Intrinsic Reliability improvement in Biaxially Strained SiGe p-MOSFETs

In this letter we not only show improvement in the performance but also in the reliability of 30nm thick biaxially strained SiGe (20%Ge) channel on Si p-MOSFETs. Compared to Si channel, strained SiGe channel allows larger hole mobility ({\mu}h) in the transport direction and alleviates charge flow towards the gate oxide. {\mu}h enhancement by 40% in SiGe and 100% in Si-cap SiGe is observed compared to the Si hole universal mobility. A ~40% reduction in NBTI degradation, gate leakage and flicker noise (1/f) is observed which is attributed to a 4% increase in the hole-oxide barrier height ({\phi}) in SiGe. Similar field acceleration factor ({\Gamma}) for threshold voltage shift ({\Delta}VT) and increase in noise ({\Delta}SVG) in Si and SiGe suggests identical degradation mechanisms.Comment: 4 figures, 3 pages, accepted for publication in IEEE ED

Batch solution of small PDEs with the OPS DSL

In this paper we discuss the challenges and optimisations opportunities when solving a large number of small, equally sized discretised PDEs on regular grids. We present an extension of the OPS (Oxford Parallel library for Structured meshes) embedded Domain Specific Language, and show how support can be added for solving multiple systems, and how OPS makes it easy to deploy a variety of transformations and optimisations. The new capabilities in OPS allow to automatically apply data structure transformations, as well as execution schedule transformations to deliver high performance on a variety of hardware platforms. We evaluate our work on an industrially representative finance simulation on Intel CPUs, as well as NVIDIA GPUs

Processing and properties of Ag-clad BSCCO superconductors

Long lengths of mono- and multifilament Ag-clad BSCCO (Bi-Sr-Ca-Cu-O) conductors with critical current densities of >10{sup 4} A/cm{sup 2} at 77 K were fabricated by the powder-in-tube method. {Tc} magnets were assembled by stacking pancake coils fabricated from long tapes and then tested vs applied magnetic field at various temperatures. A magnet that contained {approx}2400 m of {Tc} conductor generated a field of 3.2 T at 4.2 K. In-situ tensile and bending properties of the Ag-clad conductors were studied. Multilayer Ag/superconductor composites were fabricated by chemical etching. Preliminary results with multilayer tapes show that continuous Ag reinforcement of the BSCCO core improves strain tolerance of the tapes so they can carry 90% of their initial I{sub c} at 1% bend strain desite a higher superconductor/Ag ratio than that of unreinforced tapes

Processing and properties of long-lengths of Ag-clad BSCCO superconductors and high-{Tc} magnets

Long lengths of Ag-clad mono and multicore BSCCO tapes were fabricated by the powder-in-tube technique. The critical current density (J{sub c}) of 125-m-long monocore tapes was {approx}12,000 A/cm{sup 2} (critical current, I{sub c} 20 A) at 77 K. A 230-m-long 37-filament tape carried an I{sub c} of 14 A (corresponding to a J{sub c} of {approx}10,000 A/cm{sup 2}). Pancake-shaped coils were formed from long-length conductors by the wind-and-react approach. High-T{sub c} magnets were then assembled by stacking the pancake coils and connecting them in series. The magnets were tested as a function of applied magnetic fields at 4.2, 27, 64, and 77 K. A magnet containing 480 m of high-{Tc} tape generated a record-high field of 2.6 T at 4.2 K. Another magnet assembled with {approx}770 m of tape generated a field of {approx}1 T at 4.2 K and {approx}0.6 T at 27 K, both in an applied background field of {approx}20 T. Strain tolerance of high-{Tc} tapes was evaluated by measuring J{sub c} retention as a function of applied strain in an 0.5 T applied field at 77 K

Large-scale performance of a DSL-based multi-block structured-mesh application for Direct Numerical Simulation

SBLI (Shock-wave/Boundary-layer Interaction) is a large-scale Computational Fluid Dynamics (CFD) application, developed over 20 years at the University of Southampton and extensively used within the UK Turbulence Consortium. It is capable of performing Direct Numerical Simulations (DNS) or Large Eddy Simulation (LES) of shock-wave/boundary-layer interaction problems over highly detailed multi-block structured mesh geometries. SBLI presents major challenges in data organization and movement that need to be overcome for continued high performance on emerging massively parallel hardware platforms. In this paper we present research in achieving this goal through the OPS embedded domain-specific language. OPS targets the domain of multi-block structured mesh applications. It provides an API embedded in C/C++ and Fortran and makes use of automatic code generation and compilation to produce executables capable of running on a range of parallel hardware systems. The core functionality of SBLI is captured using a new framework called OpenSBLI which enables a developer to declare the partial differential equations using Einstein notation and then automatically carryout discretization and generation of OPS (C/C++) API code. OPS is then used to automatically generate a wide range of parallel implementations. Using this multi-layered abstractions approach we demonstrate how new opportunities for further optimizations can be gained, such as fine-tuning the computation intensity and reducing data movement and apply them automatically. Performance results demonstrate there is no performance loss due to the high-level development strategy with OPS and OpenSBLI, with performance matching or exceeding the hand-tuned original code on all CPU nodes tested. The data movement optimizations provide over 3× speedups on CPU nodes, while GPUs provide 5× speedups over the best performing CPU node. The OPS generated parallel code also demonstrates excellent scalability on nearly 100K cores on a Cray XC30 (ARCHER at EPCC) and on over 4K GPUs on a CrayXK7 (Titan at ORNL)

Processing and characterization of Ag-clad Bi-2223 superconductors

Practical applications of high-temperature superconductors will be governed by their current transport and mechanical characteristics. With careful control of the processing parameters high-quality long- length mono- and multifilament Bi-2223 conductors have been fabricated by the powder-in-tube technique. A critical current density (Jc) of up to 1.2 x 104 A cm{sup -2} has been observed at 77 K in a 1260-m-long multifilament conductor containing 37 monocore filaments. A high-temperature superconducting magnet and a prototype transformer were fabricated and characterized from such long-length conductors. Efforts further improve the current characteristics of the Bi-2223 tapes resulted in the development of the wire-in-tube technique. A Jc value >105 A cm{sup -2} at 77 K and in self field have been obtained in a Bi-2223 tape fabricated by the wire- in-tube method. Extensive studies on the in-situ strain characteristics of the mono- and multifilament conductors have been conducted. Multilayer silver/superconductor composite tapes, fabricated by a novel chemical etching technique, were also observed to exhibit improved strain tolerance characteristics

Fizykochemiczne i mechaniczne właściwości różnych morfologicznie części drzewa herbacianego (Melaleuca alternifolia)

Tea tree fibres as underutilised fibres were investigated physically, chemically and mechanically. From this study, it was found that the tea tree leaf (TTL) had the highest density - 0.42 g/cm3, and the highest percentage of water absorption - 69.9%. From the tensile strength, the tea tree trunk (TTT) gave the highest value - 65.44 MPa, followed by the tea tree branch (TTB) - 48.43 MPa and tea tree leaf (TTL) - 47.47 MPa. The chemical composition of fibres showed TTT had the highest cellulose content, which is 33.9%, followed by TTB -27.2%, and TTL - 13.5%. Meanwhile TTL had the highest extractive value - 16.4%, almost 3 times higher than TTB and TTT due to the existence of tea tree oil in TTL. From the FTIR result, TTL, TTB and TTT had similar spectra and no major differences. This paper aims to rationalise the potential of underutilised tea tree (Melaleuca alternifolia) waste as a novel source of natural fibre, to become a potential reinforcement or filler in the development of a new biocomposite.Na podstawie badań stwierdzono, że liście drzewa herbacianego mają najwyższą gęstość 0.42 g/cm3 i najwyższą zawartość procentową absorpcji wody 69.9%. Badając wytrzymałość stwierdzono, że włókna z pnia drzewa herbacianego charakteryzują się najwyższą wytrzymałością 65.44 MPa, podczas gdy włókna z gałęzi mają wytrzymałość 48.43 MPa, a z liści 47.47 MPa. Badanie składu chemicznego wykazało, że włókna z pnia mają najwyższą zawartość celulozy 33.9%, podczas gdy z gałęzi 27.2% i liści 13.5%. Możliwość ekstrakcji jest największa dla liści 16.4%, prawie trzykrotnie wyższa niż dla gałęzi i pnia w wyniku zawartości w liściach olejku z drzewa herbacianego. Na podstawie badań FTIR stwierdzono, że poszczególne rodzaje morfologiczne włókien mają zbliżone rozkłady spektralne bez zasadniczych różnic. Głównym celem artykułu jest udowodnienie możliwości wykorzystania odpadów z drzewa herbacianego jako nowego źródła włókien naturalnych mogącego służyć jako potencjalne wzmocnienie lub wypełnienie przy opracowaniu nowych biokompozytów

Fabrication of superconducting joints for Ag-clad BSCCO conductors

Potential applications of high-T{sub c} superconductors include motors, generators, transmission cables, magnets, etc. At present, resistive connections are used to connect various high-T{sub c} components for such applications. However, to improve efficiency, it is imperative that the resistive connection be replaced by a true superconducting joint. Using a novel etching technique, we have fabricated superconducting lap and butt joints between Ag-clad BSCCO conductors. The Ag sheath from one side of the tape was selectively etched to expose the underlying superconductor core. Joints were formed by bringing the two tapes together and heat treating them. Detailed microstructural analysis and current transport measurements of the joints have been performed. Critical current (I{sub c}) through a monofilament lap- and butt-joint were 10 and 23 A, respectively. I{sub c} within the joint for mono- and multifilament conductors were 37 and 21 A, respectively. Additionally, effects of various joint configurations, processing techniques, and strain on the transport property of the joint are also being studied

Fabrication and properties of silver and silver-sheathed BSCCO conductors

Significant progress has been made in the development of silver- sheathed BSCCO conductors for potential electric power and high-field magnet applications. High critical current density (J{sub c}) has been achieved in mono- and multifilament conductors fabricated by the powder-in-tube technique; J{sub c} up to 12,000 A/cm{sup 2} has been observed at 77 K, in an 1260-m-long multifilament conductor. A high- {Tc} magnet generated a self-field of {approx} 3.2 T at 4.2 K. A 0.25 KVA high-{Tc} transformer has been developed with the use of a racetrack-wound solenoid. Strain tolerance of the conductors was evaluated by in-situ tensile and bending tests. Tensile testing indicated that multifilament conductors have better strain tolerance than monofilament conductors and are able to retain 90% of their initial current (I{sub c}) at a strain of {ge}1%. Effect of superconducting/Ag ratio on bending characteristics of the conductors was also evaluated; preliminary results indicate that the irreversible strain limit of the monofilament conductor increases with decreasing superconductor/Ag ratio