bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Woody Biomass Torrefaction Process
Authors: Hasan Mahmudul , Haseli Yousef
Published: January 2019

Torrefaction is a thermal pretreatment process which usually takes place at temperatures between 200–300°C. Torrefied biomass has been proven in numerous studies to have superior combustion properties compared to raw biomass. The objective of this study is to develop a model to estimate solid energy yield, elemental compositions and enthalpy of solid and volatile yield. Formation enthalpy of raw and torrefied biomass is calculated using the correlations developed for elemental compositions and HHV of torrefied biomass. Solid yield is determined by anhydrous weight loss model for torrefied wood. Specific heat correlations for raw biomass and char are used to calculate the sensible heat required for torrefaction process. Sensible heat and formation enthalpy give the total enthalpy for raw and torrefied biomass. During torrefaction, a mixture of volatile compositions is released. Experimental mass fractions of the volatiles components are taken from published literature, which allowed us to determine the enthalpy of formation and specific heat of the volatiles. Finally, the model results associated with the torrefaction process are compared with experimental data.
A Holey Cavity for High-Capacity Ultrasound Imaging
Authors: Ghanbarzadeh-Dagheyan Ashkan , Heredia-Juesas Juan , Liu Chang , Molaei Ali , Martinez-Lorenzo Jose Angel
Published: January 2019

Compressive sensing (CS) theory states that, if certain conditions are met, a signal can be retrieved at a sampling rate that is lower than what Nyquist theorem requires. Among these conditions are the sparsity of the signal and the incoherence of the sensing matrix, which is constructed based on how the sensing system is designed. One effective method to render the sensing matrix incoherent is to use random processes in its construction. Diverse approaches have been proposed to randomize the sensing matrix including transmission at random transmitter positions and spectral coding with the use of a physical structure that responds very differently at disparate frequencies. In this work, a holey cavity with various frequency modes is used to spectrally code the ultrasound wave fields. Then, with the use of CS theory and simulations, it is shown that the sensing system that is equipped with such a cavity performs meaningfully better than a regular system in terms of sensing capacity, beam focusing, and imaging. What is more, the validity of Born approximation is investigated in this work to show its extent of applicability in imaging relatively small targets. Due to computational limitations, the simulation domain has been selected to be comparatively small; yet, the achieved results evidently show the concept and warrant further studies on holey cavities in ultrasound imaging, including their fabrication and experimental corroboration. The decrease in the number of measurements necessary for correct image reconstruction can make ultrasound sensing systems more efficient in size and scan time in a variety of applications including medical diagnosis, non-destructive testing, and monitoring.
Viscoelastic Behavior of Carbon Nanotube Yarns and Twisted Coils
Authors: Khanbolouki Pouria , Tehrani Mehran
Published: January 2019

Coiled structures made from polymer and Carbon Nanotube (CNT) yarns are used as artificial muscles, stretchable conductors, and energy harvesters. The purpose of this work is to present our latest understanding of the mechanical behavior of these CNT-based structures. CNT yarns are fabricated by inserting twists in sheets spun from CNT forests. Over twisting the CNT yarns results in coiled CNT yarns, similar to a spring where the spring radius is comparable to the diameter of the CNT yarn. In this study, we explain the development and validation of a viscoelastic model, to capture damping and hysteresis in CNT yarns under quasi-static and dynamic loads. Confirmation of linear viscoelastic behavior of CNT yarns can lead us to the development of a model for coiled CNT yarns. Coiled CNT yarns, on the other hand, show a complex non-linear viscoelastic behavior. Possible mechanisms responsible for this non-linear behavior are discussed.
Multi-Scale Modeling of Power Plant Performance Enhancement Using Asynchronous Thermal Storage and Heat Rejection
Authors: Gagnon Lauren B. , Helmns Dre , Carey Van P.
Published: January 2019

The study summarized in this paper links a model of thermal energy storage (TES) unit performance to a subsystem model including heat exchangers that cool down the storage at night when air temperatures are low; this cool storage is subsequently used to precool the air flow for a power plant air-cooled condenser during peak daytime air temperatures. The subsystem model is also computationally linked to a model of Rankine cycle power plant performance to predict how much additional power the plant could generate as a result of the asynchronous cooling augmentation provided by this subsystem. The goal of this study is to use this model to explore the parametric effects of changing phase change material (PCM), melt temperature, and the energy input and rejection control settings for the system. With this multi-scale modeling, the performance of the TES unit was examined within the context of a larger subsystem to illustrate how a high efficiency, optimized design target can be established for specified operating conditions that correspond to a variety of applications. Operating conditions of interest are the mass flow rate of fluid through the flow passages within the TES, the volume of the TES, and the amount of time the system remains in the extraction process in which thermal energy is inputted to the device by melting PCM, and the PCM melt temperature. These conditions were varied to find combinations that maximized efficiency for a 50 MW power plant operating in the desert regions of Nevada during an average summer day. By adjusting the flow rate within the fluid flow passages and the volume of the TES to achieve complete melting of the PCM during a set extraction time, indications of the parametric effects of system flow, melt temperature, and control parameters were obtained. The results suggest that for a full-sized power plant with a nominal capacity of 50 MW, the kWh output of the plant can be increased by up to 3.25% during the heat input/cold extraction period, depending on parameter choices. Peak power output enhancements were observed to occur when the system operated in the extraction phase during limited hours near the peak temperatures experienced throughout a day, while total kWh enhancement was shown to increase as the extraction period increased. For the most optimized conditions, cost analyses were performed, and it was estimated that the TES system has the potential to provide additional revenue of up to $1,366 per day, depending on parameter choices as well as the local cost of electricity. Results obtained to date are not fully optimized, and the results suggest that with further adjustments in system parameters, weather data input, and control strategies, the predicted enhancement of the power output can be increased above the results in the initial performance predictions reported here.
The Influence of Primary Blast Wave on the Posterior Part of the Eyeball
Authors: Tong Junfei , Gu Linxia
Published: January 2019

With the increasing application of improvised explosive devices, the ratio of traumatic ocular injury significantly increased in the past decades, which has become the fourth most happened injury to military deployment. The ocular injury treatment is costly and has been less effective, which influences the military service and life experience of the soldiers. With years of research on the traumatic ocular injury through experiment or computational simulations, the primary blast wave related overpressure was found to induce macular damage, globe rupture. While the influence of the primary blast wave on the posterior part of the eyeball was poorly understood, such as the optic nerve. In this work, we developed a three-dimensional computation model, which included lamina cribrosa (LC), optic nerve and cerebrospinal fluid (CSF). The strain evaluated in optic nerve was found to exceed neural tissue’s physiological loading range, which might explain the vision loss after the blast.
Disc Turbine for Energy Harvesting
Authors: Pascoa Jose C. , Candido Silvio , Charrua-Santos Fernando , Espirito-Santo Antonio , Canario Marco
Published: January 2019

Energy harvesting is part of a current paradigm of distributed production and use of energy. However, we are aware that the size of turbomachinery used to produce the energy can be an advantage, in terms of higher efficiencies when using larger machines. This is one main reason why distributed production and use of energy has not known a very large popularization in the past. Still, with present day fluid dynamics tools and new production technologies it is now becoming possible to expand this concept. A less used turbomachinery is the disc or Tesla turbine or pump. This is based on a series of parallel discs that rotate under the action of a common shaft. These parallel discs impart a movement to the flow by means of viscous effects, due to viscous adherence of the fluid to the rotating discs. Disc turbines offer and inherent advantage to provide a capability of energy harvesting when fluids include living elements, or when the fluid is mostly comprised of slurries. In this paper we present an experimental and numerical analysis of the flow in this special kind of turbomachine. The experimental activities use a direct operating mode to assess the operation of the pump-as-turbine. An experimental set-up provides a set of results that allow to characterize the design conditions of the disc turbomachine under analysis. Further, a numerical simulation is performed for direct and inverse operation modes. After careful validation of the numerical model using the experimental results, the performance of the disc turbine is verified for a range of conditions. Among these are pure water and slurry fluids. The results allow us to provide the set of conditions in which the disc turbine can be used for energy harvesting.
A Review of Propulsion Systems for CubeSats
Authors: Pascoa Jose C. , Teixeira Odelma , Filipe Gustavo
Published: January 2019

Educational purposes have been the trigger for CubeSat development. Most of this class of nano-satellites where initially developed as hands-on projects at universities and institutes, mostly being of very simple construction and complexity. However, in the most recent years low cost sensors and mobile technology started to be translated into nano-satellites, and this expanded their possible mission profiles, prompting the attention of companies and government agencies. Today, many tasks that previously where only possible to be developed within a multi-million dollar/euro framework can be accomplished by nano-satellites, at a tiny fraction of their cost. One of the major weaknesses of these devices is the low level of available power onboard, and the lack of efficient state-of-the-art propulsion systems. The present paper provides a throughout discussion on the diverse propulsion technologies used for CubeSat and other micro-satellite systems. If only attitude correction is requested then, present day technologies can be readily used. However, for orbit change or interplanetary nano-spacecraft propulsion, present day technologies are not able to provide the necessary performance under the restricted power budget on-board. New routes are herein proposed for the development of thrusters for nano-satellites and other comparable size spacecrafts.
Path Generation Algorithm Verification of Five DOF Robotic Arm With Linear Actuator Using MATLAB Sim-Mechanics
Authors: M. Abou Elyazed Maged , Zaghloul A. S. , AbdelHamid Ahmed Y.
Published: January 2019

Manipulators have been considered the backbone of industrial world for decades. The main aspect of industrial robotic arm is its ability to track a certain path in the 3D space. Using liner actuators to drive multi degrees of freedom robot offers high load capacity, but path generation algorithm of such robot is relatively complicated and computationally expensive. Furthermore, limitations in the joints workspace are existed. In this work, five degrees of freedom robotic arm is constructed to guaranty suitable workspace. Forward and inverse kinematic algorithms are evaluated. Moreover, path generation algorithm in Cartesian space is held using three different motion planning techniques. Sim-Mechanics toolbox under MATLAB is used to verify the introduced forward kinematics, inverse kinematics, and path generation algorithms. Thus, a comparison between the three introduced motion planning techniques is illustrated. Finally, the generated paths are experimentally applied on the case study. The work aims to illustrate the importance of simulation in the field of robotic arm algorithms verification.
Conductive Heating of Li-Ion Batteries at Low Temperatures
Authors: Xu Zhibang , Xu Meng , Wang Xia , Zhao Peng
Published: January 2019

Lithium-ion (Li-ion) batteries have been increasingly used in electric vehicles (EVs) in the past ten years due to their high energy and power density. However, the poor performance at low temperatures is the main challenge to the deployment of EVs equipped with Li-ion batteries because it has great influence on the driving range. In this study, conductive heating method is proposed to improve the lithium ion battery performance at low temperatures (−20°C ∼ −5°C). Both experimental testing and numerical simulation are employed to compare different heating protocols to minimize the temperature gradient, external heating power and heating time. Results show that simultaneous heating with small external power and high discharge voltage can obtain optimal performance as compared to preheating protocol. In addition, internal heating combined with external heating could heat up the battery from −20°C to 0°C in only 1 minute which is an effective strategy.
A Novel Framework in Manufacturing Automation to Implement Cyber-Manufacturing Systems
Authors: Guerra-Zubiaga David A. , Schwaig Kathy S. , Felix Mason B. , Calfee John D. , Sims Aubrey M. , Vo Tu H.
Published: January 2019

Cyber Manufacturing system (CMS) is the future of manufacturing system integration, which can completely change the manufacturing industry in all areas to benefit everyone from the companies to the consumers. This research paper describes how this form of manufacturing can be achieved through the cooperation of several areas of digital manufacturing. The included Manufacturing Automation Framework displays how the different systems can work together to achieve successful cyber manufacturing. The framework provides the basic structure of the system needed to easily transfer the technology and ideas to various industries.
A Reforming Characteristics of a Mid-Temperature Methane-Steam Reformer With Various Configurations
Authors: Cho Kyungin , Yun Jinwon , Yu Sangseok
Published: January 2019

A external methane-steam reformer is applied to fuel delivery of high temperature fuel cell system. When the reformer is equipped for high temperature fuel cell system, the heat supply of the methane steam reformer is critical to improve the system efficiency. Typically, system efficiency is improved as the waste heat is utilized. However, the general performance of steam reformer is designed to provide the rated performance at high temperature. In this study, characteristics of mid-temperature steam reformer are investigated. At mid-temperature operation of steam reformer, it is important to understand the performance of the reformer include inlet flow rate, temperature, and reformer geometry, and so on. Among them, the characteristics of the reforming catalyst are the most fundamental and most important in the performance of the reformer. Also, it is possible to optimize the performance of the reformer by understanding the reforming rate depending on the reformer inlet temperature, the amount of heat source, and the SCR (Steam to Carbon Ratio). Therefore, experimental study was carried out to understand the characteristics of the reforming catalyst. In order to carry out the experiment, the length of the reformer and the number of the heat source tubes were made variously so that the performance characteristics according to the volume of the reforming catalyst layer were confirmed. Through analysis of the experimental results, the characteristics of the reforming catalyst, which is an important factor in the performance of the reformer, can be understood under various conditions.
Determination of Johnson Cook Material Model Constants and Their Influence on Machining Simulations of Tungsten Heavy Alloy
Authors: Sagar Chithajalu Kiran , Priyadarshini Amrita , Gupta Amit Kumar , Shukla Sidharth Kumar
Published: January 2019

Tungsten Heavy Alloys (WHA) are used in counterbalance and ballast weights for aerodynamic balancing in fixed and rotary wing aircraft. Manufacturing these components for closer tolerances using machining is a challenging task. The present work aims to develop a 2D Finite Element (FE) model to simulate the chip formation process during machining of WHA using Johnson Cook Material Model (JCMM). The model constants for 95%WHA are determined based on the high strain rate test data using least square method. The calculated values are further optimized using Genetic Algorithm (GA) and Artificial Bee Colony (ABC) algorithm, which are then used as material inputs for FE simulation of machining WHA. The predicted results such as cutting force, chip geometry, shear stress, shear angle are presented and compared with the experimental results under similar cutting conditions. It has been observed that the constants obtained from ABC algorithm show minimum error in the cutting performance measures for all the experimental results.
Gaseous Fuel Leakage From Natural Gas Infrastructure
Authors: Hormaza Mejia Nohora A. , Brouwer Jack
Published: January 2019

Hydrogen has often been studied as a possible fuel of the future due to its capabilities to support zero emissions and sustainable energy conversion. Hydrogen can be used in a fuel cell to generate electricity at high efficiencies and with zero emissions. In addition, hydrogen can be renewably produced via electrolysis reactions that are powered from otherwise curtailed renewable energy. One possible means of storing and delivering renewable hydrogen is to inject it into the existing natural gas (NG) system and thus decarbonize gas end-uses. The NG system has potential to serve as a storage, transmission and distribution system for renewably produced hydrogen. Despite the potential of hydrogen to reduce the carbon intensity of the NG system, the unique characteristics of hydrogen (low molecular weight, high diffusivity, lower volumetric heating value, propensity to embrittle pipeline materials) has led to justified concerns over the safety of introducing hydrogen blends into the NG system. While many studies have attempted to quantitatively predict leakage rates of hydrogen using classical fluid mechanics theories, such as Hagen-Poiseuille flow, there have been limited studies which quantitatively assess gaseous fuel leakage to support the predictions made from theoretical analyses and computations. In this paper we present a summary of the literature related to gaseous fuel leakage and results from preliminary experiments which support the idea that entrance effects may significantly affect gaseous fuel leakage from practical leak scenarios such as NG fittings, resulting in similar leakage rates between hydrogen and NG.
The Strain Rates of the Brain and Skull Under Dynamic Loading
Authors: Hosseini Farid Mohammad , Eslaminejad Ashkan , Ramzanpour Mohammadreza , Ziejewski Mariusz , Karami Ghodrat
Published: January 2019

Accurate material properties of the brain and skull are needed to examine the biomechanics of head injury during highly dynamic loads such as blunt impact or blast. In this paper, a validated Finite Element Model (FEM) of a human head is used to study the biomechanics of the head in impact and blast leading to traumatic brain injuries (TBI). We simulate the head under various direction and velocity of impacts, as well as helmeted and un-helmeted head under blast waves. It is shown that the strain rates for the brain at impacts and blast scenarios are usually in the range of 36 to 241 s−1. The skull was found to experience a rate in the range of 14 to 182 s−1 under typical impact and blast cases. Results show for impact incidents the strain rates of brain and skull are approximately 1.9 and 0.7 times of the head acceleration. Also, this ratio of strain rate to head acceleration for the brain and skull was found to be 0.86 and 0.43 under blast loadings. These findings provide a good insight into measuring the brain tissue and cranial bone, and selecting material properties in advance for FEM of TBI.
An Experimental and Numerical Study of Heat Transfer and Flow Characteristics of Laminar Flow in a Circular Tube With Wedge-Shaped Wavy-Tape Inserts
Authors: Liang Yunmin , Liu Peng , Zheng Nianben , Shan Feng , Liu Zhichun , Liu Wei
Published: January 2019

In this study, a new type of tube inserts, named wedge-shaped wavy-tape insert, which is designed from bionics based on the movement of cuttlefish, is reported. The numerical simulation was carried out to investigate the effects of wedge-shaped wavy-tape insert arrangements on the heat transfer and flow characteristics of laminar flow in a circular tube under constant heat flux conditions. Details of the flow structures in the circular tube with wedge-shaped wavy-tape inserts which are arranged in same phase (S-type wavy tape) and different phase (D-type wavy tape) were presented and analyzed respectively. Then stereoscopic particle image velocimetry (Stereo-PIV) measurements on the flow structures were conducted to verify the numerical results. The flow structures obtained through simulations and PIV measurements agree well. It was observed that the arrangements of wedge-shaped wavy-tape inserts have a significant influence on the thermo-hydraulic performance. The average friction factor enhancement ratio f/f0 of D-type wavy tape were about 14%–20% lower than S-type wavy tape, but average heat transfer enhancement ratio Nu/Nu0 of D-type wavy tape were about 7%–14% higher than S-type wavy tape. The best performance evaluation criterion of D-type wavy tape could be improved to 3.02. The result shown the wedge-shaped wavy-tape insert is a promising technique for laminar convective heat transfer enhancement.
Droplet Nucleation and Growth in Cryogenic Turboexpanders
Authors: Sam Ashish Alex , Kunniyoor Keerthi Raj , K. Narayanan Jayachandran , Mishra Arpit , Ghosh Parthasarathi
Published: January 2019

Cryogenic turboexpanders for nitrogen refrigeration and liquefaction cycles operating near liquefaction conditions are vulnerable to droplet formation. The turboexpander must be devoid of any traces of droplets, as this may cause damage to the blades and also result in performance deterioration. Hence, a multiphase flow analysis was conducted, based on the droplet condensation model in Ansys CFX®, to identify any possible droplet sites and its nature of propagation. A single-phase steady state simulation of the turboexpander was performed initially to identify the regions susceptible to droplet formation, followed by a multiphase analysis to study the flow field behavior and to characterize the droplet nucleation and growth. It has been observed that the low-pressure regions like vortices and wakes are susceptible to sub-cooling and thereby in droplet formation. Also, major geometrical parameters that affect the droplet nucleation have also been identified.
Performance Analysis of UAV Visual Landmark Tracking Under Rapid Motion
Authors: Jacobson Eric , Tatoglu Akin
Published: January 2019

With reduced drone cost, object tracking and localization algorithms are well studied for robotics research. In most cases, the scene is stationary and/or motion is smooth so that control system reference input varies less frequently: only at the sharp edges generated by path planning algorithm. However, using systems such as co-robots among human beings, in windy situations and/or around more sophisticated structures will require rapid localization, object detection and obstacle avoidance solutions due to continuously varying controller input and path plan. This research effort benchmarks fundamental object detecting and tracking techniques under highly dynamic disturbances. To perform these tests an experimental system was developed that could create rapid angular motion in a controlled manner. A sensor suite of a visual sensor and an IMU is assembled into a rig. It is mounted on tip of a 6-DOF multi-joint mechanism which consists of a 5-DOF robotic arm and a pendulum mounted to the end effector. While robotic arm is programmed to simulate aggressive drone motion (max. 60 degrees/sc.), pendulum generates an additional highly dynamic angular motion about another plane. This motion can be used to benchmark various types of tracking algorithms, allowing for a comparison in robustness with regards to different motions. The specific motion that will be explored in this research is rapid angular motion. A feature rich landmark is used to execute the experiments. Velocity, acceleration and viewing angle are varied continuously to benchmark basic search-based detection methods using gradient magnitude which is the fundamental step for advanced algorithms. Finally, results with different algorithm parameters are listed to compare robustness of the solutions. Overall system repeatability and precision are discussed with various plots of 2700 processed images.
Potential Aggregate Effects of Net-Zero Energy Homes (NZEHs) With Distributed Energy Generation on the U.S. Electrical Grid
Authors: Kim Dongsu , Cho Heejin , Luck Rogelio , Mago Pedro
Published: January 2019

This study evaluates potential aggregate effects of net-zero energy home (NZEH) implementations on the U.S. electrical grid in a simulation-based analysis. The aggregate impact of large-scale NZEH implementations on the U.S. electrical grid is evaluated through a simulation-based study of prototype residential building models with distributed photovoltaic (PV) generation systems. An EnergyPlus residential prototype building model (i.e., a multi-family low-rise apartment building) is used to determine the detailed electricity consumption of each residential building model using U.S. climate weather files. This study assumes that net-metering is available on the electrical grid so that the surplus on-site electricity generation can be fed to the electrical grid. This study also considers the impact of electrical energy storage (EES) within NZEHs to effectively use on-site generated electricity on the electrical grid. Finally, surveyed residential building permits in 2017 are used to estimate net-electricity demand profiles of NZEHs on a national scale. Results indicate that adding distributed PV systems to enable annual multi-family NZEH performance can significantly increase changes in imported and exported electricity demand from and to the electrical grid during the daytime. However, using the EES within NZEHs helps reduce the peak electricity demand during the daytime. The stored electricity in the EES can also be used during the evening time. The peak net-electricity differences on the U.S. electrical grid-level could potentially be reduced during the daytime and shifted to the evening. Comparison of hourly electricity demand profiles for the actual U.S. demand versus the calculated net-demand on a national scale indicates that the percentage differences of U.S. net-electricity demand include about 4.5% and 4.8% for the multi-family NZEH without the EES on representative winter and summer days, respectively, at a maximum point. In addition, when the EES is added within the multi-family NZEH, the peak percentage differences could be reduced to about 3.4% and 4.3% on representative winter and summer days, respectively, at a maximum point.
Heat Transfer by a Rotating Liquid Jet Impingement Cooling System
Authors: Lu Qi , Parameswaran Siva , Ren Beibei
Published: January 2019

The circular, liquid jet impingement provides a convenient way of cooling surfaces. To effectively cool the devices inside the electric vehicle, a rotating jet impingement cooling system is designed to evaluate the potential of the jet impingement for high heat flux removal. The liquid used for jet impingement is automatic transmission fluid. The jet impingement system consists of a rotating pipe with two nozzles and a cylindrical ring which is attached to the heat source. To reduce the computational loads, first, the CFD simulation for a laminar flow inside the pipe is carried out to estimate the flow velocities at the nozzle exits. Then, the rotating jet impingement cooling of a cylinder with a uniform surface temperature is investigated numerically for stable, unsubmerged, uniform velocity, single phase laminar jets. The numerical simulation using the commercial code is performed to determine the heat flux removal performance over the cylindrical surface. The numerical results are compared with the empirical formula and experimental measurements from the literature. Furthermore, the effects of the Reynolds number and pipe rotation on the jet impingement cooling performance are also investigated.
Motion Capture of the Selective Hand Picking Movements As the Basis for the Design of Mechanically Assisted Picking Tools in Coffee Plantations in Colombia
Authors: Hernandez Barbosa Jeyson Andres , Roa Prada Sebastian , Hernandez Bolivar Dario J. , Ruiz Romero Brajan Nicolas , Rueda Oscar E.
Published: January 2019

Besides oil, coffee is one of the most traded commodities worldwide. Colombia is known as the producer of the highest quality coffee in the world, thanks to its smooth taste and aroma. One of the key elements that are responsible for the quality of Colombian coffee is its harvesting method, in which it is enforced that only mature fruits are harvested. Given the terrain conditions in which coffee trees grow, the preferred harvesting method in Colombia is selective hand picking, in which each coffee grain is individually teared off from the branch that is attached to.

This work focuses on the analysis of the motion of a human hand performing the action of manual selective coffee harvesting. The analysis is based on the data collected from a custom made motion capture system, which consists of a glove capable of sensing the angular movement of the joints, and accelerations at the tip of the fingers, by means of a set of flex sensors and accelerometers, respectively. The methods followed in this investigation include the study of the biomechanics of the hand, as applied to the motion of hand picking of coffee, which proved to be fundamental for the analysis of the experimentally measured data. After processing the experimental data, the patterns of movement done by a human coffee harvester can be simulated and replicated, which allows identifying trajectories that a good harvester follows, as compared to other harvesters, which collect smaller amounts of grains during the same period of time.

After having parameterized the motion of efficient selective hand picking, the results from this investigation serve as the basis for the design and optimization of an electromechanical tool to assist in the process of coffee harvesting, which minimizes the amount of green beans removed from the branches of the coffee trees.
Mechanistic Modeling of Dynamic Zero-Net Liquid Holdup (ZNLH) in Gas-Liquid Cylindrical Cyclone (GLCC©) Separator
Authors: Kolla Srinivas Swaroop , Karpurapu Megharaj Praneeth , Mohan Ram S. , Shoham Ovadia
Published: January 2019

Over the past 2 decades, GLCC© compact separators have been replacing the conventional vessel type separators in the Oil & Gas Industry, because of its numerous advantages. Despite these advantages, GLCC separators face two critical problems affecting the performance under extreme operating conditions, namely, Liquid Carry Over (LCO) into the gas leg and Gas Carry Under (GCU) into the liquid leg. This study focuses on the LCO phenomenon. Having a deeper insight into the LCO flow phenomenon helps us to enhance the technical performance of GLCC at these extreme conditions. Several studies were presented in the past on experimental investigations and mechanistic modeling of LCO. In the above cases, mechanistic modeling of LCO was based on Zero Net liquid Holdup (ZNLH) parameter. The liquid holdup in the upper part of the GLCC before it is blown out by gas flow is referred to as ZNLH. ZNLH is an important phenomenon affecting the GLCC pressure behavior and performance characteristics. Above mentioned experimental investigations performed to calculate ZNLH were carried out under static conditions where the effects of superficial liquid velocities were neglected. Investigations have been carried out in this study under dynamic conditions to evaluate the effect of superficial liquid velocities on ZNLH. We found that Dynamic ZNLH results are different from static ZNLH data as they show lower liquid holdup for the same gas velocities. A mechanistic model is proposed in this study to predict dynamic ZNLH and this model is validated against the dynamic ZNLH experimental data. It may be noted that a suitable ZNLH model will help in improving the predictions of the LCO mechanistic model considerably.
On Continuum Based Multiscale Modelling of Engineered Soft Tissue Constructs
Authors: Bennedsen Jacob , Yan Karen Chang
Published: January 2019

Engineered tissue constructs are assembled through combining scaffolds, cells and biologically active molecules for restoring, maintaining, or improving damaged tissues or whole organs. Cells in engineered tissue constructs often experience mechanical forces during the fabrication process, maturation process, and under in vivo conditions. These mechanical forces/stimuli induce cellular responses and affect cell viability, proliferation, and differentiation. While it is critical to understand the mechanical milieu of cells in tissue constructs, it is also extremely challenging due to the time and length scale span. Multiscale modeling approaches have been emerged to provide linkage among different length scale. One of the approaches is continuum based multiscale modeling to link organ, tissue and cellular levels. A representative volume element (RVE) with periodic or random microstructure serves as a vehicle to connect different length scales. This study focuses on effects of RVE selection, microstructure, and boundary conditions on the mechanical environment at cellular level. In particular, cell embedded alginate tissue constructs were studied. Hyperelastic models were used for modeling alginate and cells. Multi-cellular FE models were generated. The results of the average properties and the stress/strain experienced by cells were compared under different conditions.
Motivational Tools for Engineering Students in Privileged Developing Countries: Examples From UAE
Authors: El-Khasawneh Bashar
Published: January 2019

The topic of this paper could be irrelevant to well-developed and developing countries, however, it is quite challenging to educate students in privileged income developing countries in which all primary needs of education, health, shelter and basic needs (the base for Maslow’s hierarchy of needs) are taken care of by the government. This leaves little room for the young generation to aspire to. Insufficient internal drive to work hard or to prove oneself since all basic needs are taken care of and most of these students are coming from well-off families. This created a real dilemma for educators in how to motivate and encourage this generation to take education seriously and work hard towards their degree and appreciate this educational journey. This paper would discuss some of these motivational tools and a set of recommendations for the government on this issue.
Iterative Modeling of a Small Underwater Tethered Remotely Operated Vehicle
Authors: Aldana Andrés F. , Esteban Villegas Helio Sneyder , Roa Prada Sebastián
Published: January 2019

Remotely operated vehicles, ROV, are highly versatile robotic systems, which are currently the best alternative to carry out deep-sea tasks, that otherwise could compromise the safety of human lives. These vehicles are commonly used by several industries such as offshore oil companies, offshore wind energy companies and environmental organizations. These underwater vehicles may be classified as Free-Swimming Systems, FSS, or Tether Management Systems, TMS. Tether Management Systems use the cable to transmit data and steering commands, and as a mean for power supply. It is known that the cable has a strong influence on the dynamics and maneuverability of a ROV. To improve the motion accuracy and stability of the control of a ROV, it is necessary to understand the nature and to estimate the value of the mutual reaction forces between the ROV and the cable.

This research seeks the modeling of the overall underwater tethered vehicle, by iteratively coupling the results from the finite element analysis, FEA, of the cable with the dynamic model of the ROV, as obtained by using the standard Newton-Euler formulation. Morison equation is employed to obtain the cable transient response. In this work, the ROV tether is defined as a flexible, slender cylinder, with circular cross section and made of a material with nonlinear elastic behavior. The cable is assumed to be in a specific extended initial configuration, with one of its ends fixed in ground. The FEA analysis of the cable is performed with the help of the commercial software COMSOL Multiphysics. A commercial small ROV is selected as the case study to apply the Newton-Euler method, considering the location of its actuators and other actual parameters such as mass, matrix of mass moments of inertia and drag coefficients. To include the cable forces into the dynamic model of the ROV, it is necessary to perform an iterative process between the cable analysis results and the ROV open loop response. The modeling approach starts with an FSS system initial velocity, which is fed into the cable FEA analysis. Both analyses are iterated, following a mutual feedback scheme, until results converge, obtaining the complete tethered vehicle model. The main achievement of this investigation is to observe the cable influence on the ROV, providing results that prove to be extremely useful for future work on the control system design, taking into account the disturbances introduced by the cable.
Neural Network Based Bin Analysis for Indirect/Direct Evaporative Cooling of Modular Data Centers
Authors: Walekar Abhishek , Siddarth Ashwin , Guhe Abhishek , Sukthankar Nikita , Agonafer Dereje
Published: January 2019

With an increase in the need for energy efficient data centers, a lot of research is being done to maximize the use of Air Side Economizers (ASEs), Direct Evaporative Cooling (DEC), Indirect Evaporative Cooling (IEC) and multistage Indirect/Direct Evaporative Cooling (I/DEC). The selection of cooling configurations installed in modular cooling units is based on empirical/analytical studies and domain knowledge that fail to account for the nonlinearities present in an operational data center. In addition to the ambient conditions, the attainable cold aisle temperature and humidity is also a function of the control strategy and the cooling setpoints in the data center.

The primary objective of this study is to use Artificial Neural Network (ANN) modelling and Psychrometric bin analysis to assess the applicability of various cooling modes to a climatic condition. Training dataset for the ANN model is logged from the monitoring sensor array of a modular data center laboratory with an I/DEC module. The data-driven ANN model is utilized for predicting the cold aisle humidity and temperatures for different modes of cooling. Based on the predicted cold aisle temperature and humidity, cold aisle envelopes are represented on a psychrometric chart to evaluate the applicability of each cooling mode to the territorial climatic condition. Subsequently, outside air conditions favorable to each cooling mode in achieving cold aisle conditions, within the ASHRAE recommended environmental envelope, is also visualized on a psychrometric chart. Control strategies and opportunities to optimize the cooling system are discussed.
A Future Trend in Sensing Enterprise Systems
Authors: Zamiri Majid , Artifice Andreia , Marcelino-Jesus Elsa , Sarraipa Joao , Jardim-Goncalves Ricardo
Published: January 2019

The widespread use of sensorial technologies has created new opportunities for enterprises, as these new sources of data assist in increasing the context-awareness in which enterprises operate and enable them to better anticipate and adapt to changes in the business environment. This leads to better decision-making and greater profitability, as well as to reduced operating risks. However, if enterprises are to get any benefit from these new data sources, there is a need for tools, which will enable them to deal with the complexity of the multitude of data sources, both from physical and virtual objects, as well as a means to extract relevant and correct information and knowledge from it. Having access to data is not enough. The real value to enterprises comes from being able to process it, interpret it and being able to make accurate forecasts upon which they can base their business decisions. This paper presents the blockchain technology which is intended to support the development of sensing enterprise systems for intelligent knowledge management. Since the creation of the internet, blockchain is the most important technology created that is in constant development and has still much more to develop. In a simple way, blockchain is a computational technology for register of operations, decentralized, free-access, transparent, global, continuous. It is a public database that is accessible for everyone and is much more secure and reliable than other forms currently known to perform similar operations. Thus, it is intended to demonstrate the importance of this recent technology in business processes and the future trends of its use in sensing enterprise business processes. The proposed framework intends to demonstrate and serve as the foundation for new business models supported by the new capabilities provided by sensorial technologies in the support of enterprise applications.
Flow and Heat Transfer of Mist/Steam Two-Phase Flow in Two-Pass Rectangular Channels With Paralleled and V-Shaped Rib Turbulators
Authors: Jiang Guangwen , Gao Jianmin , Shi Xiaojun , Zhao Wang , Li Yunlong
Published: January 2019

The heat and flow characteristics of mist/steam two-phase flow in U-shaped internal cooling passage of gas turbine blade are studid numerically in this paper. The standard k-ε model was used as the turbulence model combined with the DPM model to calculate the influence of mist/steam mass ratio and mist diameter on flow and heat transfer of U-passage with different shaped ribs. The result indicates that under the same working condition, the U-shaped channel with 45 deg. V-shaped ribs has better heat transfer performance than other channels and heat transfer non-uniformity of the U-shaped channel with 75 deg. ribs is the worst among all channels studied in this paper. The heat transfer performance of the U-shaped channel with V-shaped ribs is higher than that of the channel with paralleled ribs. As for the mist/steam cooling in U-shaped passage with same ribs structure, heat transfer non-uniformity increases with the increasing of heat transfer performance. When mists diameter increases from 5μm to 15μm, the heat transfer performance of the Second-Flow-Passage increases obviously and the heat transfer non-uniformity increases at the same time. The heat transfer performance has not been further enhanced when the mists diameter continuously increases after mist diameter are larger than 10μm.
Bench Scale Experimental Study of Slug Flow Phenomena Using PID Control
Authors: Schmidt Daniel S. , Staal Derek W. , McClung Jeffery W. , Behl Mark V. , Tyagi Mayank
Published: January 2019

Offshore petroleum production operations pose a unique set of challenges. A common undesirable phenomenon that occurs in these multiphase flow systems is known as slug flow. Slug flow is an oscillatory flow regime that creates large bullet shaped bubbles (also known as Taylor Bubbles) followed by large slugs of liquid. This high-rate alternation of liquid and gas production volumes in the surface facilities causes severe pressure oscillations. These oscillations adversely affect the structural health and individual components. A bench-scale closed flow loop was built with capabilities of measuring pressure and flow rates at different relevant sections. PID control strategy to mitigate the harmful effects of slug flow regime showed promise, although the tests were performed in the low pressure conditions of bench scale setup. The sensors and valve were programmed with MATLAB® to provide real time analysis, and a PID controller was utilized to adjust the back pressure. Initial experimental data and visual observation provided better understanding of slug flow regime and some quantitative data was obtained through image processing. Theoretical estimates of Taylor bubble velocities were found to be in agreement with presented observations. Further experiments are being carried out to gather data and showcase this model to develop better multiphase flow control strategies.
Waterblock Modelling for GPU Liquid Cooling
Authors: Vargas-Vazquez Jose-Carlos , Gutierrez-Garcia Jose-Angel , Hernandez-Guerrero Abel , Luviano-Ortiz Luis , Zuñiga-Cerroblanco Jose-Luis
Published: January 2019

Nowadays, cooling of electronic chips is one of the most serious challenges due to the exponential growth in the demand of increasingly powerful computer systems; the overheating of these components has become a problem of high importance. For this reason, the new cooling technologies such as liquid cooling systems replace the conventional air-cooling systems to avoid the effect of hotspots generated on a chip. To make matters worse, the current use of video games is requiring a tremendous amount of energy dissipation, over passing the cooling requirements of CPUs. Therefore, in this paper a new geometry is proposed to keep cool the graphic processor unit (GPU) in a CPU, using water as the working fluid. The main aim of the design is to enhance the heat dissipation in the GPU, decrease the pressure drop during the cooling process and reduce the amount of material used to build the waterblock. A numerical simulation solves the energy and momentum equations. The thermal performance of the proposed geometry is compared with a commercial heat sink geometry previously characterized. The results for the new geometry show that greater heat dissipation is not reached (results are about the same as the results for the commercial geometry) but due to the modification made, there is less pressure drop, while reducing the size of the waterblock. These results make this new geometry quite a good candidate for the new state of the art of cooling waterblocks.