bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of the Phase Change Temperature Range and the Phase Change Hysteresis of a PCM on the Performance of an Air-PCM Heat Storage Unit
Authors: Charvat Pavel , Zalesak Martin , Klimes Lubomir
Published: January 2020

The influence of the phase change temperature range and the hysteresis of the enthalpy-temperature relationship h(T) of PCMs on the performance of thermal energy storage (TES) systems is rarely quantified. In the present study, the quantification is done by the comparison of the amounts of heat stored in (and discharged from) the air-PCM heat exchanger (TES unit) operating between constant air temperatures. All simulations were conducted for the same mean phase change temperature of the PCM (30 °C). The inlet air temperature of the air-PCM HEX was 40 °C during the heat charging period and 20 °C during the heat discharge period. The maximum considered phase change temperature range of the PCM was 10 °C. The maximum phase transition hysteresis, in the study defined as the temperature difference between the melting and solidification peaks, was 4 °C. The results indicate that in case of the PCMs with a wide phase change temperature range and a significant hysteresis of the h(T) curves, the influence of these properties cannot be neglected in the simulation studies in order to achieve accurate results.
Kinnikinnic River Trash Collector Design
Authors: Felhofer Samantha , Kraft Kaleigh , Flynn Reilly , Mudlaff Amanda , Samuelson Brett , Kumpaty Subha
Published: January 2020

A senior design team from the Milwaukee School of Engineering assisted the Milwaukee Harbor District with a trash collecting solution for the Kinnickinnic River. The design objectives were: the use of solar panels to generate charge for the continuous operation of the trash solution, an innovative and cost-efficient way to clear debris blockages from the conveyor, low cost, and a design that can operate as autonomously as possible to require the least amount of human intervention. The Kinnickinnic River experiences a reverse flow and a substantial rise in water level during and after storms. The need for a trash solution in the section of the river that passes underneath Becker St. in downtown Milwaukee is due to the extreme pollution that has collected over the years. The city of Milwaukee, through the Harbor District and other non-profit organizations, have made plans to beautify the areas that have suffered from the residual pollution and simultaneously launch a promotional campaign to raise environmental awareness. Through school programs and the reality of the team’s trash solution in the river, the Kinnickinnic River will once again flourish in both flora and fauna. The team has created a design that will fit the river’s needs taking into consideration the solar energy available and various flow simulations. A full design solution with design details and specifications for manufacturing will be submitted to the Harbor District of Milwaukee for their review. The current design makes use of a floating platform base, 24 solar panels, eight lead acid batteries, a DC motor to run a conveyor belt to pull trash out of the water and to run a rake system to aid in pushing trash onto the conveyor, a gearbox to produce the necessary torque, a boom and cable system to catch trash further in the river, and a dumpster located on a dock in front of the trash collector. Finite Element Analysis and Computational Fluid Dynamics simulations were run to test the designs developed for the conveyor mechanism and the raking system and to test the amount of force placed on the trash collector by the water and air velocities. Further simulations may be run to test more components of the trash collector as needed. A prototype of the conveyor and rake system was produced to simulate the functionality of the design. Additionally, the selected solar panels for the design were tested using a data collector and analyzed to ensure power to the design would be enough.
New Intelligent Battery Management System for Drones
Authors: Hashemi Seyed Reza , Esmaeeli Roja , Aliniagerdroudbari Haniph , Alhadri Muapper , Alshammari Hammad , Mahajan Ajay , Farhad Siamak
Published: January 2020

Drones or Unmanned Aerial Vehicles (UAV) are the aircraft controlled remotely by radio waves or autonomously and can fly without a pilot and passengers. Demands for drones with long flight times are increasing significantly in the personal and commercial applications. One of the main issues about drones is their power management. However, these devices are powered by a high energy density lithium battery, but a flight time range could be about 20–40 min. Increasing the battery energy storage capacity to achieve more flight time is not usually a good idea due to the additional weight in drones. In order to solve this issue, an Intelligent Battery Management System (IBMS) is proposed to predict the maximum available energy of the battery pack to make the best decision for finding the closest charging station depending on different weather conditions. In this study, lithium-ion battery with lithium titanite oxide (LTO) anode, as a fast charging and fast discharging battery, is used as the drone power supply. The proposed IBMS can not only increase the performance and life of the battery system but also it can estimate the battery cells state of charge (SOC) based on a system identification method. Results show that the proposed system has an accurate estimation of the maximum available energy, and therefore accurate flight time prediction to find the best recharging node for the drone.
A Biaxial Infrared and Geomagnetic Composite Attitude Measurement Method of Rotating Projectile
Authors: Cao Yihan , Bu Xiongzhu , Han Wei , He Zilu
Published: January 2020

Aiming at the problem that the triaxial geomagnetic attitude measurement model can not directly figure out the complete attitude information of rotating missile or the current attitude calculation by limit ratio and integral ratio method needs calibration curves and look-up table method, after establishing missile-borne geomagnetic attitude measurement model and missile-borne infrared attitude measurement model respectively, a biaxial infrared and geomagnetic composite attitude measurement method is proposed. By the biaxial infrared attitude measurement model, the pitch angle and roll angle can be directly calculated. Combined with the biaxial geomagnetic attitude measurement model, the heading angle can be worked out finally. Through error transfer theory analysis, the direct calculation of pitch angle and roll angle is realized by alternating solution to reduce the measurement error. According to the analysis of the experimental data, the feasibility of the biaxial infrared and geomagnetic attitude measurement method is verified. And the direct calculation errors of pitch angle, roll angle and heading angle are respectively within ±0.8°, ±0.5° and ±1°. The biaxial infrared and geomagnetic attitude measurement method is simple and effective, which can meet the attitude measurement requirements of rotating projectile.
Energetics of Load Carriage by Bamboo Carrying Poles
Authors: Xu Yuning , Yang Lianxin , Chen Ken , Zhang Jiwen , Fu Chenglong
Published: January 2020

Unlike western conventions of rigid body attachments (e.g. backpack), carriers in Asia prefer to use bamboo poles, an ancient, ingenious, elastically-suspended equipment, especially when carrying heavy loads. As an elastically-suspended equipment, bamboo pole might have some potential benefits including reducing peak shoulder forces as well as saving metabolic transport cost, but certain skills should be needed for loading. Experienced carriers routinely carry loads exceeding their own body mass (Mb) for a long distance, while novices might hurt themselves. However, no skillful bamboo pole carriers’ performance or loading with heavy load has not been reported as far as we know. We set out to determine the loads capability and distances carried by skillful carriers, measure their metabolic cost for carrying the loads, and observe whether their natural walking speed changed as a function of load.

In this paper, we compared the skillful carriers’ energy expenditure on carrying loads in both normal bamboo pole on shoulder and typical backpacks with hip support. Both carrying postures were normal, just as what subjects used in their daily life. The O2 consumption and CO2 production were measured in 13 subjects while standing or walking with loads. All subjects were asked to carry loads ranging from 0 kg to their load capacity in two loading type, while walking on a 1-meter wide nearly circular level track at their preferred speed. These speeds were record by cameras placed beside the track.

Experimental results show that bamboo pole perform better under heavy load: 1. Loading by bamboo pole helped carriers to load 16% body weight heavier than by backpack on average. 2. With the load increasing, the walking speed loading by backpack would decrease from 1.3m/s (0kg) to 1.1m/s (load capacity), however loading by bamboo pole would slightly increase. 3. The rate of energy consumptions both increase with load increasing. Bamboo pole require more metabolic consumption than backpack with same load. 4. Since natural walking speed by bamboo pole faster than by backpack, the cost of transport by bamboo pole would be more economic than by backpack while the load is 50kg or more.
Insight Into the Design of Blast-Mitigating Floor Mats Using Design of Experiments
Authors: Kamel Hisham
Published: January 2020

Recently, Improvised explosive devices (IEDs) have evolved into a major and significant threat inflicting substantial human casualties and property damage. The majority of injuries are to the lower extremities since they are in close contact to vehicle floor. Floor mats have been developed to mitigate the effects of IEDs blasts. This paper reports a computational study on the energy absorbing behavior of a novel commercial floor mat — Skydex — for foot protection. The design of experiments (DOE) approach was applied to investigate the effect of shape variations on the dynamic performance of a finite element model of Skydex. The FE model was verified using experimental tests on samples produced using 3D printing technique. The DOE approach revealed significant insight into the design of Skydex. It confirmed that shape variables have strong effect on the amount of energy absorbed and the transmitted load. DOE specifically identified the radius of the mid-section of Skydex as the most influential factor in controlling the mode of deformation under compression. In addition, it uncovered the interaction effect between the radius of curvatures of the two hemispheres and upper and lower radii. Finally, DOE revealed the bi-trade-off relations between energy absorbed, transmitted load and mass. These were shown in meaningful and helpful plots which will help the development of Skydex design.
Experimental Study on Residual Formability of Single Point Incrementally Formed Part
Authors: Nikhare Chetan P.
Published: January 2020

A substantial increase in demand on the sheet metal part usage in aerospace and automotive industries is due to the increase in the sale of these products to ease the transportation. However, due to the increase in fuel prices and further environmental regulation had left no choice but to manufacture more fuel efficient and inexpensive vehicles. These heavy demands force researchers to think outside the box. Many innovative research projects came to replace the conventional sheet metal forming of which single point incremental forming is one of them. SPIF is the emerging die-less sheet metal forming process in which the single point tool incrementally forces any single point of sheet metal at any processing time to undergo plastic deformation. It has several advantages over the conventional process like high process flexibility, elimination of die, complex shape and better formability. Previous literature provides enormous research on formability of metal during this process, process with various metals and hybrid metals, the influence of various process parameter, but residual formability after this process is untouched. Thus, the aim of this paper is to investigate the residual formability of the formed parts using single point incremental forming and then restrike with a conventional tool. The common process parameters of single point incremental forming were varied, and residual formability was studied through the conventional process. The strain and thickness distribution were measured and analyzed. In addition, the forming limit of the part was plotted and compared.
Impingement Heat Transfer of Various Lobe-Shaped Nozzles
Authors: Panse Sanskar S. , Madhavan Srivatsan , Singh Prashant , Ekkad Srinath V.
Published: January 2020

This paper presents heat transfer characteristics of lobed nozzles, three different lobe configurations viz. three-, four- and six-lobe jets have been tested over a range of Reynolds numbers (based on the effective jet diameter, de) between 8000 and 16000 and normalized jet-to-target spacings (z/de) of 1.6, 3.2 and 4.8. The heat transfer results of lobed configurations were compared to the baseline configuration of circular jets. Steady-state infrared thermography (IRT) experiments were carried out for convective heat transfer coefficient calculations. Experimental results show that the three lobe configuration has a superior heat transfer performance compared to other configurations. Jet-to-target plate standoff distance had drastic effect on the heat transfer performance and contour plots for the lobed nozzles, as heat transfer performance diminished with increase in z/de. For the lobe configurations, with increase in jet-to-target spacing (z/de), the heat transfer coefficient maps tend towards a more circular profile due to the effect of jet diffusion.
Heat Transfer Interface to Graphitic Foam
Authors: Lin Fang-Ming , Anderssen Eric , Yee Raymond K.
Published: January 2020

Thermal interface materials (TIMs) used for bonding components are important for creating a thermally conductive path which improves heat dissipation. Low density, porous carbon foams are commonly used for thermal management applications and devices. Their high surface area to volume ratio enables cooling more effectively via different heat transfer methods. Many studies have adopted different methods to analytically or computationally analyze the effective thermal conductivity of carbon foams. Others have studied the participation of TIMs used in composite materials. However, very few studies have analyzed the microscale effects in heat transfer of the interaction between TIM and carbon foams. The amount of contact between a carbon foam and a bonded surface has hardly been reported in the literature. In this study, the carbon foam is deposited with thin layers of graphene until reaching the desired foam density; this type of foam is known as the graphitic foam. Graphene’s highly anisotropic thermal properties result in high thermal conductivity in the planar direction but low in the normal direction. With these anisotropic thermal characteristics, the objective of this study is to determine the effect of TIM thickness on thermal conductivity of the graphitic foam. It was hypothesized that the direction which heat enters the graphitic foam and the size of the cross-sectional area normal to the heat flux direction would affect the overall effective thermal conductivity. As commonly known, a gap created between ligands (foam structure) and the bonded surface would likely reduce the overall effective thermal conductivity. At the gap, heat is transferred via the TIMs or the graphitic foam through conduction, depending on if a direct contact exists between the graphitic foam and the bonded surface. The filler types used for the TIMs are hypothesized to play a critical role in the heat portion transferred via the TIMs. The heat transfer in 2-D becomes extremely complicated while anisotropic materials (graphene coating) and isotropic materials (TIMs) interact. Furthermore, the non-uniform structure of the carbon foam introduces more complexity to the heat transfer at the interface. A computational model using ANSYS finite element program was developed in this study to help the analysis. The results demonstrate that the parameters at the interface can be optimized to improve the overall effective thermal conductivity of the interface.
Optimal Synthesis of Topology for Compliant Mechanisms
Authors: Caputi Antonio , Russo Davide
Published: January 2020

The aim of the present work is disclosing a model suitable to provide a new tool for the synthesis of mechanisms and structures. Firstly, a framework will be introduced for the representation of a particular class of mechanisms: compliant mechanisms. For this purpose, the constitutive elements and the relations between the elements are organized in a taxonomy, similar to the ones used for the definition of ontologies.

Ontologies have been taken as inspiration for the construction of the general schema for two main reasons: the first one is the need of consistency in the physical models, in order to obtain reliable results. The second reason is that one of the main features of ontologies is modularity, which means that they may be reused, and implemented for the creation of widest classifications. In the proposed framework, mechanisms result from the combination of the constitutive elements, according to a certain topology.

The topologies are generated taking in account the defined feasible relations between elements. Once the mechanisms are defined, their behavior, in terms of mechanical response, is calculated and implemented in the schema as well. Finally, a classification of the evaluated mechanisms is provided, correlating the mechanical behavior of the mechanisms to the topological arrangement of their elements, or, in other words, their geometry.

This classification may be synthetized in a table which may be query setting the mechanical response (set of deformation allowed or denied as response of a set of generalized forces). The result of the query is the indication of the topology of the mechanism that fits the mechanical response best. The proposed table is a design tool actually, suggesting the constructive form to the designer starting from a functional requirement. Moreover, considering the table of topologies and the physical model with which it was generated, they constitute a synthesis tool for that class of mechanisms, and, ultimately, a topology, and size optimization tool.
Split Flow Modified Packed Bed Reactor for Cobalt Oxide Based High-Temperature TCES Systems
Authors: Vahedi Nasser , Oztekin Alparslan
Published: January 2020

The new generation of Concentrated Solar Power (CSP) plants requires high temperature and high energy density storage system with good cyclic stability. The potential solution satisfying such requirements is the thermochemical energy storage (TCES) using gas-solid redox reaction. Design of efficient storage reactor is very critical for applications of such storage systems. Packed bed reactors have a simpler design with no moving components and are more cost-effective compared to other available moving bed design configurations while having high-pressure drop is their main drawback. Any improvement in the pressure drop makes the design more suitable for commercial applications, especially at high temperature operating conditions. Cobalt oxide redox reaction has been considered for this study because of its unique features, especially high enthalpy of reaction (energy density) and high reaction temperature. A rectangular cross-section packed bed reactor with a large aspect ratio is selected as a reference conventional packed bed reactor. The novel split-flow packed bed reactor design configuration is proposed in which a portion of heat transfer fluid is passed through adjacent side channels. The split flow ratio of 1/3 has been considered for the case study. The transient two-dimensional numerical model is developed for solving mass, momentum, and energy equations for both gas and solid phases using suitable reaction kinetics for the reversible reduction and re-oxidation process. Complete storage cycle, including both the charging and discharging mode, has been simulated using finite element method. The split flow design performance is compared with the reference case considering the same size of the reaction bed. It is shown that the conversion time is increased while the pressure drop reduced below half of the pressure loss of the conventional design. Reduced mass flow rate passing through the bed results in considerable improvement in required pressure work with a penalty of storage performance. Further study is needed to optimize the split flow ratio and the surface heat transfer characteristics of the bed. The proposed design configuration could be a breakthrough in packed bed reactors, especially for high-temperature storage applications.
A Novel Nonlinear Time-Frequency Control Strategy for Underactuated Mechanical System
Authors: Zhang Zilong , Suh C. Steve
Published: January 2020

In this paper, a novel nonlinear time-frequency control methodology is presented to address the stabilization of an underactuated surface vessel (USV). The wavelet-domain based time-frequency control technique augmented by the adaptive filters and filtered-x least-mean-square algorithm is employed as the primary control framework. A nonlinear three degrees-of-freedom planar dynamic model for the USV with only two available control inputs is considered in the study. The equations of motion are derived based on the Newton’s Second law of motion. By using wavelet transform and filter banks, the proposed nonlinear control algorithm requires no mathematical simplification or linearization of the physical system, thus retaining all the true nonlinear dynamics of the USV model. The presented nonlinear controller consists of two adaptive finite impulse response (FIR) filers that operate on wavelet coefficients: the first one is used to model the dynamic system on-line and provide a priori information in real-time while the second one serves as a feed-forward controller and rejects the uncontrollable input signal based on the first FIR filter. The proposed nonlinear time-frequency controller properly mitigates dynamical deterioration in both the time and frequency domains and regulates the system response with the desired stability. Numerical simulations are performed in MATLAB Simulink and the results validate the effectiveness of the proposed nonlinear time-frequency control approach.
Theoretical, Experimental and Numerical Analyses for Painlevé Paradox of Two-Link Robotic Manipulator System
Authors: Zhang Sai , Shen Yunian , Yang Jiongcan
Published: January 2020

When multi-rigid-body come into contact with a rough surface in certain configurations, multiple solutions or no solution would occur in the theoretical derivation of the dynamic equation, which is termed Painlevé paradox. In this paper, two-link robotic manipulator system as a kind of Painlevé paradox model is studied from theory, experiment and simulation. The theoretical solution is obtained by the linear complementary problem (LCP) method, which offers guidance to the experiment. Then the feasibility of experiment is validated by numerical simulation. For experiment, two-link robotic manipulator set-up is built. The apparatuses verify the continuity of two-link system motion as a function of initial configuration. The two-link robotic manipulator model is also built in LS-DYNA. The experiment and simulation results show that Painlevé paradox is always accompanied with dynamic jam. Meanwhile, there is no clear boundary between dynamic jam region and non-dynamic jam region derived as the LCP solution indicates. Instead, it tends to be a gradual change process with certain transformation law. Sticking-bounce motion is found in the experiment and simulation. Several different motion characteristics are concluded corresponding to the initial angles of the two links. The summary of the variation of dynamic responses is given for further studying the mechanism of tangential impact of similar robotic manipulator system, especially for guiding how to avoid such universal but unexpected action existing in robotic manipulator system.
A Model and Vibrational Analysis of a Dolphin’s Acoustic System
Authors: Dryden Alec , Huhmann Brianna , Martin-Garcia Oscar , Duan Shawn
Published: January 2020

In this paper, a vibrational model of a dolphin’s acoustic system is presented. The working mechanism encompasses the dolphin’s lungs and nasal passage which hosts air pockets, the phonic lips, anterior and posterior bursae, the melon, lower jaw, and the brain. However, this study’s components of interest were the phonic lips, anterior bursa, and the surrounding muscle tissues. The phonic lips were modeled as rigid plates, surrounding muscles were modeled as springs, and the bursa was modeled as a damper. The chosen mechanical elements produced an underdamped system.

There were two cases considered: a system in which the dolphin produces one click and a system in which the dolphin produces a series of clicks, called a click train. The former case is produced when the posterior phonic lip quickly and suddenly impacts the anterior phonic lip. Therefore, this was modeled as an impulse input. The latter case is produced when the posterior and anterior lip periodically engage one another. This was modeled as a sawtooth input. Using commercial computer software, a total of four different scenarios were considered, a healthy dolphin scenario and sick dolphin scenario for each input type.
A Preliminary Study of the Effects of Micro-Encapsulated Phase Change Materials Intermixed With Grout in Vertical Borehole Heat Exchangers
Authors: Aljabr Ahmad , Chiasson Andrew , Selvacanabady Abinesh , Alsagri Ali Sulaiman
Published: January 2020

A thermal analysis of a GCHP system is performed to investigate the effect of adding micro-encapsulated PCM into the borehole grout to improve the thermal performance of GCHP systems. The apparent heat capacity method is used in the numerical model, simulated in COMSOL. The PCM’s thermal properties were varied to study the effect of each property, such as PCM melting temperature, transition temperature range, PCM thermal conductivity, and the amount of PCM within the grout.

Even though the low thermal conductivity of PCM compared to ordinary grout adversely affects the GCHP system performance, a potential reduction (∼2%) in borehole length is achieved. The best melting temperature is that which results in a complete melting of PCM around the peak load, instead of around the average load. The melting temperature must be chosen properly for each GCHP scenario, otherwise the benefit from using PCM may not be achieved. There is an insignificant change in the heat pump consumption because EFT is more favorable in PCM cases around the melting temperature, but less favorable after melting completely.
Rapid Qualification of Additive Manufactured Parts Using OpenMETA
Authors: Myers Michael R.
Published: January 2020

This paper focuses on a method to integrate additive manufacturing (AM) structure, processing, and property-geometry modeling methods to facilitate the qualification and certification of AM-fabricated metal parts and enable their rapid deployment. The conventional approach to qualifying AM parts is to destructively evaluate a significant number of parts, measure the properties of interest, and look for anomalies in each part. This approach also requires statistical sampling of parts for destructive testing to verify the process is still operating correctly over time. This is costly, time consuming, and negates much of the benefits offered by AM. The approach outlined in this paper leverages OpenMETA, a suite of tools that provide a unified design space, a unified system representation across engineering specialties, and multidisciplinary workflow for optimization, design-of-experiments, and trade-off studies. OpenMETA provides the ability to conduct high-fidelity, low-fidelity, and hybrid analyses within one framework. Test benches are built within OpenMETA that capture the requirements for the component in an executable manner to support automated analysis such as thermal analysis, finite element analysis, and high-fidelity physics-based (HFPB) analysis. Test benches also describe the intended environment in which the component will be used after manufacture. This description of the environment might include details of the surrounding components, the interfaces to those components, and corrosive agents. Test bench results are used to estimate and assess component performance related to requirements. This paper focuses on one technology for manufacturing the parts, a wire-fed, robotic, pulsed-arc AM process, although the OpenMETA platform can be applied to other AM technologies.
Control Design of a Mobile Robot in the Environment of Obstacles Based on a Rounded V-Shape Lyapunov Function
Authors: Lee Ho-Hoon
Published: January 2020

This paper proposes a V-shape Lyapunov function method with application to the design of a control scheme for a mobile robot navigating through multiple obstacles. The proposed design method solves the serious problem of input saturation due to big position errors in the beginning of the control associated with the conventional parabolic Lyapunov function method. The resulting control consists of a trajectory generation scheme and a motion control scheme. The trajectory generation scheme computes the translational and rotational reference velocities in real time that drive the robot to a given goal position while avoiding multiple obstacles. The motion control scheme computes the driving force and rotational torque to track the reference velocities. The nonholonomic constraints of the mobile robot are used in the design of the kinematic trajectory generation scheme, where a repulsive potential function is used for obstacle avoidance. The dynamic model of the robot is used in the design of the motion control scheme. Under certain conditions, the proposed control guarantees asymptotic stability while keeping all internal signals bounded. The effectiveness of the proposed control method has been shown with realistic computer simulations.
Vibration Correction With Kalman Filtering Based Data Fusion for Absolute Gravimeters
Authors: Wen Yi , Wu Kang , Li Zhenxing , Yao Jiamin , Guo Meiying , Wang Lijun
Published: January 2020

Free-fall absolute gravimeters are important classical high precision absolute gravimeters in many branches of scientific research. But its performance is always troubled by the ground vibration. Vibration correction method is used to correct the result by detecting the ground vibration with sensors. A Kalman filter based fusion method is proposed to obtain more accurate ground vibration signal by fusing the outputs of the seismometer and the accelerometer. Experiment is conducted with the homemade T-1 absolute gravimeter, the standard deviation of the corrected results using seismometer data and fused data are 586.32 μGal (1 μGal = 10−8 m/s2) and 508.59 μGal respectively, much better than the uncorrected result’s 6548.96 μGal. The results prove the superiority of fused data over data measured from single sensor. It is believed that the application scene of the vibration correction will be broadened and the performance of the vibration correction will also be improved by using the proposed fusion method in the future.
Optimal Design for Deployable Structures Using Origami Tessellations
Authors: Cardona Carolina , Tovar Andres , Anwar Sohel
Published: January 2020

This work presents innovative origami optimization methods for the design of unit cells for complex origami tessellations that can be utilized for the design of deployable structures. The design method used to create origami tiles utilizes the principles of discrete topology optimization for ground structures applied to origami crease patterns. The initial design space shows all possible creases and is given the desired input and output forces. Taking into account foldability constraints derived from Maekawa’s and Kawasaki’s theorems, the algorithm designates creases as active or passive. Geometric constraints are defined from the target 3D object. The periodic reproduction of this unit cell allows us to create tessellations that are used in the creation of deployable shelters. Design requirements for structurally sound tessellations are discussed and used to evaluate the effectiveness of our results. Future work includes the applications of unit cells and tessellation design for origami inspired mechanisms. Special focus will be given to self-deployable structures, including shelters for natural disasters.
A Case Study of the Unsteady Response of a Hingeless Helicopter Rotor Blade
Authors: Sarker Pratik , Chakravarty Uttam K.
Published: January 2020

The helicopter is an essential means of transport for numerous tasks including carrying passengers and equipment, providing air medical services, firefighting, and other military and civil tasks. While in operation, the nature of the unsteady aerodynamic environment surrounding the rotor blades gives rise to a significant amount of vibration to the helicopter. In this study, the unsteady forced response of the Bo 105 hingeless helicopter rotor blade is investigated at the forward flight in terms of the coupled flapping, lead-lag, and torsional deformations. The mathematical model for the steady-state response of the rotor blade is modified to include the unsteady airfoil behavior by using the Theodorsen’s lift deficiency function for three degrees of freedom of motion. The nonlinear mathematical model is solved by the generalized method of lines in terms of the time-varying deflections of the rotor blade. The unsteady airloads are found to create larger deformations compared to that of the steady-state condition for a given advance ratio. The azimuth locations of the peak loadings also vary with different degrees of freedom. The first three natural frequencies and mode shapes of the rotor blade are presented. The model for the forced response analysis is validated by finite element results.
A Fast Estimation Model for Angular Spectrum Based Focused Ultrasound Wave Simulation in Layered Tissue Media
Authors: Arif Tariq M. , Ji Zhiming
Published: January 2020

High-Intensity Focused Ultrasound (HIFU) is a popular non-invasive therapeutic tool and widely used in many clinical settings. The simulation models used for HIFU responses are computationally expensive and time-consuming. Among many numerical HIFU simulation methods, the Rayleigh-Sommerfeld approach is considered to be a reliable one. However, Rayleigh-Sommerfeld is suitable for homogeneous medium, and for a heterogeneous media, many approximations should be made in order to reduce the calculation time. In this study, we propose a fast methodology for estimating focused ultrasound pressure-temperature field responses through layered tissue media. A computationally efficient nonlinear angular spectrum-based method that can address the effects of varying attenuations, reflections and refractions from tissue layers is implemented to calculate reference datasets. From the simulation datasets, a profile function coupled with a GUI code is constructed for estimating the pressure-temperature response by using a Gaussian function and a Genetic Algorithm. The HIFU response model illustrated in this study can be advantageous and time-effective when multiple simulations are required on a similar complex patient model, and it can be used to guide and reduce the sets of simulations required for planning HIFU treatment.
Characteristics Study of Mild-Detonating Fuse and Flexible Linear Shaped Charge for Metal Plate Cutting
Authors: Lee Juho , Lee Joosik , Lee Heon Joo , Kang YounKil
Published: January 2020

In many types of spacecraft and missile systems, the vehicle’s skin cutting are carried out by using the mild-detonating fuse (MDF) or the flexible linear shaped charge (FLSC). MDF is a very thin metal tube that filled with explosive charges and has an axisymmetric shape. FLSC is an inverted chevron-shaped flexible tube that generates hypervelocity jet to penetrate or cut thick metal structures. In this study, the characteristics of MDF and FLSC for metal plate cutting are identified. First, the fracture mechanisms due to MDF and FLSC are numerically analyzed in 2-D plane strain using ANSYS AUTODYN, one of commercial hydrocodes. By using proposed numerical scheme, the effects of the cutting methods and the design parameters on cutting performance, fragmentation and backward shock waves are studied; the pros and cons of MDF and FLSC for metal plate cutting are clarified. The numerical method and the results of this study provide the guidelines to select metal plate cutting method and help to establish the design method for optimal metal plate cutting; the number of the expensive explosive experiments can be reduced.
Development of Small-Sized Motor-Driven Gyroscopic Power Generator Works Under Low-Frequency Vibration
Authors: Toyoshima Akio , Hosaka Hiroshi , Yamashita Akira
Published: January 2020

In order to realize a small-sized energy harvester with high output, this study prototypes a small motor-driven gyroscopic power generator. Supplying energy to sensors and devices is the biggest problem for Internet of Things (IoT) systems. One solution is gyroscopic power generators, which are a type of vibrational generator that amplify the inertia force of weights by rotating them at high speed, and in doing so can obtain greater output than conventional generators that use simple vibration for the same mass weight. This paper reports on a motor-driven type gyroscopic generator in which the flywheel is spun with an embedded motor, and which is superior in applicability to random vibration generators. The generators of this type that have been studied thus far are very large and have been primarily used for wave power generation in the ocean. However, when the shape of this gyroscopic power generator type is miniaturized proportionally, the output per volume decreases in proportion to the fifth power of the dimension. This makes it difficult to maintain the power output while miniaturizing the generator size. In this research, the structure of the gyroscopic power generator is thoroughly refined and miniaturization is realized by making full use of the available space. By using a motor with high design freedom, the spindle motor and flywheel are unified. From this accomplishment, not only is the required space reduced, the number of mechanical parts and the friction loss are decreased as well. The prototype generator has a size of about 150 mm on its long side. When a swinging vibration of 50 degrees in amplitude and 2 Hz in frequency is applied, a net output of 0.104 W is obtained. This output power is sufficient to drive sensors and low power wide area (LPWA) radio circuits.
Precise Control of Precursor Sticking Coefficient on Substrates With Large Aspect Ratios in ALD
Authors: Kunene T. J. , Tartibu L. , Jen T. C.
Published: January 2020

In this paper, the Atomic Layer Deposition (ALD) process in the reactor scale was simulated using ANSYS® Fluent® 19.1 and ChemKin-PRO commercial packages in order to solve transport and chemistry equations. Trenched substrates with large aspect ratios (AR) of 33 ≤ AR ≤ 300, at a reactor scale of an ALD process, were considered a temperature of 473K and 573K. Trimethlyaluminum (TMA) and Ozone reactants were used to formulate a precise Sticking Coefficients (SC) for a satisfactory dose (precursor exposure level) in order to deposit conforming Al2O3 films. The estimated error in the empirical correlation of SCs was determined and compared to published experimental data. An empirical correlation based on simulated models was derived. This correlation can be exploited to determine precise precursor exposure levels for an ALD process irrespective of the type of reactor used.
Packaging Challenges of Thin High Bandwidth POP
Authors: Tung Fletcher (Cheng-Piao) , Tsai Jensen (Ying-Chou) , Wang Yu-Po , Lin Joe (Chih-Nan) , Fan Gary (Yue-Long)
Published: January 2020

Components for Smartphone has been the biggest driving force of IC industry for years, and one of the most important IC is application processor (AP). AP needs to work with low power double data rate (LPDDR), the mobile DRAM together for the primary processing of cellular phone and other smart functions. At the beginning, they were packaged separately and then mounted onto printed circuit board (PCB) very close to each other. Nowadays, AP for flagship Smartphone is packaged with a variety of PoP (package on package) structures to shorten the communication distance between AP and LPDDR as well as to save more rooms for battery. High bandwidth package on package (HBW-POP) is the most popular structure among them. As compared to other substrate based PoP, HBW-POP provides the most top side pin count while keeps larger ball pitch for system assembly house to mount LPDDR packaged by fine-pitch ball grid array (FBGA) on top of it. And compared to novel Fan-Out based PoP, HBW-POP has lower cost for AP packaging.

In addition, maximum package height of HBW-POP has been shrinking. It is because when LPDDR is mounted onto HBW-POP, the combination is always the tallest chips on the PCB, which determines how slim specific Smartphone can be. HBW-POP consists of 3 parts to encapsulate AP die, and they are top 2-layer substrate, middle molding and bottom 3-layer substrate. Each part has its own coefficient of thermal expansion (CTE) and rigidity, and the warpage performance of HBW-POP is important to align the warpage behavior of LPDDR.

The warpage of HBW-POP needs to align with FBGA properly during reflow for good joint, but when HBW-POP becomes thinner, the rigidity of its different parts is changed, which result in different warpage behavior during the reflow.

In this paper, we will review the challenges of thin HBW-POP packaging, meanwhile we will explore possible solutions to address each challenge. The study includes the screening of different thickness combination of the 3 parts of HBW-POP, and the optimization of the rigidity and CTE of them. Design of Experiments (DOE) are conducted to find solutions which can meet warpage target, and finally, we present more different tests to prove the reliability of our results.
Investigation of Conduit Flow Past Corrugated Structures Using Large Eddy Simulations
Authors: Kumar Sushrut , Suri Ujjwal , Sachdeva Paras , Singh Raj Kumar
Published: January 2020

The present paper studies the characteristics of a fully turbulent flow of water through a conduit by use of corrugated structures. Methodologies including rough-ribbed walls and particle injection have been utilized for turbulence attenuation in the past. Screens and corrugations are yet another effective tools for reducing turbulence. The proposed investigation focuses on the application of square and hexagonal cross-sectional corrugations which are introduced in the flow for turbulence attenuation inside rectangular conduits. Large Eddy Simulations in three dimensions were performed with OpenFOAM using a pressure-implicit solver and the standard Smagorinsky subgrid-scale model. Dampening of the spanwise velocity component and a relative increase in streamwise velocity component downstream of the corrugation was observed. The power spectral densities (PSD) of the flow upstream and downstream of the corrugation were examined and compared. A significant decrease in turbulent flow power density was observed. Furthermore, characteristics including turbulence intensity contours and isosurfaces of the Q-criterion were visualized. The results conclusively indicate a subsequent decrease in the turbulent nature of flow past corrugated structures.
Prediction of Oscillatory Heat Transfer Coefficient in Heat Exchangers of Thermo-Acoustic Systems
Authors: Machesa M. G. K. , Tartibu L. K. , Tekweme F. K. , Okwu M. O.
Published: January 2020

The characterisation of heat transfer in oscillatory flow of thermo-acoustic based heat exchangers is a cumbersome issue. This is due to the nature of the heat transfer between the gas particles moving along the device at high amplitude and the solid surface of the heat exchangers. In addition, the change in velocity, pressure and temperature induces nonlinear effect. As a result, the performance of heat exchangers negatively affects the efficiency of thermo-acoustic systems. Hence, it is necessary to determine to oscillatory heat transfer coefficient in order to measure the performance of heat exchangers in thermo-acoustic systems. Although it is possible to conduct experimental investigation or perform numerical analysis in order to determine oscillatory heat transfer coefficient, the former requires costly time consuming experiment while the latter involves the resolution of complex mathematical models. In this paper, an improved adaptive neurofuzzy inference system and artificial neural network trained by particle swarm optimization are proposed to predict oscillatory heat transfer coefficient. This paper is intending to provide clarity on the benefits of these new approaches on the computation of geometrical configuration and the working parameters of heat exchangers in thermo-acoustic systems.
Technical Issues Associated With Arterial Pulse Signal Measurements Using a Microfluidic-Based Tactile Sensor
Authors: Wang Dan , Reynolds Leryn , Alberts Thomas , Vahala Linda , Hao Zhili
Published: January 2020

This paper presents three technical issues associated with arterial pulse signal measurements using a microfluidic-based tactile sensor: motion artifact, overlying tissue at an artery and inter-subject variation. Arising from the sensor-artery interaction upon hold-down pressure on the sensor, a measured pulse signal is a combination of the sensor design, hold-down pressure, overlying tissue at an artery, the arterial wall and the true pulse signal in the artery. Meanwhile, motion artifact causes change in the sensor-artery interaction and also plays a non-negligible role in a measured pulse signal. The influence of motion artifact on a measured pulse signal can be reduced by a sensor with high stiffness. To obtain a pulse signal at near-zero transmural pressure with reasonable accuracy, matching the sensor design with the overlying tissue at an artery is critical for achieving good conformity of the sensor to the artery (for signal transmission) with minimal distortion of the true one in the artery. For simplicity, a uniform layer is utilized to adjust the sensor design. While a uniform layer added to a sensor improves its conformity with the radial artery (RA) embedded deep under the skin, a uniform layer is also needed as a cushion to reduce suppression of the true pulse signal at the superficial temporal artery (STA) near the skin. Due to inter-subject variation (i.e, overlying tissue and artery size), the absolute values of arterial indices derived from a measured pulse signal at the same artery are not comparable between subjects. Post-exercise recovery of arterial indices derived from measured pulse signals is suggested to serve as a better assessment of the cardiovascular (CV) system.
Different Methods of Programming for Mechanical Engineering Students: A Case Study
Authors: Han Mingli , Duan Chang
Published: January 2020

The paper is to present a case study where different methods of programming are utilized by Mechanical Engineering Students to design a device. The objective is to provoke discussion and explore best practices on teaching Mechanical Engineering students the programming aspects. The task is to design a low-cost device that can accurately measure the period of a simple pendulum. Same raw materials, infrared break beam sensor and Arduino microcontroller, are given. But different programming approaches can be undertaken. Option 1 is to use C language and Arduino’s free Integrated Development Environment. Option 2 is to use Simulink with Arduino Support. Student survey is designed based on whether it is intuitive, whether it is easier to debug, etc. Further studies can be conducted to understand the effectiveness of a mixture of these different methods and sequence of exposure to these different methods.