• (-201) β-Gallium oxide substrate for high quality GaN materials

      Roqan, Iman S.; Mumthaz Muhammed, Mufasila (SPIE-Intl Soc Optical Eng, 2015-03-13)
      (-201) oriented β-Ga2O3 has the potential to be used as a transparent and conductive substrate for GaN-growth. The key advantages of Ga2O3 are its small lattice mismatches (4.7%), appropriate structural, thermal and electrical properties and a competitive price compared to other substrates. Optical characterization show that GaN layers grown on (-201) oriented β-Ga2O3 are dominated by intense bandedge emission with a high luminescence efficiency. Atomic force microscopy studies show a modest threading dislocation density of ~108 cm-2, while complementary Raman spectroscopy indicates that the GaN epilayer is of high quality with slight compressive strain. Room temperature time-findings suggest that the limitation of the photoluminescence lifetime (~500 ps) is due to nonradiative recombination arising from threading dislocation. Therefore, by optimizing the growth conditions, high quality material with significant optical efficiency can be obtained.
    • A 24 GHz CMOS oscillator transmitter with an inkjet printed on-chip antenna

      Ghaffar, Farhan A.; Yang, Shuai; Cheema, Hammad M.; Shamim, Atif (Institute of Electrical and Electronics Engineers (IEEE), 2016-08-15)
      CMOS based RF circuits have demonstrated efficient performance over the decades. However, one bottle neck with this technology is its lossy nature for passive components such as inductors, antennas etc. Due to this drawback, passives are either implemented off chip or the designers work with the inefficient passives. This problem can be alleviated by using inkjet printing as a post process on CMOS chip. In this work, we demonstrate inkjet printing of a patterned polymer (SU8) layer on a 24 GHz oscillator chip to isolate the lossy Si substrate from the passives which are inkjet printed on top of the SU8 layer. As a proof of concept, a monopole antenna is printed on top of the SU8 layer integrating it with the oscillator through the exposed RF pads to realize an oscillator transmitter. The proposed hybrid fabrication technique can be extended to multiple dielectric and conductive printed layers to demonstrate complete RF systems on CMOS chips which are efficient, cost-effective and above all small in size. © 2016 IEEE.
    • 28.3THz bowtie antenna integrated rectifier for infrared energy harvesting

      Gadalla, Mena N.; Shamim, Atif (Institute of Electrical and Electronics Engineers (IEEE), 2014-10)
      The design, fabrication and characterization of an asymmetric 28.3 THz antenna integrated rectifier (rectenna) using Au/Al2O3/Pt is presented. The rectenna design comprises a sharp tip bowtie antenna and a tunneling Metal-insulator-Metal (MIM) diode. The design benefits from the geometric field enhancement around the nano tips of the bowtie antenna. Simultaneous optimization of the antenna's length and flare angle resulted in a relative intensity enhancement of 104 for a 10 nm gap. In order to benefit from the field enhancement, the THz diode is realized through the overlap of the bowtie sharp tips exactly at the hot spot. Dissimilar electrodes are used to allow THz signals rectification at zero bias, which is critical for energy harvesting applications. The rectenna exhibits a zero bias responsivity of 10 A/W. © 2014 European Microwave Association.
    • A 2:1 MUX Based on Multiple MEMS Resonators

      Hafiz, Md Abdullah Al; Kosuru, Lakshmoji; Younis, Mohammad I.; Fariborzi, Hossein (Elsevier BV, 2017-01-09)
      Micro/nano-electromechanical resonator based mechanical computing has recently attracted significant attention. This paper reports a realization of a 2:1 MUX, a concatenable digital logic element, based on electrothermal frequency tuning of electrically connected multiple arch resonators. Toward this, shallow arch shaped microresonators are electrically connected and their resonance frequencies are tuned based on an electrothermal frequency modulation scheme. This study demonstrates that by reconfiguring the same basic building block, the arch microresonator, complex logic circuits can be realized.
    • 2D-Driven 3D Object Detection in RGB-D Images

      Lahoud, Jean; Ghanem, Bernard (IEEE, 2017-12-25)
      In this paper, we present a technique that places 3D bounding boxes around objects in an RGB-D scene. Our approach makes best use of the 2D information to quickly reduce the search space in 3D, benefiting from state-of-the-art 2D object detection techniques. We then use the 3D information to orient, place, and score bounding boxes around objects. We independently estimate the orientation for every object, using previous techniques that utilize normal information. Object locations and sizes in 3D are learned using a multilayer perceptron (MLP). In the final step, we refine our detections based on object class relations within a scene. When compared to state-of-the-art detection methods that operate almost entirely in the sparse 3D domain, extensive experiments on the well-known SUN RGB-D dataset [29] show that our proposed method is much faster (4.1s per image) in detecting 3D objects in RGB-D images and performs better (3 mAP higher) than the state-of-the-art method that is 4.7 times slower and comparably to the method that is two orders of magnitude slower. This work hints at the idea that 2D-driven object detection in 3D should be further explored, especially in cases where the 3D input is sparse.
    • 3-Coil resonance-based wireless power transfer system for implantable electronic

      Yi, Ying; Buttner, Ulrich; Fan, Yiqiang; Foulds, Ian G. (Institute of Electrical and Electronics Engineers (IEEE), 2013-05)
      This paper presents a 3-coil resonance-based wireless power transfer (R-WPT) system using a single layer of inductor coil windings, in a pancake configuration, in order to obtain a compact system for implantable electronic applications. A theoretical analysis and experimental measurements in terms of quality factor Q and power transfer efficiency (PTE), was done. Our proposed 3-coil scheme can achieve a high PTE with a resonance frequency of 2.46 MHz over a transfer distance of up to 30 mm, by using two 15-mm radius implant coils. The achieved experimental PTE is more than 85%at a 5 mm separation distance, and about 50% PTE at a distance of 20 mm. © 2013 IEEE.
    • 3-D numerical investigation of subsurface flow in anisotropic porous media using multipoint flux approximation method

      Negara, Ardiansyah; Salama, Amgad; Sun, Shuyu (Society of Petroleum Engineers (SPE), 2013)
      Anisotropy of hydraulic properties of subsurface geologic formations is an essential feature that has been established as a consequence of the different geologic processes that they undergo during the longer geologic time scale. With respect to petroleum reservoirs, in many cases, anisotropy plays significant role in dictating the direction of flow that becomes no longer dependent only on the pressure gradient direction but also on the principal directions of anisotropy. Furthermore, in complex systems involving the flow of multiphase fluids in which the gravity and the capillarity play an important role, anisotropy can also have important influences. Therefore, there has been great deal of motivation to consider anisotropy when solving the governing conservation laws numerically. Unfortunately, the two-point flux approximation of finite difference approach is not capable of handling full tensor permeability fields. Lately, however, it has been possible to adapt the multipoint flux approximation that can handle anisotropy to the framework of finite difference schemes. In multipoint flux approximation method, the stencil of approximation is more involved, i.e., it requires the involvement of 9-point stencil for the 2-D model and 27-point stencil for the 3-D model. This is apparently challenging and cumbersome when making the global system of equations. In this work, we apply the equation-type approach, which is the experimenting pressure field approach that enables the solution of the global problem breaks into the solution of multitude of local problems that significantly reduce the complexity without affecting the accuracy of numerical solution. This approach also leads in reducing the computational cost during the simulation. We have applied this technique to a variety of anisotropy scenarios of 3-D subsurface flow problems and the numerical results demonstrate that the experimenting pressure field technique fits very well with the multipoint flux approximation method. Furthermore, the numerical results explicitly emphasize that anisotropy could not be ignored for the proper model of subsurface flow.
    • 3-D waveform tomography sensitivity kernels for anisotropic media

      Djebbi, Ramzi; Alkhalifah, Tariq Ali (EAGE Publications, 2014)
      The complications in anisotropic multi-parameter inversion lie in the trade-off between the different anisotropy parameters. We compute the tomographic waveform sensitivity kernels for a VTI acoustic medium perturbation as a tool to investigate this ambiguity between the different parameters. We use dynamic ray tracing to efficiently handle the expensive computational cost for 3-D anisotropic models. Ray tracing provides also the ray direction information necessary for conditioning the sensitivity kernels to handle anisotropy. The NMO velocity and η parameter kernels showed a maximum sensitivity for diving waves which results in a relevant choice of those parameters in wave equation tomography. The δ parameter kernel showed zero sensitivity; therefore it can serve as a secondary parameter to fit the amplitude in the acoustic anisotropic inversion. Considering the limited penetration depth of diving waves, migration velocity analysis based kernels are introduced to fix the depth ambiguity with reflections and compute sensitivity maps in the deeper parts of the model.
    • A 35fJ/Step differential successive approximation capacitive sensor readout circuit with quasi-dynamic operation

      Omran, Hesham; Alhoshany, Abdulaziz; Alahmadi, Hamzah; Salama, Khaled N. (Institute of Electrical and Electronics Engineers (IEEE), 2016-10-06)
      We propose a successive-approximation capacitive sensor readout circuit that achieves 35fJ/Step energy efficiency FoM, which represents 4× improvement over the state-of-the-art. A fully differential architecture is employed to provide robustness against common mode noise and errors. An inverter-based amplifier with near-threshold biasing provides robust, fast, and energy-efficient operation. Quasi-dynamic operation is used to maintain the energy efficiency for a scalable sample rate. A hybrid coarse-fine capacitive DAC achieves 11.7bit effective resolution in a compact area. © 2016 IEEE.
    • 3D Aware Correction and Completion of Depth Maps in Piecewise Planar Scenes

      Thabet, Ali Kassem; Lahoud, Jean; Asmar, Daniel; Ghanem, Bernard (Springer Science + Business Media, 2015-04-16)
      RGB-D sensors are popular in the computer vision community, especially for problems of scene understanding, semantic scene labeling, and segmentation. However, most of these methods depend on reliable input depth measurements, while discarding unreliable ones. This paper studies how reliable depth values can be used to correct the unreliable ones, and how to complete (or extend) the available depth data beyond the raw measurements of the sensor (i.e. infer depth at pixels with unknown depth values), given a prior model on the 3D scene. We consider piecewise planar environments in this paper, since many indoor scenes with man-made objects can be modeled as such. We propose a framework that uses the RGB-D sensor’s noise profile to adaptively and robustly fit plane segments (e.g. floor and ceiling) and iteratively complete the depth map, when possible. Depth completion is formulated as a discrete labeling problem (MRF) with hard constraints and solved efficiently using graph cuts. To regularize this problem, we exploit 3D and appearance cues that encourage pixels to take on depth values that will be compatible in 3D to the piecewise planar assumption. Extensive experiments, on a new large-scale and challenging dataset, show that our approach results in more accurate depth maps (with 20 % more depth values) than those recorded by the RGB-D sensor. Additional experiments on the NYUv2 dataset show that our method generates more 3D aware depth. These generated depth maps can also be used to improve the performance of a state-of-the-art RGB-D SLAM method.
    • 3D elastic full-waveform inversion for OBC data using the P-wave excitation amplitude

      Oh, Juwon; Kalita, Mahesh; Alkhalifah, Tariq Ali (Society of Exploration Geophysicists, 2017-08-17)
      We suggest a fast and efficient 3D elastic full waveform inversion (FWI) algorithm based on the excitation amplitude (maximum energy arrival) of the P-wave in the source wavefield. It evaluates the gradient direction significantly faster than its conventional counterpart. In addition, it removes the long-wavelength artifacts from the gradient, which are often originated from SS correlation process. From these advantages, the excitation approach offers faster convergence not only for the S wave velocity, but also for the entire process of multi-parameter inversion, compared to the conventional FWI. The feasibility of the proposed method is demonstrated through the synthetic Marmousi and a real OBC data from North Sea.
    • 3D elastic-orthorhombic anisotropic full-waveform inversion: Application to field OBC data

      Oh, Juwon; Alkhalifah, Tariq Ali (Society of Exploration Geophysicists, 2016-09-06)
      For the purpose of extracting higher resolution information from a 3D field data set, we apply a 3D elastic orthorhombic (ORT) anisotropic full waveform inversion (FWI) to hopefully better represent the physics of the Earth. We utilize what we consider as the optimal parameterization for surface acquired seismic data over a potentially orthorhombic media. This parameterization admits the possibility of incorporating a hierarchical implementation moving from higher anisotropy symmetry to lower ones. From the analysis of the radiation pattern of this new parameterization, we focus the inversion of the 3D data on the parameters that may have imprint on the data with minimal tradeoff, and as a result we invert for the horizontal P-wave velocity model, an ε1 model, its orthorhombic deviation, and the shear wave velocity. The inverted higher resolution models provide reasonable insights of the medium.
    • 3D face recognition with asymptotic cones based principal curvatures

      Tang, Yinhang; Sun, Xiang; Huang, Di; Morvan, Jean-Marie; Wang, Yunhong; Chen, Liming (Institute of Electrical and Electronics Engineers (IEEE), 2015-05)
      The classical curvatures of smooth surfaces (Gaussian, mean and principal curvatures) have been widely used in 3D face recognition (FR). However, facial surfaces resulting from 3D sensors are discrete meshes. In this paper, we present a general framework and define three principal curvatures on discrete surfaces for the purpose of 3D FR. These principal curvatures are derived from the construction of asymptotic cones associated to any Borel subset of the discrete surface. They describe the local geometry of the underlying mesh. First two of them correspond to the classical principal curvatures in the smooth case. We isolate the third principal curvature that carries out meaningful geometric shape information. The three principal curvatures in different Borel subsets scales give multi-scale local facial surface descriptors. We combine the proposed principal curvatures with the LNP-based facial descriptor and SRC for recognition. The identification and verification experiments demonstrate the practicability and accuracy of the third principal curvature and the fusion of multi-scale Borel subset descriptors on 3D face from FRGC v2.0.
    • 3D facial expression recognition based on histograms of surface differential quantities

      Li, Huibin; Morvan, Jean-Marie; Chen, Liming (Springer Science + Business Media, 2011)
      3D face models accurately capture facial surfaces, making it possible for precise description of facial activities. In this paper, we present a novel mesh-based method for 3D facial expression recognition using two local shape descriptors. To characterize shape information of the local neighborhood of facial landmarks, we calculate the weighted statistical distributions of surface differential quantities, including histogram of mesh gradient (HoG) and histogram of shape index (HoS). Normal cycle theory based curvature estimation method is employed on 3D face models along with the common cubic fitting curvature estimation method for the purpose of comparison. Based on the basic fact that different expressions involve different local shape deformations, the SVM classifier with both linear and RBF kernels outperforms the state of the art results on the subset of the BU-3DFE database with the same experimental setting. © 2011 Springer-Verlag.
    • 3D head pose estimation and tracking using particle filtering and ICP algorithm

      Ben Ghorbel, Mahdi; Baklouti, Malek; Couvet, Serge (Springer Science + Business Media, 2010)
      This paper addresses the issue of 3D head pose estimation and tracking. Existing approaches generally need huge database, training procedure, manual initialization or use face feature extraction manually extracted. We propose a framework for estimating the 3D head pose in its fine level and tracking it continuously across multiple Degrees of Freedom (DOF) based on ICP and particle filtering. We propose to approach the problem, using 3D computational techniques, by aligning a face model to the 3D dense estimation computed by a stereo vision method, and propose a particle filter algorithm to refine and track the posteriori estimate of the position of the face. This work comes with two contributions: the first concerns the alignment part where we propose an extended ICP algorithm using an anisotropic scale transformation. The second contribution concerns the tracking part. We propose the use of the particle filtering algorithm and propose to constrain the search space using ICP algorithm in the propagation step. The results show that the system is able to fit and track the head properly, and keeps accurate the results on new individuals without a manual adaptation or training. © Springer-Verlag Berlin Heidelberg 2010.
    • 3D imaging using X-Ray tomography and SEM combined FIB to study non isothermal creep damage of (111) oriented samples of γ / γ ′ nickel base single crystal superalloy MC2

      Jouiad, Mustapha; Ghighi, J.; Cormier, Jonathan; Ostoja-Kuczynski, Elisabeth; Lubineau, Gilles; Méndez, José (Trans Tech Publications, 2012-01)
      An unprecedented investigation consisting of the association of X-Ray tomography and Scanning Electron Microscopy combined with Focus Ion Beam (SEM-FIB) is conducted to perform a 3D reconstruction imaging. These techniques are applied to study the non-isothermal creep behavior of close (111) oriented samples of MC2 nickel base superalloys single crystal. The issue here is to develop a strategy to come out with the 3D rafting of γ' particles and its interaction whether with dislocation structures or/and with the preexisting voids. This characterization is uncommonly performed away from the conventional studied orientation [001] in order to feed the viscoplastic modeling leading to its improvement by taking into account the crystal anisotropy. The creep tests were performed at two different conditions: classical isothermal tests at 1050°C under 140 MPa and a non isothermal creep test consisting of one overheating at 1200°C and 30 seconds dwell time during the isothermal creep life. The X-Ray tomography shows a great deformation heterogeneity that is pronounced for the non-isothermal tested samples. This deformation localization seems to be linked to the preexisting voids. Nevertheless, for both tested samples, the voids coalescence is the precursor of the observed damage leading to failure. SEM-FIB investigation by means of slice and view technique gives 3D views of the rafted γ' particles and shows that γ corridors evolution seems to be the main creep rate controlling parameter. © 2012 Trans Tech Publications, Switzerland.
    • 3D inkjet printed disposable environmental monitoring wireless sensor node

      Farooqui, Muhammad Fahad; Shamim, Atif (IEEE, 2017-10-24)
      We propose a disposable, miniaturized, moveable, fully integrated 3D inkjet-printed wireless sensor node for large area environmental monitoring applications. As a proof of concept, we show the wireless sensing of temperature, humidity and H2S levels which are important for early warnings of two critical environmental conditions namely forest fires and industrial gas leaks. The temperature sensor has TCR of -0.018/°, the highest of any inkjet-printed sensor and the H2S sensor can detect as low as 3 ppm of gas. These sensors and an antenna have been realized on the walls of a 3D-printed cubic package which encloses the microelectronics developed on a 3D-printed circuit board. Hence, 3D printing and inkjet printing have been combined in order to realize a unique low-cost, fully integrated wireless sensor node. Field tests show that these sensor nodes can wirelessly communicate up to a distance of over 100m. Our proposed sensor node can be a part of internet of things with the aim of providing a better and safe living.
    • 3D inkjet printed flexible and wearable antenna systems

      Shamim, Atif (IEEE, 2017-12-22)
      With the advent of wearable sensors and internet of things (IoT), there is a new focus on electronics which can be bent so that they can be worn or mounted on non-planar objects. Moreover, there is a requirement that these electronics become extremely low cost, to the extent that they become disposable. The flexible and low cost aspects can be addressed by adapting additive manufacturing technologies such as inkjet printing and 3D printing. This paper presents inkjet printing as an emerging new technique to realize low cost, flexible and wearable antenna systems. The ability of inkjet printing to realize electronics on unconventional mediums such as plastics, papers, and textiles has opened up a plethora of new applications. A variety of antennas such as wide-band, multiband, and wearable, etc, which have been realized through additive manufacturing techniques are shown. Many system level examples are also shown, primarily for wireless sensing applications. The promising results of these designs indicate that the day when electronics can be printed like newspapers and magazines through roll-to-roll and reel-to-reel printing is not far away.
    • 3D inkjet printed radio frequency inductors and capacitors

      Vaseem, Mohammad; McKerricher, Garret; Shamim, Atif (Institute of Electrical and Electronics Engineers (IEEE), 2016-12-08)
      Inkjet printing has emerged as an ideal method for the fabrication of low cost and efficient electronic systems. However, most of the printed designs at present utilize 2D inkjet printing of metallic inks on conventional substrates. In order to have fully printed RF components, the substrate must also be printed. 3D printing of polymers can be an ideal mechanism for printing substrates, however typically such materials cannot handle high sintering temperatures (>150 0C) required for nanoparticles based metallic inks. In this work, an all-inkjet printed process is demonstrated that utilizes 3D inkjet printing of a UV-cured dielectric material in combination with the printing of a particle free conductive silver organo-complex (SOC) ink for realization of inductors and capacitors. The processing temperature does not exceed 80 0C and still state of the art conductivity of 1×107 S/m is achieved. Both the conductive ink and dielectric have roughness values under 500 nm. The inductor and capacitor exhibit quality factors of 8 and 20 respectively in the high MHz and GHz regime.
    • 3D Multisource Full‐Waveform Inversion using Dynamic Random Phase Encoding

      Boonyasiriwat, Chaiwoot; Schuster, Gerard T. (Society of Exploration Geophysicists, 2010-10-17)
      We have developed a multisource full‐waveform inversion algorithm using a dynamic phase encoding strategy with dual‐randomization—both the position and polarity of simultaneous sources are randomized and changed every iteration. The dynamic dual‐randomization is used to promote the destructive interference of crosstalk noise resulting from blending a large number of common shot gathers into a supergather. We compare our multisource algorithm with various algorithms in a numerical experiment using the 3D SEG/EAGE overthrust model and show that our algorithm provides a higher‐quality velocity tomogram than the other methods that use only monorandomization. This suggests that increasing the degree of randomness in phase encoding should improve the quality of the inversion result.