Fragmentation mechanisms based on single drop steam explosion experiments using flash X-ray radiography

Flash X-ray and high-speed regular photography were used to investigate the fragmentation processes during the vapor explosion of single drops of molten metal immersed in water. For relatively low ambient flow velocities (< 5 m/s), a comparison of the breakup of hot and cold drops shows that whereas cold drops breakup due to the stripping of fragments by the relative flow, the fragmentation of a hot drop is dominated by the growth and collapse of a vapor bubble. X-ray radiographs show during the growth of the bubble, that fine filaments of metal protrude from the drop and the drop surface becomes highly convoluted. Using a simple model for the bubble dynamics, an estimate of the energy budget shows that the majority (about 80%) of the thermal energy transfer occurs during bubble collapse. For hot drops at higher flow velocities (> 45 m/s), vapor bubble growth is diminished and high-speed motion of vapor within the bubble leads to an enhanced fragmentation rate.     

The Instant Controlled Pressure Drop Process as a New Post-harvesting Treatment of Paddy Rice: Impacts on Drying Kinetics and End Product Attributes

The instant controlled pressure drop (DIC) process was used as a post-harvesting treatment, followed by hot air drying and shade polishing. DIC treatment, which is carried out at P = 0.4–0.6 MPa, has many advantages in terms of processing time (not exceeding 30 s) and drying kinetics (about 3 h instead of 1 day under standard 50 °C hot air flow conditions). Shade polishing gives high quality rice with a whole-grain yield of 68-70% rather than the usual 52-60%. A tasting evaluation was carried out by an international panel and the rice was found to be perfect after a cooking time of 6 min, with an overcooked time of 18 min as against 17 min and 20 min, respectively, for conventional products. The shaded shelf life of the final product is much longer than 18–24 months.     

Detonation propagation through a nonuniform layer of hydrogen-oxygen in a narrow channel

Experiments were carried out to study detonation propagation through a nonuniform layer of stoichiometric hydrogen-oxygen in a narrow channel. Premixed stoichiometric hydrogen-oxygen was injected through a series of 1.3 mm diameter, 4.8 mm spaced holes into a 7 mm wide optically accessible channel initially filled with an inert gas. A Chapman-Jouguet detonation wave was transmitted into the test section from a pre-detonator of equal height. The height of the layer was varied by changing the time of hydrogen-oxygen injection relative to the arrival-time of the detonation wave. Schlieren photography was used to record the progression of the detonation wave. Soot foils mounted to the back window, were used to record the detonation cellular structure and visualization of the soot incandescence provided tracking of the reaction zone. With the channel initially filled with argon, detonation propagation was only possible when the layer height accommodated at least 8–11 detonation cells. Detonation propagation was not possible when the channel initially contained nitrogen, or carbon dioxide, indicating strong mixing with the injected premixed hydrogen-oxygen. Numerical simulations confirmed the strong mixing between the injected premixed hydrogen-oxygen with the prefilled inert gas. The simplified mixing condition, i.e., injection of premixed hydrogen-oxygen, provides a unique data set for numerical code validation and verification for a linear RDE geometry.     

AK-GWO: a novel hybrid optimization method for accurate optimum hierarchical stiffened shells

Engineering with Computers - An attempt has been made to propose a novel prediction model based on the Gaussian process regression (GPR) approach. The proposed GPR was used to predict blast-induced...     

Femtojoule-Power-Consuming Synaptic Memtransistor Based on Mott Transition of Multiphasic Vanadium Oxides

To realize the potential of Mott transition of multiphasic vanadium oxides (VO_x) for memory applications, the development of VO_x memtransistors on SiO₂ wafer is introduced. Through electrical characterizations, the volatile memory behaviors of the VO_x memtransistors are observed in both two- and three-terminal measurements. Their capacitive memory and resistive switching mechanisms are strongly related to the mixed VO_x/SiO₂ interface (called VSiO_x). VSiO_x supports the Mott transition in VO_x at low bias voltages (<0.5 V), leading to the low power consumption of the memtransistor. Moreover, the fast switching time (≈35 ns) and tunable memory retention with the synaptic functions (potentiation and depression) of the memtransistors (by using the gate and drain biases) are demonstrated. Overall, the findings open up major opportunities for constructing ultrafast and femto-joule power-consuming neuromorphic devices.     

Joint server and network optimization toward load‐balanced service chaining

Prior service chaining systems address server and network load balancing issues individually, which may not ensure efficient system performance. To this end, in this paper, we study the design, implementation, complexity analysis, and evaluation of Nearest First and Local‐Global Transformation algorithm, which jointly supports server and network load balancing for chaining virtualized network functions (VNFs) in data center environment. The algorithm firstly constructs service chains by a greedy strategy, which both considers server and network latency. Then a searching technique, which replaces a selected VNF with another candidate and swaps the order of VNFs in service chains, is applied to improve the solutions. We have implemented the algorithm using Software‐defined networking and OpenFlow concepts. The numerical results indicate that, compared with a sequential approach, Nearest First and Local‐Global Transformation increases the system bandwidth utilization up to 45%. The results also show that it is worth applying the second phase of our algorithm since it considerably enhances the system performance by 20%.     

Synthesis and properties of natural rubber modified with stearyl methacrylate and divinylbenzene by graft polymerization

The graft polymerizations of stearyl methacrylate (SMA) and divinylbenzene (DVB) onto natural rubber (NR) were carried out in a solution process using benzoyl peroxide (BPO) as an initiator in toluene or chloroform. The main products of the grafted NR include an uncrosslinked (sol) part [sol(SMA–NR–DVB): s‐SNRD] and a crosslinked (gel) part [gel(SMA–NR–DVB), g‐SNRD]. s‐SNRD was obtained by extraction using tetrahydrofuran. It was identified by IR and ¹H‐NMR spectroscopies. The glass transition temperature (T_g) and thermal properties of s‐SNRD and g‐SNRD were studied by DSC and TGA. The glass transition temperature and thermal decomposition temperature of s‐SNRD and g‐SNRD were higher than were those of NR. The light resistance and weatherability of s‐SNRD were measured with a Weather‐o‐Meter. The light resistance and weatherability of s‐SNRD are better than are those of NR. The effects of the initiator concentration, mol ratio of SMA to DVB, reaction time, temperature on grafting ratio, and crosslinking ratio were investigated. The highest grafting ratio and crosslinking ratio in the graft polymerization of SMA and DVB onto NR were obtained when the mol ratio of SMA to DVB and BPO were 4.0 and 2 wt %, at 80°C for 48 h, respectively. Following several studies on oil‐absorptive polymers in our laboratory, 9 the oil absorptivity of g‐SNRD was examined using crude oil. The oil absorptivity of g‐SNRD was 600% when the immersion time was 10 min. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2464–2470, 2001