bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved Performance of Transcritical Carbon Dioxide As a Refrigerant in Army Tactical Environmental Control Units
Authors: Manzione John A. , Calkins Frank E. 
Published: November 2021

Abstract
Commercially available heat pumps have traditionally relied upon fluorocarbon working fluids commonly known as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). These fluids are recognized as substances which destroy the earth’s ozone layer, and they are being phased out of production and use. Hydrofluorocarbons (HFCs) have been proposed as the next industry standard, but HFCs have extremely high global warming potential and, like their predecessors, are subject to regulation by the U.S. Environmental Protection Agency under provisions of the U.S. Clean Air Act. Similar restrictions exist internationally. HFCs are also costly and impose a handling and maintenance logistics burden, and in some cases pose performance limitations in high ambient temperatures. Consequently, they may represent only an interim solution for military air-conditioning and refrigeration needs.
On the other hand, carbon dioxide is inexpensive, safe, widely available, and fundamentally feasible. Operating at substantially higher working pressures, carbon dioxide (CO2) offers the potential of lighter, more compact systems, as well as providing environmental, performance, and logistics advantages that are attractive for military applications. With CO2, the Army sees the potential for smaller, lighter, systems with lower life-cycle costs. The U.S. Army Communications and Electronics Command’s Research, Engineering and Development Center has developed a first prototype packaged-unitary compact CO2 heat pump built within the physical constraints of existing Army ECUs (Environmental Control Units),. The performance of this unit has been further improved by the addition of an internal suction line heat exchanger. The unit is lighter in weight than the current military standard unit. When tested under a range of military operational conditions, it achieves a higher Coefficient of Performance (COP) but a lower capacity, than the military standard unit.
This paper will address the Army’s CO2 Development Program, with emphasis on fabrication and testing of the improved CO2 heat pump.
Evaluation of Fuel Cell Based Combined Heat and Power Systems for Residential Applications
Authors: Gunes M. Burak , Ellis Michael W. 
Published: November 2021

Abstract
Residences in the United States use 10.8 × 109 MJ (10.25 quadrillion Btus) per year, and the resulting energy cost exceeds $5 billion annually. Electricity use accounts for over 30 percent of residential energy needs. This electricity is typically provided by large remote power plants that discharge more than 60 percent of input energy as waste heat to the environment. The advent of fuel cell power systems makes on-site power generation feasible for residential applications. With on-site generation, waste heat can be recovered and used to meet the thermal needs of the residence including space heating and water heating. Combined heat and power (CHP) systems can substantially reduce the energy required for residential applications.
The energy use and economic benefits of fuel cell based CHP systems are investigated for single-family residential applications. Hourly energy use profiles for electricity and thermal energy are determined for typical residential applications. A mathematical model of a residential fuel cell based CHP system is developed. The system incorporates a fuel cell system to supply electricity and thermal energy, a vapor compression heat pump to provide cooling in the summer and heating in the winter, and a thermal storage tank to help match the available thermal energy to the thermal energy needs. The performance of the system is evaluated for different climates.
Results from the study include an evaluation of the major design characteristics of the system, load duration curves, an evaluation of the effect of climate on energy use characteristics, and a comparison of the life cycle cost of the fuel cell based CHP system to the life cycle costs of conventional residential energy systems.
Thermodynamic Diagnosis of a Small Scale Gas Turbine With Neural Networks
Authors: Bidini Gianni , Fantozzi Francesco , Barelli Linda 
Published: November 2021

Abstract
Real time monitoring and the diagnostics of fault critical power plants, such as small scale gas turbine based ones, is proved to increase their availability and rentability. However, the diagnostic tool requires high speed calculators and fast response models to produce time efficient action, therefore encouraging model free application such as Artificial Neural Networks (ANN) techniques.
To this aim, the present paper investigates the performances of an ANN based diagnostic system realized for a small scale commercial gas turbine.
After a data harvesting campaign on two existing installations, a diagnostic tool (DT), provided by the gas turbine manufacturer, was operated to produce a sufficient comprehensive diagnostic data base to be used to training and testing the ANN system. The DT system evaluates performance deterioration causes (i.e. compressor fouling) modifying diagnostic parameters, such as efficiencies and combustion parameters, in order to meet data provided by thermodynamic simulation with data gathered on field therefore requiring a relatively high number of input variables (namely 9).
The results obtained show good agreement with the ones provided by the DT diagnostic tool with a percentage error not exceeding 4%. Moreover, the ANN model utilized in the diagnosis was implemented considering only 3 input parameters therefore resulting in a less complicated system, not considering the dramatic increase in execution time due to the lack of any iterative calculation.
The next step is to extend the monitoring to the overall gas turbine’s components and to integrate the monitoring system with an artificial intelligence based supervising system for diagnostic purposes which derives from ANN outputs damage presence, fault source and evaluation.
Thermal Utility Influence on the Cogenerative Performance of a Below Ambient Pressure Discharge Gas Turbine (BAGT)
Authors: Bianchi M. 
Published: November 2021

Abstract
The use of gas turbine for heat and power production is widespread. Usually, the temperature of the gas exhausted from a gas turbine is greater than that required from the thermal utilities. Therefore, it may results convenient, before gas cooling, to produce additional work expanding the high temperature flue gas below the ambient pressure. Subsequently, a compressor will discharge to the ambient the cooled gas.
In the present paper, a thermodynamic analysis of a gas turbine working with the discharge pressure below ambient pressure (BAGT) is carried out considering different cogenerative applications. It resulted that the BAGT is especially convenient for low thermal utility temperature that strongly increases the gas turbine electric efficiency.
Moreover, in order to obtain high electric performance also with high thermal utility temperature, the employment of an additional heat exchanger (BAGT + cooler) has been taken into account.
Comparison of Exergy, Energy Utilization Factors and CO2 Production of CHP Systems Using Fuel Cell and Engine Power Cycles
Authors: Kowalski Gregory J. , Zenouzi Mansour 
Published: November 2021

Abstract
The following paper develops tools using energy and exergy analysis of heat engine and fuel cell based CHP systems to determine which type should be used to minimize fuel consumption and CO2 production. In the near future, physical plant and energy resource managers will have to decide how to satisfy electrical power requirements and reduce CO2 and other “greenhouse gas” emissions. Preliminary results demonstrate these tools provide useful information and indicate that heat engine based cogeneration devices are more desirable than the fuel cell based devices for systems with a large heat load to require power ratio. Fuel cell cogeneration devices are preferred for systems with a large power requirement as compared to the heat load.
Insulated Pressure Vessels for Vehicular Hydrogen Storage: Analysis and Performance Evaluation
Authors: Aceves S. M. , Martinez-Frias J. , Garcia-Villazana O. , Espinosa-Loza F. 
Published: November 2021

Abstract
Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH2) or ambient-temperature compressed hydrogen (CH2). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (fuel flexibility, lower energy requirement for hydrogen liquefaction and reduced evaporative losses). The work described here is directed at verifying that commercially available pressure vessels can be safely used to store liquid hydrogen. The use of commercially available pressure vessels significantly reduces the cost and complexity of the insulated pressure vessel development effort. This paper describes a series of tests that have been done with aluminum-lined, fiber-wrapped vessels to evaluate the damage caused by low temperature operation. All analysis and experiments to date indicate that no significant damage has resulted. Required future tests are described that will prove that no technical barriers exist to the safe use of aluminum-fiber vessels at cryogenic temperatures. Future activities also include a demonstration project in which the insulated pressure vessels will be installed and tested on two vehicles. A draft standard will also be generated for obtaining certification for insulated pressure vessels.
A Spring-Loaded Constant Force Exercise Device
Authors: Chatham Matthew J. , Todd Beth A. , Parker Joey K. , House Audrey S. , Taylor Jenny L. 
Published: November 2021

Abstract
Bone mineral density loss has been observed in astronauts who have spent a significant amount of time in a micro-gravity environment [1]. The lack of mechanical stress placed on the bones while in this environment is a major factor in the decrease in bone mineral density. To counteract these effects, resistive exercise has been the focus of many studies. Weighted plates have been used to provide a constant force resistance in ground-based bed rest studies. Bed rest has been established as one of the best ways to simulate the long-term effects of micro-gravity on earth [2]. In weightlessness, however, an alternate source of resistive force is required Some exercise devices provide resistance with elastic bands. Unfortunately, these elastic bands tend to lose their mechanical stiffness with use, requiring many spare elastic bands to be available for long duration missions in space. A more robust system that requires less maintenance would be preferable. Metallic helical springs meet this requirement The mechanical properties of helical springs are predictable, and these springs have a long life, making them well suited for long duration missions. However, helical springs exhibit linear behavior. That is, the resistive force provided by the spring is directly proportional to the amount of deflection. Therefore, a mechanism was designed to interact with the linear springs to provide a constant output force over a given length of travel.
Endovascular Embolization With Cyanoacrylate Mixtures: An In Vivo Study of Polymerization Kinetics
Authors: Gounis Matthew J. , Lieber Baruch B. , Hopkins L. N. 
Published: November 2021

Abstract
A cerebral arteriovenous malformation (AVM) is a congenital vascular lesion of the brain composed of a complex tangle of arteries and veins, which are linked by one or more fistulae [1]. Arterial blood is shunted through the AVM directly to the venous system, precluding arterial blood from perfusing adjacent brain structures. The most common presentation of this disease is cerebral hemorrhage secondary to AVM rupture, with an associated mortality of 15% and a morbidity of 50% [1]. One modality to treat this pathology is endovascular embolization. Generally, endovascular embolization serves as an adjunct treatment to either surgery or radiosurgery, but is a curative treatment in approximately 15% of AVM cases [2]. The most common embolic agent used to occlude AVMs is a mixture of n-butyl 2-cyanoacrylate (NBCA) and Lipiodol®. NBCA is a rapidly polymerizing liquid adhesive that polymerizes with contact to blood. Lipiodol® is an ethiodized oil, which imparts radiopacity to the embolic mixture. Moreover, Lipiodol® has been reported to delay the polymerization of NBCA [3]. To further increase the polymerization time of NBCA, minute quantities of glacial acetic acid (GAA) may be added to the embolic mixture.
Contour Based Implementation of Long Bone Adaptation
Authors: Roberts Michael D. , Hart Richard T. 
Published: November 2021

Abstract
The adaptation of bone to its mechanical demands is often described as a feedback control system wherein some aspect of the tissue strain environment acts as a driving signal to initiate cellular-level formation and resorption processes on bone surfaces. While this description may be somewhat simplified, the control system view is useful for organizing ideas, experiments, and simulations of adaptation. In the past 25 years, several investigators have introduced mathematical models and (finite element-based) computer simulations of bone adaptation, using numerous candidate driving mechanical signals as proposed bone mass regulators [1]. These simulations generally use the finite element method — including the appropriate geometry, material description, and loading — to calculate the needed tissue strain parameter being considered as the specific regulation signal. Based on the adaptive response being simulated — geometric and/or material property changes — the finite element model is updated, and re-analyzed in a series of discrete time steps.
The Effect of Number of Cycles on Microdamage Accumulation in Bovine Trabecular Bone
Authors: Moore Tara L. Arthur , Gibson Lorna J. 
Published: November 2021

Abstract
Microdamage, in the form of small cracks, exists in healthy bone. Microdamage can be created by an overload or by repetitive motion (fatigue) during daily activities. Usually, microdamage is repaired during bone remodeling and a steady state is maintained. However, in cases of excessive microdamage creation or slowed bone remodeling, microdamage can coalesce to create a fracture. Our previous work [1,2] has investigated microdamage accumulation with increasing strain in bovine trabecular bone loaded in monotonic compression and compressive fatigue. Specimens fatigued at relatively high load levels fail after a few loading cycles, while specimens fatigued at lower load levels may undergo thousands of cycles before failure. During high cycle fatigue, microdamage may accumulate by the growth of pre-existing microcracks, as well as by the crack initiation seen in low cycle fatigue.
Evaluation of Muscle Forces in a Synergistic Lumbar Spine Using Kinematics-Based Approach and Optimization
Authors: Shirazi-Adl A. , El-Rich M. , Pop D. , Parnianpour M. 
Published: November 2021

Abstract
Alternative methods have been proposed to solve the redundant problem of spinal active-passive load distribution. Due to the shortcomings in existing reduction, optimisation and EMG-driven models, and combination thereof, a novel kinematics-based approach is introduced that utilises the spinal passive-active synergy. Our recent studies demonstrate that, for a given task, the posture may be so adjusted as to yield an optimal load configuration requiring minimum muscle exertion [1]. In the current study, a solution technique for the redundant spinal system is described and applied to the analysis of a lumbar spine in an optimal posture obtained by varying the lordosis and pelvic tilt under a total of 2800N compression. The forces in lumbar muscles are subsequently computed for this optimal posture.
Effect of Frequency of Cyclic Loading on Biomechanical Properties of Lumbar Intervertebral Joints
Authors: Natarajan Raghu N. , Williams Jamie R. , Andersson Gunnar B. J. 
Published: November 2021

Abstract
Epidemiological studies suggest that repetitive loading, including vibration, is of importance in the development of back injuries including disc injuries. Yet the present information from the literature does not allow dose-response relationships to be developed, thereby making it challenging to develop accurate guidelines for prevention of occupational musculoskeletal disorders of the spine. Biomechanical response of individual motion segments as a function of applied load frequency may provide data on the ability of the disc to withstand prolonged cyclic loading. The hypothesis of the current study is that the rate of decrease in disc stiffness at the end of 30 loading cycles increases suddenly if the frequency of compressive loading is greater than 15 Hz. A finite element model was used for this study.
Instability Analysis of a Cervical Spine Model Under Flexion and Compression Loading
Authors: Tchako Abraham , Sadegh Ali M. 
Published: November 2021

Abstract
An improved and detailed 3-D FE model of human cervical spine was created using digitized geometric measurement. The model was validated with the in-vivo studies of Moroney, Panjabi and Fuller. Clinical instability of the spine for two cases involving flexion and compression loading (simulating injuries in motorcycle vaulting, football and diving accidents) were analyzed. The instability was based on the check list of Panjabi and White. It was determined that flexion moment of 10 Nm or compressive force of 500N result in the onset of clinical instability.
3D Kinematic Analysis of the Carpometacarpal Joints
Authors: Patterson Rita M. , El-shennawy Maged , Nakamura Koji , Viegas Steven F. 
Published: November 2021

Abstract
Carpometacarpal joint motion has been difficult to accurately measure with standard methods. There has been relatively little information on the kinematics of the 2nd through 5th carpometacapal (CMC) joints. It is however, generally accepted that the range of motion in the 2nd through the 5th CMC joints increases from the radial to the ulnar side of the hand, with the 2nd CMC joint being essentially immobile, while the 5th CMC joint simultaneously flexes and adducts1. The purpose of this study is to investigate the 3D dynamic kinematics of the 2nd – 5th CMC joints during flexion/extension motion (FEM), radio-ulnar deviation (RUD), and pronation/supination motion (PSM).
Use of Burmester’s Circular Theory in the Determination of the Optimal Four-Bar Link Reproducing Actual Tibia-Femur Relative Motion
Authors: Danieli G. A. , Mundo D. , Sciarra V. 
Published: November 2021

Abstract
The paper presents an application of Burmester’s circular theory to the determination of the optimal mechanism used to reproduce the motion of the tibia with respect to the femur. The research takes its start from the idea of studying an external fixator to guide the motion of a tibia in a way physically compatible to the actual patient’s anatomy, in order to firmly guide the two bones after, for instance, joint reconstructive surgery, while avoiding any contact between the articular surfaces. The physiological data were determined in researches presented in other papers.
However, in the initial research phases the idea was to determine the best position of an existing four-bar link, produced for an orthopaedic tutor, without any attempt at synthesising an ad hoc one. The idea of using Burmester’s theory in this operation was in reality an old one, but previous attempts were not successful.
Naturally, the required four-bar link had also to be small in order to fit on the external fixator. The results of the research are extremely satisfactory, since it was possible to determine a mechanism which allows relative motion with errors in the order of fractions of millimetres, when the imposed motion had to keep the two bones separated by a minimum of one millimetre. As a consequence the two bones will never go in compression, while a gentle pulling of the ligaments will always be present.
Using the approach, typical four-bar links for different human typologies were also determined.
The Effect of Talar Component Design on Talar Stresses in Total Ankle Arthroplasty
Authors: Smolinski Patrick , Galik Karol , Conti Stephen , Miller Mark C. 
Published: November 2021

Abstract
Total ankle arthroplasty offers an alternative to ankle arthrodesis or fusion in the treatment of diseases of the ankle. Due to the high complication rate in early designs, ankle replacement components have not evolved into any accepted standard form and several widely varying designs are currently in use.
An Equivalent Linkage Model for Understanding Stiffness Effects of Biarticular Muscles
Authors: Russell Donald L. , English Chad E. 
Published: November 2021

Abstract
The purpose of this paper is to describe a method for aiding in the intuitive understanding of the effects of bi-articular muscles on the stiffness of a limb. In particular, a kinematic analysis of a mechanical model of a human arm is performed. The results are manipulated into a form that makes evident a mathematical decomposition of the kinematics. This gives rise to a mechanical analog to the decomposition: an equivalent four-bar linkage with single-joint muscles. Further insight is gained as the equivalent linkage provides an intuitive direction associated with each set of muscles.
Fracture Toughness of the Growth Cartilage Reserve Zone Is Anisotropic
Authors: Williams John L. , Gove Nicholas K. , Flowers G. Adam , Schmidt Thomas L. 
Published: November 2021

Abstract
In the developing proximal tibial epiphysis the anterior ossifying tibial tuberosity is separated from the secondary ossification center of the tibial epiphysis by a bipolar growth plate known as the ‘cartilage bridge.’ We tested the fracture toughness of the central part of this growth cartilage in 18-week old calves in the direction perpendicular to the plate (mean 4962 N/m, SD 1846) and found it to be greater (p = 0.0004) than in the parallel direction (mean 2909 N/mm, SD 1122). Part of the reason for this anisotropy is the presence of vascular channels which cross the bridge from the epiphysis into the tuberosity. In addition, we hypothesize that the anisotropy reflects an arrangement of collagen primarily along the length of the ‘cartilage bridge.’