bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Inlet Location on Ventilation Flow Through a Room Fitted With Solar Chimney
Authors: Nazir Kashif , Huynh B. P.
Published: January 2019

Solar chimney (thermal chimney) is a device which absorbs solar radiation to heat the air. The heated air, becoming buoyant, rises through the chimney’s passage and induces further air currents. When fitted to a building, solar chimney can thus induce fresh outside air to flow through the building for ventilation. Because only natural means (solar radiation here) are involved to cause the air flow, solar chimney is considered a natural-ventilation device. This work investigates computationally natural ventilation induced by a roof-mounted solar chimney through a real-sized 3-dimensional room, using a commercial CFD (Computational Fluid Dynamics) software package which employs the Finite Volume Method. Chien’s turbulence model of low-Reynolds-number K-ε is used in a Reynolds-Averaged Navier-Stokes (RANS) formulation. Computational domain that includes regions outside the room’s inlet opening and chimney’s exit allows for employing realistic boundary conditions for the computational model. Ventilation rate and air-flow pattern through the room are considered in terms of the location of the room’s inlet opening. It is found that while ventilation flow-rate through the room is higher with the room-inlet opening being located high on the wall opposite to the chimney’s entrance, a room-inlet opening being located near the ground results in better flow pattern with more flow through the living area in the lower part of the room.
Nonlinear Vibration Analysis of a Fractional Viscoelastic Euler-Bernoulli Microbeam
Authors: Bakhtiari-Nejad Firooz , Loghman Ehsan , Pirasteh Mostafa
Published: January 2019

Nonlinear vibration of a simply-supported Euler-Bernoulli microbeam with fractional Kelvin-Voigt viscoelastic model subjected to harmonic excitation is investigated in this paper. For small scale effects the modified strain gradient theory is used. For take into account geometric nonlinearities the Von karman theory is applied. Beam equations are derived from Hamilton principle and the Galerkin method is used to convert fractional partial differential equations into fractional ordinary differential equations. Problem is solved by using the method of multiple scales and amplitude-frequency equations are obtained for primary, super-harmonic and sub-harmonic resonance. Effects of force amplitude, fractional parameters and nonlinearity on the frequency responses for primary, super-harmonic and sub-harmonic resonance are investigated. Finally results are compared with ordinary Kelvin-Voigt viscoelastic model.
Optimization of Curved Spacer Prototype Design for Flow Improvement in Centrifugal Pump Impeller
Authors: Hermez Munther Y. , Jawad Badih , Liu Liping , Abro Sabah
Published: January 2019

An optimization of modified shrouded impeller with a curved spacer to suppress the unsteady flow recirculation was pursed. Centrifugal pumps are required to sustain a stable operation of the system they support under all operating conditions. Effect of minor geometrical modifications on the flow inside the three dimensional impeller passages are yet not fully understood, leading to costly trial and error approaches in the solution of instability problems. The idea of using a curved spacer to enhance the specified centrifugal impeller characteristics was validated. This modification with positioning the successful curved spacer prototype model at the impeller inlet section provided a wider pressure operation range at both low and high flow rates in a high-speed centrifugal pump type.

Seven curved spacer models were numerically analyzed in combination with the same original closed type impeller. The research investigated the effects of each inlet curved spacer model on the impeller’s performance improvement. The flow field inside a centrifugal pump is known to be fully turbulent, three-dimensional, and unsteady associated with secondary flow recirculation and separation at the impeller’s inlet and exit section. The rotor-stator interaction mechanisms or other unsteady effects often influence the water flow. The present research addresses the problem of Net Positive Suction Head Required (NPSHR) increase due to flow recirculation at the impeller suction side. The three dimensional unsteady water flow inside different models were analyzed by using a 3-D Navier-Stokes code with a standard k-ε turbulence model. The computational domain consists of four main zones: inlet, impeller hub, vanes, and outlet. The measurements with test rig were conducted for the pump hydraulic performances and flow field in the impeller passages. The numerical simulation and experimental tests of prototype performance concluded:

(1) Positioning a 3-D curved spacer at the impeller inlet section has a great impact on the centrifugal pump performance.

(2) Favorite effects were achieved on impeller performance by separating the inlet flow region into two lanes.

(3) The curved spacer resulted in improvement of closed impeller inlet static and total pressure values.

(4) Q-ΔP-η data and flow structures in the impeller passages were analyzed.
Development and Testing of a Lab-Scale Air-Gap Membrane Distillation Unit for Water Desalination
Authors: Lakeh Reza Baghaei , Cornell Keaton , Ly Benny , Chan Aaron , Jankhah Sepideh
Published: January 2019

As the population grows, one issue that is continually being addressed is the lack of clean water resources. In order to explore viable solutions, rapid experimentation and research has been underway to alleviate the water crisis. With the addition of new emerging technology, the development, improvement, and understanding of various techniques used to treat non-potable water has expanded. One subcategory of water filtration in particular that has seen rapid growth is Membrane Distillation (MD). MD is a filtration process that utilizes thermal energy to desalinate and decontaminate water. Compared to current industry leading techniques such as reverse osmosis, MD does not require such large operating pressures, leading to less power consumption. MD is accomplished primarily by flowing contaminated feed water at elevated temperatures across semi-permeable membranes. The membranes used are made to allow water vapors to penetrate through and separate from the contaminated liquid portion. By maintaining a temperature difference across the membrane, a pressure gradient is created, which drives the vapor of feed water through the pores in the membrane. Once the vapor passes through the membrane, it condenses through various methods and is collected. Air Gap Membrane Distillation (AGMD) has shown significant ability to desalinate water effectively in small scales. The air gap between the membrane and condensation plate minimizes heat loss through conduction, making AGMD a more attractive option for upscaling. In this project a laboratory-scale test cell was developed to test AGMD using different membranes, and operational parameters. In order to test such parameters, a unique design with baffled channels to induce turbulence was designed and manufactured. Feed water and coolant temperature differences, flow rates, membrane porosity, and air gap thickness are among the parameters that has been studied in this research. Temperatures of the hot feed were varied from 40°C to 80°C while the cold feed temperature was kept at a near constant temperature of 0°C. Flow rates of feed water and coolant water range from 1 to 3 L/Min. It was observed that the permeate flux is an increasing function of feed water temperature and membrane porosity. The air gap thickness plays a major role in permeate flux and energy consumption of the system.
Radiative Transport and Hydrodynamic Modeling of Microalgae Photosynthesis in Bio-Flow Reactors
Authors: Chen Lea-Der
Published: January 2019

A simplified two-phase flow PCH (physicochemical hydrodynamics) model is developed for modelling and simulation of microalgae growth in bio-flow reactor. The model considers carbon balance through coupled gas-phase and liquid-phase transport equations. The transport model accounts for interfacial transport of CO2 from gas bubble/slug to liquid, and microalgae photosynthesis reactions. A simplified photosynthesis reaction is adopted in the model, which assumes a pseudo-first order reaction for glucose pathway. The reaction rate is calculated assuming that it is proportional to the solar absorption rate by microalgae in the liquid. The reaction model also includes a simplified photoinhibition sub-model which assumes that the rate of photoinhibition is proportional to the square-root of solar irradiation reaching the algae cell. The Beer-Lambert law is used to calculate the radiative transfer of solar flux in seeded microalgae liquid flow. Analytical solution was obtained for single-channel bio-flow reactor. Decrease of the CO2 concentration in gas bubble/slug and in liquid flow is assumed to be the result of the microalgae growth in bio-flow reactor. Two efficiency parameters are defined: CO2 conversion efficiency and photosynthesis efficiency. The conversion efficiency is calculated based on the decrease of CO2 between the bio-flow reactor inlet and exit. The photosynthesis efficiency is based upon the heating value of microalgae yield versus solar irradiation. The rate of microalgae yield is calculated by multiplying the mass stoichiometric coefficient of photosynthesis reaction to CO2 consumption rate. Model analysis provided some insight of the microalgae formation in bio-flow reactor as interpreted from the PCH-coupled photosynthesis model that includes a dimensionless number as a potential scaling parameter for gas-phase only CO2 supply operation; photosynthesis efficiency increases with increasing CO2 molar concentration (i.e., number of moles per unit volume) at the reactor inlet for both gas-phase and liquid-phase only CO2 supply; an optimal irradiation flux for maximum photosynthesis efficiency — a factor to consider should artificial light source be used for harvesting algae.
Investigation of the Scattering of Focused Ultrasonic Waves at Bones
Authors: Schaal Christoph , Durgesh Vibhav
Published: January 2019

High-intensity focused ultrasound (HIFU) can be used for the ablation of tissue, such as in the case of prostate cancer. However, targeting tissue deeper inside the body remains challenging due to the increased attenuation and scattering of the ultrasonic waves. In this work, the partial and complete obstruction of the ultrasonic beam from a HIFU transducer at bones is investigated. Ultrasonic transmission and reflection under such conditions have scarcely been the focus of previous research. Thus, this work provides a reference based on numerical and experimental results. To this end, numerical simulations are conducted for various bone obstruction configurations. In addition, a diffraction-based shadowgraph technique is used for the ultrasound visualization in laboratory experiments. Imaging of focused ultrasonic waves is performed in water with no obstruction, varying partial obstruction, as well as with complete obstruction by bones phantoms. It is shown that there is reasonable agreement between the findings from experiments and simulations. While the field of view in experiments is limited, the entire pressure field in the area of interest can be investigated in numerical simulations. Overall, the results of this work provide a basis for future research in the field of therapeutic ultrasound.
Track Shape, Resulting Dynamics and Injury Rates of Greyhounds
Authors: Mahdavi Fatemeh , Hossain Md Imam , Hayati Hasti , Eager David , Kennedy Paul
Published: January 2019

A challenge for greyhound racing is optimizing the tracks to minimize the risk of injuries. The effects of different track design variables on greyhound injury rates has not been explored sufficiently. The purpose of this paper is to present some preliminary findings on the effect of greyhound racetrack design variables such as the track curvature and lure alignment. An analysis was carried out of two years of greyhound racing injury data from three different tracks in New South Wales, Australia. The data from before and after an intervention was introduced were compared. Variables in the study, which may affect\ the analysis were investigated to minimize the errors. The analysis showed that there is a reduction in injury rates for a longer lure arm in the tracks with short or no straight section.

To verify the effect of track design variables on the greyhound dynamics a kinematic simulation of greyhound center of gravity was created. The simulation considered fundamental variables correlating directly with kinematics between the greyhound and the track. The simulation data showed that the rate of change in the rotation of the greyhound heading direction decreases when the track running path has a more gradual curvature. The result of the simulation showed excellent agreement with that of injury data analysis.
Numerical and Analytical Analyses of Bi-Stable Element As Negative Stiffness
Authors: Oyelade Akintoye Olumide
Published: January 2019

In this paper, negative stiffness in static state is made stable by constraining it in positive matrix. The stability of the system is tested using energy function. The motion of the two mass model system is described with a system of two coupled nonlinear differential equations. The numerical results are validated by comparing the predictions with calculations from analytical method. For small oscillations about the static equilibrium position the numerical model agree with analytical model. The developed model can be served as an efficient means of eliciting negative stiffness.
Dynamic Analysis and Parametric Excitation of a Multi-Span Beam Structure Coupled With a Sequence of Moving Rigid Bodies
Authors: Gao Hao , Yang Bingen
Published: January 2019

Dynamic analysis of a multi-span beam structure carrying moving rigid bodies is essentially important in various engineering applications. With many rigid bodies having different speeds and varying inter-distances, number of degrees of freedom of the coupled beam-moving rigid body system is time-varying and the beam-rigid body interaction is thus complicated. Developed in this paper is a method of extended solution domain (ESD) that resolves the issue of time-varying number of degrees and delivers a consistent mathematical model for the coupled system. The governing equation of the coupled system is derived with generalized assumed mode method through use of exact eigenfunctions and solved via numerical integration. Numerical simulation shows the accuracy and efficiency of the proposed method. Moreover, a preliminary study on parametric resonance on a beam structure with 10 rigid bodies provides guidance for future development of conditions on parametric resonance induced by moving rigid bodies, which can be useful for operation of certain coupled structure systems.
Thermoeconomic Analysis of Reverse Brayton Cycle Based Cryocooler
Authors: Dhillon Aman Kumar , Ghosh Parthasarathi
Published: January 2019

In the present study, the performance of an RBC cryocooler with 10 kW cooling load at 65 K has been analyzed using Aspen HYSYS V8.6®. Helium, neon and helium-neon mixture are used as working fluids for the process cycle. A thermodynamic and cost model for the RBC cryocooler has been developed using exergoeconomic tool to analyze the cycle. It has been previously reported that to have same impact on the cycle exergy efficiency improvement, a small improvement in the heat exchanger effectiveness is required in contrast to a substantial improvement in the compressor efficiency. But it will also increase the capital cost of the cryocooler. The exergy efficiency, relative cost ratio and exergoeconomic factors for each component have been found to identify the major sources of cost. The effect of using different working fluids on the thermoeconomics of the cycle have been presented in this paper. Conclusions from this study might be utilized by the scientist and design engineer in improving the cycle efficiency from the thermoeconomic point of view.
Using Adsorption Cooling and Thermal Solar Collection for Residential Cooling Applications in Canada
Authors: McNally Jordan , Baldwin Christopher , Cruickshank Cynthia A.
Published: January 2019

An adsorption chiller is a type of chiller that uses heat input as the driving force for chemical compression of a refrigerant and provides cooling with low electrical consumption. An experimental setup was designed, instrumented, and constructed to meet constant inlet temperature and flow rate requirements for the commercially available adsorption chiller unit tested. Two types of tests were conducted, one with a constant hot water temperature which represents a district style heating system and another with a varying hot water temperature, representing a system using flat plate solar collectors. Numerous tests were run with constant inlet temperatures across the complete operating range of the chiller and at varying flow rates for each of the three main inputs. It was determined that variations in temperature had a much more significant impact on the performance of the chiller, compared to the variations in flow rate, which were almost negligible within tested range. Dynamic inlet temperature tests were run using the modified system which uses data from a weather file to simulate a system using flat plate solar collectors and vary the hot water inlet temperature to the system. The results showed that when the average hot water inlet temperature is lower than 60°C and higher than 75°C, the difference in performance between constant inlet temperature and dynamic inlet temperature tests was very small. However, the cooling capacity at 75°C was about 4 kWth greater than at 60°C. Majority of the test produced a thermal COP between 0.45 and 0.50. Therefore, based off the solar collector system’s capacity to maintain a suitable average hot water temperature, the cooling performance of the chiller can be deemed suitable for residential applications.
Material and Posture Modeling for Sleeping on Soft Low-Density Porous Material
Authors: Yamaguchi Takahiro , Kimura Hajime , Sakuma Atsushi , Takahashi Kazushige , Mimura Shigetoshi
Published: January 2019

Sleeping is one of the most important factors that influence the quality of human life, and this state of existence should be thoroughly investigated to improve the quality of the life. The mechanical design of bedding has great influence on the comfort of a mattress. Thus, objective and conventional techniques to evaluate the mechanics of mattress comfort could help improve the quality of sleep. In this report, an analysis technique for the assessment of the sleeping posture of humans is presented to facilitate the development of mattress design technology. Herein, an analytical model which imitates the human body has been formulated to determine the design parameters of a mass-spring-joint system on a soft underlay. The physical model is composed of five components that represent the head, chest, hip, femur, and calf, with each body part being represented by a simple ball model. The spring joint connecting the five parts reflects the neck, lumbar, hip, and knee joints. The specifications of the body model are determined by actual measurements and previous studies. In order to determine the physical properties of the mattress, two types of mattress urethane foam material are tested using the ball indenter method. The parameters include Young’s modulus, plateau stress, and other physical parameters. Variation due to the type of mattress has been observed in the laying test using a pressure distribution sensor sheet. In the analysis performed using the physical model, the variation in the lying posture and the extent of body sinking are observed to be the same during experiments. Both variations are compared using the change in force distribution in each body part. In conclusion, it was found that the observed changes in distribution are the same in the experimental and physical models. Therefore, the proposed model reliably reflects the design characteristics of the mattress.
Development of Equations of Motion for a Stewart Platform Under Prescribed Mount Motion
Authors: Ono Takeyuki , Eto Ryosuke , Yamakawa Junya , Murakami Hidenori
Published: January 2019

Analytical equations of motion are critical for real-time control of translating manipulators, which require precise positioning of various tools for their mission. Specifically, when manipulators mounted on moving robots or vehicles perform precise positioning of their tools, it becomes economical to develop a Stewart platform, whose sole task is stabilizing the orientation and crude position of its top table, onto which various precision tools are attached.

In this paper, analytical equations of motion are developed for a Stewart platform whose motion of the base plate is prescribed. To describe the kinematics of the platform, the moving frame method, presented by one of authors [1,2], is employed. In the method the coordinates of the origin of a body attached coordinate system and vector basis are expressed by using 4 × 4 frame connection matrices, which form the special Euclidean group, SE(3). The use of SE(3) allows accurate description of kinematics of each rigid body using (relative) joint coordinates. In kinetics, the principle of virtual work is employed, in which system virtual displacements are expressed through B-matrix by essential virtual displacements, reflecting the connection of the rigid body system [2]. The resulting equations for fixed base plate reduce to those for the top plate, obtained by the Newton-Euler method.

A main result of the paper is the analytical equations of motion in matrix form for dynamics analyses of a Stewart platform whose base plate moves. The control applications of those equations will be deferred to subsequent publications.
Hybrid Alumina Composites for Cutting Tool Inserts: Material Design and Development
Authors: Waqar Taha , Akhtar Syed Sohail , Arif Abul Fazal M. , Al-Athel Khaled S.
Published: January 2019

A successful approach to the development of reinforced materials for enhanced cutting tool inserts requires the formulation and application of innovative concepts at each step of material design development. In this paper, reinforced ceramic-based cutting tools with enhanced thermal and structural properties are developed for high-speed machining applications using a computational approach. A mean-field homogenization, effective medium approximation and J-integral based fracture toughness evaluation using an in-house code are used for predicting the effective structural and thermal properties for tool inserts as a function of reinforcement type, volume fraction, particle size and interface between matrix and reinforcement. Initially, several potential reinforcements are selected at the material design phase. SiC, TiB2, cBN and TiC were all found to be suitable candidates when reinforced into an alumina matrix as both single and hybrid inclusions for the enhancement of thermal and structural properties. For validation purposes, alumina-cubic boron nitride-silicon carbide composites are developed using Spark Plasma Sintering as hybrid systems, which are in line with the designed range of volume fraction and reinforcement particle size. Structural and thermal properties such as elastic modulus, fracture toughness and thermal conductivity are measured to complement the computational material design model.
Virtual Interaction Between Patients and Occupational Therapists Using an Assistive Robotic Device With Cyber-Physical System
Authors: Cheng Marvin H. , Huang Po-Lin , Chu Hao-Chuan , Peng Li-Han , Bakhoum Ezzat
Published: January 2019

In this paper, we propose to design, develop, and study a cyber-physical system that enables patients and therapists to virtually interact for rehabilitation activities with assistive robotic devices. The targeted users of this system are post-stroke patients. On the patient’s side, an assistive robotic device can generate the force that the therapist applies to the patient. On the therapist’s side, another robotic device can reproduce the responsive force generated by the patient. With this system, the interaction can be virtually established. In addition, by integrating real human trajectories, the proposed assistive robotic system can help patients to perform rehabilitation activities in their own pace. Such an assistive robotic system and virtual interacting scheme can minimize both patient’s and therapist’s traveling time. The assistive functions of this light weight design can also help patients to in their ADLs.
A Study on Evolution of Splat Radius and Temperature in Thermal Spray Process
Authors: Dash Manpreet , Kumar Sangharsh , Bandyopadhyay Partha Pratim , Bhattacharya Anandaroop
Published: January 2019

The impact process of a molten metal droplet impinging on a solid substrate surface is encountered in several technological applications such as ink-jet printing, spray cooling, coating processes, spray deposition of metal alloys, thermal spray coatings, manufacturing processes and fabrication and in industrial applications concerning thermal spray processes. Deposition of a molten material or metal in form of a droplet on a substrate surface by propelling it towards it forms the core of the spraying process.

During the impact process, the molten metal droplet spreads radially and simultaneously starts losing heat due to heat transfer to the substrate surface. The associated heat transfer influences impingement behavior. The physics of droplet impingement is not only related to the fluid dynamics, but also to the respective interfacial properties of solid and liquid. For most applications, maximum spreading diameter of the splat is considered to be an important factor for droplet impingement on solid surfaces. In the present study, we have developed a model for droplet impingement based on energy conservation principle to predict the maximum spreading radius and the radius as a function of time. Further, we have used the radius as a function of time in the heat transfer equations and to study the evolution of splat-temperature and predict the spreading factor and the spreading time and mathematically correlate them to the spraying parameters and material properties.
Effect of Oscillating Water Column Chamber Inclination on the Performance of a Savonius Rotor
Authors: Prasad Deepak D. , Ahmed Mohammed Rafiuddin , Lee Young-Ho
Published: January 2019

The global power potential of the waves that hit all the coasts worldwide has been estimated to be in the order of 1 TW. On an average, each wave crest transmits 10–50 kW/m of energy and this corresponds to 15 to 20 times more energy per meter than wind or solar energies. Wave energy is environmentally friendly and is the most consistent of all the intermittent sources. While wind, solar and wave are all intermittent, wave is the most consistent. Availability of waves is 90% compared to 30% for wind and solar energy. The oscillating water column (OWC) is the most investigated wave energy converter (WEC). OWC is a partially submerged hollow structure positioned, either vertically or at an angle. The bidirectional flow of air above the water column is used to drive a turbine. Majority of the OWC devices have chambers which are perpendicular to the incident waves. These conventional OWCs suffer severely from flow separation that occurs at the sharp corners of the chamber. In order to address this issue, researchers have proposed inclining the chamber at an angle with respect to the incident waves. This improves the flow characteristics. In addition to this, the flow in the chamber which ultimately decides the turbine performance, also increases. In the present study, the effect of OWC inclination on rotor performance was numerically studied using commercial computational fluid dynamics (CFD) code ANSYS CFX. The results highlight that the 55° inclined OWC showed improved performance when compared to the conventional OWC and current OWC. The maximum power for the inclined OWC was 13% higher than that recorded for the rotor in the current OWC and 28% than that recorded in the conventional OWC at mean wave condition. The 55° inclined OWC recorded peak rotor power of 23.2 kW which corresponded to an efficiency of 27.6% at the mean sea state. The peak power and efficiency at maximum sea state was 26.5 kW and 21.5% respectively. Higher oscillation was observed in the 55° inclined OWC. The combination of increased flow rate and energy in the flow lead to better performance of the 55° inclined OWC.
Disappearance of Strengthened Micro Texture of Modified 9Cr-1Mo Steel Caused by Stress-Induced Acceleration of Atomic Diffusion at Elevated Temperatures
Authors: Luo Yifan , Miura Hideo
Published: January 2019

The change of the lath martensitic structure in the modified 9Cr-1Mo steel was observed in the specimens after the intermittent fatigue and creep tests using EBSD (Electron Back-Scatter Diffraction) analysis. The Kernel Average Misorientation (KAM) value and the image quality (IQ) value obtained from the EBSD analysis were used for the quantitative evaluation of the change in the lath martensitic texture. It was found that the lath martensitic texture started to disappear clearly after 107–108 cycles under the fatigue loading at temperatures higher than 500°C when the amplitude of the applied stress exceeded a critical value. Similar change also appeared in the creep test. The critical value decreased monotonically with the increase of the test temperature. This microstructure change decreased the strength of the alloy drastically.

In order to explicate the dominant factors of the change quantitatively, the changes of the microstructure and the strength of the alloy were continuously measured by applying an intermittent creep test at elevated temperatures. It was found that the effective activation energy of atomic diffusion decreased drastically under the application of mechanical stress at elevated temperatures. The effective diffusion length for the disappearance was about 9 μm, and this value was much larger than the initial pitch of the lath martensitic texture of about 0.5 μm, and smaller than the average size of the initial austenite grains of about 20 μm. Therefore, the stress-induced acceleration of atomic diffusion was attributed to the disappearance of the initially strengthened micro texture. The change of the micro texture caused the drastic decrease in the yielding strength of this alloy. Finally, the prediction equation of the lifetime of the alloy was proposed by considering the stress-induced acceleration of atomic diffusion under the application of mechanical stress at elevated temperatures.
Some Studies on NOX Reduction From a Diesel Engine Using Stabilized Emulsion
Authors: Kumar Naveen , Pali Harveer Singh , Bansal Sidharth
Published: January 2019

The twentieth century has seen a rapid twenty-fold increase in the use of fossil fuels. Personal and commercial transportation consumes 2% of the total world energy. The main products of combustion of fossil fuel are carbon mono oxide (CO), unburned hydrocarbons (HC), Carbon dioxide (CO2), oxides of sulfur (SOx), oxides of nitrogen (NOx) and particulate matter. Oxides of nitrogen (NOx) are the major diesel engine pollutants and referred to as mixtures of nitric oxide (NO) and nitrogen dioxide (NO2). NOx emissions are required to be controlled because NO and NO2 contribute to the formation of smog, an environmental and human health hazard. NO2 is also directly of concern as a human lung aggravation. To reduce NOx emissions from a diesel engine, the introduction of water in the combustion chamber of a diesel engine is a promising option as vaporization of water reduces adiabatic flame temperature and micro-explosion phenomena lead to improved mixing. In the present study, stable D/W emulsion, with varying water content, up to 3% were prepared using span 80 as a surfactant. The results indicated a reduction in NOx and smoke with increasing water volume fraction in the emulsion compared to diesel baseline. However, beyond 2% water content led to increased ignition delay and higher diffusion phase heat release resulting in noisy engine operation. Therefore, it can be concluded that diesel-water emulsion with 2% water could be used for significant reduction of NOx emissions from diesel and biodiesel operation of a CI Engine.
Examining Pulmonary Toxicity of Engineered Nanoparticles Using Clustering for Safe Exposure Limits
Authors: Ramchandran Vignesh , Gernand Jeremy M.
Published: January 2019

Experimental toxicology studies for the purposes of setting occupational exposure limits for aerosols have drawbacks including excessive time and cost which could be overcome or limited by the development of computational approaches. A quantitative, analytical relationship between the characteristics of emerging nanomaterials and related toxicity is desired to better assist in the subsequent mitigation of toxicity by design. Quantitative structure activity relationships (QSAR’s) and meta-analyses are popular methods used to develop predictive toxicity models. A meta-analysis for investigation of the dose-response and recovery relationship in a variety of engineered nanoparticles was performed using a clustering-based approach. The primary objective of the clustering is to categorize groups of similarly behaving nanoparticles leading to the identification of any physicochemical differences between the various clusters and evaluate their contributions to toxicity. The studies are grouped together based on their similarity of their dose-response and recovery relationship, the algorithm utilizes hierarchical clustering to classify the different nanoparticles. The algorithm uses the Akaike information criterion (AIC) as the performance metric to ensure there is no overfitting in the clusters. The results from the clustering analysis of 2 types of engineered nanoparticles namely Carbon nanotubes (CNTs) and Metal oxide nanoparticles (MONPs) for 5 response variables revealed that there are at least 4 or more toxicologically distinct groups present among the nanoparticles on the basis of similarity of dose-response. Analysis of the attributes of the clusters reveals that they also differ on the basis of their length, diameter and impurity content. The analysis was further extended to derive no-observed-adverse-effect-levels (NOAEL’s) for the clusters. The NOAELs for the “Long and Thin” variety of CNTs were found to be the lowest, indicating that those CNTs showed the earliest signs of adverse effects.
Investigating the Effect of Tool Coating on Cutting Forces and Tool Wear During Micro-Milling of Polycarbonate Glass
Authors: Hanson Craig , Chen Xingbang , Jahan Muhammad P. , Ma Jianfeng , Arbuckle Gregory K.
Published: January 2019

Polycarbonate glass is one of the most widely used materials in the optical industries for making impact resistance lenses. Besides optical applications, polycarbonate glass has found applications in automotive and biomedical industries. The objective of this study is to investigate the effect of tool coating on the reduction of tool wear and cutting forces during micro-milling of polycarbonate glass. Both numerical modeling and experimental investigation have been carried out to investigate the effectiveness of various tool coatings on the carbide tool in minimizing the cutting forces, and hence tool wear. A series of experiments were conducted using CNC micro-milling of polycarbonate glass by varying feed rate, depth of cut, and tool coating. The three types of cutting tools used in this study were uncoated, titanium nitride (TiN) coated, and titanium aluminum nitride (TiAlN) coated tungsten carbide tools. The cutting forces have been recorded using the Kistler force dynamometer and the tool wear were analyzed using scanning electron microscope (SEM). It was found that all tools had reduced instances of failure, chipping, and abrasion at a moderately higher feed rate and depth of cut. Both very low and high feed rate were found to result in comparatively higher tool wear. The cutting forces increased with an increase of depth of cut, except for the TiAlN coated tool in some instances. With the increase of feed rate, the cutting forces gradually increased or stayed relatively constant across all depths of cut. It was found that the TiAlN coated tool reduced the amount of tool wear and cutting force across all feed rates and depths of cut. There is also a critical depth of cut around 0.3–0.5 mm and feed rate around 576–768 mm/min that reduced the amount of tool wear for the micro-milling of polycarbonate glass. Finally, the numerical modeling and simulation results of cutting forces were found to be in good agreement with the experimental cutting forces and the validated FEM models were then used to predict the cutting forces for higher spindle speed.
Numerical Modeling and Approximation of the Coupling Lamb Wave Propagation With Fluid-Structure Interaction Problem
Authors: Ebna Hai Bhuiyan Shameem Mahmood , Bause Markus
Published: January 2019

So far, mathematical modelling of Lamb wave propagation under fluid-structure interaction (FSI) was limited to the case of rigid structure. We extend this concept to account for structural dynamics. Thereby, we provide a model that is suitable for the structural health monitoring (SHM) during the operation of the structure. The model we develop is referred to as the “eXtended Fluid-Structure Interaction” (eXFSI) problem, which is a one-directional coupling of typical FSI problem with an ultrasonic wave propagation in fluid-solid and their interface (WpFSI). Here, the strongly coupled problem of acoustic & elastic wave equations is denoted by WpFSI. Next, we explore the approach to the efficient numerical solution of the problem. We use a combination of Finite Element and Finite Difference methods and employ a dual-loop algorithm to balance the computational cost and quality of the numerical solution. To facilitate our solution algorithm, we rely upon the software library package DOpElib.
Thermal Modeling of a Building Integrated Radiative Cooler for Space Cooling Applications
Authors: Lamba Ravita , Zeyghami Mehdi , Young David , Goswami D. Yogi , Kaushik S. C.
Published: January 2019

Recent developments of plasmonic emitters that emit infra-red radiation in the range of 8–13 micron wavelengths that can be transmitted through the atmosphere have opened up the potential of cooling buildings passively by radiating heat through this atmospheric window into the deep space. This paper presents an analysis of the potential of this method to cool buildings radiatively 24 hours per day. Air conditioning units consume a large amount of electricity and are the main drivers of peak electricity loads. A transient thermal model of a building integrated radiative cooling (BIRC) system was carried out for passive radiative cooling of buildings. A MATLAB code was developed for solving the heat transfer model of the BIRC system using a numerical iterative approach. The effects of operating parameters such as cooling emissive power and ambient conditions on the performance of the system were studied. Furthermore, effects of non-radiative heat transfer processes were studied by considering different heat transfer coefficients. Based on this analysis, energy savings potential of radiative cooling of buildings was estimated for the climatic conditions of Miami, FL, and Chicago, IL, USA for a fraction of a roof surface covered with a radiative cooler. Further, the results of this analysis are in line with previous studies estimating the cooling potential of up to 100 W/m2 with radiative cooling systems. These results will help in estimating the economic value of cooling buildings by using plasmonic emitting surfaces on the building skins.
Negative Effective Stiffness Content in Cracked Rotors
Authors: AL-Shudeifat Mohammad A. , Alhammadi Fatima K.
Published: January 2019

The appearance of cracks in rotor systems affects the whirl response in the neighborhood of the critical whirl rotational speeds. The combined effect of the crack depth and the unbalance force vector angle orientation with respect to the crack opening direction on the effective stiffness content of the cracked rotor system in the neighborhood of the critical rotational speed is addressed here. The effective stiffness expression of the cracked system can be obtained from the direct integration of the equations of motion of the cracked rotor system. The cracked rotor equations of motion can be expressed by the Jeffcott rotor or the finite element models. The appearance of cracks in rotor systems converts them into parametrically excited dynamical systems with time-periodic stiffness components. The interaction between the time-periodic stiffness and the external periodic forcing function of the unbalance force significantly alters the effective stiffness content in the system at both transient and steady state operations. For wide range of crack depths and unbalance force vector angles, the effective stiffness has been found to be of negative values. This means that the cracked rotor system tends to have more resistance to deflect towards the center of its whirl orbit and less resistance to deflect away under the unbalance force excitation effect. Consequently, in the negative stiffness content zone of the unbalance force vector angles, the cracked rotor system tends to exhibit a sharp growth in the vibration whirl amplitudes. However, for positive effective stiffness values, the shaft has more resistance to deflect away from its whirl orbit center. Therefore, the cracked rotor system is at higher risk of failure in the negative effective stiffness zone of unbalance force vector angles than the positive effective stiffness zone of these angles.
Effectiveness of Using Mixed Coordinates in Modeling Wind Turbines
Authors: Nada Ayman A. , Al-Shahrani Ali S.
Published: January 2019

This paper presents the effectiveness of using mixed, nodal and/or modal coordinates in modeling wind turbines. The paper shows that the nodal model exhibits excellent numerical properties, especially in the case of highly rotations. In the case where the rotation of the rotor-blade is extremely high, the geometric stiffness effect must be taken into account, and therefore, the nonlinear stiffness terms should be included within the model. On the other side, the dynamics of the tower as well as other components can be modeled using a set of modal coordinates. The paper shows a method of utilizing experimental modal coordinates for low speed components and those that deflected by simple motion shapes. The wind-turbine model based on the floating frame of reference formulation and by using the suggested mixed coordinates can be utilized for design process, identification and health monitoring aspects.
The Value of Energy Flexibility: Integrating Wind Resources in New York State
Authors: Conlon Terence M. , Modi Vijay , Waite Michael B.
Published: January 2019

This paper explores the effects of energy system flexibility on the contribution of wind generation to the New York State (NYS) electricity generation mix. First, the benefits of NYS-specific flexible hydropower are investigated. For all simulations, a mixed integer linear program minimizes net load to determine the maximum aggregate capacity factor for the installed wind power. A similar routine explores the benefits of three different types of energy flexibility: flexible supply, flexible demand, and bidirectional flexibility (i.e. energy storage). To compare across technologies, a novel method of standardizing flexibility inputs, Potential Flexible Energy (PFE), is introduced.

With 30 GW wind capacity in NYS (average electricity demand of 18.7 GW), introducing electric vehicles with an average load of 1.44 GW and daily available battery capacity of 34.5 GWh (roughly equivalent to the daily use of 3.4 million passenger EVs) increases statewide wind utilization by 840 MW (9.0% of wind potential and 4.5% of average load). Added flexibility in the form of energy storage yields similar results: with 3.2 GW charge/discharge capability and 76.8 GWh storage capacity, statewide wind utilization increases by an average of 660 MW (7.0% of wind potential and 3.5% of average load).

Because of transmission constraints and the geographic distribution of high-potential wind resources, increased wind utilization is only achieved when flexibility is added in the region where 86% of the 30 GW simulated wind capacity is located.
Effect of Process Parameters on Compressive Properties of ULTEM 9085 Produced by FDM Process
Authors: Gebisa Aboma Wagari , Lemu Hirpa G.
Published: January 2019

Fused deposition modeling (FDM), one of the additive manufacturing (AM) technologies, is a promising digital manufacturing technique that produces parts, layer by layer, by heating, extruding and depositing filaments of thermoplastic polymers. The properties of FDM-produced parts apparently depend on the processing parameters. These processing parameters have conflicting advantages that need to be investigated. This paper investigates the effect of process parameters on the compressive properties of parts produced by the FDM process. The study is carried out on a high performance polymeric material called ULTEM 9085. Full factorial design of experiment is used to analyze the effects of process parameters on the compressive properties of the material. Five parameters: namely, air gap, raster width, raster angle, contour number and contour width, of the FDM machine are considered in the current study. The results show that, with the exception of the raster width, all other considered parameters have significant interaction effect on the compressive strength. For the compressive strain, air gap, contour number and contour width showed substantial interaction effects.
Motion Capture and Data Elaboration to Analyse Wheelchair Set-Up and Users’ Performance
Authors: Regazzoni Daniele , Vitali Andrea , Rizzi Caterina , Colombo Zefinetti Filippo
Published: January 2019

Using a wheelchair can be a challenging task for people with reduced force and control of muscles of abdomen or lower back. Spinal cord injured (SCI) people are the majority of those who are spending most of the day on a wheelchair and a proper training and chair setup is mandatory to reach a good level of functionality and to avoid harms and side effects. In order to assess the complex motion of a person self-pushing a wheelchair, a motion capture (Mocap) system has been arranged and a group of SCI patients has been acquired in a hospital gym. The Mocap system uses three Microsoft Kinect RGB-D sensors and iPisoft to perform the recording of the 3D motion. The main goal of the research is to provide therapists with a quantitative method to define a preliminary configuration in an objective way once is given the user’s medical conditions and his/her way of using the wheelchair. Working side by side with physiotherapists, the main parameters to be evaluated (e.g. pushing angles) have been identified and algorithms have been identified to automatically extract them from the 3D digital avatar model data coming from the Mocap system. The performance of the patients is then analyzed taking into account the wheelchair setup (e.g. position and inclination of the seat and of the back). The influence of geometric parameters on patients’ motion is analyzed so that design guidelines for configuration can be found. The overall outcome is to maximize performance and minimize side effects and fatigue, providing users with a better experience on the wheelchair.