Mind the (synthesis) gap: examining where academic FPGA tools lag behind industry

Firstly, we present VTR-to-Bitstream v2.0, the latest version of our open-source toolchain that takes Verilog input and produces a packed, placed— and now routed—solution that can be programmed onto the Xilinx commercial FPGA architecture. Secondly, we apply this updated tool to measure the gap between academic and industrial FPGA tools by examining the quality of results at each of the three main compilation stages: synthesis, packing & placement, routing. Our findings indicate that the delay gap (according to Xilinx static timing analysis) for academic tools breaks down into a 31% degradation with synthesis, 10% with packing & placement, and 15% with routing. This leads us to believe that opportunities for improvement exist not only within VPR, but also in the front-end tools that lie upstream

Optimum correction of thrust transient measurements

Optimum correction of distorted thrust transient measurement

Severe storm initiation and development from satellite infrared imagery and Rawinsonde data

The geographical distribution of potential temperatures, mixing ratio, and streamlines of flow patterns at 850, 700, and 500 mb heights are used to understand the prestorm convection and the horizontal convergence of moisture. From the analysis of 21 tornadoes the following conclusions are reached: (1) Strong horizontal convergence of moisture appeared at the 850, 700, and 500 mb levels in the area 12 hours before the storm formation; (2) An abundantly moist atmosphere below 3 km (700 mb) becomes convectively unstable during the time period between 12 and 24 hours before the initiation of the severe storms; (3) Strong winds veering with height with direction parallel to the movement of a dryline, surface fronts, etc; (4) During a 36-hour period, a tropopause height in the areas of interest is lowest at the time of tornadic cloud formation; (5) A train of gravity waves is detected before and during the cloud formation period. Rapid-scan infrared imagery provides near real-time information on the life cycle of the storm which can be summarized as follows: (1) Enhanced convection produced an overshooting cloud top penetrating above the tropopause, making the mass density of the overshooting cloud much greater than the mass density of the surrounding air; (2) The overshooting cloud top collapsed at the end of the mature stage of the cloud development; (3) The tornado touchdown followed the collapse of the overshooting cloud top

Initiation of stabilized detonations by projectiles

A high-speed projectile in combustible gas can initiate and stabilize a detonation wave under suitable conditions [1]. In this paper, numerical simulations of projectile induced detonation waves are presented. Using a one-step irreversible reaction model, the transition from shock-induced combustion to stabilized oblique detonation is observed via numerical simulations. An analysis of this transition by means of the critical decay-rate model, which considers a balance between energy-release due to reaction, and quenching due to shock-curvature, is presented

Ultracold Molecule Assembly with Photonic Crystals

Photoassociation (PA) is a powerful technique to synthesize molecules directly and continuously from cold and ultracold atoms into deeply bound molecular states. In freespace, however, PA efficiency is constrained by the number of spontaneous decay channels linking the initial excited molecular state to a sea of final (meta)stable rovibronic levels. Here, we propose a novel scheme based on molecules strongly coupled to a guided photonic mode in a photonic crystal waveguide that turns PA into a powerful tool for near deterministic formation of ultracold molecules in their ground rovibrational level. Our example shows a potential ground state molecule production efficiency $> 90\%$, and a saturation rate $>10^6$ molecules per second. By combining state-of-the-art cold atomic and molecular physics with nanophotonic engineering, our scheme presents a novel experimental package for trapping, cooling, and optical manipulation of ultracold molecules, opening up new possibilities in the direction of ultracold chemistry and quantum information