Attrition of Victorian brown coal during drying in a fluidized bed

Analyzing the attrition of Victorian brown coal during air and steam fluidized bed drying, the change in particle size distribution over a range of initial moisture contents (60% to 0%) and residence times (0 to 60 minutes) was determined. Dried at a temperature of 130°C with a fluidization velocity 0.55 m/s and an initial particle size of 0.5–1.2 mm, both fluidization mediums show a shift in the particle size distribution between three and four minutes of fluidization, with a decrease in mean particle size from 665 µm to around 560 µm. Using differential scanning calorimetry (DSC), the change in particle size has been attributed to the transition between bulk and non-freezable water (approximately 55% moisture loss) and can be linked to the removal of adhesion water, but not to fluidization effects. This is proved through the comparison of air fluidized bed drying, steam fluidized bed drying, and fixed bed drying—the fixed bed drying is being used to determine the particle size distribution as a function of drying. The results show the three drying methods produce similar particle size distributions, indicating that both fluidization and fluidization medium have no impact upon the particle size distribution at short residence times around ten minutes. The cumulative particle size distribution for air and steam fluidized bed dried coal has been modeled using the equation P_d = A₂ + (A₁ ? A₂)/(1 + (d/x₀)^p), with the resultant equations predicting the effects of moisture content on the particle size distribution. Analyzing the effect of longer residence times of 30 and 60 minutes, the particle size distribution for steam fluidized bed dried coal remains the same, while air fluidized bed dried coal has a greater proportion of smaller particles.     

Terahertz scanning techniques for paint thickness on CFRP composite solid laminates

Terahertz ray (T-ray) scanning applications are promising tools. The use of T-ray for nondestructive evaluation was investigated on composite materials. In this characterization procedure, electromagnetic properties, such as the refractive index, were analyzed. The estimates of properties are in good agreement with known data. We successfully demonstrated the characteristics of T-ray propagating through Carbon fiber-reinforced plastic (CFRP) composites to acquire the refractive index by using the characterized material properties. A T-ray technique was developed for measuring paint thickness on CFRP laminates. Good results were obtained from tests performed on standard paint samples with thickness starting from approximately 100 μm. The method was based on reflection mode measurement with time of flight. Another method developed for measuring paint thickness using resonance frequencies was utilized to determine paint thickness on composite laminates. The paint thickness deduced from resonance frequencies agrees well with the result obtained directly from time-domain echoes.     

Tool and process design for progressive forming of an automotive bracket part using finite element analysis

This paper deals with the design procedure of the tool and process for automotive bracket part fabrication. Finite element analysis is introduced to the progressive process to investigate the causes of defects that occur during the forming and bending stages. This paper proposes a new guideline for the progressive process design that modifies the intermediate stages in the progressive process. Finite element analysis and pilot tests are performed again using new strip layout and tool shapes to confirm the validity of the proposed process design. The analysis result shows that the modified process design eliminates defects such as non-uniform thickness distribution and initiation of crack. Then, the automotive bracket part is successfully fabricated through pilot tests using the progressive tools designed in accordance with the proposed guideline.     

Model test assessment of the generation of underground cavities and ground cave-ins by damaged sewer pipes

Ground cave-ins caused by damaged sewer pipes have been frequently reported in metropolitan areas and have caused severe socioeconomic losses. In this study, model experiments were conducted to determine how damaged sewer pipes generate ground cave-ins or cavities, with a focus on the influence of the soil type and density. Digital images of the model ground were captured to evaluate the internal deformation of the model grounds. Additionally, the vertical displacement at the surface, the size of the cavity, and the weight of the discharged soil were measured in each test. The results indicate that uniform soil with no fines content was more vulnerable to ground cavities than well-graded soil with fines content. Loose soil led to a ground cave-in with significant deformation over the entire model ground, whereas deformation was concentrated only on the ground cavities in the dense soil ground.     

Wetting characteristics of a water droplet on solid surfaces with various pillar surface fractions under different conditions

A numerical study was carried out using a molecular dynamics program to examine the wetting characteristics of nano-sized water droplets on surfaces with various pillar surface fractions under different conditions. Square-shaped pillars had surface fractions that increased from 11.1 % to 69.4 %. The pillars had 4 different heights and 3 different surface energies. When the pillar surface fraction changed, the contact angle of a water droplet also changed due to the attraction between the droplet and the pillar surface or the inner attraction of the water molecules. The pillar height also has different effects on the water droplet depending on the magnitude of surface energy.     

Developing a big data analytics platform for manufacturing systems: architecture,method, and implementation

Manufacturing industries have recently promoted smart manufacturing (SM) for achieving intelligence, connectedness, and responsiveness of manufacturing objects consisting of man, machine, and material. Traditional manufacturing platforms, which identify generic frameworks where common functionalities are shareable and diverse applications are workable, mainly focused on remote collaboration, distributed control, and data integration; however, they are limited to incorporating those characteristic achievements. The present work introduces an SM-toward manufacturing platform. The proposed platform incorporates the capabilities of (1) virtualization of manufacturing objects for their autonomy and cooperation, (2) processing of real and various manufacturing data for mediating physical and virtual objects, and (3) data-driven decision-making for predictive planning on those objects. For such capabilities, the proposed platform advances the framework of Holonic Manufacturing Systems with the use of agent technology. It integrates a distributed data warehouse to encompass data specification, storage, processing, and retrieval. It applies a data analytics approach to create empirical decision-making models based on real and historical data. Furthermore, it uses open and standardized data interfaces to embody interoperable data exchange across shop floors and manufacturing applications. We present the architecture and technical methods for implementing the proposed platform. We also present a prototype implementation to demonstrate the feasibility and effectiveness of the platform in energy-efficient machining.     

Evaluation of Oxygen-Limitation on Lipid Oxidation and Moisture Content in Corn Oil at Elevated Temperature

The role of oxygen-limitation on lipid oxidation and moisture content were tested in corn oil heated to 60, 100, and 140 °C. The degree of oxidation was determined by analyzing headspace oxygen content, conjugated dienoic acids (CDA), and p-anisidine value (p-AV). The moisture content in bulk oil was analyzed by the Karl Fischer method. Oxygen-limited samples heated to 100 and 140 °C had significantly more lipid oxidation than oxygen-unlimited samples at early timepoints (p < 0.05). After this period, the oxygen-unlimited samples had more lipid oxidation based on CDA and p-AV assays. During those initial periods, oxygen-limited samples had significantly higher moisture content than oxygen-unlimited samples (p < 0.05), which implies that moisture content in oils plays an important role in the rate of lipid oxidation. The increased moisture content in bulk oil under oxygen-limited conditions is due to headspace moisture rather than moisture inside the oil. However, the effects of oxygen-limitation on lipid oxidation were less clear at 60 °C than at 100 or 140 °C.     

Water-soluble PPV and C60 nanocomposite with enhanced miscibility and enhanced photo-induced charge transfer through ground state electrostatic interactions

We report the preparation of highly charged nanocomposites comprised of water-soluble, anionic fullerene and cationic poly-phenylenevinylene (PPV) derivatives. The nanocomposites display high fluorescence quenching efficiency (99%) presumably due to enhanced miscibility between cationic PPV and anionic C₆₀ via electrostatic interactions. We show that complexation between the cationic PPV and anionic C₆₀ derivatives leads to formation of nanocomposites with optical and electronic properties distinct from individual components without preferential electrostatic interactions. Photo-induced charge transfer quenches fluorescence from the PPV component is consistent with the frontier energy offsets of PPV and C₆₀, and cyclic voltammetry and UV–Vis spectroscopy measurements. This result confirms high miscibility between donor and acceptor and resonance Raman spectra indicate a conformational changes of the PPV backbone upon complex formation.     

Leaching kinetics of neodymium in sulfuric acid from E-scrap of NdFeB permanent magnet

The leaching kinetics of neodymium in NdFeB permanent magnet powder was analyzed for the purpose of recovery of neodymium in sulfuric acid (H₂SO₄) from E-scrap (electric scrap) of NdFeB permanent magnet powder treated by oxidation roasting to form a reactant. The reaction was conducted with H₂SO₄ concentrations ranging from 2.5 to 3.5M, a pulp density of 110.8 g/L, an agitation speed of 750 rpm, and a temperature range of 30 to 70 °C. After 4 h of leaching, the neodymium content in the E-scrap powders was completely converted into a neodymium sulfate (Nd₂(SO₄)₃) solution phase in H₂SO₄ in the condition of 70 °C and 3.0M H₂SO₄. Based on a shrinking core model with sphere shape, the leaching mechanism of neodymium was determined by the rate-determining step of the ash layer diffusion. Generally, the solubility of pure rare earth elements in H₂SO₄ is decreased with an increase in leaching temperatures. However, the leaching rate of the neodymium in E-scrap powders increased with the leaching temperatures in this study because the ash layer included in the E-scrap powder provided resistance against the leaching. Using the Arrhenius expression, the apparent activation energy values were determined to be 2.26 kJmol^?1 in 2.5M H₂SO₄ and 2.77 kJmol^?1 in 3.0 M H₂SO₄.     

Microstructure and electrical conductivity of Mo/TiN composite powder for alkali metal thermal to electric converter electrodes

A Mo/TiN composite powder has been synthesized by a sol–gel method to improve the electrical performance and microstructural stability of the alkali metal thermal to electric converter electrode. The core (TiN)–shell (Mo) structure of the composite powder is confirmed by energy-dispersive X-ray spectroscopy and scanning electron microscopy. The composite powder is primarily composed of submicron (400–800 nm) particles that are coated on a core (>3–5 μm) particle. The Mo/TiN composite electrode exhibits high electrical conductivities of 1000 Scm⁻¹ at 300 °C and 260 Scm⁻¹ at 700  °C in an Ar atmosphere. The electrode exhibits excellent tolerance against grain growth during thermal cycling tests (R.T.↔800 °C), where the average growth rate of Mo grains in the Mo/TiN composite electrodes is controlled less than 0.5%/time (0.62→0.65 μm), while the growth rate in Mo electrodes is 306.7%/time (0.24→3.92 μm). It can be concluded that the Mo/TiN composite powder will suppress the degradation of the electrode and enhance the performance and durability of the unit cell at elevated temperatures.