Register Transfer Level (RTL) simulation is widely used in design space exploration, verification, debugging, and preliminary performance evaluation for hardware design. Among various RTL simulation approaches, software simulation is the most commonly used due to its flexibility, low cost, and ease of debugging. However, the slow simulation of complex designs has become the bottleneck in design flow. In this work, we explore the sources of computation overhead of RTL simulation and conclude them into four factors. To optimize these factors, we propose several techniques at the supernode level, node level, and bit level. Finally, we implement these techniques in a novel RTL simulator GSIM. GSIM succeeds in simulating XiangShan, the state-of-the-art open-source RISC-V processor. Besides, compared to Verilator, GSIM can achieve speedup of 7.34x for booting Linux on XiangShan, and 19.94x for running CoreMark on Rocket.

Sewer pipe is an essential infrastructure in the city as it undertakes the transportation and circulation of wastewater resources. But sewer pipe it is easy to have faults and cause serious secondary urban accidents, such as road holes and road collapse. Because of the complex underground circumstance, inspecting large-area sewer pipes using closed-circuit television or periscope television is difficult. In this study, we proposed a collaborative sewer pipe inspection approach by using novel low-cost pipe robotic capsules, which capture the images of the pipeline inner walls when floating with the water flow. A set of workers collaboratively drop and salvage capsules to cover a large-area pipe network. The routes of workers and pipe capsules are optimized by a meta-heuristic algorithm integrating local search and simulated annealing. The deep neural network is used to recognize faults from raw captured images. A field experiment in Shenzhen was conducted to evaluate the performance of the proposed approach. The results demonstrate that it outperforms the naive inspection method with a shorter travel distance and less waiting time. It is also effective for inspecting the large-area sewer pipe networks with an overall precision of 0.92. It will help us to eliminate the potential safety risk of the public and promote the level of urban governance.