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Polymorphic circuits are a special kind of circuits which possess some different build-in functions and these functions are activated by environment parameters, like light and VDD. Some theories have been proposed to guide the design of polymorphic circuits, including the definition of complete polymorphic gate sets and algorithms to judge the completeness of a polymorphic gate set. However, the previous algorithms have to enumerate all the polymorphic signals for judging the completeness of a polymorphic gate set, and it is not easy to be conducted manually. In this paper, a straightforward method is proposed to judge the completeness of a polymorphic gate set. And the correctness of the straightforward method is proved theoretically. Some examples are given to show that the proposed method could be conducted step by step. Its actual computing cost is usually low, and it is suitable for manual operation.

With the rapid development of Internet of things (IOT) and indoor positioning technologies such as Wi-Fi and RFID, indoor mobile information systems have become a new research hotspot. Based on the unique features of indoor space and urgent needs on indoor mobile applications, in this paper we analyze some key issues in indoor mobile information systems, including positioning technologies in indoor environments, representation models for indoor spaces, query processing techniques for indoor moving objects, and index structures for indoor mobile applications. Then, we present an indoor mobile information management system named IndoorDB. Finally, we give some future research topics about indoor mobile information systems.

In recent years, mobile operating systems, represented by android and iOS, have become more and more popular in smartphones. However, the energy issue in smartphones, which refers to the poor battery capacity and management schemes, has been the bottle-neck to further advance the development in this area. Generally, mobile applications have to consider both performance and energy consumption. But unfortunately, few works have been focused on this issue. In this paper, we aim at conducting an experimental study on the performance and energy tradeoffs for mobile applications. In particular, we focus on mobile database applications as they are one of the basic applications on mobile operating systems. In detail, we use the android system as the basic mobile platform, and the TPC-H benchmark as the workload, and build a benchmark platform called TPCdroid to conduct performance and energy measurement. In TPCdroid, we control the mobile database performance by changing the processor frequency. The initial experimental results show that lowering frequency is not always helpful for reducing energy consumption. Moreover, we found that the traditional energy reducing technologies based on X86 and magnetic disks are not suitable for mobile database applications running on ARM and flash memory. Finally, we analyse the relationship between performance and energy consumption under different kinds of workloads, which is done by adjusting the parameters reflecting performance and energy consumption for mobile database applications. The results show that the energy consumption has a dynamic connection with the performance in mobile database applications.