A post-processing method for true random number generators based on hyperchaos with applications in audio-based generators

True random number generators (TRNG) are important counterparts to pseudorandom number generators (PRNG), especially for high security applications such as cryptography. They produce unpredictable, non-repeatable random sequences. However, most TRNGs require specialized hardware to extract entropy from physical phenomena and tend to be slower than PRNGs. These generators usually require post-processing algorithms to eliminate biases but in turn, reduces performance. In this paper, a new post-processing method based on hyperchaos is proposed for software-based TRNGs which not only eliminates statistical biases but also provides amplification in order to improve the performance of TRNGs. The proposed method utilizes the inherent characteristics of chaos such as hypersensitivity to input changes, diffusion, and confusion capabilities to achieve these goals. Quantized bits of a physical entropy source are used to perturb the parameters of a hyperchaotic map, which is then iterated to produce a set of random output bits. To depict the feasibility of the proposed post-processing algorithm, it is applied in designing TRNGs based on digital audio. The generators are analyzed to identify statistical defects in addition to forward and backward security. Results indicate that the proposed generators are able to produce secure true random sequences at a high throughput,which in turn reflects on the effectiveness of the proposed post-processing method.     

Conductive biodegradable film of N-octyloxyphenyl-N′-(4-methylbenzoyl)thiourea

Thiourea derivatives are versatile family of ligands which provides wide range of electronic properties since they consist of rigid π-systems on their structures. In this work, a new type of thiourea compound with general formula Me-C₆H₄C(O)NHC(S)NHC₆H₄-OC₈H₁₇ of N′-(4-methylbenzoyl)thiourea (MBTU) was successfully synthesised and characterized by using NMR, FTIR and UV–vis analysis. The development of new conductive biodegradable film based on MBTU has been accomplished by incorporating chitosan to the polymer-dopant system via solution-cast technique. The impedance measurement technique was employed to determine conductivity of biodegradable film. It shows that, with the addition of MBTU, the increasing of conductivity is from 10 ^?9 to 10 ^?8 Scm ^?1 . TNM results show that the conductivity of biodegradable film is governed by electronic conducting species. It is proven that MBTU compound exhibits promise and has great potential to be explored and used as doping system in conductive materials application in the future.     

水下搅拌摩擦焊接:一种具有改善接头性能巨大潜力的搅拌摩擦焊接新方法（英文）

搅拌摩擦焊接(FSW)是一种固态焊接方法,它能够焊接普通熔焊过程难以焊接的材料;且与熔焊相比,具有高效节能和环境友好的特点。尽管FSW与熔焊相比有更多的优点,但是FSW过程中的热循环会溶解或者粗化热处理铝合金中的沉淀强化相,使接头软化,从而导致其力学性能下降。水下搅拌摩擦焊接(UFSW)是一种可以克服这些缺陷的方法。这种方法适合于在焊接过程中对热敏感的合金,且已广泛用于热处理铝合金。本文对UFSW的研究现状和发展提供了全面的文献综述。与FSW进行对比,从不同角度讨论和总结UFSW的重要性;并对材料流动、温度变化、工艺参数、显微组织和力学性能等基本原理进行详细阐述。结果表明,与FSW相比,UFSW是一种可以改善接头强度的新方法。     

Characterization of carboxy methylcellulose doped with DTAB as new types of biopolymer electrolytes

The investigation of new solid biopolymer electrolyte (BEs) system based on carboxy methylcellulose (CMC) is creating opportunity for new types of electrochemical devices, which may themselves, in turn, revolutionize many industrial areas. Biodegradable carboxy methylcellulose (CMC) doped with dodecyltrimethyl ammonium bromide (DTAB) as BEs were prepared via solution-casting method. Upon addition of 35 wt. % of DTAB, highest ionic conductivity of 7·72 × 10^???4 Scm^???1 was achieved due to its higher amorphous region compared to other samples prepared. This result had been further proven in FTIR study. Temperature dependence relationship obeys the Arrhenius rule from which the activation energy, E _a, for ionic conductivity and activation energy for relaxation process, E _τ , were evaluated. The divergent values between E _a for ionic conductivity and relaxation process E _τ shows that the ions hop by jumping over a potential barrier.     

Review on underwater friction stir welding: A variant of friction stir welding with great potential of improving joint properties

Friction stir welding (FSW) is a solid-state welding process which is capable of joining materials which are relatively difficult to be welded by fusion welding process. Further, this process is highly energy-efficient and environmental-friendly as compared to the fusion welding. Despite several advantages of FSW over fusion welding, the thermal cycles involved in FSW cause softening in joints generally in heat-treatable aluminum alloys (AAs) due to the dissolution or coarsening of the strengthening precipitates leading to decrease in mechanical properties. Underwater friction stir welding (UFSW) can be a process of choice to overcome these limitations. This process is suitable for alloys that are sensitive to heating during the welding and is widely used for heat-treatable AAs. The purpose of this article is to provide comprehensive literature review on current status and development of UFSW and its importance in comparison to FSW with an aim to discuss and summarize different aspects of UFSW. Specific attention is given to basic principle including material flow, temperature generation, process parameters, microstructure and mechanical properties. From the review, it is concluded that UFSW is an improved method compared with FSW for improving joint strength. Academicians, researchers and practitioners would be benefitted from this article as it compiles significantly important knowledge pertaining to UFSW.