Phase‐Changeable Fatty Acid Available for Temperature‐Regulated Drug Release

This paper describes a mixture of fatty acids that is available for temperature‐controlled release of drugs. The mixture consists of two fatty acids with different melting points. At a specific composition, the mixture represents a single melting point of 38–40 °C which is slightly above the normal human body temperature. To demonstrate its use in the temperature‐regulated release, this study fabricates fatty acid‐incorporated polymer fibers containing dye‐loaded polymer particles in their core. Below the melting point of the mixture, it will be in a solid state to restrict the passing of dye loaded in the core whereas the dye can be released instantly through the generated pores at a temperature slightly higher than the melting point. The release profiles of the dye can be further manipulated by varying the amount of the mixture contained in the fibers and the composition of the mixture.

     

Nanofiber‐Based Hydrocolloid from Colloid Electrospinning Toward Next Generation Wound Dressing

Nanofiber‐based hydrocolloid scaffold is prepared by colloid electrospinning of thermoplastic polyurethane (TPU)/sodium carboxymethyl cellulose (S.CMC) in tetrahydrofuran (THF)/dimethylformamide (DMF). The most suitable process of electrospinning for successful formation of fibers is investigated by controlling the concentration of polymeric solution and co‐solvent ratio. In order to accomplish high wettability, the amount of colloid (S.CMC) and the co‐solvent ratio (THF/DMF), which affects the morphology of fibers, are adjusted. Finally, the open wound healing effect is confirmed using nanofiber‐hydrocolloid from in vivo animal studies. A detailed study of the wound healing process is also demonstrated for the first time.

     

Synthesis,characterization, and application of oligomer‐type‐based phosphites

Organic alkyl and aryl phosphites are effective antioxidants and photostabilizers with applications in a wide range of polymers. The primary role of phosphites is to decompose hydroperoxide. However, aryl phosphites are also capable of reacting as antioxidants by affecting the kinetics. In particular, oligomer‐type phosphites have a greater effect on polymer degradation because of their high compatibility, reactivity, and solubility with almost all polymers. Generally, phosphites are sensitive to hydrolysis. In order to overcome this hydrolytic sensitivity in phosphites, a novel hydrolytically stable oligomeric phosphite incorporating a sterically hindered aromatic alcohol (2,4‐di‐tert‐butyl‐6‐methylphenol) that gives hydrolytic stability to the phosphite was synthesized and characterized, and its performance as an antioxidant for polypropylene was investigated. J. VINYL ADDIT. TECHNOL., 22:146–155, 2016. © 2014 Society of Plastics Engineers     

Trajectory generation to suppress oscillations in under-constrained cable-driven parallel robots

Cable-driven parallel robots (CDPRs) have many advantages over conventional link-based robot manipulators in terms of acceleration due to their low inertia. This paper concerns about under-constrained CDPRs, which have a less number of cables than six, often used favorably due to their simpler structures. Since a smaller number of cables than 6 are employed, however, their payloads have extra degrees of motion freedom and exhibit swaying motions or oscillation. In this paper, a scheme to suppress unwanted oscillatory motions of the payload of a 4-cable-driven CDPR based on a Zero-vibration (ZV) input-shaping scheme is proposed. In this method, a motion in the 3-dimensional space is projected onto the independent motions on two vertical planes perpendicular to each other. On each of the vertical plane, the natural frequency of the CDPR is computed based on a 2-cable-driven planar CDPR model. The precise dynamic model of a planar CDPR is obtained in order to find the natural frequency, which depends on the payload position. The advantage of the proposed scheme is that it is possible to generate an oscillation-free trajectory based on a ZV input-shaping scheme despite the complexity in the dynamics of the CDPR and the difficulty in computing the natural frequencies of the CDPR, which is required in any ZV input-shaping scheme. To verify the effectiveness of the proposed method, a series of computer simulations and experiments were conducted for 3- dimensional motions with a 4-cable-driven CDPR. Their results showed that the motions of the CDPR with the proposed method exhibited a significant reduction in oscillations of the payload. However, when the payload moves near the edges of its workspace, the improvement in oscillation reduction diminished as expected due to the errors in model projection.

     

Bioleaching of trace elements and rare earth elements from coal fly ash

International Journal of Coal Science & Technology - Coal fly ash originated from coal combustion has high concentrations of metals. If suitable leaching techniques are identified, then coal...     

Microstructure-Based Estimation of Strength and Ductility Distributions for $$\alpha +\beta $$ Titanium Alloys

Titanium alloys are processed to develop a wide range of microstructure configurations and therefore material properties. While these properties are typically measured experimentally, a framework for property prediction could greatly enhance alloy design and manufacturing. Here a microstructure-sensitive framework is presented for the prediction of strength and ductility as well as estimates of the bounds in variability for these properties. The framework explicitly considers distributions of microstructure via new approaches for instantiation of structure in synthetic samples. The parametric evaluation strategy, including the finite element simulation package FEpX, is used to create and test virtual polycrystalline samples to evaluate the variability bounds of mechanical properties in Ti-6Al-4V. Critical parameters for the property evaluation framework are provided by measurements of single crystal properties and advanced characterization of microstructure and slip system strengths in 2D and 3D. Property distributions for yield strength and ductility are presented, along with the validation and verification steps undertaken. Comparisons between strain localization and slip activity in virtual samples and in experimental grain-scale strain measurements are also discussed.

     

Flow characteristics of fresh air discharged from a ventilation duct for mine ventilation

Journal of Mechanical Science and Technology - Regarding mine ventilation in a tunnel with one mining face, the turbulent flow structure and Mean age of air (MAA) of fresh air discharged from the...     

A study on piezoelectric energy harvester using kinetic energy of ocean

Electricity generation through fossil fuels has caused environmental pollution. Accordingly, research on new renewable energy (solar, wind, geothermal heat, etc.) to replace fossil fuels and solve this problem is in progress. These devices can consistently generate power. However, they have several drawbacks, such as high installation costs and limitations in possible set-up environments. Therefore, the piezoelectric harvesting technology, which is able to overcome the limitations of existing energy technologies, is actively being studied. The piezoelectric harvesting technology uses the piezoelectric effect, which occurs in crystals that generate voltage when stress is applied. Its advantages include a wider installation base and a lower technological cost. This study investigated a piezoelectric energy-harvesting device based on constant wave motion. This device can harvest power in a constant turbulent flow in the middle of the sea. The components of the device are circuitry, percussion bar, triple layer piezoelectric bender, bearing and rudder. A multiphysical analysis coupled with the structure and piezoelectric elements was also conducted to estimate the device performance. The analysis accuracy was improved by applying the impact energy to the bender calculated based on the shape of the wave in the East Sea. The proposed device’s performance was finally confirmed by experiments.     

Experimental study on the life prediction of servo motors through model-based system degradation assessment and accelerated degradation testing

The advent of smart factories has resulted in the frequent utilization of industrial robots within factories to increase production automation and efficiency. Due to the increase in the number of industrial robots, it has become more important to prevent any unexpected breakdowns of the factory. As a result, the lifespan prediction of machinery has become a crucial factor because such failures can be directly associated with factory productivity resulting in significant losses. Most of the failures occur within one of the core components of the robot arm, the servo motor, and thus we will focus on the analysis of the servo motor in this study. However, sensor attachment to such equipment is considered difficult due to the dynamic movement of the robot arm, meaning that internal instrumentation should be utilized during analysis. In addition, no definite measure to determine the degradation of the motor exists, and thus a new degradation index is proposed in this study. Therefore, in this study, the lifespan of the servo motor will be estimated through accelerated degradation testing methods based on a new system degradation assessment method, which estimates the fault of the system using observer-based residuals with encoder data obtained from internal instrumentation.     

Dynamic analysis of the wind turbine drivetrain considering shaft bending effect

In the previous research, shaft torsional flexibility was only considered in the wind turbine drivetrain. However, if shaft is longer and thinner than other parts, two components which are connected by shaft affect each other by rotation about bending axis. It means that there are deflections of shaft about not only torsional direction but also bending direction. In this research, we introduced spherical joint which have 3 spring stiffness about all rotational axis to define shaft. And we analyzed that how shaft bending affect drivetrain rotation, translation motion and gear mesh contact force. To do these processes, we simulated the 3-dimensional wind turbine drive train model which has bearing stiffness, gear mesh stiffness, and shaft flexibility. The gear mesh stiffness was defined by Fourier series. And the equation of motion was acquired by Lagrange equation and kinematical constraints to represent shaft flexibility. About numerical analysis, the Newmark method was used to get results. Lastly, fast Fourier transform which converts results from time domain to frequency was used.