Wei Li

• University of Kentucky

The structural stability and electrochemical performance of intrinsic and B doped T-graphene nanotubes with different tube lengths are systematically studied by using the first-principles calculations within the framework of density...

Using first-principles calculation based on density functional theory, the effects of B, Al and B-Al doping on the structural stability and electrochemical properties of silicene were systematically studied, and their potential as anode materials for lithium ion batteries was evaluated. The calculated results of formation energy indicate that the d...

The influence of N/F substitution and site‐exchange of Li and Fe ions on properties of Li2FeSiO4 are investigated by first‐principles calculation, including the structural parameters, mechanical, electrochemical, and magnetic properties of Li2FeSiO4. The calculated results show that site‐exchange of Li and Fe ions occurs during the removal of lithi...

Production scheduling faces three challenges, which are inconsistent key performance indicators (KPIs), processing time uncertainties, and production schemes. Applying modern portfolio theory (MPT), Li et al. (2021) proposed a ToB(α) heuristic to balance trade-offs in one-stage production. However, production schemes for optimizing average performa...

Production scheduling faces three challenges, two of which are trade-offs and the third is processing time uncertainty. The two sources of trade-offs are between inconsistent key performance indicators (KPIs), and between the expected return and the risk of KPI portfolios. Given the KPIs of total completion time (TCT) and variance of completion tim...

Production scheduling involves operational level decision making at the shop floor that covers not only the manufacturing stage of the product life-cycle, but also the use stage of the processes. Triple bottom line (TBL) including economic, environmental, and social pillars has been introduced to holistically evaluate the performance of a productio...

We propose a trade-off balancing (TOB) heuristic in a no-wait flow shop to minimise the weighted sum of maximum completion time ( Cmax) and total completion time (TCT) based on machine idle times. We introduce a factorisation scheme to construct the initial sequence based on current and future idle times at the operational level. In addition, we pr...

In sustainable manufacturing, inconsistencies exist among objectives defined in triple-bottom-lines (TBL) of economy, society, and environment. Analogously, inconsistencies exist in flow shop scheduling among three objectives of minimizing total completion time (TCT), maximum completion time (MCT), and completion time variance (CTV), respectively....

We balance trade-offs between two fundamental and possibly inconsistent objectives, minimization of maximum completion time and minimization of total completion time, in scheduling serial processes. We use a novel approach of current and future deviations (CFD) to model the trade-offs between the two completion times. We also use weights α and β to...

The product returns involve considerable uncertainties that have an impact on the economic (i.e., total cost) and environmental (i.e., global warming potential, water use and energy use) performance measures of a product configuration design. This is because it directly affects the number of reusable, remanufacturable and/or recyclable components/i...

In modern cities, public transit is important for meeting people’s transportation needs. Dynamic bus dispatching plays an important role in a transit system, especially when the system experiences extreme weather, fluctuations in passenger flows, etc. Consequently, the assumption presented in the literature that departure timetables of buses are pr...

Within a hospital, the operating room (OR) department has the largest cost and revenue. Because of the aging population, the demand for surgical services has been increasing sharply in recent years. At the other hand, the rate of OR capacity expansion is lower than the rate of increasing demand. As a result, OR managers must leverage their resource...

Balancing trade-offs between production cost and holding cost is critical for production and operations management. Utilization of a production line affects production cost, which relates to makespan, and work-in-process (WIP) inventories in a production line affect holding cost, which relate to flowtime. There are trade-offs between two objectives...

Operating room (OR) scheduling is important. Because of increasing demand for surgical services, hospitals must provide high quality care more efficiently with limited resources. When constructing the OR schedule, it is necessary to consider the availability of downstream resources, such as intensive care unit (ICU) and post anaesthesia care unit (...

The operating room (OR) is responsible for most hospital admissions and is one of the most cost and work intensive areas in the hospital. From recent trends, we observe an ironic parallel increase among expenditure and waiting time. Therefore, improving OR scheduling has become obligatory, particularly in terms of patient flow and benefit. Most of...

No-wait flow shop production has been widely applied in manufacturing. However, minimization of total completion time for no-wait flow shop production is NP-complete. Consequently, achieving good effectiveness and efficiency is a challenge in no-wait flow shop scheduling, where effectiveness means the deviation from optimal solutions and efficiency...

No-wait flow shop production has been widely applied in manufacturing, where no waiting time is allowed between intermediate operations. However, minimization of makespan for no-wait flow shop production is NP-hard. In this paper, we propose an average idle time (AIT) heuristic to minimize makespan in no-wait flow shop production. First, we take th...

Operating room (OR) planning is critical in healthcare systems to reduce cost and improve the efficiency of OR scheduling. The OR planning problem is complicated, involving many conflicting factors, such as overtime and idle time, both of which affect OR utilization and consequently affect cost to a hospital. Allocating different types of surgeries...

The development of more efficient and better performing priority dispatching rules (PDRs) for production scheduling is relevant to modern flow shop scheduling practice because they are simple, easy to apply and have low computational complexity, especially for large-scale problems. While the current research trend in scheduling is towards finding s...

Uneven workflow in serial flow lines is common when job work content varies. Unfortunately, work content imbalance between stations or between jobs degrades system performance. The effect of this imbalance can be mitigated by proper job sequencing. In this paper, we uncouple the influence of station-to-station and job-to-job imbalance within a set...

In no-wait flow shop production, each job must be processed without any interruption from its start time on the first machine to its completion time on the last machine. To minimize makespan in no-wait flow shop production is one of the main concerns in industry. In this paper, we propose an average departure time (ADT) heuristic for minimizing mak...

Optimisation of product family design has been emphasised and studied for many years. However, previous studies only took overall cost or profit as an optimisation objective, but ignored the supply risk of a product family. Moreover, the discount associated with the bidding price, which is common in practice, was not considered in the modelling. In...

Utilization and work-in-process (WIP) inventories of flow lines are two managerial concerns in manufacturing systems. They relate to two objectives in flowshop production scheduling respectively. Minimization of maximum completion time relates to utilization improvement of flow lines, and minimization of average completion time relates to WIP inven...

Variation in sequential task processing times is common in manufacturing systems. This type of disturbance challenges most scheduling methods since they cannot fundamentally change job sequences to adaptively control production performance as jobs enter the system because actual processing times, are not known in advance. Some research literature i...

Abstract In thermal error compensation technology on computer numerical control (CNC) machine tool, selecting appropriate and stable temperature-sensitive points for modeling and compensation, is crucial for improving the accuracy of machine. In this paper, the temperature-sensitive points are changeable is proved by analyzing batches of experiment...

The efficient scheduling of operating room (OR) slates is critical in a hospital setting, especially given OR slates are linked with preoperative and postoperative services. Wait list minimization is a common goal in OR scheduling, one that is broadly defined and can be achieved from many perspectives. Due to the complexity of OR scheduling, and th...

As a typical manufacturing paradigm, one-of-a-kind production (OKP) challenges production scheduling and control differently than mass production. High throughput in OKP is a typical example of mass customization, which is one of the important strategies in the current economy where the objective is to maximize the customer satisfaction by producin...

Although research in flow shop production scheduling has been carried out for many decades, there is still a gap between theoretical research and industrial applications – especially in some manufacturing paradigms in which adaptive production control is necessary, such as in one-of-a-kind production (OKP). This paper presents an average processing...

In a one-of-a-kind production (OKP) company, the operation routing and processing time of an order are usually different from the others due to high customisation. As a result, an OKP company needs to dynamically adjust the production resources to keep the production lines reconfigurable. Through a proper assignment of operators in different sectio...

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 real time adaptive production scheduling and control. Indeed, many of the most popular heuristics...

Three criteria are important to evaluate a heuristic for adaptive production control, which are optimality, computational complexity and flexibility. However, the stability of a schedule generated by a heuristic is also important from the perspective of manufacturing systems. In this paper, we carry out case studies on variation in processing time...

In one-of-a-kind production (OKP) companies, the number of production resources in each work centre of a production line is flexible in shifts because the resource demands of customer orders are always different from shift to shift. In this paper an optimisation model is established to achieve an optimal resource allocation plan ensuring that all j...

One-of-a-kind production (OKP) is a competitive production mode aiming at achieving mass customization. Whereas, dynamics in OKP cause difficulties on production scheduling, which may be manifested as frequent changes of customer orders, differences of production processes, different processing times of products, and so on. For production schedulin...

Modern manufacturing companies are moving toward mass customization to produce customized products based on requirements of individual customers with efficiency of mass production. One-of-a-kind production (OKP) is a typical production mode that aims at achieving mass customization through computer-aided systems. Because frequent changes and distur...

Frequent changes or disturbances from customers and suppliers in One-of-a-Kind Production (OKP) make it difficult to schedule and control the production on OKP shop floors. Therefore, the OKP shop floor is normally managed manually and often runs into a fire fighting situation. To solve this problem, an adaptive control structure is introduced in t...

Dynamics caused by mass customization in one-of-a-kind production complicate the production scheduling and control on hybrid flow shop problems that are intrinsically and mathematically stubborn. The existing models or heuristics for hybrid flow shop scheduling were derived under restrictive assumptions, such as no operator absence/machine breakdow...