To build a 16-bit audio delta-sigma (Δ-Σ) digital-to-analog converter (DAC), a low noise reconstruction filter has been presented in this paper. By using the direct charge transfer (DCT) technique, the low noise and small area is implemented. In addition, a fully differential operational amplifier (op-amp) with proposed switch capacitor (SC) common mode feed back (CMFB) circuit is employed for low-noise design in this system. The proposed reconstruction filter is designed in TSMC 0.35μm CMOS process. And a peak signal-to-noise density ratio (SNDR) of 95.3 dB and a dynamic range (DR) of 97.2 dB for a 5k Hz input signal is achieved at a 1.8V supply voltage.

Ant System (AS) was the first Ant Colony Optimization (ACO) algorithm, which converged too slowly and consumed huge computation. Among the variants of AS, Ant Colony System (ACS) was one of the most successful algorithms. But ACS converged so rapidly that it always was in early stagnation. An improved Ant Colony System based on Negative Biased (NBACS) was introduced in the paper to overcome the early stagnation of the ACS. Experiments for Traveling Salesman Problem (TSP) showed that better solutions were obtained at the same time when the convergence rate accelerated more rapidly.

In the past few years, there have been tremendous interest in the peer-to-peer(P2P) content delivery. This communication paradigm dramatically increases the traffic over inter-ISP links. In particular, BitTorrent(BT), the most popular P2P application, generates a huge amount of traffic on the Internet. BitTorrent’s performance is limited by the fact that typical internet users have much lower upload bandwidths than download bandwidths. This results in the overall average download speed of a BitTorrent-like file download system to be bottle-necked by the much lower upload capacity. We think about to utilize idle users’ spare upload capacity to largely improve the download speed beyond what can be achieved in a conventional BitTorrent network. In this paper, we design a system that is completely compatible with the already existing clients who conform to the BitTorrent protocol, at the same time, we analyze this system’s steady-state performance and present simulation results.

Structured peer-to-peer (P2P) systems are creating a large proportion of network traffic in today’s Internet. Peer-to-peer systems enable access to data spread over an extremely large number of machines. A P2P system typically involves thousands or millions of live peers in the network. Multi-dimensional data indexing has received much attention in a centralized database. In this paper, we propose and evaluate a multi-dimensional searching scheme in structured P2P networks. We present the design and implementation of a peer-to-peer index service for high dimensional data that is capable of handling complex queries. We design a VibIndex scheme in structured P2P overlay networks. We analyze this scheme’s performance and present simulation results. Our simulation results demonstrated the benefits of the proposed system and show that the approach is able to search efficiently.