Suchergebnisse

The traffic in concubines flourished in Ming-Qing Jiangnan as a result of large scale interactions of political and socioeconomic contexts. How women were situated within the system is central to this study, which revolves around two major arguments. First, the traffic in concubines as a means for disaster relief during difficult times was legitimized as a benevolent policy. Second, women were not necessarily the victims of the commercialized market in concubines. To study concubinage in general and individual concubines in the market system in Jiangnan, the following issues command attention: the political and socioeconomic conditions fostering concubinage, the market system of women, the roles of brokers, the value indicators and resultant prices, the transaction procedures for the sale of women with specific contents of contracts, the effects of the market system on the concubines'lives, and the regulations of law and the judicial practice in penal cases.

Continuing advances in wireless communications and MEMS (Micro-Electro Mechanical Systems) technologies have fostered the construction of a wide variety of sensor and ad hoc networks. These networks have broad applications spanning wide areas, such as environmental monitoring, infrastructure maintenance, traffic management, energy management, disaster mitigation, personal medical monitoring, smart building, as well as military and defence. While these applications require high performance from the network, they suffer from resource constraints (such as limited battery power, processing capability, buffer space, etc.) that do not appear in traditional wired networks. The inherent infrastructure-less characteristic of the sensor and ad hoc networks creates significant challenges. This dissertation addresses these challenges with two protocol designs. The main contributions of this dissertation are the design and evaluation of CS-MAC (stands for CDMA Sensor MAC), a novel multi-channel media access control (MAC) protocol for direct sequence code division multiple access (DS-CDMA) wireless sensor networks. Our protocol design uses combination of DS-CDMA and frequency division to reduce the channel interference and consequently improves system capacity and network throughput. We provide theoretical characterisation of the mean multiple access interference (MAI) at a given node in relation to the number of frequency channels. We show that by using only a small number of frequency channels, the mean MAI can be reduced significantly. Through discrete event simulation (using UC Berkerly NS-2 simulator), we provide comparison of our proposed system to a pure DS-CDMA system as well as a contention based system. Simulation results reveal that our proposed system can achieve significant improvement in system efficiency (measured in packet/second/channel) of a contention based system. When the same number of packets are transmitted in the network, our system consumes much less communication energy compared to the contention ...