Browsing by Author "Li, Wei"

Now showing 1 - 6 of 6
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    Adaptive production scheduling and control in one-of-a-kind production
    (2010) Li, Wei; Tu, Yiliu (Paul); Xue, Deyi
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    Adaptive production scheduling and control in one-of-a-kind production
    (2005) Li, Wei; Tu, Yiliu (Paul); Xue, Deyi
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    An Improved Particle Filter Algorithm for Geomagnetic Indoor Positioning
    (2018-03-19) Huang, He; Li, Wei; Luo, De An; Qiu, Dong Wei; Gao, Yang
    Geomagnetic indoor positioning is an attractive indoor positioning technology due to its infrastructure-free feature. In the matching algorithm for geomagnetic indoor localization, the particle filter has been the most widely used. The algorithm however often suffers filtering divergence when there is continuous variation of the indoor magnetic distribution. The resampling step in the process of implementation would make the situation even worse, which directly lead to the loss of indoor positioning solution. Aiming at this problem, we have proposed an improved particle filter algorithm based on initial positioning error constraint, inspired by the Hausdorff distance measurement point set matching theory. Since the operating range of the particle filter cannot exceed the magnitude of the initial positioning error, it avoids the adverse effect of sampling particles with the same magnetic intensity but away from the target during the iteration process on the positioning system. The effectiveness and reliability of the improved algorithm are verified by experiments.
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    An efficient heuristic for adaptive production scheduling and control in one-of-a-kind production
    (Elsevier, 2011) Nault, Barrie R; Li, Wei; Xue, Deyi; Tu, Yiliu
    Even though research in flow shop production scheduling has been carried out for many decades,there is still a gap between research and application especially in manufacturing paradigms such as one-of-a-kind production(OKP) that intensely challenges realtime adaptive production scheduling and control.Indeed,many of the most popular heuristics continue to use Johnson’s algorithm(1954) as their core. This paper presents a state space(SS)heuristic,integrated with a closed-loop feedback control structure,to achieve adaptive production scheduling and control in OKP. Our (SS) heuristic,because of its simplicity and computational efficiency,has the potential to become a core heuristic.Through a series of case studies,including an industrial implementation in OKP,our SS-based production scheduling and control system demonstrates significant potential to improve production efficiency.
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    Hot Blogging: Exploring English Writing Experiences of Undergraduate Students in China
    (2015-01-29) Li, Wei; Guo, Yan
    Little investigation has been conducted in the field of English as a Foreign Language (EFL) regarding writing experiences through blogs. This study explores students’ perceptions and experiences of using blogs in EFL writing in China. It draws upon Vygotsky’s constructivist theory and sociocultural theory in language learning. Thirty-one undergraduate students with English majors from a Chinese university participated in the study. Data for the study were collected from students’ blog and microblog entries, two questionnaires administered at the beginning and the end of the blog project, individual interviews, and informal conversations. Results indicate students reported that even though they were aware that English writing is an important component in the English exams and it is one of their weakest skills, they did not spend enough time on it. They found that the exam-oriented nature of the writing tasks on the blog designed by the researcher were not stimulating. They preferred to write about their personal feelings and post comments about current events on their microblogs rather than academic writing on their blogs. They created a new concept of “Anywhere, anytime English learning.” This means they preferred to share their personal comments on microblogs on their smart phones. Pedagogical implications of using blogs and microblogs to practice writing outside the classroom are discussed.
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    Operating room scheduling and adaptive control using a priority first fit decreasing heuristic
    (2015-06) Li, Wei; Mitchell, Victoria L.; Nault, Barrie R.; Brind, Denise
    Operating room (OR) scheduling is a critical factor affecting overall hospital performance. We examine OR scheduling from two perspectives. In the first perspective we propose a scheme for OR block scheduling that uses a heuristic developed for a three-machine flow shop where the three phases of the peri-operative process (pre-op, OR, and post-op) correspond to the three-machine flow shop. This approach facilitates a hospital-as-a-system perspective. The second perspective used to examine OR scheduling is adaptive control of the OR slate. Recognizing that there are many factors affecting OR throughput performance, especially preemptions from emergent and urgent cases, adaptive control of the OR slate is necessary. To realistically improve performance, adaptive control of the OR slate should incorporate constraints on how surgeries can be rescheduled. We examine the benefits from adaptive control of the OR slate that uses a priority first fit decreasing (PFFD) heuristic while incorporating constraints on OR slate rescheduling. The PFFD heuristic is a priority-driven variation of the classic FFD heuristic used in bin packing problems. We develop a scheme for OR block scheduling and our PFFD heuristic. We then demonstrate our PFFD heuristic in a simulation-based case study, and subsequently run a simulation using 1000 instances to test the performance of our PFFD heuristic in OR slate scheduling and OR slate adaptive control showing improvements in performance relative to the frequently used first-come-first-served rule.