Electromagneto-thermo-mechanical behaviors of conductive circular plate subject to time-dependent magnetic fields

This paper presents an analysis on electromagneto-thermo-mechanical behaviors of conductive plates, an analytical solution is given for a conductive circular plate in a time-dependent magnetic field by using a T-method of the eddy current which is widely used in the eddy current analysis of conductive and superconductive structures. The solution is expressed in an analytical series form and it is suitable for a circular plate under any arbitrary axisymmetric magnetic fields changing in time. Some interesting results including the eddy current, the increment of temperature, and the electromagneto-thermal stresses are investigated, respectively, in this paper. Some characteristics such as the distribution of temperatures, the in-plane electromagnetic stresses and the dynamic response of the conductive plate are first studied and displayed. This study not only reveals some characteristics on the eddy current, the temperature of the plate, the in-plane electromagnetic thermal stresses and the dynamic responses of the conductive plate which is in a time-dependent magnetic field, but presents a new possible way to simplify the analysis of the electromagnetic coupling problem for conductive structures.     

Bacterial DNA sample preparation from whole blood using surface-modified Si pillar arrays

A novel bacterial DNA sample preparation device for molecular diagnostics has been developed. On the basis of optimized conditions for bacterial adhesion, surface-modified silicon pillar arrays for bacterial cell capture were fabricated, and their ability to capture bacterial cells was demonstrated. The capture efficiency for bacterial cells such as Escherichia coli, Staphylococcus epidermidis, and Streptococcus mutans in buffer solution was over 75% with a flow rate of 400 microL/min. Moreover, the proposed method captured E. coli cells present in 50% whole blood effectively. The captured cells from whole blood were then in- situ lyzed on the surface of the microchip, and the eluted DNA was successfully amplified by qPCR. These results demonstrate that the full process of pathogen capture to DNA isolation from whole blood could be automated in a single microchip.     

Size-controlled cubic coordination polymer nanoparticles from chiral dipyridyl Zn-salen

Size-controlled crystalline nanocubic coordination polymer particles from chiral Zn-salen and Co(II) have been obtained. PXRD patterns show that these particles have an identical unit cell regardless of a wide range of size distributions. Furthermore, cubic particles with epitaxial layers have been obtained with a simple manipulation during the synthesis.     

Collapse simulation of tubular structures using a finite element limit analysis approach and shell elements

This paper describes the collapse simulation of thin-walled tubular structures using a finite element limit analysis approach and degenerated four-node shell elements. The simulation traces the path of sequential deformation of the structure modelled by considering the strain-hardening effect, which is important for the analysis of collapse behaviour and energy absorption efficiency. The collapse analysis of some square tubes was used to verify the simulation method proposed. Numerical results are compared with experimental observations for sequential collapse loads and deformation modes, showing fairly good coincidence. The collapse analysis of an S-rail was then carried out for sequential collapse loads as well as deformation modes and its results are compared with elasto-plastic analysis results obtained from the explicit dynamic code PAM-CRASH. The energy absorption capacity was studied for a variety of rectangular cross-section aspect ratios. The results show that the energy absorption capacity increases as the height-to-width aspect ratio becomes larger. Results also demonstrate that the finite element limit analysis can predict the plastic collapse load and collapse mode of thin-walled structures efficiently and systematically. The present algorithm with a simple formulation has the advantage of stable convergence, computational efficiency and easy access to strain-hardening materials compared to the incremental rigid–plastic finite element analysis.     

Effect of rib height on heat transfer in a two pass rectangular channel (AR = 1:4) with a sharp entrance at high rotation numbers

Blockage ratio effects on heat transfer in 1:4 AR channels with developing flow is experimentally determined. The blockage ratios (e/D_h) were 0.078 and 0.156. Reynolds numbers up to 40 K and rotational speeds up to 400 rpm were considered. The rotation number (Ro) and local buoyancy parameter (Bo_x) were extended to 0.65 and 1.5, respectively. The entrance dominates over rotation on the trailing surface first pass. The leading surface is dominated by rotation. Rotation effects are reduced by the ribs and heat transfer is similar for both walls in the second pass. Rotation effects were similar for both blockage ratios. The correlations show that the buoyancy parameter is useful to predict heat transfer in the extended range.     

In situ-grown hexagonal silicon nanocrystals in silicon carbide-based films

Silicon nanocrystals (Si-NCs) were grown in situ in carbide-based film using a plasma-enhanced chemical vapor deposition method. High-resolution transmission electron microscopy indicates that these nanocrystallites were embedded in an amorphous silicon carbide-based matrix. Electron diffraction pattern analyses revealed that the crystallites have a hexagonal-wurtzite silicon phase structure. The peak position of the photoluminescence can be controlled within a wavelength of 500 to 650 nm by adjusting the flow rate of the silane gas. We suggest that this phenomenon is attributed to the quantum confinement effect of hexagonal Si-NCs in silicon carbide-based film with a change in the sizes and emission states of the NCs.     

Effects of work hardening models on low-cycle fatigue evaluations of coiled tubing with CT-100 steel

In the present study, low-cycle fatigue life of a coiled tubing (CT) with a CT-100 steel was evaluated by using various work hardening models. Tensile and low-cycle fatigue tests were performed, and experimental results were used to calibrate material model constants. A nonlinear finite element model was constructed in the ABAQUS program by using a CT fatigue test machine. During the test cycles, bending and straightening conditions were repeated and histories of strains were collected. The multiaxial low-cycle fatigue life was calculated by using Manson–Coffin relation and Tresca criterion. The kinematic and combined hardening models can be used to evaluate the fatigue life of CT, and their results are conservative compared with the fatigue test results. Results of the present study can be used as the basic data in establishing CT fatigue analysis.