Additive manufacturing of PA12 carbon nanotube composites with a novel laser polymer deposition process

The facile manufacture of PA12 MWCNT/silica (50/50 by weight) nanocomposite powders through a high energy mixing process is presented, which are useful to generate 3D objects by a novel Laser Polymer Deposition (LPD) process. The mixing as well as the LPD process led to no discernible changes in the material properties (DSC, SEM, LD) of the core-shell nanocomposites, enabling the recycling of unconverted powder. The built parts yield ultimate tensile stresses and Young's modulus at 10%–20% of the bulk material. Partially unmolten particles and voids were identified as the main mechanical failure mechanism in the built parts. The mechanical properties are better with low additive content (Young's modulus: 89.8 ± 5.4 MPa; UTS: 12.9 ± 5.3 MPa with 0.25 wt% additives). Electronic conductivity up to the region of moderate conductivity could be achieved by multiwalled carbon nanotube (MWCNT) network formation (8 × 10⁻⁴ S cm⁻¹ at 1.25 wt% of additives). A variant of the processing strategy revealed that a higher mechanical strength can be achieved by a laser induced remelting of the traces following their initial construction.     

Illumination and voltage effects on the forward and reverse bias current–voltage (I-V) characteristics in In/In2S3/p-Si photodiodes

Journal of Materials Science: Materials in Electronics - The illumination and voltage effects on the I-V measurements of the fabricated In/In2S3/p-Si photodiode were investigated in dark and under...     

Multi-focus image fusion for different datasets with super-resolution using gradient-based new fusion rule

Multimedia Tools and Applications - Multi-focus image fusion methods combine two or more images which have blurred and defocused parts to create an all-in-focused image. All-in-focused image has...     

Line crack subject to antiplane shear

Field equations of nonlocal elasticity are solved to determine the state of stress in a plate with a line crack subject to a constant anti-plane shear. Contrary to the classical elasticity solution, it is found that no stress singularity is present at the crack tip. By equating the maximum shear stress that occurs at the crack tip to the shear stress that is necessary to break the atomic bonds, the critical value of the applied shear is obtained for the initiation of fracture. If the concept of the surface tension is used, one is able to calculate the cohesive stress for brittle materials.     

Understanding and managing disaster evacuation on a transportation network

Uncertain population behaviors in a regional emergency could potentially harm the performance of the region's transportation system and subsequent evacuation effort. The integration of behavioral survey data with travel demand modeling enables an assessment of transportation system performance and the identification of operational and public health countermeasures. This paper analyzes transportation system demand and system performance for emergency management in three disaster scenarios. A two-step methodology first estimates the number of trips evacuating the region, thereby capturing behavioral aspects in a scientifically defensible manner based on survey results, and second, assigns these trips to a regional highway network, using geographic information systems software, thereby making the methodology transferable to other locations. Performance measures are generated for each scenario including maps of volume-to-capacity ratios, geographic contours of evacuation time from the center of the region, and link-specific metrics such as weighted average speed and traffic volume.     

Controlled Generation of Solid Spheroidal Dielectric Microparticles

Our recent research has been pioneering the generation of single solid particles with adjustable eccentricity. This new technique permits the production of particles in the range of 200 w m to 2 mm and an approximate eccentricity of 1:1.2 to 1:1.8 along an axis. Single droplets consisting of multiacrylate monomers were levitated by an ultrasonic levitator and were cured by UV illumination after adjusted eccentricity. For special applications we can produce particles that are attached to a stem (optical fiber), which allows a controlled orientation of the particle. One possible application for such particles is the investigation of light scattering on nonspherical particles.     

Nonlocal polar elastic continua

A continuum theory of nonlocal polar bodies is developed. Both the micromorphic and the non-polar continuum theories are incorporated. The balance laws and jump conditions are given. By use of nonlocal thermodynamics and invariance under rigid motions, constitutive equations are obtained for the nonlinear micromorphic elastic solids. The special case, nonpolar, nonlocal elastic solids, is presented.     

Analysis of the particle stability in a new designed ultrasonic levitation device

The use of acoustic levitation in the fields of analytical chemistry and in the containerless processing of materials requires a good stability of the levitated particle. However, spontaneous oscillations and rotation of the levitated particle have been reported in literature, which can reduce the applicability of the acoustic levitation technique. Aiming to reduce the particle oscillations, this paper presents the analysis of the particle stability in a new acoustic levitator device. The new acoustic levitator consists of a piezoelectric transducer with a concave radiating surface and a concave reflector. The analysis is conducted by determining numerically the axial and lateral forces that act on the levitated object and by measuring the oscillations of a sphere particle by a laser Doppler vibrometer. It is shown that the new levitator design allows to increase the lateral forces and reduce significantly the lateral oscillations of the levitated object.