High-speed flow calculations past 3-D configurations based on the Reynolds averaged Navier-Stokes equations

A computational fluid dynamics tool has been developed capable of analyzing the viscous supersonic/hypersonic flow about realistic configurations. This techniques can predict the flow in regions of canopies, wings, and canards in addition to the usual simple symmetric configurations. It also allows for interactions between aerodynamic surfaces such as the vortex interaction between canards and wings

Partial-reflection studies of D-region winter variability

D-region electron densities were measured from December, 1972, to July, 1973, at Urbana, Illinois (latitude 40.2N) using the partial-reflection technique. During the winter, electron densities at altitudes of 72, 76.5, and 81 km show cyclical changes with a period of about 5 days that are highly correlated between these altitudes, suggesting that the mechanism responsible for the winter anomaly in D-region ionization applies throughout this height region. From January 13 to February 3, a pronounced wave-like variation occurred in the partial-reflection measurements, apparently associated with a major stratospheric warming that developed in that period. During the same time period, a traveling periodic variation is observed in the 10-mb height; it is highly correlated with the partial-reflection measurements. Electron density enhancements occur approximately at the same time as increases in the 10-mb height. Comparison of AL and A3 absorption measurements with electron density measurements below 82 km indicates that the winter anomaly in D-region ionization is divided into two types. Type 1, above about 82 km, extends horizontally for about 200 km while type 2, below about 82 km, extends for a horizontal scale of at least 1000 km

Proposed parametric cooling of bilayer cuprate superconductors by terahertz excitation

We propose and analyze a scheme for parametrically cooling bilayer cuprates based on the selective driving of a $c$-axis vibrational mode. The scheme exploits the vibration as a transducer making the Josephson plasma frequencies time-dependent. We show how modulation at the difference frequency between the intra- and interbilayer plasmon substantially suppresses interbilayer phase fluctuations, responsible for switching $c$-axis transport from a superconducting to resistive state. Our calculations indicate that this may provide a viable mechanism for stabilizing non-equilibrium superconductivity even above $T_c$, provided a finite pair density survives between the bilayers out of equilibrium.Comment: 4 pages + 7 page supplementa

Multicomponent metal-organic framework membranes for advanced functional composites.

The diverse chemical and structural properties of metal-organic frameworks (MOFs) make them attractive for myriad applications, but their native powder form is limiting for industrial implementation. Composite materials of MOFs hold promise as a means of exploiting MOF properties in engineered forms for real-world applications. While interest in MOF composites is growing, research to date has largely focused on utilization of single MOF systems. The vast number of different MOF structures provides ample opportunity to mix and match distinct MOF species in a single composite to prepare multifunctional systems. In this work, we describe the preparation of three types of multi-MOF composites with poly(vinylidene fluoride) (PVDF): (1) co-cast MOF MMMs, (2) mixed MOF MMMs, and (3) multilayer MOF MMMs. Finally, MOF MMMs are explored as catalytic membrane reactors for chemical transformations

Tuning gastropod locomotion: Modeling the influence of mucus rheology on the cost of crawling

Common gastropods such as snails crawl on a solid substrate by propagating muscular waves of shear stress on a viscoelastic mucus. Producing the mucus accounts for the largest component in the gastropod's energy budget, more than twenty times the amount of mechanical work used in crawling. Using a simple mechanical model, we show that the shear-thinning properties of the mucus favor a decrease in the amount of mucus necessary for crawling, thereby decreasing the overall energetic cost of locomotion.Comment: Corrected typo

Penelitian Awal Tentang Penggunaan Consol Fiber Steel Sebagai Campuran Pada Balok Beton Bertulang

Dalam dunia konstruksi, balok beton bertulang adalah barang yang sering kita jumpai. Penelitian ini bertujuan untuk mengetahui pengaruh penggunaan consol fiber steel pada campuran beton yang digunakan pada balok beton bertulang. Serat baja ini mempunyai beberapa tipe, namun untuk penelitian ini kita menggunakan serat baja dengan tipe hooked. Dalam penelitian ini dilakukan 2 jenis percobaan, yaitu pengujian kuat tekan dan momen nominal beton yang menggunakan campuran serat consol fiber steel ini. Kuat tekan dan momen nominal beton dilakukan pengujian pada 7, 14, dan 28 hari. Dari hasil kuat tekan dan momen nominal yang didapatkan, kita membandingkannya dengan harga untuk mencari efisiensi dari penggunaan serat baja tersebut. Hasil pengujian menunjukkan bahwa untuk kuat tekan, beton dengan jumlah kadar serat 0,75% merupakan campuran yang paling efisien dengan hasil 18,90 MPa. Sedangkan untuk momen nominal, beton dengan jumlah kadar serat 0,5% merupakan campuran yang paling efisien dengan hasil 1,47 kNm. Hal ini membuktikan bahwa penambahan consol fiber steel pada campuran beton dapat meningkatkan kekuatan beton dilihat dari kuat tekan maupun momen nominalnya

Optimasi Proses Pengukuran Dimensi Dan Defect Ubin Keramik Menggunakan Pengolahan Citra Digital Dan Full Factorial Design

Theinspection process of surface quality of ceramic tile could be done by using image processing technique throughthe optimization by using Center for Ceramics's parameteron Indonesian National Standard (SNI) ISO 10545.This research will analyze from light intensities (level 300lx, 600lx, and 900lx), and camera distances (50cm, 75cmand 100cm), with three times replication using full factorial design. This research uses Matlab 2009a softwareto identify area and defect on dry spots ceramic tile's surface. The result obtained from this research is there weresignificant influencing factors: light intensity, and camera distance, as well as the interaction of these factorstowards the error rate percentage of measuring areaand defect on ceramic tile's surface. The smallest error ratevalue from measuring tile's surface and diameter of dry spots with light intensity of 300lx and camera distance of50cm had been obtained the error rate value for each measurement about 0.0675% and 2.30%, with combinationof grayscale value for the error rate measurements of tile's surface and diameter of dry spots were 0.2989 x 0.1140x R + G+0.5870 x B. Based on the correlation coefficient value between light intensity, camera distance towardsthe error rate of measuring areaand defect on tile's surface, each of them was obtained correlation coefficient valueof camera distance with error rate had 0.518 and 0.516, which meant a strong correlation. The positive correlationcoefficient value showed a unidirectional relationship of two variables, where the rise of one variable would causethe rise of another variable and the decline of one variable would cause the decline of another variable

Enhanced aging properties of HKUST-1 in hydrophobic mixed-matrix membranes for ammonia adsorption.

Metal-organic frameworks (MOFs) in their free powder form have exhibited superior capacities for many gases when compared to other materials, due to their tailorable functionality and high surface areas. Specifically, the MOF HKUST-1 binds small Lewis bases, such as ammonia, with its coordinatively unsaturated copper sites. We describe here the use of HKUST-1 in mixed-matrix membranes (MMMs) prepared from polyvinylidene difluoride (PVDF) for the removal of ammonia gas. These MMMs exhibit ammonia capacities similar to their hypothetical capacities based on the weight percent of HKUST-1 in each MMM. HKUST-1 in its powder form is unstable toward humid conditions; however, upon exposure to humid environments for prolonged periods of time, the HKUST-1 MMMs exhibit outstanding structural stability, and maintain their ammonia capacity. Overall, this study has achieved all of the critical and combined elements for real-world applications of MOFs: high MOF loadings, fully accessible MOF surfaces, enhanced MOF stabilization, recyclability, mechanical stability, and processability. This study is a critical step in advancing MOFs to a stable, usable, and enabling technology