Pentacene-Based Low-Voltage Strain Sensors With PVP/$ hbox{Ta}_{2}hbox{O}_{5}$ Hybrid Gate Dielectrics

Field-controllable pentacene-semiconductor-based strain sensors were fabricated with hybrid gate dielectrics using polyvinyl phenol (PVP) and high-$k$ inorganic tantalum pentoxide $(hbox{Ta}_{2}hbox{O}_{5})$ onto polyethylene naphthalate films. The $hbox{Ta}_{2}hbox{O}_{5}$ gate-dielectric layer combined with a thin PVP layer to form very smooth and hydrophobic surfaces turns out to improve the molecular structures of pentacene films significantly. The PVP– $hbox{Ta}_{2}hbox{O}_{5}$ hybrid-gate-dielectric films exhibit a high dielectric constant of 19.27 and a leakage-current density of as low as 100 $hbox{nA/cm}^{2}$ . The sensors employing a thin-film-transistor-like Wheatstone bridge configuration able to operate at reduced voltage ($sim$4 V) show good device characteristics with a field-effect mobility of 1.89 $hbox{cm}^{2}/hbox{V} cdot hbox{s}$ and a threshold voltage of $-$0.5 V. The strain sensor characterized with bending at 45$^{circ}$ with respect to the bridge bias direction with different bending radii of 50-, 40-, 30-, 20-, and 8-mm displays output signals improved in linearity in a low range of operating voltages.      

Large-Scale Synthesis of Graphene Films by Joule-Heating-Induced Chemical Vapor Deposition

We report large-area synthesis of few-layer graphene films by chemical vapor deposition (CVD) in a cold-wall reactor. The key feature of this method is that the catalytic metal layers on the SiO₂/Si substrates are self-heated to high growth temperature (900°C to 1000°C) by high-current Joule heating. Synthesis of high-quality graphene films, whose structural and electrical characteristics are comparable to those grown by hot-wall CVD systems, was confirmed by transmission electron microscopy images, Raman spectra, and current–voltage analysis. Optical transmittance spectra of the graphene films allowed us to estimate the number of graphene layers, which revealed that high-temperature exposure of Ni thin layers to a carbon precursor (CH₄) was critical in determining the number of graphene layers. In particular, exposure to CH₄ for 20 s produces very thin graphene films with an optical transmittance of 93%, corresponding to an average layer number of three and a sheet resistance of ~600 Ω/square.     

Anti-buckling S-shaped vertical microprobes with branch springs

We propose the S-shaped vertical probes with branch springs for the wafer-level testing of IC chips. The conventional S-shaped vertical probe requires a guide structure to prevent buckling due to the large overdrive actuation involved. However, the guide structure not only increases the cost of fabrication, but it also requires a troublesome assembly procedure. In this paper, we present the S-shaped vertical probe with branch springs on the left and right sides of the main spring to prevent buckling. This probe was designed using finite-element methods and fabricated using Ni-Co electroplating. The performances of the probe for the wafer-level testing of IC chips were measured with the probe test equipments. Compared to the identical conventional S-shaped probe, the proposed probe has the overdrive (60 μm) that is 1.2 times larger and the contact force (25 mN) that is 2.5 times larger. This new S-shaped vertical probe satisfies the design requirements for a vertical probe without the guide structure and has the potential for use as a cost-effective guide-free probe card for the wafer-level testing of IC chips.     

Discrete Logarithm Problems with Auxiliary Inputs

Let g be an element of prime order p in an abelian group, and let α∈? _p . We show that if g,g ^α , and \(g^{\alpha^{d}}\) are given for a positive divisor d of p?1, the secret key α can be computed deterministically in \(O(\sqrt{p/d}+\sqrt{d})\) exponentiations by using \(O(\max\{\sqrt{p/d},\sqrt{d}\})\) storage. If \(g^{\alpha^{i}}\) (i=0,1,2,…,2d) is given for a positive divisor d of p+1, α can be computed in \(O(\sqrt{p/d}+d)\) exponentiations by using \(O(\max\{\sqrt{p/d},\sqrt{d}\})\) storage. We also propose space-efficient but probabilistic algorithms for the same problem, which have the same computational complexities with the deterministic algorithm.As applications of the proposed algorithms, we show that the strong Diffie–Hellman problem and related problems with public \(g^{\alpha},\ldots,g^{\alpha^{d}}\) have computational complexity up to \(O(\sqrt{d}/\log p)\) less than the generic algorithm complexity of the discrete logarithm problem when p?1 (resp. p+1) has a divisor d≤p ^1/2 (resp. d≤p ^1/3). Under the same conditions for d, the algorithm is also applicable to recovering the secret key in \(O(\sqrt{p/d}\cdot \log p)\) for Boldyreva’s blind signature scheme and the textbook ElGamal scheme when d signature or decryption queries are allowed.     

Energy-Efficient Double-Edge Triggered Flip-Flop

This paper presents a novel design for a double-edge triggered flip-flop (DETFF). A detailed analysis of the transistors used in the DETFF is carried out to determine the critical path. Therefore, the proposed DETFF employs low-V _th transistors at critical paths such that the power-delay product as well as the large area consumption caused by the low-V _th transistors can be resolved simultaneously. Therefore, the proposed DETFF fully utilizes the multi-V _th scheme provided by advanced CMOS processes without suffering from a large area penalty, slow clock frequency, and poor noise immunity. The proposed design is implemented using a typical 0.18-μm 1P6M CMOS process. The measurement results reveal that the proposed DETFF reduce the power-delay product by at lease 25% (i.e., dissipated energy).     

High-performance liquid chromatographic enantioseparation of β-amino acids using a long-tethered (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid-based chiral stationary phase

Reversed-phase high-performance liquid chromatographic methods were developed for the separation of enantiomers of eleven unnatural β²-amino acids on a new chiral stationary phase, using the 11-methylene-unit spacer of aminoundecylsilica gel for the bonding of (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid as selector. The nature and concentration of the acidic and organic modifiers, the pH, the mobile phase composition, and the structures of the analytes substantially influenced the retention and resolution. Separations were carried out at constant mobile phase compositions in the temperature range 7–40 °C and the changes in enthalpy, Δ(ΔH°), entropy, Δ(ΔS°), and free energy, Δ(ΔG°) were calculated. The elution sequence was determined in some cases: the S enantiomers eluted before the R enantiomers.     

Existence of solutions for a fully nonlinear fourth-order two-point boundary value problem

In this paper, we investigate the existence of solutions of a fully nonlinear fourth-order differential equation $$x^{(4)}=f(t,x,x',x'',x'''),\quad t\in [0,1]$$ with one of the following sets of boundary value conditions; $$x'(0)=x(1)=a_{0}x''(0)-b_{0}x'''(0)=a_{1}x''(1)+b_{1}x'''(1)=0,$$ $$x(0)=x'(1)=a_{0}x''(0)-b_{0}x'''(0)=a_{1}x''(1)+b_{1}x'''(1)=0.$$ By using the Leray-Schauder degree theory, the existence of solutions for the above boundary value problems are obtained. Meanwhile, as an application of our results, an example is given.     

A High-Order Immersed Boundary Method for Acoustic Wave Scattering and Low-Mach Number Flow-Induced Sound in Complex Geometries

A new sharp-interface immersed boundary method based approach for the computation of low-Mach number flow-induced sound around complex geometries is described. The underlying approach is based on a hydrodynamic/acoustic splitting technique where the incompressible flow is first computed using a second-order accurate immersed boundary solver. This is followed by the computation of sound using the linearized perturbed compressible equations (LPCE). The primary contribution of the current work is the development of a versatile, high-order accurate immersed boundary method for solving the LPCE in complex domains. This new method applies the boundary condition on the immersed boundary to a high-order by combining the ghost-cell approach with a weighted least-squares error method based on a high-order approximating polynomial. The method is validated for canonical acoustic wave scattering and flow-induced noise problems. Applications of this technique to relatively complex cases of practical interest are also presented.     

Several optimization problems in satellite optical communications: Models and solutions

In this paper, we address several optimization problems in satellite optical communications. We show that the inter-satellite links with swaying transmitters can be described as an equivalent fading model. We further indicate that the instantaneous signal-to-noise ratio follows the reciprocal Pareto distribution. Then we conduct the analysis on several performance metrics such as the first and second moments of signal-to-noise ratio, the amount of fading, as well as the outage probability. Based on these metrics, we establish optimization models and provide the corresponding solutions.