Numerical Investigation on Microelectronic Chip Cooling Using Multiple Orifice Synthetic Jet Actuator Based on Theory Field Synergism

AbstractSynthetic jet is applied to the field of heat and mass transfer, because the periodical suck and blow enhances forced convection heat transfer. A multiple orifice synthetic jet actuator (SJA) is designed for the cooling of microelectronic chips. By using fin, it can achieve higher effectiveness of heat transfer with a combination of active and passive scheme in heat dissipation. Numerical simulation of the flow field of the multiple orifice SJA is performed to analyze the mechanism of the heat dissipation. Based on the above work, numerical simulations presenting the effects of heat dissipation with different flat-to-orifice distances are performed in this study. The theory Field Synergism of the optimization of convection heat transfer is introduced to evaluate the effects of the parameters on heat transfer by comparing the magnitude of the integral value. The results verify that the larger the integral value is, the higher the heat transfer coefficient is. And there is an optimum impinging distance at which the synergy degree between velocity field and temperature gradient field reaches its peak and the heat transfer coefficient is the highest

Simulation of Microstructure during Laser Rapid Forming Solidification Based on Cellular Automaton

The grain microstructure of molten pool during the solidification of TC4 titanium alloy in the single point laser cladding was investigated based on the CAFE model which is the cellular automaton (CA) coupled with the finite element (FE) method. The correct temperature field is the prerequisite for simulating the grain microstructure during the solidification of the molten pool. The model solves the energy equation by the FE method to simulate the temperature distribution in the molten pool of the single point laser cladding. Based on the temperature field, the solidification microstructure of the molten pool is also simulated with the CAFE method. The results show that the maximum temperature in the molten pool increases with the laser power and the scanning rate. The laser power has a larger influence on the temperature distribution of the molten pool than the scanning rate. During the solidification of the molten pool, the heat at the bottom of the molten pool transfers faster than that at the top of the molten pool. The grains rapidly grow into the molten pool, and then the columnar crystals are formed. This study has a very important significance for improving the quality of the structure parts manufactured through the laser cladding forming

Functional Ecological Gene Networks to Reveal the Changes Among Microbial Interactions Under Elevated Carbon Dioxide Conditions

Biodiversity and its responses to environmental changes is a central issue in ecology, and for society. Almost all microbial biodiversity researches focus on species richness and abundance but ignore the interactions among different microbial species/populations. However, determining the interactions and their relationships to environmental changes in microbial communities is a grand challenge, primarily due to the lack of information on the network structure among different microbial species/populations. Here, a novel random matrix theory (RMT)-based conceptual framework for identifying functional ecological gene networks (fEGNs) is developed with the high throughput functional gene array hybridization data from the grassland microbial communities in a long-term FACE (Free Air CO2 Enrichment) experiment. Both fEGNs under elevated CO2 (eCO2) and ambient CO2 (aCO2) possessed general characteristics of many complex systems such as scale-free, small-world, modular and hierarchical. However, the topological structure of the fEGNs is distinctly different between eCO2 and aCO2, suggesting that eCO2 dramatically altered the interactions among different microbial functional groups/populations. In addition, the changes in network structure were significantly correlated with soil carbon and nitrogen dynamics, and plant productivity, indicating the potential importance of network interactions in ecosystem functioning. Elucidating network interactions in microbial communities and their responses to environmental changes are fundamentally important for research in microbial ecology, systems microbiology, and global change

Author Correction: Strong indirect coupling between graphene-based mechanical resonators via a phonon cavity.

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Strategi Pembangunan Pariwisata melalui Sinergitas Dinas Pariwisata dengan Desa Adat ( Studi Kasus pada Pengelolaan Obyek Wisata Pantai Labuan Sait dalam Meningkatkan Retribusi Daerah di Kabupaten Badung)

A gradual Tourism development is very important to improve the quality of tourism each year to compete with other tourist attraction. The synergy between the Central Government with local government plays an important role to the development of tourism. The background to this research is the development of tourism which is still insufficient in Labuan Sait both in terms of means and infrastructure, promotion, as well as structuring tourism. This study measures how does tourism development strategy through the synergy with the customary village tourism office on the management of Beach Tourism Labuan Sait in increasing the levy County in Badung Regency with the theory of development that uses the concept of planning development by Sjahrizal in the regional development planning in the era of autonomy. The indicator consists of planning, implementation, monitoring and evaluation. In addition also use the concept of synergy from Najiyati and Rahmat which consists of indicators communication and coordination as well as indicators of the SWOT by Freddy Rangkuti. Method used in this study is a qualitative method with descriptive approach with data collection techniques in the form of in-depth interviews to several informants associated with this research. The results of the research showed that the development strategy of tourism through the synergy with the customary village Tourism Office on the management of Beach Tourism Labuan Sait in improving regional levies in Badung Regency are still insufficient. That is because the is still lacking from the indicator monitoring and implementation and evaluation of the impact against the decline of levy of admission attractions Labuan Sait in the 2017.     Keywords: Development, Tourism, Synergy, and Strateg

Tightly-bound and room-temperature-stable excitons in van der Waals degenerate-semiconductor Bi4O4SeCl2 with high charge-carrier density

Excitons, which represent a type of quasi-particles consisting of electron-hole pairs bound by the mutual Coulomb interaction, were often observed in lowly-doped semiconductors or insulators. However, realizing excitons in the semiconductors or insulators with high charge carrier densities is a challenging task. Here, we perform infrared spectroscopy, electrical transport, ab initio calculation, and angle-resolved-photoemission spectroscopy studies of a van der Waals degenerate-semiconductor Bi4O4SeCl2. A peak-like feature (i.e., alpha peak) is present around ~ 125 meV in the optical conductivity spectra at low temperature T = 8 K and room temperature. After being excluded from the optical excitations of free carriers, interband transitions, localized states and polarons, the alpha peak is assigned as the exciton absorption. Moreover, assuming the existence of weakly-bound excitons--Wannier-type excitons in this material violates the Lyddane-Sachs-Teller relation. Besides, the exciton binding energy of ~ 375 meV, which is about an order of magnitude larger than those of conventional semiconductors, and the charge-carrier concentration of ~ 1.25 * 10^19 cm^-3, which is higher than the Mott density, further indicate that the excitons in this highly-doped system should be tightly bound. Our results pave the way for developing the optoelectronic devices based on the tightly-bound and room-temperature-stable excitons in highly-doped van der Waals degenerate semiconductors.Comment: Accepted by Communications Material