Palmprint recognition has received tremendous research interests due to its outstanding user-friendliness such as non-invasive and good hygiene properties. Most recent palmprint recognition studies such as deep-learning methods usually learn discriminative features from palmprint images, which usually require a large number of labeled samples to achieve a reasonable good recognition performance. However, palmprint images are usually limited because it is relative difficult to collect enough palmprint samples, making most existing deep-learning-based methods ineffective. In this paper, we propose a heuristic palmprint recognition method by extracting triple types of palmprint features without requiring any training samples. We first extract the most important inherent features of a palmprint, including the texture, gradient and direction features, and encode them into triple-type feature codes. Then, we use the block-wise histograms of the triple-type feature codes to form the triple feature descriptors for palmprint representation. Finally, we employ a weighted matching-score level fusion to calculate the similarity between two compared palmprint images of triple-type feature descriptors for palmprint recognition. Extensive experimental results on the three widely used palmprint databases clearly show the promising effectiveness of the proposed method.
To provide energy savings and ecological benefits, dimming control is a crucial factor in indoor visible light communication (VLC) system where desired brightness levels can be achieved. General dimming control methods have an adverse effect on communication, e.g., limiting the achievable data rate or degrading the error performance. In this paper, we propose a code-based method weight threshold check code (WTCC), which can achieve dimming control as well as improve spectral efficiency further. Moreover, the proposed WTCC has a low implementation complexity with a simple encoding/decoding structure. Finally, simulations have been carried out in terms of normalized power requirement, spectral efficiency, and error performance, which prove WTCC can provide a balance between the two basic functions of VLC: illumination and communication.
Software transactional memory is an effective mechanism to avoid concurrency bugs in multithreaded programs. However, two problems hinder the adoption of such traditional systems in the wild world: high human cost for equipping programs with transaction functionality and low compatibility with I/O calls and conditional variables. This paper presents Convoider to solve these problems. By intercepting interthread operations and designating code among them as transactions in each thread, Convoider automatically transactionalizes target programs without any source code modification and recompiling. By saving/restoring stack frames and CPU registers on beginning/aborting a transaction, Convoider makes execution flow revocable. By turning threads into processes, leveraging virtual memory protection and customizing memory allocation/deallocation, Convoider makes memory manipulations revocable. By maintaining virtual file systems and redirecting I/O operations onto them, Convoider makes I/O effects revocable. By converting lock/unlock operations to no-ops, customizing signal/wait operations on condition variables, and committing memory changes transactionally, Convoider makes deadlocks, data races, and atomicity violations impossible. Experimental results show that Convoider succeeds in transparently transactionalizing twelve real-world applications with averagely incurring only 28% runtime overhead and perfectly avoid 94% of thirty-one concurrency bugs used in our experiments. This study can help efficiently transactionalize legacy multithreaded applications and effectively improve the runtime reliability of them.
Visible light communications (VLCs) utilizing multi-color light-emitting diodes (LEDs) can achieve a high modulation bandwidth and high-quality illumination compared with phosphor-converted LEDs, which have attracted much attention. However, the spectrum overlapping of different colors may cause the crosstalk problem, which should be considered in the practical multi-color LED-based VLC systems. Due to the ever-increasing energy consumption, the interest in an energy-saving communication technique has further increased. In this paper, in order to maximize energy efficiency, an optimization problem of the optical power allocation scheme is formulated for the multi-color LED-based VLC systems under the necessary communication requirements and illumination constraints with luminance, chromaticity, and signal to interference plus noise ratio (SINR) constraints. Simulation results indicate that the proposed optimal power allocation scheme can reduce energy consumption while satisfying the illumination and communication requirements.
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