Industrial and Manufacturing Systems Engineering Faculty Research and Publications

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Correlating Electronic Transport and 1/f Noise in MoSe2 Field-Effect Transistors
(2018) Kwon, Jiseok; Prakash, Abhijith; Das, Suprem R.; Janes, David B.
Two-Dimensional Transition Metal Dichalcogenides (2D TMDCs) such as MoS2, MoSe2, WS2, and WSe2 with van der Waal's type interlayer coupling are being widely explored as channel materials in a Schottky Barrier Field Effect Transistor (SB FET) configuration. While their excellent electrostatic control and high on/off ratios have been identified, a clear correlation between electronic transport and the low-frequency noise with different atomic-layer thickness is missing. For multilayer channels in MoS2 FETs, the effects of interlayer-coupling resistance on device conductance and mobility have been studied, but no systematic study has included interlayer effects in consideration of the intrinsic (channel) and extrinsic (total device) noise behavior. Here, we report the 1/f noise properties in MoSe2 FETs with varying channel thicknesses (3–40 atomic layers). Contributions of channel vs access/contact regions are extracted from current-voltage (transport) and 1/f noise measurements. The measured noise amplitude shows a direct crossover from channel- to contact-dominated noise as the gate voltage is increased. The results can be interpreted in terms of a Hooge relationship associated with the channel noise, a transition region, and a saturated high-gate-voltage regime whose characteristics are determined by a voltage-independent conductance and noise source associated with the metallurgical contact and the interlayer resistance. Both the channel Hooge coefficient and the channel/access noise amplitude decrease with increasing channel thickness over the range of 3–15 atomic layers, with the former remaining approximately constant and the latter increasing over a range of 20–40 atomic layers. The analysis can be extended to devices based on other TMDCs.
Open Access
Rotary Ultrasonic Machining of Rocks: An Experimental Investigation
(2018-03-19) Fernando, Pksc; Zhang, Meng; Pei, Zhijan
Rock drilling is widely used to explore and mine energy resources. It has also been used to extract samples to study the earth’s geological composition and topography and to explore different planets. Percussive drilling is, as of right now, the most commonly used rock drilling method. Due to the high hardness and abrasiveness of rock, tool wear in rock drilling is severe, thus limiting its penetration rate and resulting in high cost. Therefore, it is crucial to develop more costeffective rock drilling processes. Rotary ultrasonic machining has been used to drill many materials including metal alloys, ceramics, and composites, and its cost advantages have been demonstrated in many previous studies. This article presents the first experimental investigation of rotary ultrasonic machining of rocks. Three types of rocks (basalt, marble, and travertine) were used. Six input variables (tool rotation speed, feedrate, ultrasonic power, abrasive size, abrasive concentration, and drill bit diameter) were examined and two output variables (cutting force and surface roughness) were measured. Results indicate that rotary ultrasonic machining can drill holes of high quality on rocks of different hardness with a much lower cutting force and at a penetration rate of approximately three times faster than percussive drilling.
Open Access
Experimental investigations on core drilling by ultrasonic-vibration-assisted grinding for hard-to-machine materials - A review
(2016-06-16) Qin, N.; Lei, J.; Pei, Zhijian J.; zpei; Pei, Zhijian J.
Ultrasonic-vibration-assisted grinding (UVAG), a hybrid machining process combining material removal mechanisms of diamond grinding and ultrasonic machining, has been used to machine various hard-to-machine materials. Large amount of research work on UVAG has been carried out since it is invented. However there are few review papers to cover the current literature on UVAG. The emphasis of this literature review is the experimental investigations of the drilling process with ultrasonic vibration using a core drill with metal-bonded diamond abrasives. Experimental results are summarised and compared. The inconsistent results and their reasons are discussed. Furthermore, directions of future research on UVAG are also presented. © 2016 Inderscience Enterprises Ltd.
Open Access
Femtosecond Laser Backside Ablation of Gold Film on Silicon Substrate
(2016) Lei, Shuting; Grojo, D.; Ma, J.; Yu, Xiaoming; Wu, H.; lei; Lei, Shuting
Femtosecond laser ablation of gold thin film on the front and backside of silicon substrate is investigated, with backside ablation being the focus and front side ablation for comparison. The experiments are performed using 100 fs pulses delivered through an ultrafast laser source combined with an OPA for wavelength conversion at 1300 nm. We create a single shot ablation matrix by varying focus position and pulse energy. The laser beam is characterized using an IR imaging technique at both the front and backside of the substrate. It is found that the pulse profile experiences little distortion after passing though the 1 mm silicon substrate, despite the high pulse energy used. However, a comparison of the front and back ablation site indicates significant attenuation of pulse energy due to nonlinear absorption. Two types of damage happen depending on laser fluence: ablation and burst. Burst damage is confirmed with finite element simulation. © 2016 The Authors
Open Access
Surface grinding of carbon fiber-reinforced plastic composites using rotary ultrasonic machining: Effects of tool variables
(2016-09-22) Wang, H.; Ning, F. D.; Hu, Y. B.; Fernando, Pksc; Pei, Zhijian J.; Cong, W. L.; zpei; Pei, Zhijian J.
Carbon fiber-reinforced plastic composites have many superior properties, including low density, high strength-to-weight ratio, and good durability, which make them attractive in many industries. However, due to anisotropic properties, high stiffness, and high abrasiveness of carbon fibers in carbon fiber-reinforced plastic, high cutting force, high tool wear, and high surface roughness are always caused in conventional machining processes. This article reports an investigation using rotary ultrasonic machining in surface grinding of carbon fiber-reinforced plastic composites in order to develop an effective and high-quality surface grinding process. In rotary ultrasonic machining surface grinding of carbon fiber-reinforced plastic composites, tool selection is of great importance since tool variables will significantly affect output variables. In this work, the effects of tool variables, including abrasive size, abrasive concentration, number of slots, and tool end geometry, on machining performances, including the cutting force, torque, and surface roughness, are experimentally studied. The results show that lower cutting forces and torque are generated by the tool with higher abrasive size, lower abrasive concentration, and two slots. Lower surface roughness is generated by the tool with smaller abrasive size, smaller abrasive concentration, two slots, and convex end geometry. This investigation will provide guides for tool selections during rotary ultrasonic machining surface grinding of carbon fiber-reinforced plastic composites.
Open Access
A Process Capability Analysis Method Using Adjusted Modified Sample Entropy
(2016) Koppel, Siim; Chang, Shing I.; changs; Chang, Shing I.
The evolution of sensors and data storage possibilities has created possibilities for more precise data collection in processes. However, process capability analysis has become more difficult. Traditional methods, such as process capability ratios, cannot handle large volumes of process data over time because these methods assume normal process distribution that is not changing. Entropy methods have been proposed for process capability studies because entropy is not dependent on distribution and can therefore provide accurate readings in changing distribution environments. The goal of this paper is to explore the use of entropy-based methods, specifically modified Sample Entropy to identify process variations over time. A study based on simulated data sets showed that the proposed method provides process capability information. © 2016 The Authors
Open Access
Spatial competitive games with disingenuously delayed positions
(2019-07-01) Soltanolkottabi, Marzieh; Ben-Arieh, David; Wu, Chih-Hang John; davidbe; chw; Soltanolkottabi, Marzieh; Ben-Arieh, David; Wu, Chih-Hang John
During the last decade, spatial games have received great attention from researchers showing the behavior of populations of players over time in a spatial structure. One of the main factors which can greatly affect the destiny of such populations is the updating scheme used to apprise new strategies of players. Synchronous updating is the most common updating strategy in which all players update their strategy at the same time. In order to be able to describe the behavior of populations more realistically several asynchronous updating schemes have been proposed. Asynchronous game does not use a universal and players can update their strategy at different time steps during the play. In this paper, we introduce a new type of asynchronous strategy updating in which some of the players hide their updated strategy from their neighbors for several time steps. It is shown that this behavior can change the behavior of populations but does not necessarily lead to a higher payoff for the dishonest players. The paper also shows that with dishonest players, the average payoff of players is less than what they think they get, while they are not aware of their neighbors’ true strategy.
Open Access
Damage formation on fused silica illuminated with ultraviolet-infrared femtosecond pulse pairs
(2015-05-12) Yu, X.; Chang, Zenghu; Corkum, P. B.; Lei, Shuting T.; lei
Open Access
Limitations to laser machining of silicon using femtosecond micro-Bessel beams in the infrared
(2015-04-20) Grojo, D.; Mouskeftaras, A.; Delaporte, P.; Lei, Shuting T.; lei
Open Access
Effects of Screen Size on Biochemical Conversion of Big Bluestem Biomass for Biofuel Production
(2015-09-03) Song, X. X.; Zhang, Meng; Zhang, Ke; Pei, Zhijian J.; Wang, Donghai H.; meng; zpei; dwang
Open Access
Mathematical Model of Innate and Adaptive Immunity of Sepsis: A Modeling and Simulation Study of Infectious Disease
(2015-09-08) Shi, Z. Z.; Wu, Chih-Hang J.; Ben-Arieh, David; Simpson, S. Q.; chw; davidbe
Open Access
Super-strengthening and stabilizing with carbon nanotube harnessed high density nanotwins in metals by shock loading
(2015-10-23) Lin, Dong; Saei, M.; Suslov, S.; Jin, S. Y.; Cheng, G. J.; dongl
Open Access
Fabricating nanostructures on fused silica using femtosecond infrared pulses combined with sub-nanojoule ultraviolet pulses
(2014-10-01) Yu, Xiaoming; Chang, Zenghu; Corkum, P. B.; Lei, Shuting; lei
Circular craters with diameters of 500 nm are fabricated on the surface of fused silica by femtosecond ultraviolet–infrared (UV–IR) pulse trains with 0.8 nJ UV pulse energy. UV damage thresholds at different IR energies and UV–IR delays are measured. Diameters and depths of the ablated craters can be modified by adding the IR pulse and varying the UV–IR delays. These results demonstrate the feasibility of nanomachining using short wavelength lasers with pulse energy far below normal damage thresholds.
Open Access
On monitoring of multiple non-linear profiles
(2013-12-16) Chou, Shih-Hsiung; Chang, Shing I.; Tsai, Tzong-Ru; changs
Most state-of-the-art profile monitoring methods involve studies of one profile. However, a process may contain several sensors or probes that generate multiple profiles over time. Quality characteristics presented in multiple profiles may be related multiple aspects of product or process quality. Existing charting methods for simultaneous monitoring of each multiple profile may result in high false alarm rates. Or worse, they cannot correctly detect potential relationship changes among profiles. In this study, we propose two approaches to detect process shifts in multiple non-linear profiles. A simulation study was conducted to evaluate the performance of the proposed approaches in terms of average run length under different process shift scenarios. Pros and cons of the proposed methods are discussed. A guideline for choosing the proposed methods is introduced. In addition, a hybrid method combining the salient points of both approaches is explored. Finally, a real-world data-set from a vulcanisation process is used to demonstrate the implementation of the proposed methods.
Open Access
Real-time detection of wave profile changes
(2014-09-14) Chang, Shing I; Tavakkol, Behnam; Chou, Shih-Hsiung; Tsai, Tzong-Ru; changs
A statistical process control (SPC) framework is proposed to detect potential changes of a wave profile on a real-time basis. In regular profile monitoring, change detection takes place when a complete profile is generated. In this study, the detection of a potential profile change takes place before the entire information on the profile of interest is fully available. The main research goal is to make a correct process decision as soon as possible. A real-world example of condensation-water-temperature profile monitoring was used to demonstrate the proposed framework. A simulation study was also conducted. The simulation results confirm that the proposed framework is capable of detecting profile changes without having to wait for the entire profile to be generated.
Open Access
Preliminary study on rotary ultrasonic machining of CFRP/Ti stacks
(2014-08-01) Cong, Weilong; Pei, Zhijian J.; Treadwell, C.; weilong; zpei
Reported drilling methods for CFRP/Ti stacks include twist drilling, end milling, core grinding, and their derived methods. The literature does not have any report on drilling of CFRP/Ti stacks using rotary ultrasonic machining (RUM). This paper, for the first time, reports a study on drilling of CFRP/Ti stacks using RUM. It also compares results on drilling of CFRP/Ti stacks using RUM with reported results on drilling of CFRP/Ti stacks using other methods. When drilling CFRP/Ti stacks using RUM, cutting force, torque, and CFRP surface roughness were lower, hole size variation was smaller, CFRP groove depth was smaller, tool life was longer, and there was no obvious Ti exit burr and CFRP entrance delamination. Ti surface roughness when drilling of CFRP/Ti stacks using RUM was about the same as those when using other methods.
Open Access
Rotary ultrasonic machining of optical K9 glass using compressed air as coolant: a feasibility study
(2013-11-26) Zhang, Chenglong; Cong, Weilong; Feng, Pingfa; Pei, Zhijian J.; weilong; zpei
Optical K9 glass has been used in a variety of applications, including optics, electronics, thermodynamics, and fluidics. It has been regarded as a difficult-to-cut material because of its superior mechanical properties. Rotary ultrasonic machining (RUM) using cutting fluid has been used successfully to machine many different types of brittle materials, such as ceramics, sapphire, and optical K9 glass. Dry machining has been successfully employed in the machining of some materials. However, there are no reported investigations on the RUM of optical K9 glass using compressed air as a coolant. This paper, for the first time, investigates the RUM of optical K9 glass using compressed air as a coolant. The experimental investigations focus on the effects of the input variables (ultrasonic power, spindle speed, and feedrate) on the output variables (edge chipping size, cutting force, surface roughness, and ultrasonic power consumption).
Open Access
Size reduction of poplar wood using a lathe for biofuel manufacturing: effects of biomass crystallinity on sugar yield
(2014-03-07) Zhang, Meng; Song, Xiaoxu; Pei, Zhijian J.; Deines, Timothy W.; Wang, Donghai; meng; xiaoxu; zpei; tdeines; dwang
Poplar wood can be used as a feedstock for manufacturing cellulosic biofuel (ethanol) as an alternative to petroleum-based liquid transportation fuel. Producing biofuel from poplar wood involves reducing poplar wood into small particles (known as size reduction), hydrolyzing cellulose inside poplar particles to fermentable sugars, and converting these sugars to ethanol biofuel. Size reduction is usually done by wood chipping and biomass milling. In the literature, there are inconsistent reports about effects of particle size and biomass crystallinity on sugar yield (proportional to ethanol yield). An important reason for this inconsistence is that effects of these two biomass structural features (particle size and biomass crystallinity) on sugar yield are confounded with current size reduction methods. In this study, a lathe was used to produce poplar wood particles with (statistically) the same particle size (thickness) but different levels of biomass crystallinity, making it possible to investigate effects of biomass crystallinity on sugar yield without being confounded with effects of particle size. Results from this study show that, for the three levels of biomass crystallinity tested, sugar yield increased as biomass crystallinity decreased.
Open Access
Statistical process control for monitoring a diffusion process
(2012-03-26) Tsai, Tzong-Ru; Chang, Shing I; Chou, Shih-Hsiung; Chiang, Jyun-You; Sung, Wen-Yun; changs
This study presents a new statistical process control (SPC) procedure for a process together with degradation and diffusion effects. One of such examples is the initial cool-down process of high-pressure hose production. The air temperature readings during the initial cool-down process often exhibit a non-increasing trend with a diffusion effect in that profiles generated from cycle to cycle deviate from each other more over time. A new charting procedure using the Wiener diffusion model is developed in this article. A real data set, generated from the cool-down process of high-pressure hose production, is used to demonstrate the application of proposed method.
Open Access
An experimental investigation on slicing of potassium dihydrogen phosphate (KDP) crystal
(2013-04-16) Wang, Q. G.; Gao, H.; Pei, Zhijian J.; Guo, D. M.; Teng, X. J.; zpei
Because of its unique properties, potassium dihydrogen phosphate (KDP) crystals are widely used for electro-optical applications. Slicing is needed to make KDP crystal lens with desired shapes. However, reported studies on slicing of KDP crystal are scarce. This paper presents an experimental investigation on slicing of KDP crystals. Output parameters studied include surface roughness, flatness error, parallelism error, and subsurface damage. Effects of wire sawing input variables (feed rate and diamond grit size) on output parameters are investigated. Comparisons of wire sawing and band sawing are also made.