Design and performance analysis of a nanoscaled inverter based on wrap-aroundgate nanowire MOSFETs

The design and analysis of a silicon nanowire inverter with a wrap-around-gate nMOS is presented and its performance is compared with that of a conventional inverter. The analysis shows that the nano-channel structure design can improve carrier mobility by suppressing the transverse component of the electric field. This results in an enhancement in the current drive of the nMOS, and contributes to lowering power consumption and the switching delay. Simulated power consumption and rise time of the proposed design was found to be about 20 μW and 0.5 ns, respectively, compared with 2.5 mW and 1.5 ns achievable with conventional planar MOSFETs. Investigation of the gate length shows that a nMOS with shorter gates have an improved switching response compared with long channel devices.     

Short- and long-term behaviors of drifts in the Callovo-Oxfordian claystone at the Meuse/Haute-Marne Underground Research Laboratory

Since 2000, the French National Radioactive Waste Management Agency (ANDRA) has been constructing an Underground Research Laboratory (URL) at Bure (east of the Paris Basin) to perform experiments in order to obtain in situ data necessary to demonstrate the feasibility of geological repository in the Callovo-Oxfordian claystone. An important experimental program is planned to characterize the response of the rock to different drift construction methods. Before 2008, at the main level of the laboratory, most of the drifts were excavated using pneumatic hammer and supported with rock bolts, sliding steel arches and fiber shotcrete. Other techniques, such as road header techniques, stiff and flexible supports, have also been used to characterize their impacts. The drift network is developed following the in situ major stresses. The parallel drifts are separated enough so as they can be considered independently when their hydromechanical (HM) behaviors are compared. Mine-by experiments have been performed to measure the HM response of the rock and the mechanical loading applied to the support system due to the digging and after excavation. Drifts exhibit extensional (mode I) and shear fractures (modes II and III) induced by excavation works. The extent of the induced fracture networks depends on the drift orientation versus the in situ stress field. This paper describes the drift convergence and deformation in the surrounding rock walls as function of time and the impact of different support methods on the rock mass behavior. An observation based method is finally applied to distinguish the instantaneous and time-dependent parts of the rock mass deformation around the drifts.     

A Trace-Time Framework for Prediction of Elevation Angle Over Land Mobile LEO Satellites Networks

Elevation angle is one of the most significant parameters of land mobile satellite channels, subject to rapid variations in the case of Low Earth Orbit (LEO) satellite systems. In this paper a novel trace-based framework is proposed and analyzed which is capable of predicting elevation angle as a function of time during satellite visibility window. Trace-time based modeling makes the framework practical for real-time evaluation of elevation angle and its alteration incurred by communication links in LEO satellite systems. The proposed method is particularly suitable for development of communication channel models and services in mobile LEO satellite networks where path variability is of great importance.     

Modeling and simulation of a suspended microchannel resonator nano-sensor

Microsystem Technologies - In this paper, dynamic behavior of a piezoelectric sensor based on the suspended microchannel resonator (SMR) was modelled and simulated. Dynamic behavior of SMR with...     

Novolak resins with high thermal stability,high resolution,improved photospeed and etch characteristics for advanced photoresist applications

Novolak resins provide the best overall performance for “g” and “i”-line photoresists. There is a continuing need for advanced novolak designs that will provide improved lithographic, thermal, and etch characteristics that may be reproducibly synthesized. A novolak synthesis process was developed using the solution condensation technique. Cresol mixtures with m-cresol and 3,5-xylenol at specific ratios provide reproducible novolaks with controlled molecular weights. In order to achieve high thermal and etch performance, while retaining photospeed and resolution characteristics, three basic approaches were investigated: (1) increase in molecular weight, which produces novolaks with T_g ranging from 120 to 130°C with relatively slow dissolution rates; (2) incorporation of multi-hydroxyphenols such as resorcinol to tailor the dissolution rate, resolution, thermal, etch, and adhesion characteristics; (3) partial esterification of multi-hydroxy novolaks giving a T_g range of 140 to 150°C. Lithographic evaluation of the novolak resins was performed by formulating with a 2,1,4-diazonaphthoquinone (DNQ) sensitizer. Results on resin synthesis, molecular weights, lithographic, thermal, and etch characteristics are discussed.     

Investigation of fiber migration in rotor-jet spun yarn

The fiber migration in the newly developed rotor-jet spun yarn is investigated utilizing the tracer fiber technique and a proposed image analysis method. Effects of rotor-jet spinning parameters including three air-jet nozzle types of 90Z, 60Z, and 30Z (the values of 30, 60, and 90 are jet orifice angles and Z is air rotational direction identical to rotor rotational direction) at different air pressure values of 0.2, 0.5, 0.8, and 1 bar were considered. The results showed that increasing of air pressure causes the fiber to locate in the interior position of the yarn for 90Z nozzle, while for 30Z and 60Z nozzle types, the fiber is moved toward the exterior position of the yarn. Conversely, it was indicated that with increase of air pressure mean migration intensity and migration frequency increase for 90z nozzle, whereas decrease for 30Z and 60Z nozzle types. In general, the mean migration intensity and migration frequency magnitudes of rotor-jet spun yarn with 90z nozzle type are significantly higher than those of normal rotor yarn particularly at the higher air pressure. However, rotor-jet spun yarns with 30Z and 60Z nozzle types exhibited much lower mean migration intensity and migration frequency magnitudes than normal rotor yarn.     

A probabilistic nonlocal model for crack initiation and propagation in heterogeneous brittle materials

A probabilistic damage model is developed to study crack initiation and growth in quasi‐brittle materials. Two different thresholds are considered to describe these mechanisms. A Weibull model is used to account for the randomness of crack initiation(s) and then a fracture mechanics based threshold is considered to model crack propagation. The model is integrated in a finite element code via a nonlocal damage approach. A regularization operator based on a stress regularization is introduced. Both damage thresholds are checked using the ‘regularized’ stress field to avoid mesh dependence. The interaction between propagating cracks and potential initiation sites is accounted for. Copyright © 2012 John Wiley & Sons, Ltd.     

Numerical modeling of crack propagation and shielding effects in a striping network

Thermal fatigue cracking is observed in some components of nuclear power plants. The residual lifetime prediction of cracked components is necessary to determine maintenance programs. An automatic procedure is developed for 2D modeling of multiple crack propagation within the finite element software Code_Aster^® to evaluate the crack growth rate and shielding effects in a multicracked structure in thermomechanical fatigue. It consists in a global remeshing method to model crack growth and includes a propagation strategy based on the crack length increment. A set of parametric studies is analyzed for a cracked pipe to evaluate the influence of geometrical and loading parameters on the residual lifetime of the crack network.