Effects Of Dominant Parameters Research Articles

Temperature controlled quasi-zero-stiffness metamaterial beam for broad-range low-frequency band tuning

Despite their engineering significance, locally resonant metamaterials are facing the challenge to cope with the need for broad-range band gap adjustment at low-frequencies. To tackle this problem, this study proposes using shape memory alloys (SMAs) to achieve temperature-controlled quasi-zero-stiffness (TC-QZS) metamaterial beam, which entails tunable and low-frequency band gap through ambient temperature changes. The basic configuration of the proposed TC-QZS resonator embraces a negative mechanism, steming from an SMA and a nonlinear geometrical structure. The stiffness of the positive stiffness mechanism can be effectively neutralised by the negative one, and the neutralisation can be adjusted based on temperature change applied to the SMA. The resultant stiffness variation yields broad-range tunability of the resonant frequency of the TC-QZS resonator. The band gap structure of the metamaterial beam is obtained using the transfer matrix method and verified by numerical simulation. Effects of dominant parameters on band gaps are scrutinized. Results show that the frequency range of the band gap can be continuously tuned from 26 to 69 Hz. This study provides guidance for the realisation of band gap tunibility over a wide frequnecy range and lays the groundwork for the development of elastic wave manipulation and vibration isolation.

Modified Peanut Shell as an Eco-Friendly Biosorbent for Effective Extraction of Triazole Fungicide Residues in Surface Water and Honey Samples before Their Determination by High-Performance Liquid Chromatography.

An eco-friendly sample preparation method that is based on the use of a modified peanut shell as an efficient biosorbent for the extraction of triazole residues before their analysis by high-performance liquid chromatography was reported. The four triazole fungicides were separated on a Purospher STAR RP-18 endcapped (4.6 × 150 mm, 5 μm) column with a mobile phase of 50% (v/v) acetonitrile at a flow rate of 1.0 mL min–1 and detection wavelength set at 220 nm. Peanut shells modified by didodecyldimethylammonium bromide were selected as an effective biosorbent material in the microextraction method. Scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy were used to characterize the biosorbent. The effect of dominant parameters on the proposed microextraction method including the amount of sorbent, kind and concentration of surfactant, sodium hydroxide concentration, kind and amount of salt, sample volume, adsorption time, kind and volume desorption solvent, and desorption time was studied. Under the optimum condition, a good analytical performance for the proposed microextraction method was obtained with a wide linear range within the range of 9–1000 μg L–1, and low limits of detection (0.03 μg L–1 for all analytes) were obtained. Enrichment factors were achieved within the range of 30–51. The intra and interday precision values were evaluated in terms of percentage relative standard deviations (%RSD) and were less than 0.09 and 5.34% for the retention time and peak area, respectively. The proposed microextraction methods were used for extraction and analysis of triazole fungicides in water and honey samples. The recoveries in a satisfactory range of 70.0–118.8% were obtained.

Effects of Dominant Parameters on Burning Velocity and Range of Flammability in SHS Process for Ti-Al System

Relevant to the self-propagating high-temperature synthesis (SHS) process for the Ti-Al system, burning velocity and the range of flammability are examined theoretically. The heterogeneous theory for SHS flame propagation, presented in the literature is used. It is found that the effects of particle size, mixture ratio, degree of dilution, and initial temperature on the burning velocity and/or the range of flammability are the same as those for other representative systems. It has been confirmed that even for the Ti-Al system, a parameter defined as a product of the burning velocity and the particle size can be useful in correlating experimental results for flame propagation. It has also been confirmed that a parameter defined as the square of particle size divided by the compact diameter can be useful in correlating experimental results for flame extinction. In addition, it has been demonstrated that a fair degree of agreement exists between theoretical results and experimental data in the literature, as far as the trend and approximate magnitude are concerned.

Effects of Dominant Parameters on the Burning Velocity and the Range of Flammability in the SHS Process for Ti-Al System

Relevant to Self-propagating High-temperature Synthesis (SHS) process for Ti-Al system, burning velocity and range of flammability are examined theoretically. Use has been made of the heterogeneous theory for the SHS flame propagation, presented in the literature. It is found that effects of particle size, mixture ratio, degree of dilution, and initial temperature on the burning velocity and/or the range of flammability are the same as those for other representative systems. It has been confirmed that even for the Ti-Al system, a parameter defined as a product of the burning velocity and the particle size can be useful in correlating experimental results for the flame propagation. It has also been confirmed that a parameter defined as the square of particle size divided by the compact diameter can be useful in correlating experimental results for the flame extinction. In addition, it has been demonstrated that a fair degree of agreement exists between theoretical results and experimental data in the literature, as far as the trend and approximate magnitude are concerned.