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In this work, we adopt the integration of the L-system fractal tree generation, 3D printed wind tunnel modeling, and computational fluid dynamics (CFD) simulation approach to model the wind effect on a single tree. We compare the agreement between CFD simulations and wind tunnel measurements of rigid branched structures resembling trees. First, fractal tree mesh models based on species growth and branching patterns are developed to represent tree species for wind–tree modeling. Subsequently, a scaled-down fractal tree is generated with 3D-printing and subjected to tunnel testing with load cell and particle image velocimetry measurement data under the wind speed of 10 m/s and 15 m/s. Finally, CFD based on Reynolds-Average Navier–Stokes (RANS) simulation with a full closure model and Large Eddy Simulation (LES) using appropriate momentum sink and turbulence source terms for the volumetric tree is carried out. We use both the volume-average porous media and the volume-splitting discretized zones (split number 10 × 10 × 10) to reproduce the momentum sink effect in the numerical simulation. Three tree species, namely, Peltophorum pterocarpum (yellow flame), Khaya senegalensis (African mahogany), and Hopea odorata (ironwood), are tested, and a reasonable agreement of drag force prediction and velocity profiles is obtained when comparing the CFD simulation results with wind tunnel data. The RANS modeled drag force results exhibit 20% of over-prediction, while the normalized velocity profiles display a good match of velocity decay at the tree leeward sides. On the other hand, LES produces much better results with only 3% discrepancy with the experimental results. A comparison of experimental results among the tree species is also carried out. Due to the actual random wind direction, tree slenderness representation, and structural flexibility issues, the current methodology still has the limitation for validation with urban on-site measurement. Nonetheless, this integrated approach is the first step in establishing modeling tool applicability to examine the effect of the forest structure and composition on wind loads.

High-intensity focused ultrasound (HIFU) is a non-invasive technique and widely used in medical and dental treatment for reaching and affecting deep seated tissues within the body, such as the removal of fat tissues under the skin, destruction of malignant tumour cells or target volume for the purpose of tissue debulking. This study aims to explore the damage characteristics of elastic material (regarded as soft tissue) by HIFU separated by a thin membrane all immersed in a water medium, in which the latter is used to mimic the human skin in medical treatments. Measurements of acoustic pressure along the vertical central line of HIFU transducer with and without this membrane were conducted and effects of membrane on the focal region were investigated. Results showed that the existence of the membrane serves primarily to reflect partial energy of incident ultrasound wave, and has no effect on phases of wave propagating in water. Next, Polydimethylsiloxane (PDMS) was selected as the elastic material for the experiments. The process of PDMS damage through the membrane by HIFU were recorded and the distribution of temperature around and within the ‘destroyed’ PDMS block was captured by an infrared camera. The very high temperature measured within the PDMS leading to the formations of cavity and crack within the PDMS block, can be attributed to the accumulation of the energy from the ultrasound source. Finally, the effects of PDMS with different elasticity on their damage characteristics are discussed.

The stacking faults (SFs) in an AlSb/GaAs (001) interface were investigated using a 300 kV spherical aberration-corrected high-resolution transmission electron microscope (HRTEM). The structure and strain distribution of the single and intersecting (V-shaped) SFs associated with partial dislocations (PDs) were characterized by the [110] HRTEM images and geometric phase analysis, respectively. In the biaxial strain maps εxx and εyy, a SF can be divided into several sections under different strain states (positive or negative strain values). Furthermore, the strain state for the same section of a SF is in contrast to each other in εxx and εyy strain maps. The modification in the strain states was attributed to the variation in the local atomic displacements for the SF in the AlSb film on the GaAs substrate recorded in the lattice image. Finally, the single SF was found to be bounded by two 30° PDs. A pair of 30° PDs near the heteroepitaxial interface reacted to form a Lomer-Cottrell sessile dislocation located at the vertices of V-shaped SFs with opposite screw components. The roles of misfit dislocations, such as the PDs, in strain relaxation were also discussed.

Ti2MnZ (Z=Al, Ga, In) compounds with CuHg2Ti-type structure are predicted to have the different width of band gap in two spin channels and exhibit a nearly spin gapless semiconductivity. There are different origins of the band gap in spin-up and spin-down channels. The width of the band gap can be adjusted by changing the lattice parameter or doping congeners. These compounds are completely-compensated ferrimagnets with a zero magnetic moment.

Magnetic thermal hysteresis (MTH) associated with a paramagnetic (PM)-antiferromagnetic (AFM) phase transition was found in an Fe-24.4Mn-5.9Si-5.1Cr shape-memory alloy. Aside from the magnetic field (H), the driving rate (v) can also tune the critical temperature of the magnetic transition and cause an increase in MTH. The magnetic phase diagram obtained is discussed. The equation for MTH was deduced based on the Landau model for a PM-AFM transition that includes H and v dependence, which gives a reasonable account of the experimental results.