Study of Manufacturing Thermochromic Wood

The development of new materials such as thermochromic wood provides an interesting option for the forest products industry. Poplar veneer was colored by ultrasonic impregnation using a thermochromic agent consisting of thermochromic dye, a chromogenic agent, 1-tetradecanol, and a sensitizing agent. In optimizing the process, the most significant influence on the extent of sample color change (ΔE) was found to be the mixing ratio of thermochromic dye to chromogenic agent. Next was the mixing ratio of thermochromic dye to 1-tetradecanol and last that of thermochromic dye to sensitizing agent. Analysis of 0variance showed that the influences of all experimental parameters on ΔE were significant at the 0.01 level. The optimum mixing ratio of thermochromic dye, the chromogenic agent, 1-tetradecanol, and the sensitizing agent was 1:8:50:1. The color of these new products changed from blue to wood color as temperature increased 26-34°C and reverted from normal wood color to blue as temperature decreased from 34-26°C

Adaptive Active Anti-vibration Control for a Three-dimensional Helicopter Flexible Slung-load System with Input Saturations and Backlash

This study investigates active anti-vibration control for a three-dimensional helicopter flexible slung-load system (HFSLS) subject to input saturations and backlash. The first target of the study is to establish a model for a three-dimensional HFSLS. The second target is to develop an adaptive control law for a HFSLS by analyzing its ability to compensate for the effects of input saturations, input backlash, and external disturbances, while achieving the goal of vibration reduction. Simulation results of the numerical show that the proposed adaptive active control technology is effective in solving the oscillation suppression problem for the three-dimensional HFSLS with input saturations and backlash.</p

Observer-based fuzzy tracking control for an unmanned aerial vehicle with communication constraints

We investigate the trajectory tracking problem of underactuated aerial vehicles with unknown mass in the presence of unknown non-vanishing disturbances using an event-triggered approach, while considering the constraint that the derivative of the reference trajectory is not available. In contrast to existing references where the derivative of the reference trajectory is needed, here we first introduce a high-gain observer to estimate the unknown derivative solely from the reference trajectory. A disturbance observer is designed to compensate for non-vanishing disturbances, such as wind, etc. Fuzzy logic systems are used to approximate the model uncertainty arising from the unknown mass of the vehicle, and then we derive a thrust command law that follows from a desired stabilizing force. Additionally, unlike traditional fixed and relative threshold strategies that rely solely on control signals, we develop a new time-varying eventtriggered mechanism linked to the performance of the controlled system, taking into account factors such as tracking errors, to develop angular velocity commands, enhancing tracking accuracy while efficiently conserving communication resources, especially in the absence of Zeno behavior. We present simulation results to demonstrate the efficacy of the proposed approach and validate the theoretical findings.</p

Improved bulk density of bamboo pellets as biomass for energy production

To the best of our knowledge, there is the lack of sufficient information concerning bamboo pellets. In the preliminary research, bamboo pellets showed a low bulk density which could not meet requirement of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified (PFI). To improve its bulk density, pellets were manufactured using mixtures of bamboo and pine particles and the properties were investigated. It was found that adding pine particles to bamboo particles was an effective way to improve bulk density of bamboo pellets. When adding 40% pine particles to bamboo particles, bulk density of pellets increased from 0.54 g/cm3 to 0.60 g/cm3, meeting grade requirement of PFI utility. Furthermore, length, diameter and inorganic ash of pellets were also improved. Fine contents of pellets decreased from premium grade to utility grade according to PFI standard. Net calorific value also slightly decreased but it could meet the requirement of DIN 51731 (\u3e17,500 J/g). The effect of this interaction on bulk density, inorganic ash, Net calorific value, combustion rate and heat release rate were significant. The results from this research will be very helpful to develop bamboo pellets and provide guidelines for further research

Discovery of two new hypervelocity stars from the LAMOST spectroscopic surveys

We report the discovery of two new unbound hypervelocity stars (HVSs) from the LAMOST spectroscopic surveys. They are respectively a B2V type star of ~ 7 M$_{\rm \odot}$ with a Galactic rest-frame radial velocity of 502 km/s at a Galactocentric radius of ~ 21 kpc and a B7V type star of ~ 4 M$_{\rm \odot}$ with a Galactic rest-frame radial velocity of 408 km/s at a Galactocentric radius of ~ 30 kpc. The origins of the two HVSs are not clear given their currently poorly measured proper motions. However, the future data releases of Gaia should provide proper motion measurements accurate enough to solve this problem. The ongoing LAMOST spectroscopic surveys are expected to yield more HVSs to form a statistical sample, providing vital constraint on understanding the nature of HVSs and their ejection mechanisms.Comment: 5 pages, 3 figures, 1 table, accepted for publication in ApJ

Improved bulk density of bamboo pellets as biomass for energy production

To the best of our knowledge, there is the lack of sufficient information concerning bamboo pellets. In the preliminary research, bamboo pellets showed a low bulk density which could not meet requirement of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified (PFI). To improve its bulk density, pellets were manufactured using mixtures of bamboo and pine particles and the properties were investigated. It was found that adding pine particles to bamboo particles was an effective way to improve bulk density of bamboo pellets. When adding 40% pine particles to bamboo particles, bulk density of pellets increased from 0.54 g/cm3 to 0.60 g/cm3, meeting grade requirement of PFI utility. Furthermore, length, diameter and inorganic ash of pellets were also improved. Fine contents of pellets decreased from premium grade to utility grade according to PFI standard. Net calorific value also slightly decreased but it could meet the requirement of DIN 51731 (\u3e17,500 J/g). The effect of this interaction on bulk density, inorganic ash, Net calorific value, combustion rate and heat release rate were significant. The results from this research will be very helpful to develop bamboo pellets and provide guidelines for further research