DPLL Architecture Research Articles

The phasemeter of Taiji-1 experimental satellite

Taiji-1 is the first demonstrated experimental satellite of Taiji program in China. Phasemeter is one of the key components of the laser interferometer which is responsible for phase extraction of the heterodyne signals. In this paper, we present the architecture and implementation of Taiji-1 phasemeter. The DPLL architecture is used in Taiji-1 which is generally regarded as the best choice for space missions. We test the phasemeter on the ground and the results show that the phasemeter reaches the sensitivity of 600 [Formula: see text]rad/[Formula: see text] in the frequency range of 0.01–1[Formula: see text]Hz. It is further shown that it can reach the accuracy of 30 [Formula: see text]rad/[Formula: see text] in the frequency range of 0.1–1[Formula: see text]Hz, both of which are within the technical requirements of Taiji-1 mission.

Well-founded operators for normal hybrid MKNF knowledge bases

AbstractHybrid MKNF knowledge bases have been considered one of the dominant approaches to combining open world ontology languages with closed world rule-based languages. Currently, the only known inference methods are based on the approach of guess-and-verify, while most modern SAT/ASP solvers are built under the DPLL architecture. The central impediment here is that it is not clear what constitutes a constraint propagator, a key component employed in any DPLL-based solver. In this paper, we address this problem by formulating the notion of unfounded sets for non-disjunctive hybrid MKNF knowledge bases, based on which we propose and study two new well-founded operators. We show that by employing a well-founded operator as a constraint propagator, a sound and complete DPLL search engine can be readily defined. We compare our approach with the operator based on the alternating fixpoint construction by Knorr et al. (2011. Artificial Intelligence 175, 9, 1528–1554) and show that, when applied to arbitrary partial partitions, the new well-founded operators not only propagate more truth values but also circumvent the non-converging behavior of the latter. In addition, we study the possibility of simplifying a given hybrid MKNF knowledge base by employing a well-founded operator and show that, out of the two operators proposed in this paper, the weaker one can be applied for this purpose and the stronger one cannot. These observations are useful in implementing a grounder for hybrid MKNF knowledge bases, which can be applied before the computation of MKNF models.

A 1.2-V-only 900-mW 10 gb ethernet transceiver and XAUI interface with robust VCO tuning technique

This paper describes the design and the implementation of a fully integrated 10 Gb Ethernet transceiver in a 0.13-/spl mu/m CMOS process using only a 1.2 V supply. A coarse control algorithm that combines a voltage range monitoring circuit with a frequency lock detector provides a robust operation against process, voltage, and temperature (PVT) variations for a VCO with a ring oscillator. With the use of a blind oversampling DPLL architecture, four channels of XAUI transceivers can share a single PLL, eliminating the clock synchronization problem between channels. Also, the total number of clock domains for the entire chip is reduced to three, making the integration of the XAUI with the 10G transceiver much simpler. The test chip consumes 898 mW from a 1.2 V supply.