SIMD-Optimized Search Over Sorted Data

Applications often require a fast, single-threaded search algorithm over sorted data, typical in table-lookup operations. We explore various search algorithms for a large number of search candidates over a relatively small array of logarithmically-distributed sorted data. These include an innovative hash-based search that takes advantage of floating point representation to bin data by the exponent. Algorithms that can be optimized to take advantage of SIMD vector instructions are of particular interest. We then conduct a case study applying our results and analyzing algorithmic performance with the EOSPAC package. EOSPAC is a table look-up library for manipulation and interpolation of SESAME equation-of-state data. Our investigation results in a couple of algorithms with better performance with a best case eight times speedup over the original EOSPAC Hunt-and-Locate implementation. Our techniques should generalize to other instances of search algorithms seeking to get a performance boost from vectorization.

A shallow Vs model from full wave inversion for hydraulic fracturing site

<p>In recent years, small dense arrays with inter-station distances ~1-km are widely deployed for various geotechnical proposes, including exploring the subsurface geothermal reservoirs, monitoring the hydraulic fracturing, and estimate the local seismic hazards. Those small-dense arrays record several hours or days microtremor datasets and can be used to extract noise H/V ratio and short-period Rayleigh wave dispersion curve. To fulfill those geotechnical purposes, the extracted H/V ratio and Rayleigh wave dispersive curves are used to invert for 1-D layered velocity structures based on traditional ray theory, ignoring the 3-D Rayleigh wave propagating effects. In the present-day, with advances in computational power, 3-D numerical seismic wave propagation in realistic Earth models has become feasible and this has led to efforts to invert full waveforms. However, as H/V ratios from microtremors are produced by multiple random sources close to the surface with complex scattering effects, they are still unrealistic to be simulated by 3-D numerical seismic wave simulations. In this study, we use a strategy to incorporate the theories of H/V ratios from microtremor and the 3-D waveform simulations to invert for shallow sub-surface speed model using a small array. The details of the strategy are that we first use the traditional method to build an initial speed model by jointly inverting the Rayleigh wave dispersion curves and H/V ratios, and then, we further update the initial model with full-wave inversion of the Rayleigh waveforms calculated from ambient noise cross-correlations. The small array used here was composed of 21 broadband seismic stations, aimed to monitor the underground hydraulic fracturing. Therefore, the newly build model has important geotechnical usages of locating stimulated micro-seismic events and diagnose the hydraulic fracturing effects.</p>

Design of a Small Array Antenna with an Extended Cavity Structure for Wireless Power Transmission

This paper proposes a design of a small array antenna with an extended cavity structure for wireless power transmission. The proposed array element consists of a square radiating loop, which is designed to resonate at 5.8 GHz, and an extended cavity structure to reduce the mutual coupling between adjacent elements. We derive the optimal element number in a limited space by considering the input power for each element, fabrication cost, and aperture efficiency of the system. To verify the suitability of the proposed a small array with an extended cavity structure, a 2 × 2 downscaled array antenna is fabricated and measured in a full anechoic chamber. The results confirm that the proposed antenna element with an extended cavity structure is suitable for wireless power transmission systems; the proposed array has a transmission efficiency of about 1% at a distance of 2 m when the array is applied to both transmitting and receiving antennas.

Экспонаты Музея «Пруссия» в Каталоге копий Центрального Римско-Германского музея (Майнц)

The catalogue of copies from the Roman-German Central Museum (Mainz) poses an opportunity to present to the modern researcher the volume of Prussian archaeological material available on the second floor dedicated to the 19th century. By collecting what is considered the most representative exhibits, the museum authorities put on display items copied in Mainz and stored in Prussia-Museum (Königsberg). They were created by masters from Aesti and Prussia. The only imports among the small array of findings published in the catalogue include a helmet from the Dollkeim-Kovrovo burial ground (its local origin has not been excluded) and a lock and key from the Löbertshof cemetery / Tyulenino.

Designing large-scale antenna array using sub-array

Antenna array of large scale have been examined for different applications including 5G technology. To get better data rate or a reliable link substantial number of antenna arrays have been utilized to provide high multiplexing gains as well as array gains with high directivity. In this paper a simple but efficient implementation technique of using sub-arrays for the improvement of large-sized uniform arrays. By repeating a small sub-array multiple times large arrays can be designed. This implication of utilizing small array simplifies the design of a larger array which allows the designer to concentrate on the smaller sub-array before assembling larger arrays. So, by investigating the sub arrays the performance and radiation characteristics of large arrays can be anticipated. The array-factor for a planar sub-array of 2x2 (4 elements) is analyzed using Mat-lab software and then a large array is formed by placing the 2x2 sub-array indifferent configurations in a rectangular arrangements up to 8x8 planar array. And then the results are validated with CST (Computer simulation technology) simulation results.In this way the array-factors, directivities, HPBWs, and side lobes of the constructed large arrays are analyzed and associated with the small sub-array.