bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Particle Shape on Neck Growth and Shrinkage of Nanoparticles
Authors: Mirkoohi Elham , Malhotra Rajiv
Published: July 2017

Sintering of nanoparticles to create films and patterns of functional materials is emerging as a key manufacturing process in applications like flexible electronics, solar cells and thin-film devices. Further, there is the emerging potential to use nanoparticle sintering to perform additive manufacturing as well. While the effect of nanoparticle size on sintering has been well studied, very little attention has been paid to the effect of nanoparticle shape on the evolution of sintering. This paper uses Molecular dynamics (MD) simulations to determine the influence of particle shape on shrinkage and neck growth for two common nanoparticle shape combinations, i.e., sphere-sphere and sphere-cylinder nanoparticles of different sizes. These sintering indicators are examined at two different temperature ramps. The results from this work show that depending on their relative sizes, degree of neck growth and shrinkage are both significantly affected by the nanoparticle shape. The possibility of using this phenomenon to control density and stresses during nanoparticle sintering are discussed.
Construction-Scale 3D Printing: Shape Stability of Fresh Printing Concrete
Authors: Kazemian Ali , Yuan Xiao , Meier Ryan , Cochran Evan , Khoshnevis Behrokh
Published: July 2017

Building 3D objects in sequential layers is a technique employed by rapid manufacturing processes and allows great design freedom in manufacturing. Scaling up such automated additive fabrication from building small industrial parts to constructing buildings has been challenging for researchers during the recent years. Compared to the traditional construction methods, numerous advantages are offered by a well-developed layer based automated construction process, including architectural design freedom, lower construction cost, superior construction speed, and higher degree of customization. Concrete has been recognized as most viable option as the material to be used with such a process. However, there are several main challenges that yet have to be solved. Obtaining a mixture with high shape stability in the fresh state is among these challenges. Ideally, non-stop printing of successive layers is desired in building a structure, so the total construction time is minimized.

In this paper, an experimental investigation of the shape stability of freshly printed concrete layers using a small-scale linear concrete printing setup with remote control capability is outlined. First, longer stoppage time between successive layers is examined to determine the effects on the deformations of fresh printing concrete. Then, heat application is proposed and studied as a measure to improve the shape stability of freshly printed concrete without adding any delay to the construction process. Furthermore, a one-story building is considered and the influence of each scenario on the total construction time is discussed.
Disruption Recovery Model for Complex Flow Shop Scheduling With Considering Behavior Under Environment of the Internet of Things
Authors: Hong-guang Bo , Huan-zhi Li , Hui-lin Zhang , Yi Guo , Wei Mu
Published: July 2017

Disruptions happen in the actual manufacturing system under environment of the Internet of Things and they make the system difficult to manage. However, the convenient access to information of orders, equipment and participants make disruption recovery easier. In this paper we build a disruption recovery scheduling integer programming model considering the objective of minimizing total weighted completion-time (as the original objective) and the objectives of maximizing total consumer satisfaction degree & minimizing total deviation degree (as the revising objective). A PVPS (PSO & VNS Parallel Search) algorithm is proposed. The experiments results prove all above are effective.
Rational Synthesis of Nanostructured Electrode Materials for High-Performance Supercapacitors
Authors: Wong Ching-Ping
Published: July 2017

Supercapacitors fill the gap between the batteries and capacitors in the Nyquist plots, and being considered as the candidates for next generation energy storage due to the high-power density, long-term cyclability and moderate energy density. In order to fulfill the requirement for practical applications, it is necessary to further develop the current supercapacitors and enhance the energy density. Hence in this paper, we discuss the work we have done for developing high-performance supercapacitors, including synthesis of large surface area and high conductive carbonaceous materials and highly electroactive pseudocapacitive materials. Our works may pave the way for synthesis of high-performance supercapacitor electrode materials.
Approaches to Implement Statistical Process Control for Manufacturing in Big Data Era
Authors: Chang Shing I.
Published: July 2017

It has been long overdue to revamp existing statistical process control (SPC) approaches in manufacturing since Water Shewhart first proposed the use of control charts in 1924. The combination development of big data, cloud computing, and manufacturing reshoring back to Untied States has opened up the opportunities to rethink implementation strategies of SPC for manufacturing. This paper first reviews the history of SPC development in traditional manufacturing environments and then contrasts it with the opportunities presented in big data era. Five SPC implementation approaches are proposed based on the opportunities identified.
Fundamental Study of Fused-Coating Based Metal Additive Manufacturing
Authors: Fang Xuewei , Du Jun , Wei Zhengying , Wang Xin , He Pengfei , Wang Bowen , Bai Hao , Lu Bingheng
Published: July 2017

Fused-coating based metal additive manufacturing (FCAM) is a newly established direct metal forming process. This method is characterized by deposition metal materials in a crucible and under the driving pressure the molten metal is extruded out from a special designed nozzle. Hence, dense metal parts with different kind of materials can be built on the moving substrate layer by layer. It provides a method to fabricate metal components with lower costs, clean and cheap materials compared with other AM processes. To study the feasibility of this new AM methodology, an experimental system with a molten metal stream generator, a fused-coating nozzle, a process monitor unit, an inert atmosphere protection unit and a temperature measurement unit has been established. In order to determine the proper parameters in the building process, a metal fused-coating heat transfer model analysis and experimental study is performed by using Sn63-37Pb alloy in building three-dimensional components. The process parameters that may affect fabrication are molten and substrate temperature, layer thickness, the substrate-speed, the temperature of substrate, the distance between the nozzle and substrate and the pressure. Microscopy images were used to investigate the metallurgical bonding between layers. The influence of different parameters on the layer thickness and width was studied quantitatively. At last, the optimal parameter was used to fabricate complex metal parts to demonstrate the feasibility of this new technology compared with other AM methods.
Ultrasonic Nano-Crystal Surface Modification Assisted Gas Nitriding of Ti6Al4V Alloy
Authors: Liu Jun , Ren Zhencheng , Ma Chi , Dong Yalin , Ye Chang
Published: July 2017

The effects of Ultrasonic Nanocrystal Surface Modification (UNSM) on the gas nitriding of Ti6Al4V alloy has been investigated. The gas nitriding was performed at 700 and 800 °C. The microstructure after UNSM and gas nitriding was characterized using X-ray diffraction and scanning electron microscopy. Microstructural investigations revealed the formation of an approximately 10 μm thick severe plastic deformation (SPD) layer after UNSM treatment. After nitriding at 700 °C and 800 °C, a compound layer consisting of an approximately 0.2 μm and 1.9 μm thick nitride layer was observed in UNSM-treated Ti6Al4V alloy, which exhibits a nearly two-fold increase in nitride layer thickness as compared with the un-treated sample. This suggests that the nitrogen adsorption and the reaction capability are enhanced in the UNSM-treated Ti6Al4V alloy. This enhancement can be attributed to the high density dislocations and grain boundaries introduced by UNSM that serve as efficient diffusivity channels for interstitial gaseous atoms.
Asymmetric Flexure Hinge for Compliant Vibrational Tissue Cutting
Authors: Jones Justin A. , Lee Yuan-Shin , Moore Jason Z.
Published: July 2017

This work investigates the compliance of a novel flexure hinge mechanism for tissue cutting. This hinge is to be used with ultrasonic axial vibration to induce transverse displacement. This transverse motion can aid in reducing tissue cutting force as well as possible target deflection by reducing the parallel tissue cutting force. The finite element method, FEM, is used to evaluate several flexural hinge designs to develop empirical equations for the compliance in the axial, transverse, and rotational directions. To generate appreciable transverse motion from an axially applied ultrasonic vibration an asymmetric flexural hinge is needed. In order to design an asymmetric complaint mechanism to fully take advantage of the transverse cutting motion the compliance with respect to geometry was explored. The ratio of thickness, length, and distance between the hinges were iterated while end loads were applied to derive the compliance equations. The empirical models are presented for each design study. It is shown that the rotational stiffness is the dominating factor of the stiffness matrix. It is also shown that the relationship between the rotational stiffness and the distance between hinges forms a piecewise equation. This is due to notch elements spaced close to each other can be modeled as a lumped element while notch elements spaced further apart need to be independently modeled.
Gantry Scheduling for Two-Machine One-Buffer Composite Work Cell by Reinforcement Learning
Authors: Arinez Jorge , Ou Xinyan , Chang Qing
Published: July 2017

In this paper, a manufacturing work cell with a gantry that is in charge of moving materials/parts between machines and buffers is considered. With the effect of the gantry movement, the system performance becomes quite different from traditional serial production lines. In this paper, reinforcement learning is used to develop a gantry scheduling policy in order to improve system production. The gantry learns to take proper actions under different situations to reduce system production loss by using Q-Learning algorithm and finds the optimal moving policy. A two-machine one-buffer work cell with a gantry is used for case study, by which reinforcement learning is applied. Compare with the FCFS policy, the fidelity and effectiveness of the reinforcement learning method are also demonstrated.
Procedure for Selecting Key Performance Indicators for Sustainable Manufacturing
Authors: Kibira Deogratias , Brundage Michael , Feng Shaw , Morris K. C.
Published: July 2017

The need for an open, inclusive, and neutral procedure in selecting key performance indicators (KPIs) for sustainable manufacturing has been increasing. The reason is that manufacturers seek to determine what to measure in order to improve environmental sustainability of their products and manufacturing processes. A difficulty arises in understanding and selecting specific indicators from a large number of stand-alone indicator sets available. This paper presents a procedure for individual manufacturers to select KPIs for measuring, monitoring and improving environmental aspects of manufacturing processes. The procedure is the basis for a guideline, being proposed for standardization within ASTM International. That guide can be used for (1) identifying candidate KPIs from existing sources, (2) defining new candidate KPIs, (3) selecting appropriate KPIs based on KPI criteria, and (4) composing the selected KPIs with assigned weights into a set. The paper explains how the developed procedure complements existing indicator sets and sustainability-measurement approaches at the manufacturing process level.
Characterization of Machining Distortion due to Residual Stresses in Quenched Aluminum
Authors: Garcia Destiny R. , Hill Michael R. , Aurich Jan C. , Linke Barbara S.
Published: July 2017

Manufacturing methods and procedures are advancing through research and development, to optimize machine tools, machining strategies, and the overall manufacturing system. In the aerospace industry, machining distortions, or the deviation of part shape from the original intent after being released from a fixture, occur, reducing productivity. Residual stresses locked into the workpiece are a primary factor contributing to machining distortions. The residual stresses are induced by prior material processing steps such as rolling, forging, heat treating, etc. — which are needed in the aerospace industry for high strength.

Machining distortions result in significant economic losses due to reworking, remanufacturing, and/or rejecting components in the manufacturing and aerospace industries. Quenched 7050 T74 aluminum was used to investigate material removal with respect to milling distortions. Using material with a known residual stress profile, a prismatic u-shape geometry was machined and distortions were characterized, quantified, and described in detail. This paper shows a transparent and repeatable method for characterizing distortion for machined parts. The results from the distorted u-shapes indicate similar characteristics from distortion due to bulk residual stresses and machining factors.
Deposition of Bead Arrays With Variable Diameter by Self-Focusing of Electrohydrodynamic Jets
Authors: Martinez-Prieto Nicolas , Fratta Gabriela , Cao Jian , Ehmann Kornel
Published: July 2017

Electrohydrodynamic processes were used for direct-writing of bead arrays with controllable bead sizes. Experiments were conducted to align layers of bead-on-string structures in an effort to create three-dimensional patterns. The results show that the jet focuses on previously deposited droplets allowing for the selective deposition of material over already deposited patterns. Jet attraction to already deposited solutions on the substrate is attributed to the charge transport at the liquid ink-metal collector interface and the dielectric properties of the water/poly(ethylene oxide) solution under an electric field. The deposition process consists of 3 steps: (1) deposition of a layer of bead-on-string structures, (2) addition of extra volume to the beads by subsequent passes of the jet, and (3) evaporation of the solvent resulting in an array of beads with varying sizes. Patterns with up to 20 passes were experimentally obtained. The beads’ height was seen to be independent of the number of passes. The process reported is a simple, fast, and low-cost method for deposition of bead arrays with varying diameters.
Ultrasonic Pelleting and Synchronized Torrefaction of Cellulosic Biomass for Bioenergy Production
Authors: Yang Yang , Eisenbarth Nicholas , Song Xiaoxu , Zhang Meng , Wang Donghai
Published: July 2017

The U.S. is sustainably producing of over 1 billion dry tons of biomass annually. This amount of biomass is sufficient to produce bioenergy that can replace about 30 percent of the nation’s current annual consumption of conventional fossil fuels. This then gives us the opportunity to turn waste into bioenergy that can assist in meeting the U.S. Renewable Fuel Standard (RFS). Besides being converted into bioethanol through the biochemical platform, biomass can also be utilized solid fuels to generate bioenergy through the thermochemical platform. Co-firing power plants use torrefied biomass pellets combined with coal for electricity generation. A two-step process, torrefaction followed by pelleting, is the prevailing technique that the industry is currently using to produce torrefied biomass pellets. Torrefaction converts biomass into biochar with high heating value, and pelleting densifies torrefied biochar into pellets with high durability and density. For the same purpose, we developed the ultrasonic pelleting and synchronized torrefaction of cellulosic biomass process, which is a single-step process to generate high quality solid fuel pellets with high heating value together with good durability and density. This study reports the first experimental investigation to demonstrate the feasibility of the novel process. Key process parameters have been identified, and their effects on the feasibility of generating quality torrefied biomass pellets are reported. Pellets are evaluated from the aspects of feasibility, durability, heating value, and thermal stability.
Boundary Control on Embedded Heaters for Composite Joining
Authors: Smith Brandon P. , Ashrafi Mahdi , Tuttle Mark E. , Devasia Santosh
Published: July 2017

This paper demonstrates the use of boundary control on embedded resistive heaters with the purpose of precision temperature control for curing high strength adhesives when joining composite adherends. This is particularly useful in the presence of heatsinks, where a uniform heating technique will lead to temperature variations in the bondline. The major contribution of this work is to reduce such temperature variations by using boundary control on the embedded heater. This technique is demonstrated experimentally for bonding a single-lap joint, and the temperature variation in the bond area was reduced from 20.3% to 2.7%.
Design of Anisotropic Boring Tools With L/D = 10 for Chatter Free Cutting
Authors: Takahashi Wataru , Suzuki Norikazu , Shamoto Eiji
Published: July 2017

This paper presents design of a novel boring bar with a ratio of cylinder length to diameter (L/D) of 10 to suppress chatter vibration regardless of low stiffness. It is essentially difficult to decrease the compliance of the long slender structures. However, nominal compliance of the displacement along the depth of cut direction against the resultant cutting force may be regulated by giving the designated anisotropy upon the boring bar dynamics. The past research has clarified the feasibility through turning experiments by using the developed boring bar with L/D of 4. In the present study, much slenderer ones with L/D of 10 are designed, which are significantly flexible but attractive to manufacturers. Finite element analysis (FEA) is utilized to estimate dynamics of the anisotropic boring bar. Through analytical investigations, two kinds of boring bars were designed, where the compliance ratio of 1.53 or 1.88 was accomplished. Influence of several conditions on the chatter stability was investigated. Analytical investigations revealed that the chatter stability is significantly improved at a designated depth of cut by utilizing the proposed designs regardless of feed rate. In particular, the compliance ratio of 1.55 showed wider stable zone to attain chatter free boring, while chatter avoidance is impossible by use of the conventional isotropic boring bar under the same conditions.
CEL FEM Investigation of Effects of Microgrooved Cutting Tools in High Speed Machining of AISI 1045 Steel
Authors: Wu Han , Duong Nick H. , Ma J. , Lei Shuting
Published: July 2017

In this paper, the commercial FEM software package Abaqus is used to investigate the effects of microgrooved cutting tools in high speed orthogonal cutting of AISI 1045 steel. Microgrooves are designed and fabricated on the rake face of cemented carbide (WC/Co) cutting inserts. A coupled Eulerian-Lagrangian (CEL) finite element model is developed based on Abaqus to solve the evolution of the cutting temperature, chip morphology, cutting force, and phase constitutes simultaneously. This model is validated by comparing the numerical results with the experimental data for orthogonal high speed cutting of AISI 1045 steel with various cutting conditions. In addition, this model is also validated by comparing with the experimental data of regular tool and microgrooved cutting tool under the cutting speed of 120m/min. This validated CEL FEM model is then utilized to investigate the effects of microgrooved cutting tools on the phase transformation, cutting force, cutting temperature, and chip morphology in high speed orthogonal cutting of AISI 1045. The effects of microgroove width, edge distance (the distance from cutting edge to the first microgroove), and microgroove depth are examined and assessed in terms of cutting force, cutting temperature, chip morphology, and phase transformation. It is found that this CEL FEM model can capture the essential features of orthogonal high speed cutting of AISI 1045 using microgrooved cutting tools. It is also concluded that microgrooved cutting tools can not effectively reduce the cutting force in high speed machining, which is contrary to the conclusion obtained for low speed machining in previous research. However, microgrooves on the rake face have influence on the austenite percentage in the chip near the rake face. This research provides insightful guidance for optimizing the cutting performance in terms of cutting temperature, cutting force, chip morphology, and phase transformation in high speed machining of AISI 1045 steel.
Numerical Modeling of Metal-Based Additive Manufacturing Process Using Level Set Methods
Authors: Ye Qian , Chen Shikui
Published: July 2017

Modern computer technology enables people to simulate additive manufacturing (AM) process at high fidelity, which has proven to be an effective way to analyze, predict, and design the AM processes. In this paper, a new method is proposed to simulate the melting process of metal powder based AM. The physics is described using partial differential equations for heat transfer and Laminar flow. The level set methods are employed to track the motion of free surface between liquid and solid phases. The issues, including free surface evolution, phase changes, and velocity field calculation are investigated. The convergence problem is examined in order to improve the efficiency of solving this multiphysics problem.
Additive Manufacturing (AM) of Flexible Electronic Devices: Online Monitoring of 3D Line Topology in Aerosol Jet Printing Process Using Shape-From-Shading (SfS) Image Analysis
Authors: Salary Roozbeh (Ross) , Lombardi Jack P. , Rao Prahalad K. , Poliks Mark D.
Published: July 2017

The goal of this work is online quality monitoring of flexible electronic devices made using Aerosol jet printing (AJP) additive manufacturing (AM) process. In pursuit of this goal, the objective is to recover and quantify the 3D topology of AJP-printed electronic traces (lines) through in situ images. The intent is to use the estimated 3D topology for online prediction of the device electrical performance characteristics. To realize this objective different shape-from-shading (SfS) techniques are tested to recover the 3D topology of lines from high resolution in situ 2D images. These images are obtained from a CCD camera installed on our experimental Optomec AJ300 AJP setup. White light interferometry is used offline to verify the online experimental trends. Three types of SfS algorithms are tested, namely, minimization method, Pentland’s method, and Shah’s method. Tests with synthetic images and experimental data indicate that Shah’s method is more suitable. The correlation between online and offline estimates of line thickness was ∼80%.
Enterprises in Cloud Manufacturing: A Preliminary Exploration
Authors: Liu Yongkui , Xu Xun , Srinivasan Ananth , Zhang Lin
Published: July 2017

Cloud manufacturing is a new manufacturing paradigm in which manufacturing resources and capabilities offered by different enterprises are provided as cloud-based services over the Internet. In addition to the cloud manufacturing platform, enterprises as resource providers are also essential part of a cloud manufacturing system as customer orders that are submitted to the cloud platform will ultimately need to be dispatched to enterprises’ production sites for execution. So far, however, issues concerning enterprises in cloud manufacturing has attracted little attention of researchers, and the most frequently mentioned issue in existing research that are concerned with enterprises is how to connect enterprises’ resources to the cloud infrastructure. This, to a large extent, hinders the development and implementation of cloud manufacturing as the lack of research on enterprises fails to uncover the requirements for enterprises in cloud manufacturing (i.e. Cloud Manufacturing Enterprises, CMEs), and thus enterprises have no reference for evaluating the changes that need to be made to adopt this new manufacturing paradigm. This paper focuses on this important issue and conducts a preliminary exploration on CMEs. We first analyze the requirements for CMEs, and then discuss some critical issues with CMEs in detail, including enterprise information systems, enterprise architecture, and enterprise modeling.
Parametric Topology Optimization Toward Rational Design and Efficient Prefabrication for Additive Manufacturing
Authors: Jiang Long , Ye Hang , Zhou Chi , Chen Shikui , Xu Wenyao
Published: July 2017

The significant advance in the boosted fabrication speed and printing resolution of additive technology has considerably increased the capability of achieving product designs with high geometric complexity. The prefabrication computation has been increasingly important and is coming to be the bottleneck in the additive manufacturing process. In this paper, the authors devise an integrated computational framework by synthesizing the parametric level set-based topology optimization method with the DLP-based SLA process for intelligent design and additive manufacturing of not only single material structures but also multi-scale, multi-functional structures. The topology of the design is optimized with a new distance-regularized parametric level set method considering the prefabrication computation. offering the flexibility and robustness of the structural design that the conventional methods could not provide. The output of the framework is a set of mask images which can be directly used in the additive manufacturing process. The proposed approach seamlessly integrates the rational design and manufacturing to reduce the complexity of the computationally-expensive prefabrication process. Two test examples, including a freeform 3D cantilever beam and a multi-scale meta-structure, are utilized to demonstrate the performance of the proposed approach. Both the simulation and experimental results verified that the new rational design could significantly reduce the prefabrication computation cost without affecting the original design intent or sacrificing original functionality.
Predicting Sheet Forming Limit of Aluminum Alloys for Cold and Warm Forming by Developing a Ductile Failure Criterion
Authors: Sheng Z. Q. , Mallick P. K.
Published: July 2017

In this study, the forming limit of aluminum alloy sheet materials are predicted by developing a Ductile Failure Criterion (DFAC). In the DFAC, the damage growth is defined by Mclintock formula, stretching failure is defined at Localized Necking (LN) or Fracture without LN, while the critical damage is defined by a so-called effect function, which reflects the effect of strain path and initial sheet thickness. In the first part of this study, the DFAC is used to predict Forming Limit Curves of six different aluminum sheet materials at room temperature. Then, the DFAC is further developed for elevated temperature condition by introducing an improved Zener-Hollomon parameter (Z′), which is proposed to provide enhanced representation of the strain rate and temperature effect on limit strain. In warm forming condition, the improved DFAC is used to predict the FLCs of Al5083-O and failure in a rectangular cup warm draw process on Al5182+Mn. Comparison shows that all the prediction matches quite well with experimental measurement. Thanks to the proposal of effect function, the DFAC only needs a calibration at uniaxial tension and thus provides a promising potential to predict forming limit with reduced efforts.
Study of Microscale Three-Dimensional Printing Using Near-Field Melt Electrospinning
Authors: You Xiangyu , Ye Chengcong , Guo Ping
Published: July 2017

Three-dimensional (3D) printing of microscale structures with high resolution (sub-micron) and low cost is still a challenging work for the existing 3D printing techniques. Here we report a direct writing process via near-field melt electrospinning to achieve microscale printing of single filament wall structures. The process allows continuous direct writing due to the linear and stable jet trajectory in the electric near-field. The layer-by-later stacking of fibers, or self-assembly effect, is attributed to the attraction force from the molten deposited fibers and accumulated negative charges. We demonstrated successful printing of various 3D thin wall structures (freestanding single walls, double walls, annular walls, star-shaped structures, and curved wall structures) with a minimal wall thickness less than 5 μm. By optimizing the process parameters of near-field melt electrospinning (electric field strength, collector moving speed, and needle-to-collector distance), ultrafine poly (ε-caprolactone) (PCL) fibers have been stably generated and precisely stacked and fused into 3D thin-wall structures with an aspect ratio of more than 60. It is envisioned that the near-field melt electrospinning can be transformed into a viable high-resolution and low-cost microscale 3D printing technology.
Cradle-to-Grave Life Cycle Assessment of Solid-State Perovskite Solar Cells
Authors: Zhang Jingyi , Gao Xianfeng , Deng Yelin , Zha Yuanchun , Yuan Chris
Published: July 2017

With the advantages of low cost and high conversion efficiency, perovskite solar cell attracts enormous attention in recent years for research and development. However, the toxicity potential of lead used in perovskite solar cell manufacturing causes grave concern for its environmental performance. To understand and facilitate the sustainable development of perovskite solar cell, a comprehensive life cycle assessment has been conducted by using attributional life cycle assessment approach from cradle to grave, with manufacturing data from our lab experiments and literature. The results indicate that the major environmental problem is associated with system manufacturing, including gold cathode, organic solvent usage and recycling, and electricity utilization in component manufacturing process. Lead only contributes less than 1% of human toxicity and ecotoxicity potentials in the whole life cycle, which can be explained by the small amount usage of lead in perovskite dye preparation. More importantly, the uncertainties caused by life cycle inventory have been investigated in this study to show the importance of primary data source. In addition, a comparison of perovskite solar cell with conventional solar cells and other dye sensitized solar cells shows that perovskite solar cell could be a promising alternative technology for future clean power generations.
Modeling Particle Spray and Capture Efficiency for Direct Laser Deposition Using a Four Nozzle Powder Injection System
Authors: Katinas Christopher , Shang Weixiao , Shin Yung C. , Chen Jun
Published: July 2017

Powder capture efficiency is indicative of the amount of material that is added to the substrate during laser additive manufacturing processes, and thus, being able to predict capture efficiency provides capability of predictive modeling during such processes. The focus of the work presented in this paper is to create a numerical model to understand particle trajectories and velocities, which in turn allows for the prediction of capture efficiency. To validate the numerical model, particle tracking velocimetry experiments at two powder flow rates were conducted on free stream particle spray to track individual particles such that particle concentration and velocity fields could be obtained. Results from the free stream comparison showed good agreement to the trends observed in experimental data and were subsequently used in a direct laser deposition simulation to assess capture efficiency and temperature profile at steady-state. The simulation was validated against a single track deposition experiment and showed proper correlation of the free surface geometry, molten pool boundary, heat affected zone boundary and capture efficiency.
Interlaminar Toughening of GFRP: Part 2 — Characterization and Numerical Simulation of Curing Kinetics
Authors: Bian Dakai , Beeksma Bradley R. , Shim D. J. , Jones Marshall , Yao Y. Lawrence
Published: July 2017

Various methods of toughening the bonding between the interleaf and laminate glass fiber reinforced polymer (GFRP) has been developed due to the increasing applications in industries. A polystyrene (PS) additive modified epoxy is used to improve the diffusion and precipitation region between polysulfone (PSU) interleaf and epoxy due to its influence on the curing kinetics without changing glass transition temperature and viscosity of the curing epoxy. The temperature dependent diffusivities of epoxy, amine hardener, and PSU are determined by using Attenuated Total Reflection-Fourier Transfer Infrared Spectroscopy (ATR-FTIR) through monitoring the changing absorbance of their characteristic peaks. Effects of PS additive on diffusivity in the epoxy system is investigated by comparing the diffusivity between non-modified and PS modified epoxy. The consumption rate of the epoxide group in the curing epoxy reveals the curing reaction rate, and the influence of PS additive on the curing kinetics is also studied by determining the degree of curing with time. A diffusivity model coupled with curing kinetics is applied to simulate the diffusion and precipitation process between PSU and curing epoxy. The effect of geometry factor is considered to simulate the diffusion and precipitation process with and without the existence of fibers. The simulation results show the diffusion and precipitation depths which matches those observed in the experiments.
Dimensional Performance of As-Built Assemblies in Polyjet Additive Manufacturing Process
Authors: Haghighi Azadeh , Yang Yiran , Li Lin
Published: July 2017

The additive manufacturing (AM) technology provides a unique opportunity to realize as-built assemblies, i.e., assemblies which can be fabricated as a whole in one build cycle. Some of the introduced challenges, however, are the design issues of these assembly structures and understanding the dimensional performance of the AM process to ensure proper mobility. While process improvement techniques have been proposed for dealing with individual additive components, it is also necessary to study the dimensional behavior of as-built assemblies compared to individual additive components. This paper studies and compares the dimensional performance of as-built assemblies with ordinary assemblies in which the components are fabricated individually and then assembled together. A design of experiment approach is applied to study the effect of assembly type and orientation on the final clearances. The results suggest that in addition to orientation factor, the type of assembly can also play an important role in the final clearance values. In addition, a different dimensional behavior exists in the as-built assembly structures compared to ordinary assemblies, i.e., clearances in as-built assembly tend to be smaller and also more uniform along the clearance profile.
Vision-Based Real-Time Layer Error Quantification for Additive Manufacturing
Authors: Jeong Haedong , Kim Minsub , Park Bumsoo , Lee Seungchul
Published: July 2017

Quality assurance of Additive Manufacturing (AM) products has become an important issue as the AM technology is extending its application throughout the industry. However, with no definite measure to quantify the error of the product and monitor the manufacturing process, many attempts are made to propose an effective monitoring system for the quality assurance of AM products. In this research, a novel approach for quantifying the error in real-time is presented through a closed-loop vision-based tracking method. As conventional AM processes are open-loop processes, we focus on the implementation of real-time error quantification of the products through the utilization of a closed-loop process. Three test models are designed for the experiment, and the tracking data from the camera will be compared with the G-code of the product to evaluate the geometrical errors. The results obtained from the camera analysis will then be validated through comparison of the results obtained from a 3D scanner.
Nonlinear Parameter Estimation in a Typical Industrial Air Handler Unit
Authors: Feng Lujia , Pisu Pierluigi , Mears Laine , Schulte Jörg
Published: July 2017

The energy usage inside of a manufacturing plant is mainly from two sources: energy demand from the production lines to support manufacturing processes, and the plant building temperature control to maintain a comfortable working environment. It is reported that in the US, 14% of the primary energy and 32% of electricity is used by the industry and commercial building heating, ventilation and air conditioning (HVAC) system. As an important part of the HVAC system, the air handler unit (AHU) is a comprehensive air control system consisting of multiple sub-units. Accurate modeling of the supply air temperature of AHU is important for later controller design and fault detection, but it is also challenging because of the application of variable frequency drive (VFD) systems, overall degradation, and limited sensor information and meter data. Parameter estimation of the industry AHU is therefore worth studying. In this study, the authors intend to establish a deterministic physical model of AHU system, identify the unknown parameters based on the limited meter inputs, and compare the nonlinear parameter estimation results with the design parameters, in order to achieve the goal of improving the modeling accuracy without installing expensive metering systems.
Simulation Model of Automated HVAC System Control Strategy With Thermal Comfort and Occupancy Considerations
Authors: Peng Bo , Hsieh Sheng-Jen
Published: July 2017

Currently, design and control of HVAC system in buildings rely heavily on simulation tools. However, the common tools available often fail to optimize occupants’ comfort directly, nor do they consider real-time variations in occupancy that affect comfort and energy performance.

To address these limits, this research designed an occupancy-based and thermal comfort-driven building automation simulation model. A single-space prototype lab room was co-simulated using EnergyPlus and MATLAB with the help of BCVTB and MLE+ as middleware. Various climate scenarios from four cities in the U.S. in different seasons were examined. Results suggest that overall, compared to a conventional temperature-driven control strategy baseline, the proposed system can minimize thermal comfort violation (in term of PMV model, |PMV|>0.5 is considered as a violation) to 7% and reduce occupants’ thermal discomfort by 62.5% on average. Meanwhile, energy consumption remains same or reduced (up to 2% reduction). Due to its simplicity, this strategy is relatively easy to implement in real-world building automation systems with appropriate sensor placement in modern buildings.
Data-Driven Thermal Comfort Prediction With Support Vector Machine
Authors: Peng Bo , Hsieh Sheng-Jen
Published: July 2017

Personal thermal comfort is a crucial yet often over-simplified factor in building climate control. Traditional comfort models lack the adaptability to fit individuals’ demand. Recent advances of machine learning and ubiquitous sensor networks enable the data-driven approach of thermal comfort. In this paper, we built a platform that can simulate occupants with different thermal sensations and used it to examine the performance of support vector machine (SVM) and compared with several other popular machine learning algorithms on thermal comfort prediction. We also proposed a hybrid SVM-LDA thermal comfort classifier that can improve the efficiency of model training.
Characterization of Particle Emission From Fuse Deposition Modeling Printers
Authors: Simon Timothy R. , Aguilera Giovanny A. , Zhao Fu
Published: July 2017

Throughout the past decade the popularity of additive manufacture (AM) has grown tremendously. Although AM has been deemed as an environmentally friendly alternative to traditional processes, there have already been several studies done showing that AM processes can affect human health and the environment by emitting particles of a dynamic size range into its surrounding during a print. The objective of this paper is to look deeper into the issue of particle emissions from one of the most popular AM processes i.e. fused deposition modeling (FDM). Particle emissions from a Makeblock 3-D printer enclosed in a chamber and placed in a Class 1 cleanroom are measured using a high temporal resolution electrical low pressure impactor (ELPI) which takes close-to-real-time measurements of particles in the range of 6–200nm. A honeycomb cube with side length 1.25” and the NIST standard testing part are printed using acrylonitrile butadiene styrene (ABS) filament. Results show that particle emissions are closely related to the filament residence time in the extruder while less related to extruding speed. The initial spike of particle concentration right after printing starts is likely due to the long time needed to heat the extruder and the bed to the desired temperature. It is suggested that part geometry/features and build path could significantly affect particle emissions. TEM images suggest that particles may be formed through vapor condensation and coagulation of small particles.
Experimental Investigations on Surface Roughness, Cutting Forces and Tool Wear in Turning of Super Duplex Stainless Steel With Coated Carbide Inserts
Authors: Kadam Shirish , Khake Rohit , Mudigonda Sadaiah
Published: July 2017

This paper addresses experimental investigations of turning Super Duplex Stainless Steel (DSS) with uncoated and Physical Vapor Deposition PVD coated carbide inserts under dry cutting condition. The parametric influence of cutting speed, feed and depth of cut on the surface finish and machinability aspects such as cutting force and tool wear are studied and conclusions are drawn. The turning parameters considered are cutting speed of 60–360 m/min, feed of 0.05–0.35 mm/rev and depth of cut of 0.5–2 mm. Tool wear was analysed by using an optical microscope and scanning electron microscope. The study includes identification of tool wear mechanism occurring on the flank face. The characterization of the coating was made by Calo test for measurement of coating thickness and nanoindentation for hardness. Comparison of performance of PVD coatings TiAlSiN (3.3μm), AlTiN (3 μm) and AlTiN (7 μm) have been made in terms of tool life. The coatings were produced on P-grade tungsten carbide inserts by using High Power Impulse Magnetron Sputtering (HiPIMS) technology. The findings of the study also provide the economic solution in case of dry turning of super DSS.
Effect of Tempering Temperature on Hardness and Microstructure of Laser Surface Remelted AISI H13 Tool Steel
Authors: Patra Karmakar Debapriya , Gopinath Muvvala , Nath Ashish Kumar
Published: July 2017

Surface hardening was performed by laser surface remelting of AISI H13 tool steel samples using a high power fiber laser. The surface hardened samples were exposed to different tempering temperature of 500°C, 700 °C and 900 °C in a furnace for one hour and brought back to room temperature in still air and by water quenching. Changes of the laser remelted and hardened layer were investigated in terms of microstructure and hardness before and after exposure to different tempering temperatures. Laser remelting caused mainly dendritic microstructure at the top layer but the dendritic structure of the remelted layer got altered after tempering at high temperatures. Air and water quenching caused almost similar result during tempering of laser remelted layer. The microhardness variations along depth after tempering at different temperatures indicates that the surface hardening imparted by laser remelting remains almost intact up to 700 °C but gets destroyed at 900 °C. Although the experimental temperature limits gives approximate threshold values, but it provides a clear indication of a safe limit for laser surface hardened components in high temperature applications like hot-forging dies and friction stir welding tool, etc.
Preliminary Testing of Temperature Measurements in Selective Laser Melting
Authors: Cheng Bo , Cooke Stephen , Chou Y. Kevin
Published: July 2017

Selective laser melting (SLM) based on added-material manufacturing method is one of the Additive Manufacturing (AM) technologies that can build full density metallic components. In this study, a thermal imager with about 670 nm wavelength was employed to collect build surface process temperature information during SLM fabrication using Monel K500 powder. The major findings are as follows. (1) At nominal process conditions of 600 mm/s beam speed and 180 W beam power, the melt pool has a length of about 0.6 mm and a width of about 0.36 mm. (2) The obtained melt pool length/width ratio is about 1.5 for different build height. With the increase of build height, no clear trend was observed for melt pool length/width ratio and melt pool length value. (3) It is difficult to obtain true temperature in this study but it is possible to estimate melt pool dimension with the identified radiant liquidus temperature.
Empirical Modeling of Material Removal Considering Tool Condition in Chemical Mechanical Planarization Process
Authors: Wu Zhenhua
Published: July 2017

The key performance indicators in Chemical Mechanical Planarization (CMP) processes are usually assessed by measuring the material removal rate (MRR) and Within-Wafer-Nonuniformity (WIWNU), which are vitally dependent on the processing variables including down pressure, wafer rotation, polishing pad rotation, polishing table rotation, slurry flow, and the condition of the polishing pad etc. MRR is critical to the WIWNU also since MRR can infer the end-point in the polishing process. In this study, empirical approaches were conducted to model the MRR with the production CMP settings. With the collected data from real semiconductor manufacturing processes, correlation and principle component analysis (PCA) were conducted to select the features mostly related to the CMP processes, then neural network (NN) and adaptive neuro fuzzy inference system (ANFIS) based models were proposed to understand processing variables in CMP process and estimate the MRR. The NN and ANFIS models were compared on the performance metrics of 1) mean square error (MSE), and determination coefficient (R2) based on bootstrap. The bootstrap based evaluation shows that NN achieved a MSE of 9.68e03 with the R2 value of 0.81 in the training stage and MSE of 9.59e3 with the R2 value of 0.81 in the validation stage; ANFIS achieved a MSE of 126.24 with the R2 value of 0.9102 in the training stage and MSE of 6.17e4 with the R2 value of 0.3133 in the validation stage. The empirical models are promising to be integrated with the data-driven based control of CMP processes.