Computer Engineering Commons^™

Luminescence Of Defects In The Structural Transformation Of Layered Tin Dichalcogenides, Peter Sutter, H.P. Komsa, A. V. Krasheninnikov, Y Huang, Eli A. Sutter

Department of Electrical and Computer Engineering: Faculty Publications

Layered tin sulfide semiconductors are both of fundamental interest and attractive for energy conversion applications. Sn sulfides crystallize in several stable bulk phases with different Sn:S ratios (SnS2, Sn2, S3, and SnS), which can transform into phases with a lower sulfur concentration by introduction of sulfur vacancies (VS). How this complex behavior affects the optoelectronic properties remains largely unknown but is of key importance for understanding light-matter interactions in this family of layered materials. Here, we use the capability to induce VS and drive a transformation between few-layer SnS2 and SnS by electron beam irradiation, combined with in-situ cathodoluminescence spectroscopy …

Security For 5g Mobile Wireless Networks, Dongfeng Fang, Yi Qian, Rose Qingyang Hu

Department of Electrical and Computer Engineering: Faculty Publications

The advanced features of 5G mobile wireless network systems yield new security requirements and challenges. This paper presents a comprehensive survey on security of 5G wireless network systems compared to the traditional cellular networks. The paper starts with a review on 5G wireless networks particularities as well as on the new requirements and motivations of 5G wireless security. The potential attacks and security services with the consideration of new service requirements and new use cases in 5G wireless networks are then summarized. The recent development and the existing schemes for the 5G wireless security are presented based on the corresponding …

Fiber-Optic Sensor For Strain-Insensitive Temperature Measurements, Ming Han

Department of Electrical and Computer Engineering: Faculty Publications

An in-line fiber-optic temperature sensor is disclosed. In an implementation, the in-line fiber-optic temperature sensor includes an optically transmissive fiber, a reflector, a microstructured fiber defining a channel therein for receiving a fluid, and a Fabry-Perot cavity in fluid communication with the micro structured fiber. The micro structured fiber can be retained between the optically transmissive fiber and the reflector. The Fabry-Perot cavity defined by a material and configured to receive a gas having an index of refraction that changes in a known way with temperature and pressure changes in fluid communication with the channel of the micro structured fiber. …

In Situ Electron Microscopy Of Plasmon-Mediated Nanocrystal Synthesis, Peter Sutter, Ying Li, Christos Argyropoulos, Eli A. Sutter

Department of Electrical and Computer Engineering: Faculty Publications

Chemical processes driven by nonthermal energy (e.g., visible light) are attractive for future approaches to energy conversion, synthesis, photocatalysis, and so forth. The growth of anisotropic metal nanostructures mediated by excitation of a localized surface plasmon resonance (LSPR) is a prototype example of such a reaction. Important aspects, notably the growth mechanism and a possible role of plasmonic “hot spots” within the metal nanostructures, remain poorly understood. Here, we use in situ electron microscopy to stimulate and image the plasmon-mediated growth of triangular Ag nanoprisms in solution. The quantification of the time-dependent evolution of the lateral size and thickness of …

Ip Flow Mobility In The Industry: From An Economic Perspective, Jun Huang, Fang Fang, Cong-Cong Xing, Yi Qian

Department of Electrical and Computer Engineering: Faculty Publications

The popularity of social media together with the advancement of mobile Internet applications enabling the uploading of data plays a dominant role in the entire Internet traffic. IP flow mobility (IFOM) is proposed as an effective means to enhance the system capacity by offloading data from the cellular network to WiFi or Femtocells or other complementary networks. Although IFOM has been extensively investigated during the past few years, most of these studies, however, are concerned with IFOM technical issues only; little work regarding the IFOM application has been done from the service providers’ perspective. Unlike previous research, in this paper, …

Specular Reflection Reduction By Metasurface Based On Parameteradjustable Meta-Atoms, Jianxun Su, Yao Lu, Hui Zhang, Zengrui Li, Yaoqing Lamar Yang ., Yongxing Che, Kainan Qi

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, an ultra-wideband, wide angle and polarization-insensitive metasurface is designed, fabricated, and characterized for suppressing the specular electromagnetic wave reflection or backward radar cross section (RCS). Square ring structure is chosen as the basic meta-atoms. A new physical mechanism based on size adjustment of the basic meta-atoms is proposed for ultra-wideband manipulation of electromagnetic (EM) waves. Based on hybrid array pattern synthesis (APS) and particle swarm optimization (PSO) algorithm, the selection and distribution of the basic meta-atoms are optimized simultaneously to obtain the ultra-wideband diffusion scattering patterns. The metasurface can achieve an excellent RCS reduction in an ultra-wide …

Ultra-Wideband, Wide Angle And Polarization-Insensitive Specular Reflection Reduction By Metasurface Based On Parameteradjustable Meta-Atoms, Jianxun Su, Yao Lu, Hui Zhang, Zengrui Li, Yaoqing Lamar Yang, Yongxing Che, Kainan Qi

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, an ultra-wideband, wide angle and polarization-insensitive metasurface is designed, fabricated, and characterized for suppressing the specular electromagnetic wave reflection or backward radar cross section (RCS). Square ring structure is chosen as the basic meta-atoms. A new physical mechanism based on size adjustment of the basic meta-atoms is proposed for ultra-wideband manipulation of electromagnetic (EM) waves. Based on hybrid array pattern synthesis (APS) and particle swarm optimization (PSO) algorithm, the selection and distribution of the basic meta-atoms are optimized simultaneously to obtain the ultra-wideband diffusion scattering patterns. The metasurface can achieve an excellent RCS reduction in an ultra-wide …

Rainbow Peacock Spiders Inspire Miniature Superiridescent Optics, Bor-Kai Hsiung, Radwanul Hasan Siddique, Doekele G. Stavenga, Jürgen C. Otto, Michael C. Allen, Ying Liu, Yongfeng Lu, Dimitri D. Deheyn, Matthew D. Shawkey, Todd A. Blackledge

Department of Electrical and Computer Engineering: Faculty Publications

Colour produced by wavelength-dependent light scattering is a key component of visual communication in nature and acts particularly strongly in visual signalling by structurallycoloured animals during courtship. Two miniature peacock spiders (Maratus robinsoni and M. chrysomelas) court females using tiny structured scales (~ 40 × 10 μm²) that reflect the full visual spectrum. Using TEM and optical modelling, we show that the spiders’ scales have 2D nanogratings on microscale 3D convex surfaces with at least twice the resolving power of a conventional 2D diffraction grating of the same period. Whereas the long optical path lengths required …

Controllable Plasmonic Nanostructures Induced By Dual-Wavelength Femtosecond Laser Irradiation, Weina Han, Lan Jiang, Xiaowei Li, Qingsong Wang, Shaojun Wang, Jie Hu, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

We demonstrated an abnormal double-peak (annular shaped) energy deposition through dualwavelength synthesis of the fundamental frequency (ω) and the second-harmonic frequency (2ω) of a femtosecond (fs) Ti:sapphire laser. The annular shaped distribution of the dual-wavelength fs laser was confirmed through real beam shape detection. This uniquely simple and flexible technique enables the formation of functional plasmonic nanostructures. We applied this double-peak fs-laser-induced dewetting effect to the controlled fabrication and precise deposition of Au nanostructures, by using a simple, lithography-free, and single-step process. In this process, the double-peak energy-shaped fs laser pulse induces surface patterning of a thin film followed by …

Preparation Of Monolayer Mos2 Quantum Dots Using Temporally Shaped Femtosecond Laser Ablation Of Bulk Mos2 Targets In Water, Bo Li, Lan Jiang, Xin Li, Peng Ran, Pei Zuo, Andong Wang, Liangti Qu, Yang Zhao, Zhihua Cheng, Yongfeng Lu

Department of Electrical and Computer Engineering: Faculty Publications

Zero-dimensional MoS₂ quantum dots (QDs) possess distinct physical and chemical properties, which have garnered them considerable attention and facilitates their use in a broad range of applications. In this study, we prepared monolayer MoS₂ QDs using temporally shaped femtosecond laser ablation of bulk MoS₂ targets in water. The morphology, crystal structures, chemical, and optical properties of the MoS₂ QDs were characterized by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, UV–vis absorption spectra, and photoluminescence spectra. The analysis results show that highly pure, uniform, and monolayer MoS₂ QDs can be successfully prepared. Moreover, …

High-Speed Adaptive Wireless Body Area Networks, Miftadi Sudjai, Le Chung Tran, Farzad Safaei, Tadeusz Wysocki, Son Lam Phung

Department of Electrical and Computer Engineering: Faculty Publications

Adaptive ultra-wideband wireless body area network (WBAN) is proposed in this paper as a feasible mobile health platform, offering a high-speed and robust service. It employs a space-time-frequency-coded (STFC) multiband orthogonal frequency division multiplexing ultra-wideband technology. It is designed to improve the average bit error performance for high data rate applications while maintaining a reasonably high throughput in body-to-external links of a WBAN. The proposed adaptive WBAN comprises two novel components, namely, the frame transmission model and the bit error rate (BER) estimation-based adaptive algorithm. In addition, the optimization of adaptive parameters is conducted to obtain an extra improvement, hence …

Identification And Characterization Of Irregular Consumptions Of Load Data, Desh Deepak Sharma, S. N. Singh, Jeremy Lin, Elham Foruzan

Department of Electrical and Computer Engineering: Faculty Publications

The historical information of loadings on substation helps in evaluation of size of photovoltaic (PV) generation and energy storages for peak shaving and distribution system upgrade deferral. A method, based on consumption data, is proposed to separate the unusual consumption and to form the clusters of similar regular consumption. The method does optimal partition of the load pattern data into core points and border points, high and less dense regions, respectively. The local outlier factor, which does not require fixed probability distribution of data and statistical measures, ranks the unusual consumptions on only the border points, which are a few …

Tunable Subnanometer Gap Plasmonic Metasurfaces, Dennis Doyle, Nicholas Charipar, Christos Argyropoulos, Scott A. Trammell, Rafaela Nita, Jawad Naciri, Alberto Piqué, Joseph B. Herzog, Jake Fontana

Department of Electrical and Computer Engineering: Faculty Publications

The index of refraction governs the flow of light through materials. At visible and near-infrared wavelengths the real part of the refractive index is limited to less than 3 for naturally occurring transparent materials, fundamentally restricting applications. Here, we carried out experiments to study the upper limit of the effective refractive index of self-assembled metasurfaces at visible and near-infrared wavelengths. The centimeter-scale metasurfaces were made of a hexagonally close packed (HCP) monolayer of gold nanospheres coated with tunable alkanethiol ligand shells, controlling the interparticle gap from 2.8 to 0.45 nm. In contrast to isolated dimer studies, the macroscale areas allow …

Flatland Plasmonics And Nanophotonics Based On Graphene And Beyond, Pai-Yen Chen, Christos Argyropoulos, Mohamed Farhat, J. Sebastian Gomez-Diaz

Department of Electrical and Computer Engineering: Faculty Publications

In this paper, we review and discuss how the recently discovered two-dimensional (2D) Dirac materials, particularly graphene, may be utilized as new efficient platforms for excitations of propagating and localized surface plasmon polaritons (SPPs) in the terahertz (THz) and mid-infrared (MIR) regions. The surface plasmon modes supported by the metallic 2D materials exhibit tunable plasmon resonances that are essential, yet missing, ingredients needed for THz and MIR photonic and optoelectronic devices. We describe how the atomically thin graphene monolayer and metamaterial structures based on it may tailor and control the spectral, spatial, and temporal properties of electromagnetic radiation. In the …

Decreased Home Cage Movement And Oromotor Impairments In Adult Fmr1-Ko Mice, Stephen J. Bonasera, Tammy R. Chaudoin, Evan H. Goulding, Mateusz Mittek, Anna Dunaevsky

Department of Electrical and Computer Engineering: Faculty Publications

Fragile X syndrome (FXS) is a common inherited disorder that significantly impacts family and patient day-to-day living across the entire lifespan. The childhood and adolescent behavioral consequences of FXS are well-appreciated. However, there are significantly fewer studies (except those examining psychiatric comorbidities) assessing behavioral phenotypes seen in adults with FXS. Mice engineered with a genetic lesion of Fmr1 recapitulate important molecular and neuroanatomical characteristics of FXS, and provide a means to evaluate adult behavioral phenotypes associated with FXS. We give the first description of baseline behaviors including feeding, drinking, movement, and their circadian rhythms; all observed over 16 consecutive days …

Higher C-Reactive Protein Levels Predict Postoperative Delirium In Older Patients Undergoing Major Elective Surgery: A Longitudinal Nested Case-Control Study, Simon T. Dillon, Sarinnapha M. Vasunilashorn, Long Ngo, Hasan H. Otu, Sharon K. Inouye, Richard N. Jones, David C. Alsop, George A. Kuchel, Eran D. Metzger, Steven E. Arnold, Edward R. Marcantonio, Towia A. Libermann

Department of Electrical and Computer Engineering: Faculty Publications

Background—Delirium is a common, morbid, and costly postoperative complication.. We aimed to identify blood-based postoperative delirium markers in a nested case control study of older surgical patients using a proteomics approach followed by enzyme-linked immunosorbent assay (ELISA) validation.

Methods and Materials—The Successful Aging after Elective Surgery Study enrolled dementia-free adults age ≥70 undergoing major scheduled non-cardiac surgery (N=566; 24% delirium). Plasma was collected at 4 timepoints: preoperatively (PREOP), post-anesthesia care unit (PACU), postoperative day 2 (POD2) and 1 month follow-up (PO1MO). Matched pairs were selected for the independent discovery (39 pairs) and replication cohorts (36 pairs), which were …

Correction: Genomic Counter-Stress Changes Induced By The Relaxation Response, Jeffery A. Dusek, Hasan H. Otu, Ann L. Wohlhueter, Manoj Bhasin, Luiz F. Zerbini, Marie G. Joseph, Herbert Benson, Towia A. Libermann

Department of Electrical and Computer Engineering: Faculty Publications

The Competing Interests statement is incorrect. The correct Competing Interests statement is: The following authors hold or have held positions at the Benson-Henry Institute for Mind Body Medicine at Massachusetts General Hospital, which is paid by patients and their insurers for running the SMART-3RP and related relaxation/mindfulness clinical programs, markets related products such as books, DVDs, CDs and the like, and holds a patent pending (PCT/ US2012/049539 filed August 3, 2012) entitled "Quantitative Genomics of the Relaxation Response": JAD, ALW, HB.

Formation Of Aggregated Nanoparticle Spheres Through Femtosecond Laser Surface Processing, Alfred T. Tsubaki, Mark A. Koten, Michael J. Lucis, Craig Zuhlke, Natale J. Ianno, Jeffrey E. Shield, Dennis R. Alexander

Department of Electrical and Computer Engineering: Faculty Publications

A detailed structural and chemical analysis of a class of self-organized surface structures, termed aggregated nanoparticle spheres (AN-spheres), created using femtosecond laser surface processing (FLSP) on silicon, silicon carbide, and aluminum is reported in this paper. AN-spheres are spherical microstructures that are 20–100 μm in diameter and are composed entirely of nanoparticles produced during femtosecond laser ablation of material. AN-spheres have an onion-like layered morphology resulting from the build-up of nanoparticle layers over multiple passes of the laser beam. The material properties and chemical composition of the AN-spheres are presented in this paper based on scanning electron microscopy (SEM), focused …

Real-Time Pricing Strategy Based On The Stability Of Smart Grid For Green Internet Of Things, Huwei Chen, Hui Hui, Zhou Su, Dongfeng Fang, Yilong Hui

Department of Electrical and Computer Engineering: Faculty Publications

The ever increasing demand of energy efficiency and the strong awareness of environment have led to the enhanced interests in green Internet of things (IoTs). How to efficiently deliver power, especially, with the smart grid based on the stability of network becomes a challenge for green IoTs. Therefore, in this paper we present a novel real-time pricing strategy based on the network stability in the green IoTs enabled smart grid. Firstly, the outage is analyzed by considering the imbalance of power supply and demand as well as the load uncertainty. Secondly, the problem of power supply with multiple-retailers is formulated …

Shielding Effectiveness Performance Of Conductive Concrete Structures, Lim Nguyen, Aaron Krause, Christopher Tuan, Joel D. Blasey, Holly Mcnerney, Ferdinand J. Metzger

Department of Electrical and Computer Engineering: Faculty Publications

Conductive concrete mixtures have been designed and demonstrated to perform electromagnetic shielding. This paper describes the design, testing methods, and results obtained from the development of conductive concrete construction for structured electromagnetic shielding.

Direct Torque Control Of Ac Electric Machines, Wei Qiao, Zhe Zhang, Liyan Qu

Department of Electrical and Computer Engineering: Faculty Publications

This disclosure features an apparatus including a motor controller to generate control signals to control an electric motor. The motor controller includes a first saturation controller to generate a first saturation controller output based on feedback signals associated with the electric motor. The motor controller further includes a duty ratio modulator coupled to the first saturation controller. The duty ratio modulator is configured to determine activation times for a set of voltage vectors based on the first saturation controller output. The motor controller is configured to generate, at each switching cycle, a control signal based on the set of voltage …

Integrated Mid-Infrared, Far Infrared And Terahertz Optical Hall Effect (Ohe) Instrument, And Method Of Use, Tino Hofmann, Mathias M. Schubert, Stefan Schoeche, Sean Knight, Craig M. Herzinger, John A. Woollam, Greg K. Pribil, Thomas E. Tiwald

Department of Electrical and Computer Engineering: Faculty Publications

System Stage, and Optical Hall Effect (OHE) system method for evaluating such as free charge carrier effective mass, concentration, mobility and free charge carrier type in a (51) Int. Ci. sample utilizing a permanent magnet at room temperature.

Systems And Methods Using Drawings Which Incorporate Bometric Data Assecurity Information, Cliff Xiaongang Wang, Wesley E. Snyder, Benjamin S. Riggan

Department of Electrical and Computer Engineering: Faculty Publications

Systems and method using drawings as security information are disclosed. According to an aspect, a computing device may include a touchscreen display configured to receive information for drawing a security manager configured to determined one or more characteristics associated with input of the gesture information. The security manager may also be configured to authenticate a user based on the drawn security picture and the one or more characteristics associated with input of the gesture information.

In-Situ Terahertz Optical Hall Effect Measurements Of Ambient Effects On Free Charge Carrier Properties Of Epitaxial Graphene, Sean Knight, Tino Hofmann, Chamseddine Bouhafs, Nerijus Armakavicius, Philipp Kühne, Vallery Stanishev, Ivan G. Ivanov, Rositsa Yakimova, Shawn Wimer, Mathias Schubert, Vanya Darakchieva

Department of Electrical and Computer Engineering: Faculty Publications

Unraveling the doping-related charge carrier scattering mechanisms in two-dimensional materials such as graphene is vital for limiting parasitic electrical conductivity losses in future electronic applications. While electric field doping is well understood, assessment of mobility and density as a function of chemical doping remained a challenge thus far. In this work, we investigate the effects of cyclically exposing epitaxial graphene to controlled inert gases and ambient humidity conditions, while measuring the Lorentz force-induced birefringence in graphene at Terahertz frequencies in magnetic fields. This technique, previously identified as the optical analogue of the electrical Hall effect, permits here measurement of charge …