Laser-assisted photothermal imprinting of nanocomposite

We report on a laser-assisted photothermal imprinting method for directly patterning carbon nanofiber-reinforced polyethylene nanocomposite. A single laser pulse from a solid state Nd:YAG laser (10 ns pulse, 532 nm and 355 nm wavelengths) is used to melt/soften a thin skin layer of the polymer nanocomposite. Meanwhile, a fused quartz mold with micro-sized surface relief structures is pressed against the surface of the composite. Successful pattern transfer is realized upon releasing the quartz mold. Although polyethylene is transparent to the laser beam, the carbon nanofibers in the high density polyethylene (HDPE) matrix absorb the laser energy and convert it into heat. Numerical heat conduction simulation shows the HDPE matrix is partially melted or softened, allowing for easier imprinting of the relief pattern of the quartz mold.Mechanical Engineerin

Numerical investigation of fire in the cavity of naturally ventilated double skin façade with venetian blinds

Double skin façades (DSFs), offer great views, architectural aesthetics, and energy savings. Yet, in a fire event the glass façade breaks leading to risks to human life and firefighting difficulties. Shading devices incorporated to prevent unfavourable heat gains to reduce cooling load though offer energy savings potentially present other challenges in firefighting and occupants’ evacuation. In this study, Fire Dynamic Simulator (FDS) was used to numerically investigate the spread of a 5 MW HRR polyurethane GM27 fire in a multi-storey double skin façade building with Venetian blinds placed in its cavity. The blinds were positioned 0.4 m away from the internal glazing, middle of the cavity and 0.4 m away from the external glazing respectively. In each blind position the slat angle was opened at 0°, 45°, 90° and 135° respectively. The results show peak inner glazing surface temperature ranged between 283°C to 840°C depending on the thermocouple position, the Venetian blind position and slat opening angle. Without Venetian blinds, peak inner glazing surface temperatures ranged between 468°C to 614°C. In all cases except when the slat angle was 0° and the blind was positioned closer to the outer glazing, the inner glazing surface temperature from the closest thermocouple (TC 14) above the fire room exceeded 600°C, the glass breakage temperature threshold. Overall, the Venetian blind position and slat opening angle influenced the spread of fire. Venetian blind combustibility and flammability were not considered and therefore recommended for future studies

Numerical data on fire in the cavity of naturally ventilated double skin façade with Venetian blinds

This Data Article presents simulation data and methodology on fire in the cavity of naturally ventilated Double Skin Façade (DSF) with Venetian blinds. The simulation data includes glazing surface temperature data and the Input and Output Source Code files. The data for the validation of the model is also presented along with its methodology, input source code file and output temperature results. The comprehensive methodology used to obtain this data from the National Institute of Standards and Technology's (NIST) Fire Dynamics Simulator (FDS) and PyroSim are presented. The data presented can provide theoretical benchmarks for architects, engineers, researchers, and designers when incorporating Venetian blinds in DSFs. It can also help fire fighters and engineers to theoretically assess the spread of fire in buildings with DSFs incorporating Venetian blinds

Hadron-quark phase transition in asymmetric matter with dynamical quark masses

The two-Equation of State (EoS) model is used to describe the hadron-quark phase transition in asymmetric matter formed at high density in heavy-ion collisions. For the quark phase, the three-flavor Nambu--Jona-Lasinio (NJL) effective theory is used to investigate the influence of dynamical quark mass effects on the phase transition. At variance to the MIT-Bag results, with fixed current quark masses, the main important effect of the chiral dynamics is the appearance of an End-Point for the coexistence zone. We show that a first order hadron-quark phase transition may take place in the region T=(50-80)MeV and \rho_B=(2-4)\rho_0, which is possible to be probed in the new planned facilities, such as FAIR at GSI-Darmstadt and NICA at JINR-Dubna. From isospin properties of the mixed phase somepossible signals are suggested. The importance of chiral symmetry and dynamical quark mass on the hadron-quark phase transition is stressed. The difficulty of an exact location of Critical-End-Point comes from its appearance in a region of competition between chiral symmetry breaking and confinement, where our knowledge of effective QCD theories is still rather uncertain.Comment: 13 pages, 16 figures (revtex

Numerical Study on Indoor Wideband Channel Characteristics with Different Internal Wall

Effects of material and configuration of the internal wall on the performance of wideband channel are investigated by using the Finite Difference Time-Domain (FDTD) method. The indoor wideband channel characteristics, such as the path-loss, Root-Mean-Square (RMS) delay spread and number of the multipath components (MPCs), are presented. The simulated results demonstrate that the path-loss and MPCs are affected by the permittivity, dielectric loss tangent and thickness of the internal wall, while the RMS delay spread is almost not relevant with the dielectric permittivity. Furthermore, the comparison of simulated result with the measured one in a simple scenario has validated the simulation study

Enhanced Magnetization from Proton Irradiated Bulk van der Waals Magnet CrSiTe3

Van der Waals (vdWs) crystals have attracted a great deal of scientific attention due to their interesting physical properties and widespread practical applications. Among all, CrSiTe3 (CST) is a ferromagnetic semiconductor with the Curie temperature (TC) of ~32 K. In this letter, we study the magnetic properties of bulk CST single-crystal upon proton irradiation with the fluence of 1x1018 protons/cm2. Most significantly, we observed an enhancement (23%) in the saturation magnetization from 3.9 {\mu}B to 4.8 {\mu}B and is accompanied by an increase in the coercive field (465-542 Oe) upon proton irradiation. Temperature-dependent X-band electron paramagnetic resonance measurements show no additional magnetically active defects/vacancies that are generated upon proton irradiation. The findings from X-ray photoelectron spectroscopy and Raman measurements lead us to believe that modification in the spin-lattice coupling and introduction of disorder could cause enhancement in saturation magnetization. This work demonstrates that proton irradiation is a feasible method in modifying the magnetic properties of vdWs crystals, which represents a significant step forward in designing future spintronic and magneto-electronic applications