High speed decoding of the binary (47, 24, 11) quadratic residue code

An efficient table lookup decoding algorithm (TLDA) is presented to decode up to five possible errors in a binary systematic (47, 24, 11) quadratic residue (QR) code. The main idea of the TLDA is based on the weight of syndrome, the syndrome decoder together with a reduced-size lookup table (RSLT), and the shift-search method given by Reed et al. Thus, the size of the lookup table and computational complexity in a finite field can be significantly reduced. The memory size of the proposed condensed lookup table (CLT) consists of only 36.6 Kbytes and is only about 0.24% of the full lookup table (FLT) and 3.2% of the lookup up table given by Chen et al., respectively. These facts lead to significant reduction of computational time and the decoding complexity. A simulation result shows that the decoding speed of the proposed TLDA is much faster than all existing decoding algorithms. Moreover, it can be extended to decode all QR codes, including the class of the cyclic codes when the code length is moderate. The CLT makes this new decoding algorithm suitable for hardware or firmware implementations.     

On the decoding of the (24, 12, 8) Golay code

An improved syndrome shift-register decoding algorithm, called the syndrome-weight decoding algorithm, is proposed for decoding three possible errors and detecting four errors in the (24, 12, 8) Golay code. This method can also be extended to decode two other short codes, such as the (15, 5, 7) cyclic code and the (31, 16, 7) quadratic residue (QR) code. The proposed decoding algorithm makes use of the properties of cyclic codes, the weight of syndrome, and the syndrome decoder with a reduced-size lookup table (RSLT) in order to reduce the number of syndromes and their corresponding coset leaders. This approach results in a significant reduction in the memory requirement for the lookup table, thereby yielding a faster decoding algorithm. Simulation results show that the decoding speed of the proposed algorithm is approximately 3.6 times faster than that of the algebraic decoding algorithm.     

A novel efficient (t, n) threshold proxy signature scheme

All previously proposed threshold proxy signature schemes have been based on discrete logarithms required for a protocol to generate and verify a shared secret among the proxy group. Therefore, it is necessary for the proxy signers to perform many expensive modular exponential computations and communications to obtain and verify a shared secret. Moreover, most of the existing threshold proxy signature schemes reveal that the receiver cannot find out who signed the proxy signatures. We propose an efficient (t, n) threshold proxy signature scheme based on Schnorr’s scheme. Compared with existing (t, n) threshold proxy signature schemes, our scheme can reduce the amount of computations and communications. In our method, not only the original signer can know who generated the proxy signature, but also the receiver can certify the actuality of the group signers who made the proxy signature. We offer convenience and fair distribution of auditing a document’s signers.     

In2O3 + xBaO (x = 0.5-5 at.%) - A novel material for trace level detection of NOx in the ambient

Indium oxide (In₂O₃) doped with 0.5-5 at.% of Ba was examined for their response towards trace levels of NO_x in the ambient. Crystallographic phase studies, electrical conductivity and sensor studies for NO_x with cross interference for hydrogen, petroleum gas (PG) and ammonia were carried out. Bulk compositions with x ≤ 1 at.% of Ba exhibited high response towards NO_x with extremely low cross interference for hydrogen, PG and ammonia, offering high selectivity. Thin films of 0.5 at.% Ba doped In₂O₃ were deposited using pulsed laser deposition technique using an excimer laser (KrF) operating at a wavelength of (λ) 248 nm with a fluence of ∼3 J/cm² and pulsed at 10 Hz. Thin film sensors exhibited better response towards 3 ppm NO_x quite reliably and reproducibly and offer the potential to develop NO_x sensors (Threshold limit value of NO₂ and NO is 3 and 25 ppm, respectively).     

Oriented growth of A2Te3 (A = Sb, Bi) films and their devices with enhanced thermoelectric performance

Oriented thermoelectric (TE) p-Sb₂Te₃ and n-Bi₂Te₃ thin films with special nanostructures have been synthesized by a simple vacuum thermal evaporation technique. The composition and microstructure of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), presenting a well preferential crystal growth with dense slender columnar grains grown perpendicular to the substrate, and energy dispersive X-ray spectrum (EDX) indicating the compositions distribution in the films. The electric transport properties, i.e., conductivity and Seebeck coefficient, and the thermal transportation of the oriented films show optimized properties. Prototype devices were built up by p and n elements in series and parallel circuits. The largest output power and cooling could be achieved in Sb₂Te₃ parallel device with P_max = 6.51 μW at ΔT = 106 K, and cooling of 4.1 K at 2 V. The 24-pair p-n couples series device could output maximum voltage of 313 mV at ΔT = 102 K. The power generation and the cooling of the devices show times enhanced TE performances than those consisting of common films. The results proved that introducing nanostructures into films is an effective choice to obtain high-efficient micro TE device.