A Novel Design Methodology for High-Performance Programmable Decoder Cores for AA-LDPC Codes

A new parameterized-core-based design methodology targeted for programmable decoders for low-density parity-check (LDPC) codes is proposed. The methodology solves the two major drawbacks of excessive memory overhead and complex on-chip interconnect typical of existing decoder implementations which limit the scalability, degrade the error-correction capability, and restrict the domain of application of LDPC codes. Diverse memory and interconnect optimizations are performed at the code-design, decoding algorithm, decoder architecture, and physical layout levels, with the following features: (1) Architecture-aware (AA)-LDPC code design with embedded structural features that significantly reduce interconnect complexity, (2) faster and memory-efficient turbo-decoding algorithm for LDPC codes, (3) programmable architecture having distributed memory, parallel message processing units, and dynamic/scalable transport networks for routing messages, and (4) a parameterized macro-cell layout library implementing the main components of the architecture with scaling parameters that enable low-level transistor sizing and power-rail scaling for power-delay-area optimization. A 14.3 mm² programmable decoder core for a rate-1/2, length 2048 AA-LDPC code generated using the proposed methodology is presented, which delivers a throughput of 6.4 Gbps at 125 MHz and consumes 787 mW of power.Mohammad M. Mansour received his B.E. degree with distinction in 1996 and his M.S. degree in 1998 all in Computer and Communications Engineering from the American University of Beirut (AUB). In August 2002, he received his M.S. degree in Mathematics from the University of Illinois at Urbana-Champaign (UIUC). Mohammad received his Ph.D. in Electrical Engineering in May 2003 from UIUC. He is currently an Assistant Professor of Electrical Engineering with the ECE department at AUB. From 1998 to 2003, he was a research assistant at the Coordinated Science Laboratory (CSL) at UIUC. In 1997 he was a research assistant at the ECE department at AUB, and in 1996 he was a teaching assistant at the same department. From 1992–1996 he was on the Deans honor list at AUB. He received the Harriri Foundation award twice in 1996 and 1998, the Charli S. Korban award twice in 1996 and 1998, the Makhzoumi Foundation Award in 1998, and the PHI Kappa PHI Honor Society awards in 2000 and 2001. During the summer of 2000, he worked at National Semiconductor Corp., San Francisco, CA, with the wireless research group. His research interests are VLSI architectures and integrated circuit (IC) design for communications and coding theory applications, digital signal processing systems and general purpose computing systems.Naresh R. Shanbhag received the B.Tech from the Indian Institute of Technology, New Delhi, India, in 1988, M.S. from Wright State University and Ph.D. degree from the University of Minnesota, in 1993, all in Electrical Engineering. From July 1993 to August 1995, he worked at AT&T Bell Laboratories at Murray Hill in the Wide-Area Networks Group, where he was responsible of development of VLSI algorithms, architectures and implementation for high-speed data communications applications. In particular, he was the lead chip architect for AT&Ts 51.84 Mb/s transceiver chips over twisted-pair wiring for Asynchronous Transfer Mode (ATM)-LAN and broadband access. Since August 1995, he is with the Department of Electrical and Computer Engineering, and the Coordinated Science Laboratory where he is presently an Associate Professor and Director of the Illinois Center for Integrated Microsystems. At University of Illinois, he founded the VLSI Information Processing Systems (ViPS) Group, whose charter is to explore issues related to low-power, high-performance, and reliable integrated circuit implementations of broadband communications and digital signal processing systems. He has published numerous journal articles/book chapters/conference publications in this area and holds three US patents. He is also a co-author of the research monograph Pipelined Adaptive Digital Filters (Norwell, MA: Kluwer, 1994). Dr. Shanbhag received the 2001 IEEE Transactions Best Paper Award, 1999 Xerox Faculty Research Award, 1999 IEEE Leon K. Kirchmayer Best Paper Award, the 1997 Distinguished Lecturer of IEEE Circuit and Systems Society (97–99), the National Science Foundation CAREER Award in 1996, and the 1994 Darlington Best Paper Award from the IEEE Circuits and Systems society. From 1997–99 and 2000–2002, he served as an Associate Editor for IEEE Transaction on Circuits and Systems: Part II and an Associate Editor for the IEEE Transactions on VLSI, respectively. He was the technical program chair for the 2002 IEEE Workshop on Signal Processing Systems (SiPS02).     

Pretest in forced circulation molten salt heat transfer loop: Studies with thermia‐B

Molten salts have potential application as an efficient heat transfer medium in a primary and secondary heat exchanger in high temperature next‐generation nuclear power plant. Thermal hydraulic studies are vital for reliable and cost‐effective design of the nuclear power plant. Therefore heat transfer study of molten salts will play a vital role in this area. In this work, an experimental system was designed to study thermal hydraulics of the molten salt system up to 700°C. This work describes the pretest results of the experimental facility for extremely corrosive molten fluoride salts with a simulant thermia‐B as the working fluid. In the present work, the details of the system are discussed and thermal‐hydraulic data for heat transfer fluid thermia‐B has been presented. Experiments were carried out at Reynolds number in the range of 4500 to 40 500 and Prandtl number in the range of 34 to 144. Effect of Reynolds number, melting tank temperature, and heat input to test section on forced convective heat transfer was studied under turbulent conditions. Comparison of the experimental data with different empirical correlations has been presented.     

Green synthetic route of carbon quantum dot-reinforced graphene oxide-poly(vinylidene fluoride-co-hexa fluoropropylene) nanocomposites: Toward high dielectric constant and suppressed loss

A simple and green method was developed to fabricate carbon quantum dot@ graphene oxide filled poly (vinylidene fluoride-co-hexa-fluoropropylene) [CQD@GO-P(VDF-HFP)] nanocomposite films via solution casting technique. The synthetic approach was to bring CQD from bilva leafs, a renewable and sustainable resource. The effect of CQD on dielectric properties, dielectric constant, and dielectric loss in the presence of GO along with P (VDF-HFP) matrix were investigated. The result showed that the nanocomposites having 1.5 wt % of CQD@GO-P(VDF-HFP) with higher dielectric constant (≈144) at 100 Hz and suppressed loss (<1) at 1000 Hz, which is well supported by field emission scanning electron microscopy (FESEM) study. The FESEM study shows a river iceland morphology with a channel-like structure along with voids and pores that may provide a conducting network, which tends to have Maxwell Wagner-Sillars or interfacial polarization results in a high-end properties outcome. Furthermore, the suppressed loss enhanced the possibility of end use performance of CQD@GO-P(VDF-HFP) matrix with a referral memorandum of percolation theory. Thus, the present work demonstrated a new approach to develop high dielectric constant and negligible loss materials in the field of embedded devices for electronic industries through green synthetic approach. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47850.     

Numerical modelling of second‐grade fluid flow past a stretching sheet

The present numerical study reports the chemically reacting boundary layer flow of a magnetohydrodynamic second‐grade fluid past a stretching sheet under the influence of internal heat generation or absorption with work done due to deformation in the presence of a porous medium. To distinguish the non‐Newtonian behaviour of the second‐grade fluid with those of Newtonian fluids, a very popularly known second‐grade fluid flow model is used. The fourth order momentum equation with four appropriate boundary conditions along with temperature and concentration equations governing the second‐grade fluid flow are coupled and highly nonlinear in nature. Well‐established similarity transformations are efficiently used to reduce the dimensional flow equations into a set of nondimensional ordinary differential equations with the necessary conditions. The standard bvp4c MATLAB solver is effectively used to solve the fluid flow equations to get the numerical solutions in terms of velocity, temperature, and concentration fields. Numerical results are obtained for a different set of physical parameters and their behaviour is described through graphs and tables. The viscoelastic parameter enhances the velocity field whereas the magnetic and porous parameters suppress the velocity field in the flow region. The temperature field is magnified for increasing values of the heat source/sink parameter. However, from the present numerical study, it is noticed that the flow of heat occurs from sheet to the surrounding ambient fluid. Before concluding the considered problem, our results are validated with previous results and are found to be in good agreement.     

Bright Aggregation‐Induced Emission Dots for Dynamic Tracking and Grading of Patient‐Derived Xenografts in Zebrafish

Cancer prognosis will benefit from a scoring system that could grade malignant traits of patient‐derived cells by assessing their growth and metastasis in a living system. Specific tracking of patient‐derived cells requires labeling by contrast agents with good signal‐to‐noise ratio and no specific stain of host tissues. Towards this aim, aggregation‐induced emission (AIE) dots are developed for in vivo cancer tracking with emphasis on reproducible optimized formulation and specific fluorescent labeling of cells that enable enhanced spatial temporal resolution in vivo. The importance of energy‐dependent AIE dots uptake for patient‐derived cell labeling is emphasized to reveal their specific uptake by viable cancer cells. Using optically transparent zebrafish embryo, the ability is demonstrated to follow the engraftment of transplanted AIE dot labeled cells in zebrafish brains over one week. Cells detected outside the brain after 7 d are quantified as metastatic cells. Results from seven clinical samples demonstrate the utility of this methodology to differentiate low engraftment level of benign neoplasms from higher engraftment level and metastasis detected in malignant ovarian cancer specimens. Achieving clinically validated results supports the use of AIE dot labeled patient derived cells in zebrafish xenografts for future cancer prognosis.     

Open‐Shell Donor–Acceptor Conjugated Polymers with High Electrical Conductivity

Conductive polymers largely derive their electronic functionality from chemical doping, processes by which redox and charge‐transfer reactions form mobile carriers. While decades of research have demonstrated fundamentally new technologies that merge the unique functionality of these materials with the chemical versatility of macromolecules, doping and the resultant material properties are not ideal for many applications. Here, it is demonstrated that open‐shell conjugated polymers comprised of alternating cyclopentadithiophene and thiadiazoloquinoxaline units can achieve high electrical conductivities in their native “undoped” form. Spectroscopic, electrochemical, electron paramagnetic resonance, and magnetic susceptibility measurements demonstrate that this donor–acceptor architecture promotes very narrow bandgaps, strong electronic correlations, high‐spin ground states, and long‐range π‐delocalization. A comparative study of structural variants and processing methodologies demonstrates that the conductivity can be tuned up to 8.18 S cm^?1. This exceeds other neutral narrow bandgap conjugated polymers, many doped polymers, radical conductors, and is comparable to commercial grades of poly(styrene‐sulfonate)‐doped poly(3,4‐ethylenedioxythiophene). X‐ray and morphological studies trace the high conductivity to rigid backbone conformations emanating from strong π‐interactions and long‐range ordered structures formed through self‐organization that lead to a network of delocalized open‐shell sites in electronic communication. The results offer a new platform for the transport of charge in molecular systems.     

Influence of growth parameters on the dopant configuration of nitrogen-doped graphene synthesized from phthalocyanine molecules

Synthesis of nitrogen-doped graphene (NDG) via chemical vapor deposition (CVD) using phthalocyanine, a solid precursor containing carbon and nitrogen, is reported. The effect of the growth parameters (temperature, time, and carrier gas) on the surface morphology, dopant configuration, and conductivity of the films was studied. The NDG films were synthesized at different substrate temperatures of 1050 °C, 950 °C, and 850 °C for different growth times of 5–15 min in the presence of an Ar?+?H₂ gas mixture. Significantly, pyrrolic-N type defects are observed predominantly after 5 min of growth time. At 1050 °C, pyrrolic N content is around 45.4% after 5 min of growth which decreased to 24.1% after 15 min of growth, while the graphitic-N content increased from 41.2 to 76% at the same time. It is demonstrated that the conversion of pyrrolic type of nitrogen to graphitic nitrogen defects can be arrested by changing the carrier gas from Ar?+?H₂ to Ar. The pyrrolic-N content increased to 64% by changing the gas from Ar?+?H₂ to Ar at 15 min. The electrolyte gated field-effect transistors were fabricated using the obtained films, and dopant-dependent mobility was observed. The mobility for pyrrolic-N-dominated film is 13.6 cm² V^?1 s^?1 increasing to 62.8 cm² V^?1 s^?1 for graphitic-N-dominated film.

     

Engineering the Interlayer Spacing by Pre-Intercalation for High Performance Supercapacitor MXene Electrodes in Room Temperature Ionic Liquid

MXenes exhibit excellent capacitance at high scan rates in sulfuric acid aqueous electrolytes, but the narrow potential window of aqueous electrolytes limits the energy density. Organic electrolytes and room-temperature ionic liquids (RTILs) can provide higher potential windows, leading to higher energy density. The large cation size of RTIL hinders its intercalation in-between the layers of MXene limiting the specific capacitance in comparison to aqueous electrolytes. In this work, different chain lengths alkylammonium (AA) cations are intercalated into Ti₃C₂T_x, producing variation of MXene interlayer spacings (d-spacing). AA-cation-intercalated Ti₃C₂T_x (AA-Ti₃C₂), exhibits higher specific capacitances, and cycling stabilities than pristine Ti₃C₂T_x in 1 m 1-ethly-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMIMTFSI) in acetonitrile and neat EMIMTFSI RTIL electrolytes. Pre-intercalated MXene with an interlayer spacing of ≈2.2 nm, can deliver a large specific capacitance of 257 F g⁻¹ (1428 mF cm⁻² and 492 F cm⁻³) in neat EMIMTFSI electrolyte leading to high energy density. Quasi elastic neutron scattering and electrochemical impedance spectroscopy are used to study the dynamics of confined RTIL in pre-intercalated MXene. Molecular dynamics simulations suggest significant differences in the structures of RTIL ions and AA cations inside the Ti₃C₂T_x interlayer, providing insights into the differences in the observed electrochemical behavior.