bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parameter Estimation for HVAC System Models From Standard Test Data
Authors: Luthman Hannah , Gardner John F. 
Published: February 2017

Nearly all cooling systems, and an increasing proportion of heating systems, utilize the vapor compression cycle (VCC) to provide and remove heat from conditioned spaces. Even though the application of VCC’s throughout the built environment is ubiquitous, effective and accessible models of the performance of these systems remains elusive. Such models could be important tools for equipment and building designers, and building energy managers and those who are attempting to optimize building energy performance through the use of model-based control systems. A quasi-steady state, spreadsheet-based model has been developed which requires knowledge of 10 system-specific parameters. A method utilizing manufacturer’s test conditions to derive these values is presented.
The model is applied to three commercially available units and a subset of test conditions is used to identify the model parameters. The model is validated over the entire range of conditions with modeling errors ranging from 2 to 4%.
The Strength of Dissimilar Fractal Joints
Authors: Monsef Khoshhesab Mona , Li Yaning 
Published: February 2017

In this investigation, the influences of fractal geometry and material properties on the strength of dissimilar joints were studied. The fractal geometry explored was an iterative Koch curve. The interfacial layer joining two different materials was designed to be a Koch layer with three different numbers of iteration. The mechanical behaviors of the fractal dissimilar joints under both normal tensile traction and shear traction were simulated via finite element (FE) method.
In the three-phase FE models, isotropic elasto-perfect-plastic material models with different stiffness and yielding strength were used for all three phases. By varying the stiffness and strength ratio of the Koch layer and the dissimilar materials, fractal dissimilar joints with both perfect bonding and imperfect bonding were simulated and compared. It was found that the fractal geometry plays a very important role in enhancing both the tensile and shearing strength of dissimilar joints, especially for the cases with imperfect bonding.
Energy and Exergy Analysis of a Biomass Power Plant
Authors: Silva João , Teixeira Senhorinha F. , Preziati Simone , Teixeira José Carlos 
Published: February 2017

The fulfilment of energy targets regarding the use of renewable energy has been a strong incentive to the development of dedicated power plants using biomass. Because these facilities operate with low value residues, this orientation has also received a strong incentive by the quest to reduce the amount of fuel in the woods and lowering the risk of fire. This issue is a major problem in dry climates. Although the number of plants planned for Portugal was very large, the actual number of units in operation is small. The first plant to enter production in Portugal was the thermal power plant of Mortágua. In this paper the energy and exergy analysis in this plant is presented. The objective of this work is to develop an analysis for the energy conversion in the plant. This is based on parameters that were retrieved during its normal operation and include: biomass and air flow rate, temperature measurements of the flue gases throughout the facility including the economizer, the two superheaters and flue gas composition. The elemental analysis of the biomass resulting from a blend of various sources was measured in addition to its moisture (ranging between 20 and 45% depending on the sources). The analysis was carried out for a fuel batch with a moisture of 35%.
The plant was operated at three loads (full load, 80% and 65% load) and from the energy/mass balances the overall efficiency was calculated to be approximately 26%. The data were also used to perform a second law analysis of the plant which enables the calculation of the exergy destruction in the various components of the facility, including the external irreversibility. It was observed that the combustion chamber is the prime contributor to the overall loss of efficiency. The exergy efficiency was found approximately 22%.
Temporal Case-Based Reasoning for Personalized Hypertensive Treatment
Authors: Jalali Niloofar , Agboola Stephen , Jethwani Kamal , Zeid Ibrahim , Kamarthi Sagar 
Published: February 2017

Most of the current problems can be solved by referring to the solutions of the previous problems. Case Based reasoning (CBR) is one of the methods that solves a problem by retrieving the similar problems from the past and adapting the solutions of the past problems to solve the new problem. Recent studies that apply CBR include time as a parameter to retrieve most effective solutions that vary with time. This approach is more helpful in healthcare area in which one needs to look at historical evidence to find an accurate diagnostic or treatment regime. Hence, in this study, a time-based CBR is applied to track the outcomes of the drug therapy on hypertensive patients and find the most effective drug as a prescription. Initially, episodes in each patient’s medical records are chronologically ordered such that the oldest episode is placed first in the episode sequence and the latest episode is placed the last. It is assumed that the first episode of each patient is the first instance of diagnose; so when a new patient comes for checkup, his/her state (health condition) is compared with the initial state of the past patients. Therefore, the retrieval process calculates the similarity between the new patient’s current state and the most similar patients at their first episodes in the patient records. Due to the diversity of therapies for matching patients, the best treatment couldn’t be determined without knowing the efficacy of the different treatments. Therefore, the subsequent episodes of matching patients are examined to find the best treatment for the new patient. This might even require using a combination of treatments from all matching patients to find a good treatment for the new patient.
After the treatment is defined for the first visit, the record of the new patient is stored in the library for future case retrieval. This method is a novel approach to personalized treatment of patients having chronic disease by tracking the medical records past patients over a long period of time.
The current approach for treating the hypertensive patients uses evidence-based guidelines for managing the disease. However, this approach is more general and doesn’t take into account all the patient characteristics such as lab results and physical examination parameters. In the current approach the similarity between patients can’t be leveraged; the change of the treatment regime is based only on the risk parameter. However, in this method several parameters are being checked for efficiency of the medication. In contrast, the proposed CBR-based method personalizes the treatment based on what worked well for similar patients.
In this paper, the clinical records of hypertensive patients are provided by a Boston based hospital. The preliminary results confirm that the proposed approach will give good recommendation for hypertension treatment.
A Reduced-Order Model for Annular Labyrinth Seals Based on Proper Orthogonal Decomposition
Authors: Jin Hanxiang , Untaroiu Alexandrina 
Published: February 2017

Labyrinth seals are commonly used in pumps, compressors, and turbines to minimize the leakage of working fluid. They typically have a series of circular or rectangular shaped grooves designed to enhance the kinetic energy dissipation, consequently reducing the leakage rate. In this study a reduced order model is proposed for non-contacting annular labyrinth seals to describe leakage phenomenon and better understand the flow pattern as well as the energy distribution.
Both 2D and 3D reduced order models (ROM) were developed based on the transient CFD simulation results for a labyrinth seal with 20 rounded grooves circumferentially distributed. The matrix of cases analyzed consists of full order 2D and 3D models, as well as reduced order 2D and 3D models. The eigenvalues from the ROM matrix derived using Proper Orthogonal Decomposition (POD) and Snapshot techniques includes the relative energy of the flow field, however most of energy is related to only the very first few modes and corresponding eigenvalues.
The results show that 2D ROM models are more computationally efficient and can accurately reconstruct the flow field details. This method proves to have the ability to properly identify the flow characteristics, such as the recirculation flow pattern in the seal cavity.
Small Arrays of Single Beam Laser Sensors as Effective LiDAR Obstacle Detection Systems for Autonomous Vehicles
Authors: Soloiu Valentin , Ibru Bernard , Beyerl Thomas 
Published: February 2017

Ground vehicles with autonomous navigation require medium range external sensing for early obstacle detection and terrain mapping. Both are essential for path planning. The conventional method for accomplishing this is achieved by very complex and expensive LiDAR sensors with 32 to 64 individual lasers rotating rapidly and taking readings from the top of the vehicle. Our most pertinent research question however is to ascertain if a less cumbersome and cost effective setup of a small number of single beam laser rangefinder sensors can accomplish the same task. Our current method to achieve this is to sweep the sensors a variable number of steps along a predetermined angle. The information obtained is used to develop a complete and detailed view of the world around the autonomous vehicle.
This paper is focused on a small laser ranger finder attached to a programmable pan-tilt mount positioned at the front of the autonomous vehicle. These were chosen as they are the most viable type of sensors for this process due to low interference and also because long range accuracy data can be obtained with reasonable power consumption. The sensors and mount are connected to a microcontroller which gathers position and distance information of significant objects in the path of the vehicle, in polar coordinates. This information is then converted to more useful Cartesian coordinates and plotted on a point cloud which is then used for path planning in real time.
Future work will include sensor fusion of this system and an image sensor for detection of relevant objects such as traffic signs. Such systems establish a distance from the vehicle as well as distinguish them by shape and color.
Characterization of Bulk and Thin Film Fracture in Electronic Packaging
Authors: Subramanian Vijay , Alazar Tsgereda , Yazzie Kyle , Penmecha Bharat , Liu Pilin , Bai Yiqun , Malatkar Pramod 
Published: February 2017

As semiconductor packaging technologies continues to scale, it drives the use of existing and new materials in thin layer form factors. Additionally, packaging technologies continue to increase in complexity such as multi-chip packages, 3D packaging, embedded dies/passives, and system in package. This increasing packaging complexity implies that materials in thin layers are subject to non-trivial loading conditions, which may exceed the toughness of the material, leading to cracks. Furthermore, the continued focus on cost leads to a growing interest in novel, low-cost materials. It is important to ensure that the reliability of these low-cost materials is at par or better than currently used materials. This in turn, leads to significant efforts in the area of material characterization at the lab level to speed up the development process. The chosen test methods must not only provide accurate and consistent data, but they must also be applicable across a suitably wide range of materials to aid in the optimization process.
Methods for testing and characterizing fracture induced failures in various material systems in electronic packaging are investigated in this paper. The learnings from the different tests methods are compared and discussed here. More specifically, different fracture characterization techniques on (a) freestanding ‘thin’ solder resist films, and (b) filled ‘bulk’ epoxy materials like underfills and epoxy mold compounds are investigated. For thin films, learnings from different test methods for measuring fracture toughness, namely, uniaxial tension (with and without an edge pre-crack) and membrane penetration tests, are discussed. The test methods are compared by characterizing several different thin films, to gauge how well each method could distinguish differences in material (and thickness). Reasonably good agreement was found between the various thin film toughness test methods; however, ease of sample preparation, fixture, and adaptability to environmental testing will be discussed. In the case of filled epoxy resin systems, the single-edge-notch bending (SENB) technique is utilized to obtain the fracture toughness of underfills and mold compounds with filler materials. Learnings on different methods of creating pre-cracks in SENB samples are also investigated and presented. Two methods are explored in this study, namely, razor blade and laser milling. Good agreement in fracture toughness values was obtained with the two precracking methods, along with considerations about ease of sample preparation and consistency of pre-crack dimensions also examined. Morphology of the pre-cracks obtained by these methods, and their effects on fracture toughness measurements, are also discussed.
Entropy Generation for Forest Fire Propagation Prediction Through Preferential Direction Analysis
Authors: Guelpa Elisa , Verda Vittorio 
Published: February 2017

Physical models of wildfires have been widely applied for evaluating the fire front evolution in order to obtain useful information for fire management. The main drawback in adopting such models for predicting fire propagation concerns the high computational resources that are required, especially when the analysis involves large areas or when multiple scenarios are investigated, e.g. for risk analysis purpose. This is mainly due to the complexity of phenomena involved and the necessity to use multi-dimensional approaches for the reconstruction of the fire front in the landscape. Complete two dimensional analyses can be avoided provided that possible preferential paths can be identified. Once this result is obtained, the analysis is reduced to one dimensional simulations, which can be made faster through the use of reduced models, such as POD models.
In this paper, an entropy generation analysis is proposed as approach to identify preferential paths for fire propagation analysis. The analysis of the effects due to wind and slope as well as the heat transfer mechanisms, including radiation, is performed. The different contributions to the local entropy generation rate are computed in a complex scenario and the areas involving minimum and maximum total amount of entropy generation are considered for evaluating the preferential directions.
Shellside Vacuum Condensation With a Noncondensable Gas
Authors: Ritchey Susan N. 
Published: February 2017

Shell-and-tube vacuum condensers are present in many industrial applications such as chemical manufacturing, distillation, and power production [1–3]. They are often used because operating a condenser under vacuum pressures can increase the efficiency of energy conversion, which increases the overall plant efficiency and saves money. Typical operating pressures in the petrochemical industry span a wide range of values, from one atmosphere (101.3 kPa) down to a medium vacuum (1 kPa). The current shellside condensation methods used to predict heat transfer coefficients are based on data collected near or above atmospheric pressure, and the available literature on shellside vacuum condensation generally lacks experimental data. The accuracy of these methods in vacuum conditions well below atmospheric pressure has yet to be validated.
Recently, HTRI designed and constructed the Low Pressure Condensation Unit (LPCU) with a rectangular shellside test condenser. To date, heat transfer data have been collected in the LPCU for shellside condensation of a pure hydrocarbon and of a hydrocarbon with noncondensable gas at vacuum pressures ranging from 2.8 to 45 kPa (21 to 338 Torr). Traditional condensation literature methods underpredict the overall heat transfer coefficient by 20.8% ± 20.4% for the pure condensing fluid; whereas they overpredict heat transfer by 36.8% ± 40.0% with the addition of the noncondensable gas.
Over or under predicting the overall heat transfer coefficient in the presence of noncondensable gases leads to inefficient condenser designs and the inability to achieve desired process conditions. With the addition of the noncondensable gas, the measured heat exchanger duty was significantly reduced compared to the pure fluid, even at inlet mole fractions below 5%. In one case, a noncondensable inlet mole fraction of 0.63% was estimated to reduce the duty by approximately 10%.
Analysis of the acquired high-speed videos shows that the film thickness changes significantly from the top row to the bottom. The videos also display condensate drainage patterns and droplet interactions. The ripples and splashing of the condensate observed in the videos indicates that the Nusselt idealized model is not appropriate for analysis of a real condenser. This article presents the collected heat transfer data and high-speed images of shellside vacuum condensation flow patterns.
Thermal Driven Dispersion of Smoke in a Parking Space
Authors: Teixeira José C. F. , Teixeira Senhorinha F. C. F. , Cunha Pedro , Silva Angela M. 
Published: February 2017

Multi store parking spaces are complex buildings that pose specific problems to hazard management resulting from fire and pollutant release from the exhaust gases of automobiles. They are often characterized by large open spaces which do not prevent the spread of fire and smoke. The presence of large quantities of fuel just adds to the risk. In addition, the random occupancy of the space and existence of large openings make difficult the hazard containment. Structural details such as columns and beams can facilitate the accumulation of smoke in pockets. A combination of fire resistant doors and forced ventilation are the usual methods for smoke/fire mitigation.
The current legislation defines the acceptable limits for CO concentration for both continuous (50 ppm over 8 hours) and peak (200 ppm) conditions. If the parking space is above ground and has side openings, forced ventilation is not mandatory and it is acceptable that risk prevention and management can be dealt by natural ventilation only.
The commissioning of the space often requires that tests are carried out in which a smoke tracer is released into the space in order to evaluate its dispersion over time. This is performed at ambient temperature and the thermal effects on the plume are not taken into account resulting in a lower dispersion rate.
The objective of the present work is to evaluate the influence of the temperature of the release source into the smoke dispersion in a parking space. This is a large public space 113 m long, 76 m wide and 3 m in height. The computational model is implemented within the Ansys Fluent. In this, the continuity, momentum, energy and species equations are solved for the physical model which includes the building structural details and vehicles. The fluid is assumed as a mixture of CO, N2 and O2. The boundary conditions assume various conditions for the external wind through the side openings and the heat source is modeled as that resulting from the combustion of gasoline from an open fire. The time dependent variation of the heat load is assumed with a peak of 8 MW.
The results show that the temperature at the source promotes a stratification of the plume to the ceiling of the building leaving the occupied (lower) levels with a much clear atmosphere. Beams also facilitate the concentration of high levels of CO in isolated pockets. These proved to be stable while the atmosphere temperature remains high; subsequent cooling drives the smoke/pollutants to the power levels. Such behavior is also dependent upon the entrance of fresh air through the lateral openings.
Ride-On Mower Rollover Accidents: Study and Design Solutions
Authors: Sevart Kevin B. 
Published: February 2017

Each year hundreds of ride-on mower operators are injured or killed as the result of rollover accidents. Several studies have indicated that rollover accidents are the most prominent type of fatal ride-on mower accident. Rollover accidents have occurred during actual mowing operations as well as during transport or loading onto transport equipment. The mowers themselves are designed and marketed for either commercial use or consumer use. However, commercial mowers are routinely sold to and used by ordinary consumers as there are no restrictions on such sales.
The mechanism of injury is typically the weight of the machine pinning the operator, or personal contact with a rotating cutting blade. Even relatively light-weight mowing machines have caused deaths due to asphyxiation or drowning when an operator was pinned under the machine. Operators that avoid being trapped under the weight of the machine may come into contact with a rotating cutting blade and receive a serious injury, such as an amputation.
This paper presents a brief history of industry safety standards applicable to either consumer or commercial mowing machines. A discussion is presented of available accident reports and statistics. Sources of the data reviewed include the Consumer Product Safety Commission, the Occupational Health and Safety Administration and the author’s personal investigations. Several common rollover accident modes have been identified.
While it is not possible to design a ride-on mower that could not roll over, design considerations should be utilized to minimize the propensity of the machine to roll and to minimize injuries should the machine roll over. This paper describes these design considerations.
FEA Design and Crashworthiness Evaluation of a 31-Inch W-Beam Guardrail System for Placement on a 3H:1V Sloped Terrain Configuration
Authors: Silvestri Dobrovolny Chiara , Arrington Dusty R. , Schulz Nathan , Xavier Connie 
Published: February 2017

The purpose of this research was to develop a 31-inch (787 mm) W-beam guardrail system to be placed with a 3H:1V slope in front of the barrier. The structural capacity and the occupant risk factors of such a proposed guardrail system were evaluated with respect to the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) TL-3 criteria. Finite element computer models of new guardrail designs for evaluation when placed on a 3H:1V sloped terrain configuration were developed and impact simulations were conducted to support their evaluation according to MASH standards evaluation criteria.
Three barrier designs for placement on a 3H:1V slope were suggested for evaluation through predictive computer simulations. All systems appear to be crashworthy and likely to pass safety evaluation criteria required for MASH. Depending on the desired system post distance location from the 3H:1V slope break, the researchers recommend evaluation of selected design through full-scale crash testing according to MASH TL-3 criteria. The information compiled from this research will provide the Federal Highway Administration (FHWA) and State Departments of Transportation with a W-beam guardrail design as a crashworthy system to be placed with a 3H:1V slope in front of a barrier.