N queens on an fpga: mathematics,programming, or both?

This paper presents a design methodology for deriving an FPGA implementation directly from a mathematical specification, thus avoiding the switch in semantic perspective as is present in widely applied methods which include an imperative implementation as an intermediate step. The first step in the method presented in this paper is to transform a mathematical specification into a Haskell program. The next step is to make repetition structures explicit by higher order functions, and after that rewrite the specification in the form of a Mealy Machine. Finally, adaptations have to be made in order to comply to the fixed nature of hardware. The result is then given to CaSH, a compiler which generates synthesizable VHDL from the resulting Haskell code. An advantage of the approach presented here is that in all phases of the process the design can be directly simulated by executing the defining code in a standard Haskell environment. To illustrate the design process, the N queens problem is chosen as a running example

Fast, high current, high repetition rate pulse generator for injection lasers

The circuit described is capable of generating high‐current (2–50 A), fast‐rise‐time (10 nsec), square‐wave pulses into a 50‐Ω load. This circuit may be used for driving injection lasers at high repetition rates (up to 1.5 kHz) when connected to coaxial cables

Fewest repetitions in infinite binary words

A square is the concatenation of a nonempty word with itself. A word has period p if its letters at distance p match. The exponent of a nonempty word is the quotient of its length over its smallest period. In this article we give a proof of the fact that there exists an infinite binary word which contains finitely many squares and simultaneously avoids words of exponent larger than 7/3. Our infinite word contains 12 squares, which is the smallest possible number of squares to get the property, and 2 factors of exponent 7/3. These are the only factors of exponent larger than 2. The value 7/3 introduces what we call the finite-repetition threshold of the binary alphabet. We conjecture it is 7/4 for the ternary alphabet, like its repetitive threshold

Rethinking live electronic music: a DJ perspective

The author critiques the conventional understanding of live electronic music through empirical research on his own DJ practice and investigates others working in the field. In reviewing the opinions of theorists and practitioners in both the live electronic music genre and DJ-ing he argues against the body/machine dialectic that has determined much of the thinking in the former. The author forms a notion of the DJ as a real-time composer working beyond traditional binary distinctions who brings the human body and machine into a mutual relationship. Through practice-led research he charts an investigation beginning in physical human gesture and culminating in digital machine repetition. He concludes that mechanical and digital repetition do not obscure human agency in the production of live works and that this concern is imaginary

Long-term Stabilization of Fiber Laser Using Phase-locking Technique with Ultra-low Phase Noise and Phase Drift

We review the conventional phase-locking technique in the long-term stabilization of the mode-locked fiber laser and investigate the phase noise limitation of the conventional technique. To break the limitation, we propose an improved phase-locking technique with an optic-microwave phase detector in achieving the ultra-low phase noise and phase drift. The mechanism and the theoretical model of the novel phase-locking technique are also discussed. The long-term stabilization experiments demonstrate that the improved technique can achieve the long-term stabilization for the MLFL with ultra-low phase noise and phase drift. The excellent locking performance of the improved phase-locking technique implies that this technique can be used to stabilize the mode-locked fiber laser with the highly stable H-master or optical clock without stability loss