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University of Nebraska - Lincoln
Department of Electrical and Computer Engineering: Faculty Publications
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Articles 1 - 30 of 39
Full-Text Articles in Engineering
Structure-Mediated Excitation Of Air Plasma And Silicon Plasma Expansion In Femtosecond Laser Pulses Ablation, Qingsong Wang, Lan Jiang, Changji Pan, Weina Han, Guoyan Wang, Feifei Wang, Kaihu Zhang, Ming Li, Yongfeng Lu
Structure-Mediated Excitation Of Air Plasma And Silicon Plasma Expansion In Femtosecond Laser Pulses Ablation, Qingsong Wang, Lan Jiang, Changji Pan, Weina Han, Guoyan Wang, Feifei Wang, Kaihu Zhang, Ming Li, Yongfeng Lu
Department of Electrical and Computer Engineering: Faculty Publications
Femtosecond laser-induced surface structures upon multiple pulses irradiation are strongly correlated with the pulse number, which in turn significantly affects successive laser-material interactions. By recording the dynamics of femtosecond laser ablation of silicon using time-resolved shadowgraphy, here we present direct visualization of the excitation of air plasma induced by the reflected laser during the second pulse irradiation. The interaction of the air plasma and silicon plasma is found to enhance the shockwave expansion induced by silicon ablation in the longitudinal direction, showing anisotropic expansion dynamics in different directions. We further demonstrate the vanishing of air plasma as the pulse number …
Datanet: Deep Learning Based Encrypted Network Traffic Classification In Sdn Home Gateway, Pan Wang, Feng Ye, Xuejiao Chen, Yi Qian
Datanet: Deep Learning Based Encrypted Network Traffic Classification In Sdn Home Gateway, Pan Wang, Feng Ye, Xuejiao Chen, Yi Qian
Department of Electrical and Computer Engineering: Faculty Publications
A smart home network will support various smart devices and applications, e.g., home automation devices, E-health devices, regular computing devices, and so on. Most devices in a smart home access the Internet through a home gateway (HGW). In this paper, we propose a software-defined network (SDN)-HGW framework to better manage distributed smart home networks and support the SDN controller of the core network. The SDN controller enables efficient network quality-of-service management based on real-time traffic monitoring and resource allocation of the core network. However, it cannot provide network management in distributed smart homes. Our proposed SDN-HGW extends the control to …
Birefringence Imaging Chromatography Based On Highly Ordered 3d Nanostructures, Mathias M. Schubert, Tino Hofmann, David S. Hage, Erika Pfaunmiller, Craig M. Herzinger, John A. Woollam, Stefan Schoeche
Birefringence Imaging Chromatography Based On Highly Ordered 3d Nanostructures, Mathias M. Schubert, Tino Hofmann, David S. Hage, Erika Pfaunmiller, Craig M. Herzinger, John A. Woollam, Stefan Schoeche
Department of Electrical and Computer Engineering: Faculty Publications
Ellipsometers and polarimeters or the like to investigate analyte containing fluids applied to a substrate - stage having a multiplicity of nano - structures that project non - normal to a surface thereof , including dynamics of interaction there with , to the end of evaluating and presenting at least partial Jones or Mueller Matricies corresponding to a multiplicity of locations over an imaged area .
From E-911 To Ng-911: Overview And Challenges In Ecuador, Danilo Corral-De-Witt, Enrique V. Carrera, Jose A. Matamoros-Vargas, Sergio Munoz-Romero, Jose Luis Rojo-Alvarez, Kemal Tepe
From E-911 To Ng-911: Overview And Challenges In Ecuador, Danilo Corral-De-Witt, Enrique V. Carrera, Jose A. Matamoros-Vargas, Sergio Munoz-Romero, Jose Luis Rojo-Alvarez, Kemal Tepe
Department of Electrical and Computer Engineering: Faculty Publications
For years, emergency attendance institutions in Ecuador worked separately and not all of them had a 24/7 service, resulting in duplicated efforts, a waste of the scarce resources, and an absence of generalized technology. In 2012, Ecuador created an Integrated Security Service, called ECU 911, to address the need of an emergency service articulating all the first response institutions. The ECU 911 relies on the Enhanced 911 technology, having a countrywide presence. Since then, Ecuador has implemented 16 public-safety answering points and 11 decentralized operative rooms, covering all Ecuadorian territory and serving to a population of about 17 million people. …
Development Of Boron Calibration Via Hybrid Comparator Method In Prompt Gamma Activation Analysis, E. J. Artnak, S. R. Biegalski, S. Landsberger, Natale Lanno, Dennis Alexander, M. F. Byers
Development Of Boron Calibration Via Hybrid Comparator Method In Prompt Gamma Activation Analysis, E. J. Artnak, S. R. Biegalski, S. Landsberger, Natale Lanno, Dennis Alexander, M. F. Byers
Department of Electrical and Computer Engineering: Faculty Publications
The prompt gamma activation analysis (PGAA) facility at the Nuclear Engineering Teaching Laboratory at The University of Texas at Austin was utilized to quantify boron concentrations in boron carbide semiconductor films deposited on silicon substrates. Calibration was complicated by the unique and varying sample geometries analyzed. In addition, there was a dearth of solid materials available with quantified boron concentrations having comparable or readily modifiable dimensions to exploit for calibration purposes. Therefore, a novel hybrid comparator method was developed for the quantification of boron utilizing aluminum as an inexpensive and easily machinable reference material. Aluminum samples were manufactured with high …
Combined Use Of Oscillating Means And Ellipsometry To Determine Uncorrelated Effective Thickness And Optical Constants Of Material Deposited At Or Etched From A Working Electrode That Preferrably Comprises Non - Normal Oriented Nanofibers, Mathias M. Schubert, Tino Hofmann, John A. Woollam, Rebecca Y. Lai
Combined Use Of Oscillating Means And Ellipsometry To Determine Uncorrelated Effective Thickness And Optical Constants Of Material Deposited At Or Etched From A Working Electrode That Preferrably Comprises Non - Normal Oriented Nanofibers, Mathias M. Schubert, Tino Hofmann, John A. Woollam, Rebecca Y. Lai
Department of Electrical and Computer Engineering: Faculty Publications
Disclosed are systems and methods that enable determination of uncorrelated thickness of a working electrode and surface region optical constants in settings involving electrochemical processing at a working electrodes in a Piezo electric Balance system , by simultaneous application of an Ellipsometer system , the working electrode optionally having a multiplicity of nanofibers that are oriented non normally to a surface of said working electrode . Further disclosed is , simultaneous with said determinations , the monitoring of electrochemical processes at a piezoelectric balance working electrode driven by electrical energy applied between said working electrode and counter electrode .
Tunable Plasmonic Resonances In Highly Porous Nano-Bamboo Si-Au Superlattice-Type Thin Films, Ufuk Kılıç, Alyssa Mock, René Feder, Derek Sekora, Matthew J. Hilfiker, Rafal Korlacki, Eva Schubert, Christos Argyropoulos, Mathias Schubert
Tunable Plasmonic Resonances In Highly Porous Nano-Bamboo Si-Au Superlattice-Type Thin Films, Ufuk Kılıç, Alyssa Mock, René Feder, Derek Sekora, Matthew J. Hilfiker, Rafal Korlacki, Eva Schubert, Christos Argyropoulos, Mathias Schubert
Department of Electrical and Computer Engineering: Faculty Publications
We report on fabrication of spatially-coherent columnar plasmonic nanostructure superlattice-type thin films with high porosity and strong optical anisotropy using glancing angle deposition. Subsequent and repeated depositions of silicon and gold lead to nanometer-dimension subcolumns with controlled lengths. The superlattice-type columns resemble bamboo structures where smaller column sections of gold form junctions sandwiched between larger silicon column sections (“nano-bamboo”). We perform generalized spectroscopic ellipsometry measurements and finite element method computations to elucidate the strongly anisotropic optical properties of the highly-porous nano-bamboo structures. The occurrence of a strongly localized plasmonic mode with displacement pattern reminiscent of a dark quadrupole mode is …
Composite Bending-Dominated Hollow Nanolattices: A Stiff, Cyclable Mechanical Metamaterial, Biwei Deng, Rong Xu, Kejie Zhao, Yongfeng Lu, Sabyasachi Ganguli, Gary J. Cheng
Composite Bending-Dominated Hollow Nanolattices: A Stiff, Cyclable Mechanical Metamaterial, Biwei Deng, Rong Xu, Kejie Zhao, Yongfeng Lu, Sabyasachi Ganguli, Gary J. Cheng
Department of Electrical and Computer Engineering: Faculty Publications
Manufacturing ultralight and mechanical reliable materials has been a long-time challenge. Ceramicbased mechanical metamaterials provide significant opportunities to reverse their brittle nature and unstable mechanical properties and have great potential as strong, ultralight, and ultrastiff materials. However, the failure of ceramics nanolattice and degradation of strength/modulus with decreasing density are caused by buckling of the struts and failure of the nodes within the nanolattices, especially during cyclic loading. Here, we explore a new class of 3D ceramic-based metamaterials with a high strength–density ratio, stiffness, recoverability, cyclability, and optimal scaling factor. Deformation mode of the fabricated nanolattices has been engineered through …
Fiber Optic Sensor And Methods For Highly-Sensitive Detection Of Strain In Large Frequency Range, Ming Han
Fiber Optic Sensor And Methods For Highly-Sensitive Detection Of Strain In Large Frequency Range, Ming Han
Department of Electrical and Computer Engineering: Faculty Publications
An in-line fiber-optic sensing element, a system, and methods for detecting strain using a fiber optic sensor are described that include using at least two chirped grating structures. In an implementation, an in-line fiber-optic sensing element that employs example techniques in accordance with the present disclosure in includes an optically transmissive fiber including a core and an outer layer; a Fabry-Perot cavity defined by a portion of the optically transmissive fiber and two chirped fiber-Bragg grating structures, where the two chirped grating structures are separated and are configured to reflect light.
Decco: Deep-Learning Enabled Coverage And Capacity Optimization For Massive Mimo Systems, Yang Yang, Yang Li, Kai Li, Shuang Zhao, Rui Chen, Jun Wang, Song Ci
Decco: Deep-Learning Enabled Coverage And Capacity Optimization For Massive Mimo Systems, Yang Yang, Yang Li, Kai Li, Shuang Zhao, Rui Chen, Jun Wang, Song Ci
Department of Electrical and Computer Engineering: Faculty Publications
System capacity and service coverage are the most critical performance metrics in cellular wireless communication networks. Usually, system capacity enhancements are at the expense of service coverage degradations, and vice versa. This capacity-coverage tradeoff and the associated joint optimization problem becomes very challenging in massive multiple-input multiple-output (MIMO) wireless systems, due to a large amount of antenna tilt values to be configured and very sophisticated inter-cell interference conditions, under massive antenna scenarios. This paper proposes a novel approach, namely group alignment of user signal strength (GAUSS), to efficiently support the user scheduling for the massive MIMO system, and thus serve …
Critical-Point Model Dielectric Function Analysis Of Wo3 Thin Films Deposited By Atomic Layer Deposition Techniques, Ufuk Kılıç, Derek Sekora, Alyssa Mock, Rafał Korlacki, Elena M. Echeverría, Natale J. Ianno, Eva Schubert, Mathias Schubert
Critical-Point Model Dielectric Function Analysis Of Wo3 Thin Films Deposited By Atomic Layer Deposition Techniques, Ufuk Kılıç, Derek Sekora, Alyssa Mock, Rafał Korlacki, Elena M. Echeverría, Natale J. Ianno, Eva Schubert, Mathias Schubert
Department of Electrical and Computer Engineering: Faculty Publications
WO3 thin films were grown by atomic layer deposition and spectroscopic ellipsometry data gathered in the photon energy range of 0.72-8.5 eV and from multiple samples was utilized to determine the frequency dependent complex-valued isotropic dielectric function for WO3. We employ a critical-point model dielectric function analysis and determine a parameterized set of oscillators and compare the observed critical-point contributions with the vertical transition energy distribution found within the band structure of WO3 calculated by density functional theory. We investigate surface roughness with atomic force microscopy and compare to ellipsometric determined effective roughness layer thickness.
Electrical And Material Properties Of Hydrothermally Grown Single Crystal (111) Uo2, Christina L. Dugan, George Glenn Peterson, Alyssa Mock, Christopher Young, J. Matthew Mann, Michael Nastasi, Mathias Schubert, Lu Wang, Wai-Ning Mei, Iori Tanabe, Peter A. Dowben, James Petrosky
Electrical And Material Properties Of Hydrothermally Grown Single Crystal (111) Uo2, Christina L. Dugan, George Glenn Peterson, Alyssa Mock, Christopher Young, J. Matthew Mann, Michael Nastasi, Mathias Schubert, Lu Wang, Wai-Ning Mei, Iori Tanabe, Peter A. Dowben, James Petrosky
Department of Electrical and Computer Engineering: Faculty Publications
The semiconductor and optical properties of UO2 are investigated. The very long drift carrier lifetimes, obtained from current-voltage I(V) and capacitance-voltage C(V) measurements, along with the well-defined optical properties provide little evidence of an abundance of material defects away from the surface region. Schottky barrier formation may be possible, but very much dependent on the choice of contact and surface stoichiometry and we find that Ohmic contacts are in fact favored. Depth resolved photoemission provided evidence of a chemical shift at the surface. Density functional theory, with the Heyd-Scuseria-Ernzerhof (HSE) functional, indicates a band gap of a 2.19 eV and …
Broadband Plasmonic-Enhanced Forward And Backward Multiplex Coherent Anti-Stokes Raman Scattering Microscopy, Baoshan Guo, Lan Jiang, Yanhong Hua, Xin Li, Tianhong Cui, Yongfeng Lu
Broadband Plasmonic-Enhanced Forward And Backward Multiplex Coherent Anti-Stokes Raman Scattering Microscopy, Baoshan Guo, Lan Jiang, Yanhong Hua, Xin Li, Tianhong Cui, Yongfeng Lu
Department of Electrical and Computer Engineering: Faculty Publications
Coherent anti-Stokes Raman scattering (CARS) microscopy is an attractive technique for label-free biochemical-specific characterization of biological specimens. However, it has very low sensitivity in monitoring and imaging molecules present in extremely low concentrations or at fast speeds. To improve this sensitivity, especially for multiplex CARS, the intensity of the pump beam and broadband Stokes beam should be enhanced simultaneously. Therefore, the gold shell particle and gold surface are demonstrated to enhance the forward and backward CARS, respectively. Results show that a signal enhancement factor of ∼25;000 can be achieved for the gold surface and an even higher enhancement factor can …
Qtsac: An Energy-Efficient Mac Protocol For Delay Minimization In Wireless Sensor Networks, Yuxin Liu, Kaoru Ota, Kuan Zhang, Ming Ma, Naixue Xiong, Anfeng Liu, Jun Long
Qtsac: An Energy-Efficient Mac Protocol For Delay Minimization In Wireless Sensor Networks, Yuxin Liu, Kaoru Ota, Kuan Zhang, Ming Ma, Naixue Xiong, Anfeng Liu, Jun Long
Department of Electrical and Computer Engineering: Faculty Publications
Millions of sensors are deployed to monitor the smart grid. They consume huge amounts of energy in the communication infrastructure. Therefore, the establishment of an energy-efficient medium access control (MAC) protocol for sensor nodes is challenging and urgently needed. The Quorum-based MAC protocol independently and adaptively schedules nodes’ wake-up times and decreases idle listening and collisions, thereby increasing the network throughput and extending the network lifetime. A novel Quorum time slot adaptive condensing (QTSAC)-based MAC protocol is proposed for achieving delay minimization and energy efficiency for the wireless sensor networks (WSNs). Compared to previous protocols, the QTSAC-based MAC protocol has …
Electron Effective Mass In In0.33ga0.67n Determined By Mid- Infrared Optical Hall Effect, Nerijus Armakavicius, Vallery Stanishev, Sean Knight, Mathias Schubert, Vanya Darakchieva
Electron Effective Mass In In0.33ga0.67n Determined By Mid- Infrared Optical Hall Effect, Nerijus Armakavicius, Vallery Stanishev, Sean Knight, Mathias Schubert, Vanya Darakchieva
Department of Electrical and Computer Engineering: Faculty Publications
Mid-infrared optical Hall effect measurements are used to determine the free charge carrier parameters of an unintentionally doped wurtzite-structure c-plane oriented In0.33Ga0.67N epitaxial layer. Room temperature electron effective mass parameters of m_ ¼ ð0:20560:013Þm0 andm_k ¼ ð0:20460:016Þm0 for polarization perpendicular and parallel to the c-axis, respectively,were determined. The free electron concentration was obtained as (1.760.2)_1019 cm-3. Within our uncertainty limits, we detect no anisotropy for the electron effective mass parameter and we estimate the upper limit of the possible effective mass anisotropy as 7%. We discuss the influence of conduction band nonparabolicity on …
Condensation And Subsequent Freezing Delays As A Result Of Using Femtosecond Laser Functionalized Surfaces, Chongji Huang, Ryan Bell, Alfred Tsubaki, Craig Zuhlke, Dennis Alexander
Condensation And Subsequent Freezing Delays As A Result Of Using Femtosecond Laser Functionalized Surfaces, Chongji Huang, Ryan Bell, Alfred Tsubaki, Craig Zuhlke, Dennis Alexander
Department of Electrical and Computer Engineering: Faculty Publications
In this paper, the authors report on the use of femtosecond laser surface processing (FLSP) to enhance the anti-icing properties of a commonly used aircraft alloy, Al 7075-O Clad. By changing the surface morphology through FLSP and the surface chemistry through siloxane vapor deposition, the wettability of Al 7075-O Clad was altered. Tall mound and short mound FLSP functionalized surfaces were created through two sets of laser parameters. Condensation and the subsequent freezing of condensates on FLSP Al 7075-O Clad was studied. Both structure height and surface wettability were shown to play a role in the delay of freezing. Freezing …
Electron Effective Mass In Sn-Doped Monoclinic Single Crystal B-Gallium Oxide Determined By Mid-Infrared Optical Hall Effect, Sean Knight, Alyssa Mock, Rafal Korlacki, Vanya Darakchieva, Bo Monemar, Yoshinao Kumagai, Ken Goto, Masataka Higashiwaki, Mathias Schubert
Electron Effective Mass In Sn-Doped Monoclinic Single Crystal B-Gallium Oxide Determined By Mid-Infrared Optical Hall Effect, Sean Knight, Alyssa Mock, Rafal Korlacki, Vanya Darakchieva, Bo Monemar, Yoshinao Kumagai, Ken Goto, Masataka Higashiwaki, Mathias Schubert
Department of Electrical and Computer Engineering: Faculty Publications
The isotropic average conduction band minimum electron effective mass in Sn-doped monoclinic single crystal B-Ga2O3 is experimentally determined by the mid-infrared optical Hall effect to be (0.28460.013)m0 combining investigations on (010) and (_201) surface cuts. This result falls within the broad range of values predicted by theoretical calculations for undoped B-Ga2O3. The result is also comparable to recent density functional calculations using the Gaussian-attenuation- Perdew-Burke-Ernzerhof hybrid density functional, which predict an average effective mass of 0.267m0. Within our uncertainty limits, we detect no anisotropy for the electron effective mass, which …
Uneven-Layered Coding Metamaterial Tile For Ultrawideband Rcs Reduction And Diffuse Scattering, Jianxun Su, Huan He, Zengrui Li, Yaoqing Lamar Yang, Hongcheng Yin, Junhong Wang
Uneven-Layered Coding Metamaterial Tile For Ultrawideband Rcs Reduction And Diffuse Scattering, Jianxun Su, Huan He, Zengrui Li, Yaoqing Lamar Yang, Hongcheng Yin, Junhong Wang
Department of Electrical and Computer Engineering: Faculty Publications
In this paper, a novel uneven-layered coding metamaterial tile is proposed for ultra-wideband radar cross section (RCS) reduction and diffuse scattering. The metamaterial tile is composed of two kinds of square ring unit cells with different layer thickness. The reflection phase difference of 180° (±37°) between two unit cells covers an ultra-wide frequency range. Due to the phase cancellation between two unit cells, the metamaterial tile has the scattering pattern of four strong lobes deviating from normal direction. The metamaterial tile and its 90-degree rotation can be encoded as the ‘0’ and ‘1’ elements to cover an object, and diffuse …
Electrons Dynamics Control By Shaping Femtosecond Laser Pulses In Micro/Nanofabrication: Modeling, Method, Measurement And Application, Lan Jiang, An-Dong Wang, Bo Li, Tian-Hong Cui, Yong-Feng Lu
Electrons Dynamics Control By Shaping Femtosecond Laser Pulses In Micro/Nanofabrication: Modeling, Method, Measurement And Application, Lan Jiang, An-Dong Wang, Bo Li, Tian-Hong Cui, Yong-Feng Lu
Department of Electrical and Computer Engineering: Faculty Publications
During femtosecond laser fabrication, photons are mainly absorbed by electrons, and the subsequent energy transfer from electrons to ions is of picosecond order. Hence, lattice motion is negligible within the femtosecond pulse duration, whereas femtosecond photon-electron interactions dominate the entire fabrication process. Therefore, femtosecond laser fabrication must be improved by controlling localized transient electron dynamics, which poses a challenge for measuring and controlling at the electron level during fabrication processes. Pump-probe spectroscopy presents a viable solution, which can be used to observe electron dynamics during a chemical reaction. In fact, femtosecond pulse durations are shorter than many physical/chemical characteristic times, …
Ultraviolet Laser Photolysis Of Hydrocarbons For Nondiamond Carbon Suppression In Chemical Vapor Deposition Of Diamond Films, Li-Sha Fan, Loic Constantin, Da-Wei Li, Lei Liu, Kamran Keramatnejad, Clio Azina, Xi Huang, Hossein Rabiee Golgir, Yao Lu, Zahra Ahmadi, Fei Wang, Jeffrey E. Shield, Bai Cui, Jean-Francois Silvain, Yong-Feng Lu
Ultraviolet Laser Photolysis Of Hydrocarbons For Nondiamond Carbon Suppression In Chemical Vapor Deposition Of Diamond Films, Li-Sha Fan, Loic Constantin, Da-Wei Li, Lei Liu, Kamran Keramatnejad, Clio Azina, Xi Huang, Hossein Rabiee Golgir, Yao Lu, Zahra Ahmadi, Fei Wang, Jeffrey E. Shield, Bai Cui, Jean-Francois Silvain, Yong-Feng Lu
Department of Electrical and Computer Engineering: Faculty Publications
In this work, we demonstrate that ultraviolet (UV) laser photolysis of hydrocarbon species alters the flame chemistry such that it promotes the diamond growth rate and film quality. Optical emission spectroscopy and laser-induced fluorescence demonstrate that direct UV laser irradiation of a diamond-forming combustion flame produces a large amount of reactive species that play critical roles in diamond growth, thereby leading to enhanced diamond growth. The diamond growth rate is more than doubled, and diamond quality is improved by 4.2%. Investigation of the diamond nucleation process suggests that the diamond nucleation time is significantly shortened and nondiamond carbon accumulation is …
Ears-Dm: Efficient Auto Correction Retrieval Scheme For Data Management In Edge Computing, Kai Fan, Jie Yin, Kuan Zhang, Hui Li, Yintang Wang
Ears-Dm: Efficient Auto Correction Retrieval Scheme For Data Management In Edge Computing, Kai Fan, Jie Yin, Kuan Zhang, Hui Li, Yintang Wang
Department of Electrical and Computer Engineering: Faculty Publications
Edge computing is an extension of cloud computing that enables messages to be acquired and processed at low cost. Many terminal devices are being deployed in the edge network to sense and deal with the massive data. By migrating part of the computing tasks from the original cloud computing model to the edge device, the message is running on computing resources close to the data source. The edge computing model can effectively reduce the pressure on the cloud computing center and lower the network bandwidth consumption. However, the security and privacy issues in edge computing are worth noting. In this …
Optimal Computational Power Allocation In Multi-Access Mobile Edge Computing For Blockchain, Yuan Wu, Xiangxu Chen, Jiajun Shi, Kejie Ni, Liping Qian, Liang Huang, Kuan Zhang
Optimal Computational Power Allocation In Multi-Access Mobile Edge Computing For Blockchain, Yuan Wu, Xiangxu Chen, Jiajun Shi, Kejie Ni, Liping Qian, Liang Huang, Kuan Zhang
Department of Electrical and Computer Engineering: Faculty Publications
Blockchain has emerged as a decentralized and trustable ledger for recording and storing digital transactions. The mining process of Blockchain, however, incurs a heavy computational workload for miners to solve the proof-of-work puzzle (i.e., a series of the hashing computation), which is prohibitive from the perspective of the mobile terminals (MTs). The advanced multi-access mobile edge computing (MEC), which enables the MTs to offload part of the computational workloads (for solving the proof-of-work) to the nearby edge-servers (ESs), provides a promising approach to address this issue. By offloading the computational workloads via multi-access MEC, the MTs can effectively increase their …
Structure-Mediated Excitation Of Air Plasma And Silicon Plasma Expansion In Femtosecond Laser Pulses Ablation, Qingsong Wang, Lan Jiang, Jingya Sun, Changji Pan, Weina Han, Guoyan Wang, Feifei Wang, Kaihu Zhang, Ming Li, Yongfeng Lu
Structure-Mediated Excitation Of Air Plasma And Silicon Plasma Expansion In Femtosecond Laser Pulses Ablation, Qingsong Wang, Lan Jiang, Jingya Sun, Changji Pan, Weina Han, Guoyan Wang, Feifei Wang, Kaihu Zhang, Ming Li, Yongfeng Lu
Department of Electrical and Computer Engineering: Faculty Publications
Femtosecond laser-induced surface structures upon multiple pulses irradiation are strongly correlated with the pulse number,which in turn significantly affects successive laser-material interactions. By recording the dynamics of femtosecond laser ablation of silicon using time-resolved shadowgraphy, here we present direct visualization of the excitation of air plasma induced by the reflected laser during the second pulse irradiation.The interaction of the air plasma and silicon plasma is found to enhance the shockwave expansion induced by silicon ablation in the longitudinal direction, showing anisotropic expansion dynamics in different directions. We further demonstrate the vanishing of air plasma as the pulse number increases because …
Deformation Behavior Of Foam Laser Targets Fabricated By Two-Photon Polymerization, Ying Liu, John H. Campbell, Ori Stein, Lijia Jiang, Jared Hund, Yongfeng Lu
Deformation Behavior Of Foam Laser Targets Fabricated By Two-Photon Polymerization, Ying Liu, John H. Campbell, Ori Stein, Lijia Jiang, Jared Hund, Yongfeng Lu
Department of Electrical and Computer Engineering: Faculty Publications
Two-photon polymerization (2PP), which is a three-dimensional micro/nano-scale additive manufacturing process, is used to fabricate component for small custom experimental packages (“targets”) to support laser-driven, high-energy-density physics research. Of particular interest is the use of 2PP to deterministically print millimeter-scale, low-density, and low atomic number (CHO) polymer matrices (“foams”). Deformation during development and drying of the foam structures remains a challenge when using certain commercial acrylic photo-resins. Acrylic resins were chosen in order to meet the low atomic number requirement for the foam; that requirement precludes the use of low-shrinkage organic/inorganic hybrid resins. Here, we compare the use of acrylic …
Optimal Computational Power Allocation In Multi-Access Mobile Edge Computing For Blockchain, Yuan Wu, Xiangxu Chen, Jiajun Shi, Kejie Ni, Liping Qian, Liang Huang, Kuan Zhang
Optimal Computational Power Allocation In Multi-Access Mobile Edge Computing For Blockchain, Yuan Wu, Xiangxu Chen, Jiajun Shi, Kejie Ni, Liping Qian, Liang Huang, Kuan Zhang
Department of Electrical and Computer Engineering: Faculty Publications
Blockchain has emerged as a decentralized and trustable ledger for recording and storing digital transactions. The mining process of Blockchain, however, incurs a heavy computational workload for miners to solve the proof-of-work puzzle (i.e., a series of the hashing computation), which is prohibitive from the perspective of the mobile terminals (MTs). The advanced multi-access mobile edge computing (MEC), which enables the MTs to offload part of the computational workloads (for solving the proof-of-work) to the nearby edge-servers (ESs), provides a promising approach to address this issue. By offloading the computational workloads via multi-access MEC, the MTs can effectively increase their …
Effect Of Weld Nugget Size On Failure Mode And Mechanical Properties Of Microscale Resistance Spot Welds On Ti–1al–1mn Ultrathin Foils, Feng Chen, Shiding Sun, Zhenwu Ma, G Q. Tong, Xiang Huang
Effect Of Weld Nugget Size On Failure Mode And Mechanical Properties Of Microscale Resistance Spot Welds On Ti–1al–1mn Ultrathin Foils, Feng Chen, Shiding Sun, Zhenwu Ma, G Q. Tong, Xiang Huang
Department of Electrical and Computer Engineering: Faculty Publications
We use tensile–shear tests to investigate the failure modes of Ti–1Al–1Mn microscale resistance spot welds and to determine how the failure mode affects the microstructure, microhardness profile, and mechanical performance. Two different failure modes were revealed: interfacial failure mode and pullout failure mode. The welds that fail by pullout failure mode have much better mechanical properties than those that fail by interfacial failure mode. The results show that weld nugget size is also a principal factor that determines the failure mode of microscale resistance spot welds. A minimum weld nugget size exists above which all specimens fail by pullout failure …
Bias-Dependent Scanning Tunneling Microscopy Signature Of Bridging-Oxygen Vacancies On Rutile Tio2(110), Willie B. Maddox, Danda P. Acharya, G. Jeremy Leong, Peter Sutter, Cristian V. Ciobanu
Bias-Dependent Scanning Tunneling Microscopy Signature Of Bridging-Oxygen Vacancies On Rutile Tio2(110), Willie B. Maddox, Danda P. Acharya, G. Jeremy Leong, Peter Sutter, Cristian V. Ciobanu
Department of Electrical and Computer Engineering: Faculty Publications
The rutile TiO2(110) surface has long-served as a wellcharacterized, prototypical transition-metal oxide surface used in heterogeneous catalysis and photocatalytic water splitting. Naturally occurring defects on this surface, called bridging-oxygen (BO) vacancies, are important as they determine the overall reactivity of the surface. Herein, we report a bias-dependent, scanning tunneling microscopy (STM) signature of the BO vacancies on TiO2(110): for sample bias voltages past a threshold of +3 V, the bright vacancies are flanked on either side (along the oxygen row) by two dark spots approximately shaped like half-moons. The BO vacancies have a bright aspect below …
Experimental Analyses On Multiscale Structural And Mechanical Properties Of Ε-Si/Gesi/C-Si Materials, Wei Qiu, Lu-Lu Ma, Hong-Tao Wang, Ren-Rong Liang, Yu-Cheng Zhao, Yun-Shen Zhou
Experimental Analyses On Multiscale Structural And Mechanical Properties Of Ε-Si/Gesi/C-Si Materials, Wei Qiu, Lu-Lu Ma, Hong-Tao Wang, Ren-Rong Liang, Yu-Cheng Zhao, Yun-Shen Zhou
Department of Electrical and Computer Engineering: Faculty Publications
Strained silicon (ε-Si) is a promising material that could extend Moore’s law by enhancing electron mobility. A ε-Si material is usually composed of multiscale, multilayer heterostructures, where the strained-silicon film or strap is tens-of-nanometers thick, and its buffer layers are of the micrometer scale. The structural properties determine the electrical performance and reliability of ε-Si-based devices. Inhomogeneous residual stress is induced during the preparation, which induces ε-Si structure failure. In this work, biaxial strained-silicon films that contain graded and relaxed germanium-silicon buffer layers were prepared on monocrystalline silicon wafers through reduced-pressure chemical-vapor epitaxy. The layer components and thicknesses were measured …
Adaptive Transmission Range Based Topology Control Scheme For Fast And Reliable Data Collection, Haojun Teng, Kuan Zhang, Mianxiong Dong, Kaoru Ota, Anfeng Liu, Ming Zhao, Tian Wang
Adaptive Transmission Range Based Topology Control Scheme For Fast And Reliable Data Collection, Haojun Teng, Kuan Zhang, Mianxiong Dong, Kaoru Ota, Anfeng Liu, Ming Zhao, Tian Wang
Department of Electrical and Computer Engineering: Faculty Publications
An Adaptive Transmission Range Based Topology Control (ATRTC) scheme is proposed to reduce delay and improve reliability for data collection in delay and loss sensitive wireless sensor network. The core idea of the ATRTC scheme is to extend the transmission range to speed up data collection and improve the reliability of data collection.The main innovations of our work are as follows: (1) an adaptive transmission range adjustment method is proposed to improve data collection reliability and reduce data collection delay. The expansion of the transmission range will allow the data packet to be received by more receivers, thus improving the …
Metasurface Base On Uneven Layered Fractal Elements For Ultra-Wideband Rcs Reduction, Jianxun Su, Yueyang Cui, Zengrui Li, Yaoqing (Lamar) Yang, Yongxing Che, Hongcheng Yin
Metasurface Base On Uneven Layered Fractal Elements For Ultra-Wideband Rcs Reduction, Jianxun Su, Yueyang Cui, Zengrui Li, Yaoqing (Lamar) Yang, Yongxing Che, Hongcheng Yin
Department of Electrical and Computer Engineering: Faculty Publications
A novel metasurface based on uneven layered fractal elements is designed and fabricated for ultra-wideband radar cross section (RCS) reduction in this paper. The proposed metasurface consists of two fractal subwavelength elements with different layer thickness. The reflection phase difference of 180◦ (±37◦) between two unit cells covers an ultra-wide frequency range. Ultra-wideband RCS reduction results from the phase cancellation between two local waves produced by these two unit cells. The diffuse scattering of electromagnetic (EM) waves is caused by the randomized phase distribution, leading to a low monostatic and bistatic RCS simultaneously. This metasurface can achieve …