Recent Submissions

  • CFD Study of Heat Transfer Reduction Using Multiple Injectors in a DCEE Concept

    Nyrenstedt, Gustav; Alturkestani, Tariq Lutfallah Mohammed; Im, Hong G.; Johansson, Bengt (SAE Technical Paper Series, SAE International, 2019-01-15) [Conference Paper]
    Earlier studies on efficiency improvement in CI engines have suggested that heat transfer losses contribute largely to the total energy losses. Fuel impingement on the cylinder walls is typically associated with high heat transfer. This study proposes a two-injector concept to reduce heat losses and thereby improve efficiency. The two injectors are placed at the rim of the bowl to change the spray pattern. Computational simulations based on the Reynolds-Averaged Navier-Stokes approach have been performed for four different fuel injection timings in order to quantify the reduction in heat losses for the proposed concept. Two-injector concepts were compared to reference cases using only one centrally mounted injector. All simulations were performed in a double compression expansion engine (DCEE) concept using the Volvo D13 single-cylinder engine. In the DCEE, a large portion of the exhaust energy is re-used in the second expansion, thus increasing the thermodynamic efficiency. To isolate the heat losses associated with the changed spray pattern of the two-injector concept, effects of the heat release are excluded during the analysis. Results showed that the optimal injection strategy allows a decrease in the temperature close to the walls, leading to heat loss reduction up to 13 % or 2 % of the fuel energy. The residual exhaust energy was increased by 1.5 %-points with the two-injector concept when compared to the reference case. This proved the advantage of the two-injector concept compared to conventional single injector case for the DCEE application.
  • Fully Printed Flexible and Reconfigurable Antenna With Novel Phase Change VO<inf>2</inf> Ink Based Switch

    Vaseem, Mohammad; Su, Zhen; Yang, Shuai; Shamim, Atif (2018 International Flexible Electronics Technology Conference (IFETC), IEEE, 2019-01-09) [Conference Paper]
    Vanadium dioxide (VO) is identified as an attractive phase change material which can be used for switchable or reconfigurable RF components. At present, VO is deposited by expensive and complex thin film micro-fabrication techniques. With the surge in low cost, additively manufactured or printed components, it will be beneficial to print phase change materials or switches as well. However, these kinds of functional inks are not available commercially. In this work, we present, for the first time VO based ink that changes its conductive properties based on temperature. Precisely, it displays insulating properties at room temperature (resistance of ~1.2KΩ in the off-state), but becomes conductive when heated around 70°C (resistance of <10Ω in the on-state). Here, we demonstrate a fully printed thermally controlled reconfigurable antenna based on VO ink and a custom silver-organo-complex (SOC) ink supported on flexible kapton substrate. In a planar inversed F antenna (PIFA) configuration, when the switch is in the OFF state, the antenna operates at 3.5 GHz band for 5G communications, and when it is in the ON state, it operates at 2.4 GHz band suitable for WiFi, Bluetooth or Zigbee applications. The antenna performance is assessed in different bending conditions where it achieved a maximum gain of ~2 dBi at 3.2GHz with concave bending position.
  • Additively Manufactured Flexible and Stretchable Antenna Systems for Wearable Applications

    Shamim, Atif; Vaseem, Mohammad; Sizhe, An; Farooqui, Muhammad Fahad (2018 International Flexible Electronics Technology Conference (IFETC), IEEE, 2019-01-09) [Conference Paper]
    Emerging applications such as Internet of things (IoT) and wearable sensors require new kind of electronics that can be bent, stretched, worn, washed, etc. These electronics must be extremely low cost, to the extent that they become disposable. The flexibility and low-cost aspects can be addressed by using additive manufacturing techniques, such as inkjet and screen printing on light-weight and flexible substrates like paper or plastics. However, the best solution for wearable electronics is to print them directly on textiles. Though, the driving electronics are still predominantly realized in standard CMOS platforms but all the remaining parts of these systems, such as sensors, antennas, interconnects, etc, that are large and expensive to realize on CMOS, can be printed. These could be integrated with CMOS chips to demonstrate system level wearable examples. This paper will show some examples of such flexible and stretchable components and systems that have been realized through additive manufacturing. Performance issues under flexed and stretched conditions are discussed. 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.
  • Low Temperature (80 °C) Sinterable Particle Free Silver Ink for Flexible Electronics

    Vaseem, Mohammad; Shamim, Atif (2018 International Flexible Electronics Technology Conference (IFETC), IEEE, 2019-01-09) [Conference Paper]
    For the emerging field of flexible printed electronics, ink compatibility with substrate is always required. However, most of the commercial silver nanoparticle-based inks are not compatible with flexible substrates, as they need high- sintering temperatures (~150-250 °C). In addition, silver nanoparticle-based inks have several serious problems such as a complex synthesis protocol, high cost, particle aggregation, nozzle clogging, reduced shelf life, and jetting instability. These shortcomings in conductive inks are barriers for their wide spread use in practical applications. In this work, we demonstrate a silver-organo-complex (SOC) based particle free silver ink which can decompose at 80 °C and becomes conductive at this low temperature. The inkjet-printed film from this ink exhibits not only high conductivity but also excellent jetting and storage stability. To demonstrate the suitability of this ink for flexible electronics, an inkjet-printed film on flexible polyimide substrate is subjected to bending and crushing tests. The results before and after flexing and crushing are very similar, thus verifying the excellent tolerance against bending and crushing for this ink as compared to the commercial nanoparticles based ink.
  • Dynamics Analysis of a Turbulent Methane Flame in MILD Combustion Conditions

    Manias, Dimitris M.; Tingas, Alexandros-Efstathios; Im, Hong G.; Minamoto, Yuki (AIAA Scitech 2019 Forum, American Institute of Aeronautics and Astronautics, 2019-01-07) [Conference Paper]
    The dominant physical processes that characterize the combustion of a lean methane/air mixture, diluted with exhaust gas recirculation (EGR), under turbulent MILD premixed conditions are identified using the combined approaches of Computational Singular Perturbation (CSP) and Tangential Strech Rate (TSR) which identifies the driving processes of the system dynamics. The important modes that contribute the most to the TSR are identified and the competition between the processes that oppose to or promote the action of each mode is studied. Two important modes are found to compete for the largest part of the domain, one of explosive character and one of dissipative nature. This competition mostly favors the dissipative modes, suggesting that the system’s dynamics is predominantly dominant. It was also found that the key processes that trigger this competition are hydrogen-related reactions introduced by the explosive mode and carbon-related reactions introduced by dissipative modes. Furthermore, it was also found that the chemical activity of the explosive modes is enhanced by transport processes, in particular convective processes, despite their dissipative nature.
  • Impact of thermal diffusion on lean near-limit H2-CH4-air flames

    Hernandez Perez, Francisco E.; Im, Hong G.; Zhou, Zhen; Shoshin, Yuriy; van Oijen, Jeroen; de Goey, Philip (AIAA Scitech 2019 Forum, American Institute of Aeronautics and Astronautics, 2019-01-07) [Conference Paper]
    In this research work, we investigate the influence of transport models and thermal diffusion (Soret effect) on numerical predictions of zero-gravity flame balls as well as normal-gravity steady and closed burner-stabilized reacting fronts for lean hydrogen-methane-air premixed mixtures, having a 40% hydrogen (H2) and 60% methane (CH4) fuel composition, specified on a molar basis. Three transport models are considered in the simulations: mixture-averaged, multicomponent, and multicomponent with inclusion of thermal diffusion. Although differences are found between the mixture-averaged and multicomponent solutions, they are not as prominent as those found when thermal diffusion is accounted for. The inclusion of thermal diffusion leads to predictions of larger flame sizes for both the zero-gravity flame balls and the normal-gravity burner-stabilized flames. Furthermore, lower lean limits are predicted when thermal diffusion is included in the computations.
  • Prediction of Ignition Regimes in DME/Air Mixtures with Temperature and Concentration Fluctuations

    Luong, Minh Bau; Hernandez Perez, Francisco E.; Sow, Aliou; Im, Hong G. (AIAA Scitech 2019 Forum, American Institute of Aeronautics and Astronautics, 2019-01-07) [Conference Paper]
    The objective of the present study is to establish a theoretical prediction of the autoignition behavior of a reactant mixture for a given initial bulk mixture condition. The ignition regime criterion proposed by Im and coworkers based on the Sankaran number (Sa), which is a ratio of the laminar flame speed to the spontaneous ignition front speed, is extended to account for both temperature and equivalence ratio fluctuations. The extended ignition criterion is then applied to predict the autoignition characteristics of dimethyl ether (DME)/air mixtures and validated by two-dimensional direct numerical simulations (DNS). The response of the ignition mode of DME/air mixtures to three initial mean temperatures of 770, 900 K, and 1045 K lying within/outside the NTC regime, two levels of temperature and concentration fluctuations at a pressure of 30 atm and equivalence ratio of 0.5 is systematically investigated. The statistical analysis is performed, and a newly developed criterion –the volumetric fraction of Sa < 1.0, FSa,S, is proposed as a deterministic criterion to quantify the fraction of heat release attributed to strong ignition. It is found that the strong and weak ignition modes are well captured by the predicted Sa number and FSa,S regardless of different initial mean temperatures and the levels of mixture fluctuations and correlations. Sap and FSa,S demonstrated under a wide range of initial conditions as a reliable criterion in determining a priori the ignition modes and the combustion intensity.
  • A Fast Weighted SVT Algorithm

    Dutta, Aritra; Li, Xin (2018 5th International Conference on Systems and Informatics (ICSAI), IEEE, 2019-01-03) [Conference Paper]
    Singular value thresholding (SVT) plays an important role in the well-known robust principal component analysis (RPCA) algorithms which have many applications in machine learning, pattern recognition, and computer vision. There are many versions of generalized SVT proposed by researchers to achieve improvement in speed or performance. In this paper, we propose a fast algorithm to solve aweighted singular value thresholding (WSVT) problem as formulated in [1], which uses a combination of the nuclear norm and a weighted Frobenius norm and has shown to be comparable with RPCA method in some real world applications.
  • Linear kernel tests via emperical likelihood for high dimensional data

    Ding, L.; Liu, Z.; Li, Y.; Liao, S.; Liu, Y.; Yang, P.; Yu, G.; Shao, L.; Gao, Xin (The Thirty-Third AAAI Conference on Artificial Intelligence (AAAI-19), 2019-01)
  • Approximate kernel selection with strong approximate consistency

    Ding, L.; Liao, S.; Liu, Y.; Yang, P.; Li, Y.; Pan, Y.; Huang, C.; Shao, L.; Gao, Xin (The Thirty-Third AAAI Conference on Artificial Intelligence (AAAI-19), 2019-01)
  • Second order online multitask learning

    Yang, P.; Zhao, P.; Zhou, J.; Gao, Xin (The Thirty-Third AAAI Conference on Artificial Intelligence (AAAI-19), 2019-01)
  • Vertically Aligned Graphene-based Thermal Interface Material with High Thermal Conductivity

    Wang, Nan; Chen, Shujing; Nkansah, Amos; Wang, Qianlong; Wang, Xitao; Chen, Miaoxiang; Ye, Lilei; Liu, Johan (2018 24rd International Workshop on Thermal Investigations of ICs and Systems (THERMINIC), IEEE, 2018-12-31) [Conference Paper]
    High density packaging in combination with increased transistor integration inevitably leads to challenging power densities in terms of thermal management. Here, a novel highly thermal conductive and lightweight graphene based thermal interface materials (GT) was developed for thermal management in power devices. Composed by vertically graphene structures, GTs provide a continuous high thermal conductivity phase along the path of thermal transport, which lead to outstanding thermal properties. The highest through-plane thermal conductivity GTs reaches to 1000 W/mK, which is orders of magnitude higher than conventional TIMs, and even outperforms the pure indium by over ten times. In addition, a thin layer of indium metal that coated on the surface of GTs can easily form alloys with many other metals at a relatively low reflow temperature. Therefore, GTs, as an excellent TIM, can provide complete physical contact between two surfaces with minimized the contact resistance. The measured total thermal resistance and effective thermal conductivity by using 300 m thick GTs as TIM between two copper blocks reaches to ~ 3.7 Kmm2 /W and ~ 90 W/mK, respectively. Such values are significantly higher than the randomly dispersed composites presented above, and show even better thermal performance than pure indium bonding. In addition, GTs has more advantages than pure indium bonding, including low weight (density < 2 g/cm3), low complexity during assembly and maintainability. The resulting GTs thus opens new opportunities for addressing large heat dissipation issues in form-factor driven electronics and other high power driven systems.
  • 3D-Printed Cross-Flow Mixer Gradient within Minutes for Microfluidic Applications

    Sivashankar, Shilpa; Mkaouar, Hend; Mashraei, Yousof; Alamoudi, Kholod; Khashab, Niveen M.; Salama, Khaled N. (2018 IEEE Biomedical Circuits and Systems Conference (BioCAS), IEEE, 2018-12-24) [Conference Paper]
    This paper reports on a compact new cross-flow 3D mixer that is integrated with a gradient generator into one device for toxicology applications. The device has two parts: the first mixes two solvents while the second generates gradients of the obtained solutions. The outlet of the 3D cross-flow mixer is integrated with a linear channel that aids in achieving this gradient by changing flow rates. The dye-visualization test confirm the functionality of mixer and gradient. The mesh structure of the mixer provided excellent mixing regime and is confirmed by experimental and simulation results. The compact size (25 × 25 × 3 mm) and the reduced cost ($1.5) of the device enable the device to be disposable. We aim to study doxorubicin drug at different concentration generated by the device to culture human embryonic kidney (HEK) from the 293-cell line enabling the devices to be used for cellular studies. The carefully designed geometry of the device finds applications in drug toxicology testing devices, micro-total analysis systems (µ- TAs),and other lab-on-chip devices.
  • Integration of Absolute Orientation Measurements in the KinectFusion Reconstruction Pipeline

    Giancola, Silvio; Schneider, Jens; Wonka, Peter; Ghanem, Bernard (2018 IEEE/CVF Conference on Computer Vision and Pattern Recognition Workshops (CVPRW), IEEE, 2018-12-18) [Conference Paper]
    In this paper, we show how absolute orientation measurements provided by low-cost but high-fidelity IMU sensors can be integrated into the KinectFusion pipeline. We show that integration improves both runtime, robustness and quality of the 3D reconstruction. In particular, we use this orientation data to seed and regularize the ICP registration technique. We also present a technique to filter the pairs of 3D matched points based on the distribution of their distances. This filter is implemented efficiently on the GPU. Estimating the distribution of the distances helps control the number of iterations necessary for the convergence of the ICP algorithm. Finally, we show experimental results that highlight improvements in robustness, a speed-up of almost 12%, and a gain in tracking quality of 53% for the ATE metric on the Freiburg benchmark.
  • Development of Printed Sensors for Shoe Sensing Applications

    Nag, Anindya; Feng, Shilun; Mukhopadhyay, Subhas; Kosel, Jürgen (2018 12th International Symposium on Medical Information and Communication Technology (ISMICT), IEEE, 2018-12-14) [Conference Paper]
    The paper presents the design and implementation of a low-cost shoe sensing system using laser-induced graphene sensors. Commercial polymer films were laser-induced to photo-thermally form graphene, which was then used as electrodes on Kapton tapes to form sensor patches. Experiments were then conducted with these sensor prototypes to validate its functionality as pressure sensors to be used in shoe sensing system. Different weights were tested with the developed system to ensure the capability of these sensor patches to be used as pressure sensing. The results look promising to be a system for monitoring the movement of a person wearing a shoe containing these low-cost pressure sensors.
  • Development of Novel Gold/PDMS Sensors for Medical Applications

    Nag, Anindya; Feng, Shilun; Afsarimanesh, Nasrin; Mukhopadhyay, Subhas; Kosel, Jürgen (2018 12th International Symposium on Medical Information and Communication Technology (ISMICT), IEEE, 2018-12-14) [Conference Paper]
    The paper presents the design and fabrication of novel gold/PDMS sensors using the sputtering method to use them for biomedical applications. The electrodes on the sensor patches were formed by placing a masked template containing the design over the PDMS. The sensor patches were flexible in nature with interdigitated electrodes formed on them. CTx-I, being one of the significant bone turnover biomarkers to determine the condition of the bones was tested at different concentrations to validate the functionality of the patches for this purpose. The results look promising to upgrade this idea into a fully-functionalized system for medical applications.
  • A robust monitoring technique for fault detection in grid-connected PV plants

    Harrou, Fouzi; Taghezouit, Bilal; Sun, Ying (2018 7th International Conference on Renewable Energy Research and Applications (ICRERA), IEEE, 2018-12-13) [Conference Paper]
    Monitoring the operation condition of photovoltaic (PV) systems is crucial to improving their efficiency. In this paper, an effective method to supervise the DC part of PV plants under noisy environment is provided. In fact, noisy measurements make the supervision more challenging as the feature extraction of the fault is more difficult. The designed approach merges the desirable proprieties of the discrete wavelet transform and the exponentially weighted moving average scheme to appropriately detect faults in PV system. Specifically, this approach is employed to check the residuals generated by a simulation model based on a single-diode modeling for fault detection. We evaluated the efficiency of the proposed approach on a real PV system in Algeria. Results indicated that the proposed approach has good capacity in supervising the DC part of PV plants.
  • Mechanical Computing Using Multifrequency Excited NEMS Resonator

    Kazmi, Syed N.R.; Ilyas, Saad; Costa, Pedro M.F. J.; Younis, Mohammad I. (2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS), IEEE, 2018-12-13) [Conference Paper]
    A silicon based nanoelectromechanical resonator is fabricated and is actively tuned through electrostatic actuation. We present multifrequency excitation of a NEMS resonator to dynamically perform all the fundamental logic operations (NOT, NOR, XNOR, NAND, OR, AND, and XOR). The multifrequency excitation allows to uniquely define resonant and non-resonant states as high and low logic outputs for all fundamental logic gates. The performance of this logic device is examined in terms of its speed of operation, energy consumption, and integration density. This work paves the way towards energy efficient nano-elements-based mechanical computing.
  • Stretchability of Archimedean-Spiral Interconnects Design

    Alcheikh, Nouha; Hussain, Muhammad. M. (2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS), IEEE, 2018-12-13) [Conference Paper]
    The island-interconnects design represents one of the categories which is widely used in stretchable electronics. Recently, Archimedean spiral interconnects are proposed as one of the best solutions for achieving a high level of stretchability. According to existing studies, their shape designs need to be investigated. Hence, this paper aims to examine the effect of the shape and the geometrical parameters of the Archimedean spiral on their stretchability. Due to the complex geometry, we use finite element method (FEM) to calculate the maximum stress and strain under axial deformation. The results conclude that with a narrow width and larger height, the Archimedean spiral shows highly stretchability more than 277% and 440% under maximum tensile strain εmax=1% and εmax=1.7%, respectively which correspond to the critical intrinsic strain of silicon. These results can be promising to fabricate high stretchable Archimedean spiral interconnects.
  • In-Plane Air Damping of NEMS and MEMS Resonators

    Alcheikh, Nouha; Kosuru, Lakshmoji; Kazmi, Syed N. R.; Younis, Mohammad I. (2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS), IEEE, 2018-12-13) [Conference Paper]
    This paper presents a study of the quality factor dependence on the geometrical parameters of in-plane clamped-clamped micro- and nano-beams capacitive structures at low-to-high pressure range. We found that smaller length and larger beam thickness maximize the quality factor. To minimize squeeze film damping, the structures have been fabricated with large capacitive air gaps. Despite the high ratio of the gap/thickness, we report significant effect of the gap width on the quality factor. It is found that, for micro-beams, this effect is limited at low pressure while for nano-beams, it continues until high pressure range. The geometry and the air gap effects on the damping of beams resonators have been examined experimentally. A finite-element study of the effect of the capacitive gap for in-plane resonators of one and two-side electrodes is presented. It is found that the presence of the double electrodes for in-plane resonators can cause significant drop of the quality factor compared to the single-sided beam resonator.

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