Large Language Models (LLMs) have been increasingly used to optimize code efficiency. Evaluating their effectiveness and further suggesting optimization opportunities often rely on high-quality tests to demonstrate the performance bottlenecks presented in the program. However, existing approaches rely on a limited set of hand-curated inputs or LLM-generated uninteresting length-stressing tests, failing to reveal more nuanced optimization opportunities. We present WEDGE, a framework for generating performance-stressing input given the program under test. WEDGE synthesizes explicit performance-characterizing constraints in the form of branch conditions to partition the programs’ execution space into performance-specific regions. When integrated with the coverage-guided fuzzer, reaching different regions introduces explicit rewards for test generation to explore inefficient implementations. Our evaluation shows that WEDGE introduces a significant slowdown compared to the tests in CodeContests and those claimed to be optimized by existing approaches. From the utility perspective, integrating our tests substantially improves the existing code optimization approaches that rely on test-driven execution feedback. We release PERFFORGE, the performance tests generated by WEDGE, to benchmark future approaches for efficient code generation at https://github.com/UChiSeclab/perfforge.

High Speed Air Rotor-Bearing (HSAR) systems have been extensively applied for a variety of mechanical engineering parts, and potential for use in high-rotational speed, high-precision and high stiffness instrumentation. The current study presents a detailed theoretical analysis of bearing performance, in which a hybrid method combing finite difference method (FDM) and differential transformation method (DTM) is used to solve the governing equations of HSAR system. In order to realize under what kind of operating condition the non-periodic motion will occur to the HSAR system, the dynamic behavior of the rotor center is examined with different operating conditions by generating the corresponding bifurcation diagrams, Poincaré maps, and power spectra etc. The results obtained for the orbits of the rotor center are in good agreement with those obtained using the traditional FDM approach. Moreover, the hybrid method increases the accuracy and obtains better numerical stability than the FDM at real operating parameters of the bearing number and computational time-step. The results presented summarize the changes which take place in the dynamic behavior of the HSAR system as the rotor bearing number are increased and therefore provide a useful guideline for the HSAR system.

This paper considers the problem of chaos synchronization based on fuzzy sliding mode control and its applications to image encryption. We applied the fuzzy sliding mode controller to achieve chaos synchronization. Then, the Duffing-Holmes chaos states are used to act as the encryption key of cipher text. When their initial values of chaotic states are different, the state sequences are uncorrected. This concept is employed to communication secrecy and image encryption. The XOR operation is used to realize image encryption. The numerical results demonstrate that this scheme can be applied to communication secrecy and image encryption.

According to the advancement of the medical science in recent years, Taiwan has come into the aging society. Due to the increase of elderly people, the requirement of wheelchair is increasing gradually. Therefore, we develop a system to increase the security of the wheelchair. This research is to configure sensors in a wheelchair for measuring the position and the operation of wheelchair users. If the sitting posture of the wheelchair user is bad or the wheelchair user has the danger, the system will show a warning message to tell the caregiver. According to the position shown, the caregiver can go to the area to help the wheelchair user directly. In addition, a care system running on smart phone is developed, so that the caregiver can take care for wheelchair users anywhere and anytime. Finally, a novel data mining system is designed and implemented for analyzing the wheelchair operations for wheelchair users. It can find out the incorrect or unfitting sitting posture of the wheelchair user for long periods, or environmental problems to provide more useful information for the caregiver. The caregiver can take care for the wheelchair user by this integrated system.

A combined design of four concurrent error detection (CED) schemes-the alternating logic scheme, duplication of the on-set scheme, duplication of the off-set scheme, and the parity checking scheme, is proposed for field programmable logic arrays (FPLAs) which inherently has unutilized elements. One of the four CED schemes can be implemented by the proposed circuit and the unutilized elements with the constraint that the unused elements can be programmed as parts of test logic.>