Transformation from 512-point transform coefficients to 256-pointtransform coefficients for Dolby AC-3 decoder

The Dolby AC-3 standard defines 512-point and 256-point transforms to provide high audio quality when signals rapidly change in time. This authors provide theoretical derivations and proofs for the transformation from 512-point transform coefficients to 256-point transform coefficients     

Thermal polymerization of uninhibited styrene investigated by using microcalorimetry

Calorimetric studies on the bulk polymerization of uninhibited styrene monomer under low temperature conditions from 50 to 85 degrees C were reported. Various thermograms acquired by either dynamic scanning or isothermal ageing were characterized by differential scanning calorimetry (DSC) or thermal activity monitor (TAM). Isothermal curve demonstrating an autocatalytic phenomenon associated with a characteristic induction time was detected. Heat of thermal polymerization of styrene between 50 and 85 degrees C was measured to be 670+/-11 J g(-1). The findings of this study include: (1) Exothermic phenomenon of thermal-initiation and chain transfer steps in thermal polymerization were corroborated by using calorimetric investigation extended to the temperature as low as 50 degrees C; (2) activation energies in the steps of thermal-initiation and chain transfer were determined to be 125+/-6 and 60+/-5 kJ mol(-1) by using Arrhenius plot, respectively; (3) apparent activation energy was verified to be 84 kJ mol(-1) related to the individual steps of thermal-initiation and chain transfer conformed. These kinetic parameters work well in simulating the adiabatic runaway behaviors of uninhibited styrene and in good agreement with other studies.     

Characterization and bond strength of electrolytic HA/TiO<Subscript>2</Subscript> double layers for orthopaedic applications

Insufficient bonding of juxtaposed bone to an orthopaedic/dental implant could be caused by material surface properties that do not support new bone growth. For this reason, fabrication of biomaterials surface properties, which support osteointegration, should be one of the key objectives in the design of the next generation of orthopaedic/dental implants. Titanium and titanium alloy have been widely used in several bioimplant applications, but when implanted into the human body, these still contain some disadvantages, such as poor osteointegration (forming a fibrous capsule), wear debris and metal ion release, which often lead to clinical failure. Electrolytic hydroxyapatite/titanium dioxide (HA/TiO₂) double layers were successfully deposited on titanium substrates in TiCl₄ solution and subsequently in the mixed solution of Ca(NO₃)₂ and NH₄H₂PO₄, respectively. After annealing at 300∘C for 1 h in the air, the coated specimens were evaluated by dynamic cyclic polarization tests, immersion tests, tensile tests, surface morphology observations, XRD analyses and cells culture. The adhesion strength of the HA coating were improved by the intermediate coating of TiO₂ from 11.3 to 46.7 MPa. From cell culture and immersion test results, the HA/TiO₂ coated specimens promoted not only cells differentiation, but also appeared more bioactive while maintaining non-toxicity.     

Characterization and bond strength of electrolytic HA/TiO2 double layers for orthopedic applications

Insufficient bonding of juxtaposed bone to an orthopedic/dental implant could be caused by material surface properties that do not support new bone growth. For this reason, fabrication of biomaterials surface properties, which support osteointegration, should be one of the key objectives in the design of the next generation of orthopedic/dental implants. Titanium and titanium alloy have been widely used in several bioimplant applications, but when implanted into the human body, these still contain some disadvantages, such as poor osteointegration (forming a fibrous capsule), wear debris and metal ion release, which often lead to clinical failure. Electrolytic hydroxyapatite/titanium dioxide (HA/TiO2) double layers were successfully deposited on titanium substrates in TiCI4 solution and subsequently in the mixed solution of Ca(NO3)2 and NH4H2PO4, respectively. After annealing at 300°C for 1 h in the air, the coated specimens were evaluated by dynamic cyclic polarization tests, immersion tests, tensile tests, surface morphology observations, XRD analyses and cells culture. The adhesion strength of the HA coating were improved by the intermediate coating of TiO2from 11.3 to 46.7 MPa. From cell culture and immersion test results, the HA/TiO2 coated specimens promoted not only cells differentiation, but also appeared more bioactive while maintaining non-toxicity.     

Self-Steering Lasing System Enabled by Flexible Photo-Actuators with Sandwich Structure

With the flourishing development of artificial intelligence, lasing with tailored features generated by photonic crystal (PhC) lasers has been playing a more important part in the optics field and in potential applications of self-control, light detection and ranging, telecommunications, and holography imaging. As an information vehicle, the optical beam's maneuverability is influenced by the working wavelength, direction, and efficiency of the laser. Liquid crystal (LC)-based mirrorless lasers are widely investigated in manipulating the tuning of emission wavelength. Realizing fast self-steering of the laser beam to tune the emission direction is challenging because of the limitation on the complex and expensive inorganic fabrication and circuit design. In this work, a self-steered lasing from a defect-mode sandwich film composed of photomechanical deformable azobenzene cholesteric LC elastomer (CLCE) PhC layers and an isotropic gain interlayer is demonstrated. On the basis of the great light-deformability of the CLCE, the output single-mode lasing emission of the sandwich-film laser can be steered quickly by UV irradiation in a wide angular tuning range of ≈±57°. This flexible, portable, and durable laser system with controllable beam-steering and mechanical robustness is envisioned to open a gate for autonomous vehicles, self-sustaining machines, and optical devices with the core feature of photomechanical conversion.     

Dust cloud explosion characteristics and mechanisms in MgH2-based hydrogen storage materials

The mechanisms involved in premixed magnesium and hydrogen hybrid and synthetic MgH₂ dust cloud explosions were investigated. The results revealed that trace amounts of H₂ in Mg explosions can markedly increase explosion severity. Furthermore, H₂ addition can weaken the influence of oxygen deficiency on Mg explosion. Moreover, the explosion intensity of synthetic MgH₂ was far stronger than that of premixed Mg/H₂ mixture or Mg alone because the vacancy defects in Mg and H atoms can form after dehydrogenation of MgH₂, which caused that Mg and H₂ are prone to oxidation and nitrification in air atmosphere at a low temperature, thereby promoting the explosion. This demonstrates that the explosion risk of MgH₂ (even other H₂ storage materials) is related to its H₂ storage capacity and dehydrogenation temperature. Therefore, for H₂ storage materials, the better H₂ storage performances can exhibit higher explosion risks.     

Thermal explosion hazards on 18650 lithium ion batteries with a VSP2 adiabatic calorimeter

Thermal abuse behaviors relating to adiabatic runaway reactions in commercial 18650 lithium ion batteries (LiCoO₂) are being studied in an adiabatic calorimeter, vent sizing package 2 (VSP2). We select four worldwide battery producers, Sony, Sanyo, Samsung and LG, and tested their Li-ion batteries, which have LiCoO₂ cathodes, to determine their thermal instabilities and adiabatic runaway features. The charged (4.2 V) and uncharged (3.7 V) 18650 Li-ion batteries are tested using a VSP2 with a customized stainless steel test can to evaluate their thermal hazard characteristics, such as the initial exothermic temperature (T₀), the self-heating rate (dT/dt), the pressure rise rate (dP/dt), the pressure-temperature profiles and the maximum temperature (T_max) and pressure (P_max). The T_max and P_max of the charged Li-ion battery during the runaway reaction reach 903.0 °C and 1565.9 psig (pound-force per square inch gauge), respectively. This result leads to a thermal explosion, and the heat of reaction is 26.2 kJ. The thermokinetic parameters of the reaction of LiCoO₂ batteries are also determined using the Arrhenius model. The thermal reaction mechanism of the Li-ion battery (pack) proved to be an important safety concern for energy storage. Additionally, use of the VSP2 to classify the self-reactive ratings of the various Li-ion batteries demonstrates a new application of the adiabatic calorimetric methodology.