bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Optimization of Free Piston Expander for Energy Harvesting
Authors: Champagne C. , Weiss L. 
Published: April 2014

There is a growing opportunity and need for research that investigates alternate power sources. One such source is low temperature waste heat, or energy cast off to the environment as part of some larger process. Through the capture and use of this abundant energy source for power production, it is possible to enhance the overall operating efficiency of the larger system. This presents significant potential for sustainability increase and energy savings. One potential system that can operate from these sources is a low temperature, small-scale steam expander. Investigations of one such device called a Free Piston Expander (FPE) are presented in this work.
In final form, the FPE will be a MEMS based device capable of operation as part of a complete low temperature steam system. In this present study, a millimeter scale device is constructed and tested to yield insight into critical operational parameters for future microfabricated designs. Construction of this testbed device is via concentric copper tubing, allowing an effective baseline study of these determining parameters.
Parameters studied include device cross sectional area and shape as well as operational pressure. Once consistent parameters are determined, three separate variations of circular FPE design are further tested. These FPEs are designed to either constrain piston rotation or allow for rotational freedom during operation. Testing is performed on these devices for consistency in piston motion. Piston motion is characterized based on a single expansion and reaction of the piston.
Parametric Multibody Modeling of Anthropomorphic Robot to Predict Joint Compliance Influence on End Effector Positioning
Authors: Baglioni Stefano , Cianetti Filippo , Braccesi Claudio , Landi Luca 
Published: April 2014

Nowadays, in the field of robotic, one of the most important objectives is to reduce robot error positioning and improve its dynamic behaviour. One of the main source of error in end effector positioning is due to the joint compliance: robot joint components under operating conditions can be deformed as a function of their stiffness/damping properties. Generally, for industrial robots, harmonic drive gearings are used, their principal characteristics are high transmission ratio and law weight, on the other hand, to realize high transmission ratio, harmonic drive gearings work on inner gear elastic deformation, conferring to the robot joints an excessive compliance that, in some robot applications, cannot be neglected. In this research activity multibody modelling and simulation approach has been used to analyse joint compliance influence on robot position accuracy. The principal aim of this work was the formulation of a modelling procedure that starting from classical robots modelling approach (i.e. Denavit Hartenberg) defines an universal database and a parametric modelling procedure that allows the designer to use any multibody commercial codes to analyse anthropomorphic robots considering or not the compliance effect. All the procedure was developed and managed into a numerical code environment (Matlab/Simulink).
An example of commercial anthropomorphic robot was considered by assuming its principal kinematic and dynamic characteristics. Parametric models of the robot have been developed in two different multibody modelling environments (Simmechanics, Adams/View). Moreover the models structure has been built in order to control the robot movements both in motion (open loop) or in force (closed loop). In this case they are interfaced with Simulink code in a so called co-simulation approach that allows to developed a generic control system and test it by using one or more models, less or more refined.
Cooling Systems for Power Plants in an Energy-Water Nexus Era
Authors: Wong Kaufui V. , Johnston James 
Published: April 2014

Potable water is becoming scarce in many areas of the planet as the human population pushes past 7 billion. There is an increasing need for electric power since electricity is essential for modern development and progress.
Traditionally, condenser cooling systems for power plants use seawater or freshwater in conjunction with cooling tower technology. Seawater is used in plants near the sea or ocean, and seawater condenser cooling systems are typically open systems. More recently, air-cooling has been implemented and undergoing evaluations. Predictably, during the summer season in hot, semi-desert and desert areas, air-cooling would not prove very efficient. Ironically, these areas would require the most fresh, potable water if the population and/or population density is large. The need for additional power generation units to satisfy consumer demands, and hence more cooling capacities, creates a problem for utilities.
The current work researches the feasibility of using seawater cooling systems in the USA that are far from the sea. Five such locations have been identified as possibilities. Such a system has proven successful in South Florida. This system utilizes a series of cooling canals, used to dissipate the condenser heat to the surroundings. Relevant statistics of such a canal include water flow rate, total capacity, and MW of generators (both fossil-fueled and nuclear steam generators) the system is designed to cool. Additional statistics include the possible need to top-up (both amount and frequency of water required to maintain canal surface levels) or whether local natural rain water is adequate to replace evaporation and loss. Logistical information includes the estimated size of land required to accommodate the cooling canals. In estimating the canal system size and concomitantly the land required in other parts of the country, there is the tacit assumption that the thermal capacity of the surrounding land is about the same, and that the thermal conductivities of the different types of soil, and the heat transfer coefficients between the seawater and the canal are similar.
Quality of Reamed Surface Using Serrated Blades as Compared to a Conventional Acetabular Reamer
Authors: Levasseur Annie , Ménard Jérémie , Songmené Victor , Fernandes Julio , Petit Yvan 
Published: April 2014

Background: Hip arthroplasty requires the preparation of the acetabular cavity to allow a proper contact between the bone and the implant. It is essential to allow osseointegration and long-term stability of the implant. The aim of this study was to conduct experimental testing to evaluate the quality of reamed surfaces using a serrated blade acetabular reamer as compared to a conventional rasp reamer.
Method of Approach: Reaming tests were performed on a computerized numerical control tools machine at a rotational speed of 250 rpm and 3 different penetration speeds: 0.20 mm/s, 0.55 mm/s and 0.90 mm/s. For each reamer, a complete semi-hemispherical hole was perforated in 7 polyurethane samples. The reamed surfaces were digitized with a three-dimensional high resolution (40 μm) self-positioning laser scanner to carry out a quantitative analysis of the surface quality.
Results: Results demonstrated that the cutting edge and the penetration speed influence the quality of the reamed surface. The serrated blade was found to reduce surface irregularities (ranging between 0.19 mm to 0.21 mm for the conventional rasp and between 0.07 mm and 0.12 mm for the serrated blades), and to reduce inaccuracies on the reamed cavity diameter (0.13 mm ± 0.05mm for the rasps and 0.06 mm ± 0.03mm for the serrated blade).
Conclusions: The use of such tool by the surgeon may influence the stability of the acetabular implant and reduce the risks of revision surgery.
Influences of Grit Shape and Cutting Edge on Material Removal Mechanism of a Single Abrasive in Flexible Robotic Grinding
Authors: Tahvilian Amir Masoud , Champliaud Henri , Liu Zhaoheng , Hazel Bruce 
Published: April 2014

A flexible robotic grinding system has been used for in situ maintenance of large hydro turbine runners by Hydro-Quebec. Field trials for more than 20 years have proven the reliability and efficiency of the technology for hydropower equipment maintenance and repair. This portable robot named SCOMPI, is developed by IREQ, Research Institute of Hydro-Quebec and can perform high material removal rate grinding on hardly accessible areas of turbine runner blades. Due to the light weight and low rigidity of the robot, traditional position control of conventional grinding is not applicable in this process. Instead a hybrid force/position controller is employed to ensure the accuracy of the predefined material removal rate. Therefore, having a good force model for a specific removal rate is a prerequisite for controlling the grinding task. Understanding the grinding process as the cutting action of several single grits participating in the material removal process provides an insight to predict the needed forces.
This paper presents an investigation of the effects of grits shape on cutting forces in single abrasive cutting mechanism during high removal rate grinding by SCOMPI robot. A three-dimensional finite element model is developed to simulate the chip formation process with different grit shapes. Thermal results from our previous study of temperature distribution in the contact zone for this special robotic grinding are imposed to the un-deformed chips. Then, Johnson-Cook plasticity model is employed to investigate effects of hardening and thermal softening of work piece material in cutting forces. It is also found that, rake angle and cutting edges of the grit can have significant effects on the cutting and normal forces.
Design and Analysis of Ejector Powerplant System
Authors: Berana Menandro S. , Bermido Edward T. 
Published: April 2014

An ejector is a device with no moving components and is made up of four main parts: converging-diverging nozzle, suction chamber, mixing section and diffuser. It has become popular in refrigeration system as it gives the advantage of recovering expansion energy from high pressure difference into compression energy.
In this study, the potential use of ejector in powerplants that use low-grade or low temperature heat sources was conceptualized and analytically investigated. A novel combination of the ejector and the organic Rankine cycle (ORC) was proposed. The driving fluid in the ejector of the proposed powerplant cycle is the high-pressure liquid in the separator that is just circulated back to the evaporator in the ORC. Further increase in turbine temperature drop (TTD), which can increase the power output and efficiency of the plant, can be achieved through expansion, mixing and recompression processes in the ejector. Ocean thermal energy conversion (OTEC), solar-boosted OTEC (SOTEC), solar-thermal, waste-heat driven, biomass and geothermal powerplants were considered in the analysis.
Mathematical models in our previous studies were developed and used to calculate for nozzle and ejector parameters. The geometric profile of the ejector for optimization with categorized heat sources was determined. Isentropic, internally reversible, and irreversible two-phase nozzle expansions were analyzed. Two-phase flow calculations were continued in the mixing section. It was assumed that the constant-pressure mixing of the primary and secondary fluids occur at the hypothetical throat inside the constant-area section. Calculation for shock wave in the mixing section was also done. The diffuser was analyzed in a similar manner with the nozzle.
Calculation for other components and plant efficiencies was finally conducted. Ammonia and propane which are both natural working fluids were used in the analysis. Evaporator temperature range from 293.15 K to 393.15 K and condenser and ambient temperatures range from 283.15 K to 308.15 K were used in the analysis. The lowest ambient temperature of 283.15 K was used for the OTEC and SOTEC powerplants. It was shown that ammonia and propane can operate up to 11 K and 12 K below the ambient temperature, respectively. Ejector efficiency ranged from 90 to 95% for both working fluids. The maximum efficiencies of the ejector powerplant were 19.2% for ammonia and 14.9% for propane, compared to 11.7% and 9.8% of the conventional ORC. It was analytically determined that the efficiency of the ejector powerplant is higher than that of the ORC powerplant for the same working fluid and conditions of the evaporator, condenser and the ambient.
Development of an Adaptive Human-Machine-Interface to Minimize Driver Distraction and Workload
Authors: Westin Matthew , Dougherty Ronald , Depcik Christopher , Hausmann Austin , Sprouse Charles 
Published: April 2014

The original use of the vehicle dashboard was to provide enough sensory information to inform the driver of the current engine and vehicle status and performance. Over time, it has evolved into an entertainment system that includes person-to-person communication, global positioning information, and the Internet, just to name a few. Each of these new features adds to the amount of information that drivers must absorb, leading to potential distraction and possible increases in the number and types of accidents. In order to provide an overview of these issues, this paper summarizes previous work on driver distraction and workload, demonstrating the importance of addressing those issues that compete for driver attention and action. In addition, a test platform vehicle is introduced which has the capability of assessing modified dashboards and consoles, as well as the ability to acquire relevant driving performance data. Future efforts with this test platform will be directed toward helping to resolve the critical tug-of-war between providing more information and entertainment while keeping drivers and their passengers safe. The long-term goal of this research is to evaluate the various technological innovations available for inclusion in the driving environment and determining how to optimize driver information delivery without excessive distraction and workload. The information presented herein is the first step in that effort of developing an adaptive distraction/workload management system that monitors performance metrics and provides selected feedback to drivers.
The test platform (1973 VW Beetle converted to a plug-in series hybrid) can provide speed, location (GPS), 3-D acceleration, and rear proximity detection. The test drive route was a 2 km × 3 km city street circuit which took approximately 25 minutes to complete. Data is provided herein to demonstrate these capabilities. In addition, the platform has driver selectable layouts for the instrument cluster and console (LCD screens). The test platform is planned for use to determine driver preferences (e.g., dashboard/console configurations) and attention performance in addition to identifying optimal real-time feedback for drivers with different demographics.
Lateral Impact Validation of a Probabilistic Statistical Shape Finite Element Model of the Head and Neck
Authors: Eliason Travis , Francis Loren , Bredbenner Todd , Stemper Brian , Nicolella Dan , Shender Barry , Paskoff Glenn 
Published: April 2014

Injury prediction and mitigation are common overarching goals of modern biomechanical research. This research is fundamental to preventing and mitigating injuries sustained by those exposed to dangerous conditions including but not limited to occupational hazards, warfighter risks, automotive accidents, etc. Unlike traditional mechanical system research, biological systems are difficult and costly to test resulting in a need for robust and accurate numerical simulations. Models of the cervical spine are complex, nonlinear systems that must accurately model dynamic loading, large deflections, elastic, and viscoelastic behavior. In addition to individual complexities, population variance in both material properties and shape must be taken into account for accurate injury prediction.
As part of a hierarchical validation and verification (V&V) methodology, lateral impact cadaveric cervical spine experiments were compared to a high fidelity statistical shape finite element model (SSFEM) of the cervical spine and head. Specimens were mounted to a sled and accelerated using a pendulum impact with 1, 2, and 3 m/s impact velocities. The kinematics of the head and all individual cervical vertebrae were recorded with a Vicon motion capture system along with sled acceleration data. Sled accelerations were used as input boundary conditions for the probabilistic study using the SSFEM. Head and vertebrae rotations between the experimental and model responses were then compared.
A latin hypercube probabilistic analysis was performed for each impact velocity to determine the probabilistic response of each rotation metric. When comparing these responses, both the average and variation must be taken into consideration. This is accomplished using a quantitative validation metric based on the area between the cumulative distribution functions (CDF) of experimental response and the computed probabilistic response. Our results showed a very good match between the model and experiment at the higher impact velocities and a slightly stiffer response at lower rates. These results are consistent with previous validation studies performed with this SSFEM.
By expanding the validation data set with lateral impact loading, greater confidence in the model is obtained under different loading modes. This confidence allows the model to be used for probability of injury predictions as well as to identify important system variables in preventing injuries. High fidelity numeric modeling allows for rapid and cost effective assessment of hazardous loading conditions and safety equipment compared to experimental modeling. The knowledge gained from these modeling studies is fundamental and necessary for safe and effective design and injury mitigation.
Modeling the Ductile Brittle Fracture Transition in Reactor Pressure Vessel Steels Using a Cohesive Zone Model Based Approach
Authors: Chakraborty Pritam , Biner S. Bulent 
Published: April 2014

Fracture properties of Reactor Pressure Vessel (RPV) steels show large variations with changes in temperature and irradiation levels. Brittle behavior is observed at lower temperatures and/or higher irradiation levels whereas ductile mode of failure is predominant at higher temperatures and/or lower irradiation levels. In addition to such temperature and radiation dependent fracture behavior, significant scatter in fracture toughness has also been observed. As a consequence of such variability in fracture behavior, accurate estimates of fracture properties of RPV steels are of utmost importance for safe and reliable operation of reactor pressure vessels.
A cohesive zone based approach is being pursued in the present study where an attempt is made to obtain a unified law capturing both stable crack growth (ductile fracture) and unstable failure (cleavage fracture). The parameters of the constitutive model are dependent on both temperature and failure probability. The effect of irradiation has not been considered in the present study. The use of such a cohesive zone based approach would allow the modeling of explicit crack growth at both stable and unstable regimes of fracture. Also it would provide the possibility to incorporate more physical lower length scale models to predict DBT. Such a multi-scale approach would significantly improve the predictive capabilities of the model, which is still largely empirical.
Ash Sintering in a Biomass Pellet Boiler
Authors: Ribeiro Pedro , Teixeira José , Ferreira Manuel Eduardo 
Published: April 2014

The market for residential pellet burning equipments is well developed in some European countries like Germany, Austria and Italy and rapidly expanding in others. As a consequence the pellet production has also grown, although a large fraction is destined for industrial applications such as coal co-combustion. Due to the existence of chemical elements such as Na, K and Si, the pellet combustion can lead to agglomerated ashes on the grate of the burner causing problems for its proper operation.
The present work aimed to study the influence of temperature and air flows in the ash agglomeration at the grate. For this purpose, it was assembled an experimental setup that, in a brief, description consists of: i) boiler, whose burner allows the regulation of the primary and secondary air flow, ii) variable flow exhaust gases extraction system, iii) controllable feeding system, iv) heat dissipation system, v) data acquisition and control system, vi) exhaust gases analysis system.
The results indicate an increased formation of agglomerated ash with increasing of temperature. In addition, they also suggest the influence of excess air and primary air fraction in that formation, and the existence of an optimum working condition for high excess air and a primary air fraction of around 30%. The application of swirl in the secondary air improves both the flame stability and enables an efficient combustion into regions where the ash agglomeration is reduced. Moreover, they also show that there are other factors that influence the ash agglomeration, mostly related to the changing of the chemical elements ratio due to vaporization of the more volatile species.
Non-Concentrated Solar Collector for Solarthermal Chemical Reactions
Authors: Hotz Nico 
Published: April 2014

The purpose of this study is the proof that non-concentrating solar-thermal collectors can supply the thermal energy needed to power endothermic chemical reactions such as steam reforming of alcoholic (bio-) fuels. Traditional steam reformers require the combustion of up to 50% of the primary fuel to enable the endothermic reforming reaction. Our goal is to use a selective solar absorber coating on top of a collector-reactor surrounded by vacuum insulation. For methanol reforming, a reaction temperature of 220–250°C is required for effective methanol-to-hydrogen conversion. A multilayer absorber coating (TiNOX) is used, as well as a turbomolecular pump to reach ultra-high. The collector-reactor is made of copper tubes and plates and a Cu/ZnO/Al2O3 catalyst is integrated in a porous ceramic structure towards the end of the reactor tube. The device is tested under 1000 W/m2 solar irradiation (using an ABB class solar simulator, air mass 1.5).
Numerical and experimental results show that convective and conductive heat losses are eliminated at vacuum pressures of <10−4 Torr. By reducing radiative losses through chemical polishing of the non-absorbing surfaces, the methanol-water mixture can be effectively heated to 240–250°C and converted to hydrogen-rich gas mixture. For liquid methanol-water inlet flow rates up to 1 ml/min per m2 of solar collector area can be converted to hydrogen with a methanol conversion rate above 90%.
This study will present the design and fabrication of the solar collector-reactor, its testing and optimization, and its integration into an entire hydrogen-fed Polymer Electrolyte Membrane fuel cell system.