flux of 20 kW/m2 are reported here. The flow regimes were analyzed by a high-speed digital camera. The camera could provide a frames speed of up to 3025 frames/s. The electric field was maintained between the upper and lower walls of the channel. The current visualization study suggests some definitive characteristics of the flow regime and the mechanism behind the EHD-enhanced convective boiling in a narrowly-spaced channel. It is found that at the lower range of applied potential, the flow patterns change from stratified wavy flow to a plug flow type with large slugs spanning the height of the channel. At the higher range of applied potential, a new flow regime took place. This flow pattern was associated with the cross motion of the liquid inside the channel. One reason for heat transfer enhancement can be attributed to the strong heat/momentum transfer between the vapor slugs and liquid cross motions.
Surface Tension Driven Film Flow due to Condensation With a Vapor Borne Surfactant
Authors: Qiao R. , Yuan Z. , Herold K. E.
Published: November 2021

In absorption chillers, it is well known that the presence of small amounts of alcohol can enhance the absorber heat and mass transfer significantly. Similar enhancement is also observed in the condenser. Among the theories to explain such phenomena, the recently described Vapor Surfactant theory provides the most comprehensive explanation of the available data. According to this theory, the surfactant arrives at the liquid surface primarily from the vapor. As the water vapor flows toward eventual absorption/condensation, it carries the vapor borne surfactant toward the surface. Once the surfactant arrives at the surface, it tends to concentrate there due to its low solubility and low diffusivity in the liquid as well as the natural affinity of a surfactant for the surface. Non-uniform surface concentration of the surfactant leads to surface tension forces in the liquid surface layer that drive the surface flows often observed. These Marangoni flows are what enhance the heat and mass transfer processes. Although it was often theorized that Marangoni flow plays a role in enhancement, the important role of the vapor has not been well understood. A number of previous attempts have been made to compute Marangoni flow but all such attempts have assumed that the surfactant transport in the liquid is the key. This paper presents calculations of liquid film flows driven by the surfactant as it arrives at the surface from the vapor. This completely new model involves several very interesting features.

A two-dimension numerical simulation of such a flow is reported here. The geometry is a thin film (3mm × 10cm) of liquid water with a small patch of cooling centered on the bottom side. The upper surface is exposed to steam+surfactant vapor so that condensation will occur. The model computes the surface concentration of surfactant and relates that to the surface tension. Calculations show that the condensation rate is much higher when Marangoni convection is occurring, even if the surfactant concentration in the vapor is very small (120ppm). This is in accordance with observations in absorption chillers. The result helps to clarify understanding of surfactant-induced enhancement of heat and mass transfer in absorption chillers.
Thermoeconomic Analysis of a Dual-Purpose Power and Desalination Plant
Authors: Uche Javier , Serra Luis , Valero Antonio
Published: November 2021

Thermoeconomic analysis techniques are very convenient tools to be applied in the analysis of highly complex systems as it is proved in this paper. A thermoeconomic analysis has been applied to an actual dual-purpose power and desalination plant considering the dual plant as a whole system. Probably due to its complexity, this type of plants are usually analyzed separately, considering the power and the desalination plant as two independent systems, thus neglecting component interactions and avoiding the potential energy saving derived from the combined analysis.

The most important aim of this paper consists on checking the validity of thermoeconomic analysis when applied to actual complex energy systems.

Thus, this paper contains some of the most important results of a research work [1] in which a critical analysis of thermoeconomic applications when applied to actual complex energy systems, as a dual plant is. The paper is focused on (a) the thermoeconomic diagnosis of the plant operation, in which the interactions between the plant components have been studied and quantified in terms of additional fuel consumption, efficiency variation, and so on; (b) the optimization of the plant by maximizing the installation benefit, which is a consequence of the thermoeconomic cost analysis..
Life Cycle Assessment of a Solid Oxide Fuel Cell Integrated With a Gas Turbine
Authors: Olausson Pernilla L.
Published: November 2021

The solid oxide fuel cell (SOFC), alone and integrated with a gas turbine (SOFC/GT), is known for its high electrical efficiency and low emissions during operation. Before the SOFC/GT operation phase, the process life cycle also includes the extraction of ores, production of materials and components, and demolition, all these together with their intervening transports. By performing a life cycle assessment (LCA) for the SOFC/GT, the total environmental impact of the process is established and environmental “hot spots” are found.

The results of the LCA of the SOFC/GT process showed that the most contributing phase to environmental impact, within all investigated impact categories during the life cycle, is the production of the SOFC-module. The pyrolysis processes of raw materials and the assemblage of the SOFC sub-components require an extended amount of energy. Of course, both these processes are carried out under laboratory circumstances, but even when the use of energy is reduced by 50%, this phase is more dominant than other power producing processes. Further effort has to be put into development of materials and manufacturing processes in order to reduce the resources used during the production phase of the SOFC.
Optimal Operation in CHP Systems: Using Mathematical Programming and Heuristic Rules
Authors: Iversen Frank Krogh , Nielsen Anders Busk , Nielsen Mads Pagh , Andersen Jens , Grue Jeppe , Bach Inger
Published: November 2021

The power generation system in Denmark is extensively based on small combined heat and power plants (CHP plants), which produce both electricity and district heating. This work deals with smaller plants spread throughout the country. Often a heat accumulator is used to enable electricity production, even when the heat demand is low. This system forms a very complex problem, both for dimensioning, designing and operation of CHP plants. The objective of the work is the development of a tool for the optimization of the operation of CHP plants. The optimization problem is a MINLP-problem of a very large scale. Therefore, a set of heuristic rules is formulated in order to reduce the size of the problem. Different cases are being tested, involving CHP producing units to cover the demand. The results show that it is of major importance to consider the operation of the plant in detail already in the design phase. It is of major importance to consider the optimization of the operation of a plant, even at the design stage, as it may cause the contribution margin to rise significantly, if the plant is designed on the basis of a detailed knowledge of the expected operation.
Influence of Different Sets of Measurements on Gas Turbine Field Performance Determination
Authors: Pinelli M. , Spina P. R.
Published: November 2021

The paper presents a method for evaluating the influence of different sets of measurements (in terms of number and kind) on gas turbine health determination. It is analyzed how the uncertainty of measurements and variations occurring on the characteristic parameters, which have to be fixed to solve the problem, affect the health parameter estimation. The study, which was developed for different combinations of measurements and fixed characteristic parameters, leads to the identification of:

- the best set of measurements for the determination of the gas turbine operating state;

- the most appropriate characteristic parameters to fix, depending on available measurements.
The Water Membrane Evaporator for Space Shuttle Heat Rejection: Membrane Performance and Plans for Pre-Prototype Testing
Authors: Ungar Eugene K. , Almlie Jay C.
Published: November 2021

The US Space Shuttle on-orbit waste heat rejection is currently accomplished through a combination of radiators and a Flash Evaporator System (FES). Three of the FES units have been rebuilt to date because of corrosion problems. In addition, the FES has experienced freeze-ups on-orbit.

As part of NASA’s Orbiter Upgrade Program, a Water Membrane Evaporator (WME) is being developed as a replacement for the FES. The WME will use hydrophobic micropore membrane technology to passively control a water liquid/vapor interface. Waste heat acquired from the Orbiter Freon-21 coolant loop will evaporate water at the interface. The water vapor will pass through the membrane and be vented to space. The WME program takes advantage of the recent advances in hydrophobic micropore membrane technology to provide a simpler and more robust heat rejection device than the current FES.

The WME design uses a hydrophobic and hydrophilic membrane layup over 60 rectangular stainless steel Freon-21 tubes in each of 80 small cores to perform the same function as the FES. The mass and volume of the WME design is comparable to that of the FES.

In the present work, the results of membrane performance tests are presented, the membrane physics are explored, and a membrane performance prediction is developed. The WME design is described in detail and the predicted performance of the WME design is compared to that of the FES.