bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of the Risk Reduction Effectiveness in OSHA’s Workplace Atmosphere Sampling Activities
Authors: Gernand Jeremy M. 
Published: February 2017

The Occupational Safety and Health Administration (OSHA) in the United States is responsible for the promulgation and enforcement of rules to protect and enhance worker safety in most medium and large commercial enterprises. To that end, the agency has collected and processed more than 240,000 atmospheric samples of chemicals and aerosols in a variety of workplaces in the past 30 years. Though the agency spends more than $500 million per year even in the face of increasing overall employment, there exist only targeted evaluations of OSHA sampling activity for specific issues like formaldehyde or silica in the published literature.
This paper presents a comprehensive analysis of this effort including assessment of the hazard potential distribution of sampled workplace atmospheres for all recorded pollutants over the time period from 1984 to 2011, the budgetary requirements of this activity over time in comparison to the assessed risk, and an evaluation of the probable effectiveness of such activity given changes in US industrial employment over that time period. The effectiveness of the sampling program is assessed according to specific criteria including the probability of detecting exceedances of the National Institute of Occupational Safety and Health (NIOSH) recommended exposure limit (REL) for individual pollutants, the trend in the overall hazard level of detected atmospheres, the coverage of industries by worker population, and the cost-efficiency of the program in identifying hazardous atmospheres. Special attention is given to lead, toluene, and various mineral- and metal-based particulate matter, which have all seen new rules implemented in the recent past.
Findings show that the number of samples per employed person has decreased markedly since the beginning of the study period and become less aligned with the changes in population distribution among US regions, however the probability of detecting a hazardous level of a chemical or aerosol pollutant has increased. Extrapolations of this information and the associated changes in industrial sector employment indicate that US workplace atmospheres are marginally less hazardous at the end of the study period than they were at the beginning.
Modelling of Mechanical Systems With Friction Interfaces Considering Variable Normal Contact Load and Tangential Micro/Macro Slip
Authors: Li Dongwu , Xu Chao 
Published: February 2017

Mechanical structures with frictionally constrained interfaces often involve complex contact kinematics induced by tangential and normal relative motions. The tangential motion induces stick-micro/macro slip friction and causes energy dissipation. The normal motion induces normal load variation and possible separation of the joint interfaces. For effective analysis of dynamics of jointed structures, a reduced friction contact model is needed to characterize the nonlinear, coupled normal and tangential contact behaviors precisely. However, most developed microslip friction contact models considers only constant normal load.
In this paper, an improved microslip friction model with normal load variation induced by normal motion is proposed. The tangential stick-micro/macro slip friction is modeled by continuous Iwan hysteretic model. This model is characterized by a slippage uniform distribution density function and a linear stiffness at stick state. The coupling relationship between tangential nonlinear restoring force and normal load variation is built. This leads to generalization of the original Iwan hysteretic friction model to consider the effect of variable normal load. The proposed model is applied to model a 7-dofs frictional damping experimental system. The results show that normal load variation and tangential microslip motion exert an important effect on prediction of friction contact behaviors. The proposed model is capable of generating asymmetric hysteresis loops and intermittent normal separation. The numerical simulation fit well with the experimental results for the 7-dofs frictional damping system, which validates the effectiveness and accuracy of the proposed model.
Finite Element Simulation of PZT-Aided Interrogation of Composite Laminates Exhibiting Damage
Authors: Micheal Amany G. B. , Bahei-El-Din Yehia A. 
Published: February 2017

Piezoelectricity has proved effective in capturing changes in structures caused by various damage mechanisms. In one approach, piezoelectric wafer active sensors (PWAS) are mounted on the surface of the host structure and utilized as both actuators and sensors to interrogate the structure and monitor its health. This is achieved by subjecting the PWAS to a transient electric pulse and reading the resulting voltage. Changes in the stiffness of the substrate due to structural damage affect the response of the PWAS, which could be correlated to integrity of the structure. Applying this technique to fibrous composite laminates encounters particular challenges due to the presence of multiple damage mechanisms in one or more plies. Simulation of the procedure using advanced computational techniques and material models helps in understanding the reliability of PWAS in sensing damage in fibrous laminates.
This paper combines the finite element method and micromechanical modeling of composites to simulate damage detection using surface mounted PWAS. The finite element solution is obtained by the ABAQUS code with user defined material properties, which reflect the underlying damage modes. The latter are obtained in a preprocessing exercise in which the composite laminate is first subjected to a given mechanical load level and the damage mechanisms in the plies are identified using transformation field analysis, TFA (Bahei-El-Din el al., 2010). In the present work, the Mori-Tanaka averaging model is utilized within the TFA and local failure modes, which are a function of the matrix average stresses were specified. Material properties of the individual plies, which correspond to the damage mechanisms introduced at the given load level are then determined numerically in terms of the overall moduli and utilized in the finite element solution of the laminate using ABAQUS.
The methodology is applied to a quasi-isotropic, symmetric laminated beam subjected to bending. In the finite element simulation, each fibrous composite ply of the laminated beam is modelled using shell elements while the surface mounted PWAS are modeled with 3D solid elements. The bending moment is applied to the beam intermittently to allow interrogation of the laminate by applying a transient electric pulse to the PWAS and allowing the beam to vibrate for a very short period of time, which is followed by reading the voltage response. The voltage readings are correlated to the damage mechanisms in the plies.
Effect of Halogen-Free Ionic Liquids as Additives of Biolubricants for Room Temperature Titanium-Steel Contact
Authors: Bossung Kyle , DeRosa Matthew , Salas Jose , Iglesias Patricia 
Published: February 2017

The surface interactions and tribological behavior of titanium-steel contact have been previously studied under the application of several commercial Ionic Liquids (ILs). In certain cases, superior anti-wear characteristics have been experienced when lubricating using ILs. This is often attributed to the development of a protective tribolayer that forms during application. One anion in particular amide, [Tf2N], has exhibited these characteristics with particularly positive results. However, amide is an anion that contains halogens, which are toxic and can cause harm if not handled properly. Due to the toxicity of most lubricants there has been a growing need to transition to bio-lubricants due to their low impact to the environment. This particular work will investigate the use of Trihexyltetradecylphosphonium, [P6,6,6,14]-+, cation with anion decanoate [Deca] as a non-toxic alternative to amide [Tf2N]. [P6,6,6,14]-+[Deca] and [P6,6,6,14]-+[Tf2N] will be compared as additives (1.0 and 2.5 wt. %) in Coffee Bean oil (CB) for lubrication of titanium-steel contact at room temperature.
In this work, tests are conducted using a ball-on-flat reciprocating tribometer as per ASTM G133 with lubricated titanium-steel contact. An AISI 420C stainless steel ball is used on a Grade 5 6Al-4V titanium alloy disk specimen. Friction and wear volume are measured, examined, and discussed.
The Impact of the Interaction Between Impeller and Spiral Casing on the Performance of Radial Fans
Authors: Epple Philipp , Fritsche Manuel , Rußwurm Hans 
Published: February 2017

In thermal recycling plants high performance fans are needed to transport gas through the process. For this application, the fans have to fulfill very special requirements. The pyrolysis and gasification processes transform different kinds of waste, e. g. biomass and municipal scrap waste, electronic or industrial waste, into highly clean efficient synthetic gas, i.e. usable energy. Therefore, the thermal operating range of these fans lies between ambient temperatures of about 20°C and 530°C. Due to the requirements and design space of the recycling facility, new radial fans were developed according to these particular specifications.
Two different impellers were designed with an extended analytical method, as described in Epple et al. [1] and [2]. The first one was designed with a parallel flat shroud and the second one with a conical shroud. In order to fulfill the manufacturer requirements of ease of manufacturing, the impellers were designed with circular arc blades. With these two impellers and at a temperature of 530 °C, as it is needed in the recycling plants, a first Bommes spiral casing was optimized adjusting the spiral casing opening angle and the Bommes parameter, i.e. the ratio of the spiral casing width to the impeller exit width, BSC/b2 (Epple et al. [3]). The results show that the predictions of Bommes work well with impellers with conical shrouds, but for impellers with parallel shrouds the Bommes prediction does not work properly.
Analytical and Numerical Design of a High Performance Double–Throated Supersonic Blowdown Windtunnel
Authors: Epple Philipp , Steppert Michael , Steber Michael 
Published: February 2017

In this publication the focus lies on the design process of the full supersonic double throated wind tunnel. Starting with the fundamental equations of gas dynamics in combination with an analytical model of the pressure reservoir, the area of the throat at the nozzle and the runtime of the blowdown wind tunnel were computed. Based on these results, the shape of a shock free nozzle was calculated by the method of characteristics. For this purpose, a nozzle design program was developed using Python. In order to validate the results of the method of characteristics program, these results were compared with the area-Mach number relation, which is the exact analytical solution of the isentropic flow through supersonic nozzles.
The convergent part of the nozzle, which initially accelerates the flow to sonic speed, cannot be calculated by the method of characteristics, since it applies to supersonic flows only. Hence the subsonic convergent section of the nozzle was designed directly with 2D CFD using CD Adapco Star-CCM+ v. 10.06. A parametric model of the convergent nozzle section was used to find the optimum nozzle shape, i.e. a nozzle which results in a maximum mass flow rate in order to have an undisturbed flow field and Mach number in the following test section.
In order to decelerate the flow again from supersonic to subsonic flow after the test section and minimize the total pressure losses, an oblique shock diffuser was used [1]. As for the convergent subsonic nozzle, the optimum shape of a diffusor was found by 2D CFD analysis.
Putting all these elements together, i.e. nozzle, test section and diffuser the optimum supersonic wind tunnel shape was found. Finally, a full 3D simulation of the supersonic wind tunnel was performed in order to validate the complete design procedure and computations and also to include the viscous effect of the side walls. These results and the whole design process are presented and analyzed in the paper.
Design and Prototype of a Two-Axis Acoustic Levitator
Authors: Clough Justin , Sracic Michael W. , Piombino Daniel , Braaten Jonathan , Connors Scott , Pedigo Nathaniel , Prantil Vincent , Suthar Kamlesh 
Published: February 2017

The purpose of this paper is to document the process required to design and prototype a two-axis acoustic levitator and to show that the two-axis levitator improves the stability of a particle in an acoustic levitation field. The levitator design consists of the following subsystems: the transducer assemblies, which are responsible for generating the acoustic pressure field needed for levitation; the electrical system, which is responsible for providing the transducer assemblies with adequate power to maintain levitation; and the frame structure, which is responsible for locating and rigidly supporting the transducer assemblies.
The two-axis levitator is designed to have four transducers that operate at 27.2 kHz, and simulated results show that the system satisfies nearly all the design criteria and objectives. A transducer test stand and prototype were constructed to verify the design. The test stand was used to characterize all four transducers, and once the assembly was constructed the prototype operating frequency was determined to be 27.5 kHz. The prototype was used to successfully levitate Styrofoam pellets, a plastic pellet, and water droplets of various sizes. The displacement of a water droplet of approximately 1 mm in diameter was measured when levitated with both one-axis (vertical) and two-axis (vertical and horizontal) levitation. Using one-axis levitation, the water droplet displaced a maximum of 1.1 mm in the horizontal direction and 0.17 mm in the vertical direction. Using two-axis levitation, the horizontal displacement was 0.07 mm and the vertical displacement was 0.05 mm. Therefore, the two-axis acoustic levitator provides significant improvements in levitated particle stability.
Multiple Sclerosis Symptom Analyzer
Authors: Guerrera Brittany , Farrow Samantha , Zeng Gloria , Shady Sally F. 
Published: February 2017

Multiple Sclerosis (MS) is a chronic neurodegenerative disease of the central nervous system. MS is typically diagnosed between the ages of 20 and 40. There is no known cause of the disease and each individual experiences varying signs and symptoms depending on the severity of their disease. The most common symptoms include tremor, debilitated gait, visual impairment, or cognitive and emotional disturbances.
Current methods used to treat MS include oral medication and surgical treatment. The issues with oral medication are the unwanted side effects to otherwise healthy tissue and the lack of patient adherence. Surgical treatment can be invasive and require longer recovery times. An alternate strategy to treat MS is by increasing the knowledge base of the practitioner to potentially treat specific symptoms. Currently, physicians use observations and MRI scans of the brain and spinal cord to help diagnose and track the progression of MS. There are several studies that analyze existing assistive technology to aid in the treatment of MS tremors. Most of these studies did not involve large test groups, therefore it is difficult to prove their validity. Additionally, none of the current devices are able to track symptoms while simultaneously creating medical history records.
The goal of the design is to create a new device that will obtain the frequency and amplitude of tremors, while analyzing the effects of temperature and heart rate on the intensity of the tremor. With this data, the device will advance further MS research and lead to better diagnosis and treatment.
Design and Development of a Folding Electrically Assisted Bicycle
Authors: El-Sayed Mohamed , Lingerfelt David , McGuire Austin , Wicker Allan 
Published: February 2017

With the rapid development of hybrid and electrically driven transportation systems, several concepts of electrically driven bicycles have been developed and introduced to the market. Also, for storage advantage and portability several versions of folding bikes are available in the market.
In this paper, the design, development and validation process for creating a version of a folding electrically assisted bicycle is presented. The designed, developed, and road tested bicycle concept is targeted for use by college students, exercise enthusiast, or for commuting to work. It is also intended as a means of transportation for those living in large cities with a considerable riding distance and a limited space to store a bicycle. In addition to being foldable, the electrically assisted bicycle is designed with a small footprint and a ride performance comparable to any normal city bicycle.
To achieve the design objectives, the process starts with identifying the key attributes such as portability, durability, drivability, maintainability, and safety. The steps for translating the targeted attributes to design criteria and product specifications are discussed. Consequently, the analysis and integration technical tasks needed to achieve the established bicycle specifications for both architectural and performance integration efforts are identified.
During the early stages of the design phase, different alternatives and off-the-shelf components are considered. Architectural and performance integration activities including detailed virtual modeling, simulations, and analyses are implemented to develop the bicycle and achieve targeted attributes within the design constraints.
For concept proofing, the designed concept was developed and road tested. Preliminary results of physical testing demonstrate the achievement levels of different targeted attributes. While some targets were achieved, the initial physical tests indicate that further design improvements are needed through additional development and validation iterations. These improvements could be achieved through adjustment of targets, weight reduction, and alternative materials.
Design Optimization of Driveshaft and Universal Joint Using Finite Element Technique
Authors: Rahman Mosfequr , Molina Gustavo , Salekeen Sirajus , Dungan Ana , Hyers Isaac , Griffin Daniel , Berman Alexander 
Published: February 2017

Finite Element Analysis (FEA) has been performed on variety of a driveshaft and universal joints based on different shaft materials and shaft different operating angles. A driveshaft is particularly useful in applications such as taking of transferring torque from one piece of equipment to the other such as in vehicle of all kinds. A driveshaft transfers torque from the transmission to the rear end differential since these two pieces of equipment cannot be connected directly. The driveshaft has universal joints located on both ends of the shaft to allow for fluctuations in the angle of the transmission and rear differential. The driveshaft alone is composed of two parts, a female and male end, connected by a spline to allow changes in the length during operation. The driveshaft must be able to withstand the constant torque that is being applied throughout operation in order to increase safety for the operator and machine. Having a lower polar moment of inertia allows the driveshaft to turn with a lower torque value compared to a driveshaft with a higher moment of inertia. It is noted that driveshaft can be manufactured into a variety of lengths and diameters depending on the use and equipment it will be supporting. This paper describes a method of finite element implemented on variations of driveshaft and universal joints. Effect of material properties, geometry and operating angle of the driveshaft were considered for this numerical investigation. Five different materials such as structural steel, aluminum alloy, polyethylene, titanium, and carbon fiber with an outer diameter of 1.5 in of the driveshaft was used for this analysis. The effect of both metals and composite materials was observed.
Based on the analysis it was found that a 15° operating angle allowed for the longest life cycle of the driveshaft, while the carbon fiber composite presented the highest stress resistance and safety factor, approximately 6 GPa of yield tensile strength and a safety factor of 15. It was also found that titanium had an equivalent safety factor of 15. However, the tensile yield strength of titanium was much lower than that of its composite counterpart. All of the numerical experimentation was done using the Finite Element Analysis software ANSYS. Material properties for all materials were preset in the software except the composite carbon fiber whose properties were easily found from other research papers and experiments. Based on the data collected and the general assumptions that the most effective drive shaft is the one that lasts the longest. It can be concluded that a driveshaft made of carbon fiber operating at an angle of 15° presents the optimum driveshaft design.
Energy Consumption Modeling of a Heat Pump System for Combined Space Conditioning and Residential Water Heating in a Typical Household in Quito, Ecuador
Authors: Agila Gabriel , Soriano Guillermo 
Published: February 2017

This research develops a detailed model for a Water to Water Heat Pump Water Heater (HPWH), operating for heating and cooling simultaneously, using two water storage tanks as thermal deposits. The primary function of the system is to produce useful heat for domestic hot water services according to the thermal requirements for an average household (two adults and one child) in the city of Quito, Ecuador. The purpose of the project is to analyze the technical and economic feasibility of implementing thermal storage and heat pump technology to provide efficient thermal services and reduce energy consumption; as well as environmental impacts associated with conventional systems for residential water heating. An energy simulation using TRNSYS 17 is carried to evaluate model operation for one year. The purpose of the simulation is to assess and quantifies the performance, energy consumption and potential savings of integrating heat pump systems with thermal energy storage technology, as well as determines the main parameter affecting the efficiency of the system.
Finally, a comparative analysis based on annual energy consumption for different ways to produce hot water is conducted. Five alternatives were examined: (1) electric storage water heater; (2) gas fired water heater; (3) solar water heater; (4) air source heat pump water heater; and (5) a heat pump water heater integrated with thermal storage.