Operating room management under uncertainty

The operating room management problems are legion. This paper tackles the scheduling of surgical procedures in an operating theatre containing up to two operating rooms and two surgeons. We first solve a deterministic version that uses the constraint programming paradigm and then a stochastic version which embeds the former in a sample average approximation scheme. The latter produces more robust schedules that cope better with the surgeries’ time variability     

A planning and scheduling problem for an operating theatre using an open scheduling strategy

The objective of this paper is to design a weekly surgery schedule in an operating theatre where time blocks are reserved for surgeons rather than specialities. Both operating rooms and places in the recovery room are assumed to be multifunctional, and the objectives are to maximise the utilisation of the operating rooms, to minimise the overtime cost in the operating theatre, and to minimise the unexpected idle time between surgical cases. This weekly operating theatre planning and scheduling problem is solved in two phases. First, the planning problem is solved to give the date of surgery for each patient, allowing for the availability of operating rooms and surgeons. Then a daily scheduling problem is devised to determine the sequence of operations in each operating room in each day, taking into account the availability of recovery beds. The planning problem is described as a set-partitioning integer-programming model and is solved by a column-generation-based heuristic (CGBH) procedure. The daily scheduling problem, based on the results obtained in the planning phase, is treated as a two-stage hybrid flow-shop problem and solved by a hybrid genetic algorithm (HGA). Our results are compared with several actual surgery schedules in a Belgian university hospital, where time blocks have been assigned to either specific surgeons or specialities several months in advance. According to the comparison results, surgery schedules obtained by the proposed method have less idle time between surgical cases, much higher utilisation of operating rooms and produce less overtime.     

集成手术排程和护士排班的中期决策优化研究

在手术需求增大与医护人员短缺的矛盾下如何合理安排手术和配置医护资源,解决手术室实际运作中资源负荷不均衡现象,是当前手术室运作管理中亟待解决的难题。然而手术排程和手术室护士排班作为手术室科学管理的核心决策问题,却有着不同的时间域,并且会相互影响。在考虑科室手术和手术室护士偏好等硬约束和软约束前提下,构建一个集成手术排程和护士排班的手术室中期集成决策模型,设计了具有双层嵌套路径化结构的蚁群算法。通过某三甲医院10天的实际手术室运作数据,进行算法对比和分析评价,验证了算法在解决集成决策问题上的可行性和有效性。     

基于CMBBO的医院管理资源调度

手术室资源调度关系到医院资源配置的合理性,对医院竞争力具有至关重要的影响.针对BBO算法收敛速度效率低、易陷入局部最优的缺陷,提出了云模型BBO算法,并结合所建立的医院手术室资源调度模型,提出了一种基于CMBBO的医院手术资源调度模型.将该模型应用于某大型三甲医院,结果表明手术资源使用率和手术服务能力得到提升、手术等待...     

A new heuristic algorithm for the operating room scheduling problem

Due to the great importance of operating rooms in hospitals, this paper studies an operating room scheduling problem with open scheduling strategy. According to this strategy, no time slot is reserved for a particular surgeon. The surgeons can use all available time slots. Based on Fei et al.’s model which is considered to be close to reality, we develop a heuristic algorithm to solve it. The idea of this heuristic algorithm is from dynamic programming by aggregating states to avoid the explosion of the number of states. The objective of this paper is to design an operating program to maximize the operating rooms’ use efficiency and minimize the overtime cost. Computational results show that our algorithm is efficient, especially for large size instances where our algorithm always finds feasible solutions while the algorithm of Fei et al. does not.     

A hybrid genetic approach for solving an integrated multi-objective operating room planning and scheduling problem

In this paper, we propose a multi-objective integer linear programming model aiming at efficiently planning and managing hospital operating room suites. By effectively exploiting a novel hybrid genetic solution approach, the devised optimization model is able to determine, in an integrated way, (i) the operating room time assigned to each surgical specialty, (ii) the operating room time assigned to each surgical team, (iii) the surgery admission planning and (iv) the surgery scheduling. The resulting Pareto frontiers provide a set of “optimal” solutions able to support hospital managers in efficiently orchestrating the involved resources and planning surgeons and surgeries. On this basis, the proposed solution framework could represent a suitable engine for the development of advanced and effective health care management decision support systems.     

Support optimal scheduling with weighted random forest for operation resources

Operation-related resources are lots of manpower and material with the characteristics of high cost and high income in hospitals, and scheduling optimization is a very important research issue in medical service. In this paper, to cope with the actualities of operation resources scheduling, such as poor planning, lack of standardized scheduling rules, chaotic use of the operating rooms, and many human interference factors, we propose a systematic approach to optimize scheduling problems based on multiple characteristics of operating resources. We first design a framework that includes the composite dispatching rules (CDR), optimization ideology, and feedback mechanism, in which the CDR integrates flexible operating time, hold-up time of medical facilities, available time of medical staff, and multiple constraints. The optimization ideology is carried out through a learning model based on the weighted random forest (WRF) algorithm. The feedback mechanism enables the approach to realize closed-loop optimizations adaptively. Finally, the superiority of the systematic scheduling approach (SSA) is analyzed through numerical experiments on a simulation platform. Results of the simulation experiments show that the proposed scheduling method can improve performances significantly, especially in the waiting time of patients.     

Real-time load balancing scheduling algorithm for periodic simulation models

A scheduling algorithm is crucial for real-time simulations because it guarantees that each model meets its deadline. Traditional online real-time scheduling algorithms such as Earliest Deadline First (EDF) introduce a high overhead when scheduling a large number of models. In this paper, a new algorithm called time-stepped load balancing (TLS) is proposed to address the real-time execution of a model set in a time-stepped simulation. A load balancing schedule table is generated before a simulation and rebalanced at runtime to dynamically schedule the changed model set. This table is organized by the execution periods of the models and balanced according to the load of each time step. Moreover, the slack time is distributed evenly among the steps to improve the real-time reliability. An extension to the algorithm for a multi-core environment is further studied to address those models with long execution times. Experimental results show that our scheduling algorithm outperforms the classical EDF approach. The highest performance improvement of TLS over EDF reaches 3–4% in terms of saving processor resources, and the jitter is about 4 times less when 90 entities are employed in a typical tank combat simulation scenario.     

Negotiation and conflict in large scale collaboration: a preliminary field study

Coordinating activities in many settings can require people to manage conflict, potential and actual. Conflict arises from resource limitations, high-stakes consequences, uncertainty, goal conflict among stakeholders and hierarchical organizational structures. To understand coordination in such systems, we conducted a field study of management of surgical operating rooms. While coordinating interdependencies, such as progress monitoring, scheduling and rescheduling, and prodding, coordinators managed a set of complicated conflicts. They did so opportunistically, to resolve and to prevent conflict. Additionally, coordinators were concerned with perceived fairness. These findings indicate that, in the design of ICT to support coordination, we should examine not only the mechanical articulation of activities and efficient prioritization of resources, but also means to support companion social processes.     

一种提高构件化嵌入式操作系统性能的方案

本文分析了现有构件化嵌入式操作系统所用调度算法存在的缺点,提出抢占阈值调度算法是更为合适的算法。通过仿真实验比较抢占阈值调度算法、非抢占式调度算法和FIFO(First-In-First-Out)调度算法的性能,证明了上述结论。通过分析现有嵌入式系统构件模型的特点,提出了一种构件模型以及将构件映射成任务的方式,还提出了一种设计方法。整个方案能提高构件化嵌入式操作系统的性能。     

Scheduling an operating theatre under human resource constraints

In the present economic context, the operating theatre is considered as a critical activity in health care management. By virtue of its huge consumption of human and material resources, the operating theatre is one of the most important sources of expenses of the hospitals. A less costly organization of the operating rooms calls for a more rational use of the resources and a more refined planning of the surgical units. In addition to these considerations, we are concerned about the well-being of the medical staff. We integrate this human factor into the optimization procedure by stressing the human resources’ availabilities in the design of the schedules. This planning process is typically decomposed in two sequential phases: a planning stage followed by a scheduling stage. Due to this decomposition the resulting solutions may turn out to be sub-optimal. In this paper, we propose a formulation that includes both the planning and scheduling of the surgical operations. We also propose a heuristic solution procedure based on genetic algorithms to counter the large running times inherent in tackling this kind of hard optimization problem.     

Multiple model approach to nonlinear system identification with an uncertain scheduling variable using EM algorithm

This paper deals with system identification of general nonlinear dynamical systems with an uncertain scheduling variable. A multi model approach is developed; wherein, a set of local auto regressive exogenous (ARX) models are first identified at different process operating points, and are then combined to describe the complete dynamics of a nonlinear system. An expectation-maximization (EM) algorithm is used for simultaneous identification of local ARX models, and for computing the probability associated with each of the local ARX models taking effect. A smoothing algorithm is used to estimate the distribution of the hidden scheduling variables in the EM algorithm. If the dynamics of the scheduling variables are linear, Kalman smoother is used; whereas, if the dynamics are nonlinear, sequential Monte-Carlo (SMC) method is used. Several simulation examples, including a continuous stirred tank reactor (CSTR) and a distillation column, are considered to illustrate the efficacy of the proposed method. Furthermore, to highlight the practical utility of the developed identification method, an experimental study on a pilot-scale hybrid tank system is also provided.     

Maximizing the efficiency of use of nurses under uncertain surgery durations: A case study

This paper studies a nurse scheduling problem of assigning a set of nurses to surgeries scheduled on each workday in an operating room (OR) suite. This problem plays a decisive role in utilizing nurses efficiently, which is of paramount importance for OR suites to provide high-quality service at ever reduced cost. Due to significant uncertainty in surgery durations, designing schedules that achieve high nurse efficiency is complicated by the competing objective of ensuring on-time starts of surgeries. For trading off between the two performance criteria, we formulate the problem as a mixed integer programming (MIP) model with explicit probability modeling of uncertainty. We are concerned about improving nurse efficiency in terms of overtime and idle time of nurses while mastering the risk of delay of surgeries. The MIP model is applied in a large size Chinese hospital, and the results are compared with the actual performance of the OR suite. The comparisons reveal that through examining the trade-off between the performance criteria, important nurse efficiency improvements can be achieved with good on-time start performance. Moreover, the applicability of the MIP model in various problem settings is also investigated.     

Applying Lagrangian relaxation-based algorithms for airline coordinated flight scheduling problems

20 and 21 employed network flow techniques to construct coordinated scheduling models for passenger- and cargo-transportation, respectively. These models are formulated as mixed integer multiple commodity network flow problems with side constraints (NFPWS) that are characterized as NP-hard. Problem sizes are expected to be huge making the model more difficult to solve than traditional passenger/cargo flight scheduling problems. Therefore, a family of Lagrangian based algorithm is developed to solve the coordinated fleet routing and flight scheduling problems. Numerical tests are performed to evaluate the proposed algorithm using real operating data from two Taiwan airlines. The test results indicate that these solution algorithms are a significant improvement over those obtained with CPLEX. Moreover, the Lagrangian based algorithms are better than the mixed-stop heuristic, consequently they could be useful for allied airlines to solve coordinated fleet routing and flight scheduling problems.     

嵌入疲劳效应和学习效应的应急手术调度研究

为了解决突发事件下应急手术调度问题,将应急手术调度问题看作混合流水车间调度问题,并考虑了医护人员长时间工作而带来的疲劳效应和截断学习效应,构建了术前、术中、术后三阶段手术调度模型。利用改进的灰狼优化算法对三阶段应急手术调度模型进行求解,并通过仿真实验测试模型和算法的有效性。算例分析中,将改进的灰狼优化算法和传统的灰狼优化算法的算例结果进行对比,结果表明改进的灰狼优化算法更有效,能得到更好的调度结果。     

A robust scheduling method based on a multi-objective immune algorithm

A robust scheduling method is proposed to solve uncertain scheduling problems. An uncertain scheduling problem is modeled by a set of workflow models, and then a scheduling scheme (solution) of the problem can be evaluated by workflow simulations executed with the workflow models in the set. A multi-objective immune algorithm is presented to find Pareto optimal robust scheduling schemes that have good performance for each model in the set. The two optimization objectives for scheduling schemes are the indices of the optimality and robustness of the scheduling results. An antibody represents a resource allocation scheme, and the methods of antibody coding and decoding are designed to deal with resource conflicts during workflow simulations. Experimental tests show that the proposed method can generate a robust scheduling scheme that is insensitive to uncertain scheduling environments.     

Power-efficient distributed scheduling of virtual machines using workload-aware consolidation techniques

There is growing demand on datacenters to serve more clients with reasonable response times, demanding more hardware resources, and higher energy consumption. Energy-aware datacenters have thus been amongst the forerunners to deploy virtualization technology to multiplex their physical machines (PMs) to as many virtual machines (VMs) as possible in order to utilize their hardware resources more effectively and save power. The achievement of this objective strongly depends on how smart VMs are consolidated. In this paper, we show that blind consolidation of VMs not only does not reduce the power consumption of datacenters but it can lead to energy wastage. We present four models, namely the target system model, the application model, the energy model, and the migration model, to identify the performance interferences between processor and disk utilizations and the costs of migrating VMs. We also present a consolidation fitness metric to evaluate the merit of consolidating a number of known VMs on a PM based on the processing and storage workloads of VMs. We then propose an energy-aware scheduling algorithm using a set of objective functions in terms of this consolidation fitness metric and presented power and migration models. The proposed scheduling algorithm assigns a set of VMs to a set of PMs in a way to minimize the total power consumption of PMs in the whole datacenter. Empirical results show nearly 24.9% power savings and nearly 1.2% performance degradation when the proposed scheduling algorithm is used compared to when other scheduling algorithms are used.     

A two level metaheuristic for the operating room scheduling and assignment problem

Given a surgery department comprising several specialties that share a fixed number of operating rooms and post-surgery beds, we study the joint operating room (OR) planning and advanced scheduling problem. More specifically, we consider the problem of determining, over a one week planning horizon, the allocation of OR time blocks to specialties together with the subsets of patients to be scheduled within each time block. The aim of this paper is to extend and generalize existing approaches for the joint OR planning and scheduling problem. First, by allowing schedules that include patients requiring weekend stay beds which was not the case previously. Second, by tackling simultaneously both the OR planning and patient scheduling decision levels, instead of taking them into account in successive phases. To achieve this, we exploit the inherent hierarchy between the two decision levels, i.e., the fact that the assignment decisions of OR time blocks to surgical specialties directly affect those regarding the scheduling of patients, but not the reverse. The objective function used in this study is an extension of an existing one. It seeks to optimize both patient utility (by reducing waiting time costs) and hospital utility (by reducing production costs measured in terms of the number of weekend stay beds required by the surgery planning). 0–1 linear programming formulations exploiting the stated hierarchy are proposed and used to derive a formal proof that the problem is NP-hard. A two level metaheuristic is then developed for solving the problem and its effectiveness is demonstrated through extensive numerical experiments carried out on a large set of instances based on real data.     

一种可重构资源管理模型及其调度技术

针对多任务操作系统的可重构资源管理,提出了一种管理模型和在线调度算法,具体实现了把任务分配给基于块划分的可重构器件。一方面,可重构器件由一个主CPU控制,主CPU运行在线调度器和放置器;另一方面,可重构器件由具有相同垂直尺寸的固定大小的块构成,但块可以有不同的宽度,目的是为了在资源和任务之间实现更好的匹配;同时在在线调度器和放置器运行两个函数fSPLIT和fSELECT来实现任务在可重构器件上的配置和调度。仿真结果表明,提出的资源管理模型和调度算法不仅能够实现任务集平均响应时间的最小化和有效调度,而且相比于其他调度算法,还能获得更高的资源利用率。     

基于连续过程特性的炼油生产调度优化研究

针对炼油生产调度问题,基于连续过程特性建立了广义析取规划调度模型。提出了连续性、长期性等连续过程特性定义及其性能指标,基于析取范式和逻辑命题对调度初期、中期和末期的连续过程特性进行了描述,并对连续过程特性性能进行了量化表达和评价,以实现生产利润和连续过程特性性能的综合利益最大化。以某炼油过程生产调度为例,对比有无连续过程特性表达的优化调度仿真结果表明：基于连续过程特性调度模型的调度方案能够提高连续过程特性性能,且更可行、实用,验证了模型的可行性和有效性。