GSPN models of multiserver multiqueue systems

Predictors of access to pediatric eye care appointments.

AimsTo investigate impediments in the discharge process and ward round efficiency within a general paediatric ward for future flow and discharge improvement.MethodsDuring a 6-month seconded post as the paediatric patient...

Approximating a ride-sourcing system with block matching

Ten classes were randomly assigned to a group that received feedback and assistance to maintain an average teacher wait time of between 3 and 5 seconds during a sequence of mathematics lessons. A control group of 10 teachers maintained a regular wait time and received placebo feedback. The study was replicated in a sequence of language arts lessons. The use of an average teacher wait time of between 3 and 5 seconds in whole class instructional settings was associated with higher mathematics achievement and improvements in the quality of teacher and student discourse. In extended wait time classes in the mathematics component of the study, decreases were observed in the number of utterances per unit time, the average length of teacher utterances, the frequency of teacher interruptions, failure of students to respond to teacher questions, the proportion of teacher reacting to student responses, and the proportion of teacher mimicking of student responses. Increases were observed in the average length of student responses, the proportion of teacher soliciting, the proportion of teacher structuring, and the proportion of probing after a student response. Similar results were obtained in the language arts component of the study. Changes in the types of teacher questions were observed also. In mathematics there was an increase in the proportion of questions requiring application of concepts, and in language arts there was an increase in the proportion of questions requiring student comprehension.

Backfill is a technique in which lower priority jobs requiring fewer resources are initiated before one or more currently waiting higher priority jobs requiring as yet unavailable resources. Processors are frequently the resource involved and the purpose of backfilling is to increase system utilization and reduce average wait time. Generally, a scheduler backfills when the user-specified run times indicate that executing the lower priority jobs will not delay the anticipated initiation of the higher priority jobs. This paper explores the possibility of using a relaxed backfill strategy in which the lower priority jobs are initiated as long as they do not delay the highest priority job too much. A simulator was developed to model this approach; it uses a parameter ? to control the length of the acceptable delay as a factor times the wait time of the highest priority job. Experiments were performed for a range of ? values with both user-estimated run times and actual run times using workload data from two parallel systems, a Cray T3E and an SGI Origin 3800. For these workloads, overall average job wait time typically decreases as ? increases and use of user-estimated run times is superior to use of actual run times. More experiments must be performed to determine the generality of these results.

BackgroundIn emergency departments (EDs), long wait times and overcrowding are major challenges, worsened by the pandemic's increased patient volumes and demands. Lean methodology could offer a structured approach to reduce inefficiencies, improve care quality, and support nursing staff. Aim of the study: This study aims to evaluate the impact of applying a Lean approach to optimize emergency nursing care post-pandemic within an ER setting.MethodsThis study utilized a mixed-methods design in the ER of a private hospital in Egypt. Data collection involved three Lean tools: the voice of the process observation sheet, which tracked the journeys of 100 patients; voice of customer structured interviews, conducted with 90 patients to assess satisfaction with waiting times; and voice of business interviews, held with 64 staff members to evaluate satisfaction with available resources. Additionally, a cause-and-effect analysis was conducted and summarized in an A3 report, identifying key factors contributing to extended wait times.ResultsThe average wait time in the emergency department was 157.87 min, making up 77.7% of the total length of stay. The consultation phase accounted for the longest delays, with an average wait of 92.46 min. Patient satisfaction with waiting times was moderate (61.74%), while staff satisfaction with resources was higher (71.09%), but only 53.1% were satisfied with patient wait times. Key causes of delays included non-compliance with triage protocols (95.0%), lack of care pathways (90.3%), and insufficient bed capacity (83.1%). An A3 report proposed strategies to reduce wait times and enhance satisfaction.ConclusionThis study highlights waiting times as a major challenge in EDs, significantly impacting service quality, patient outcomes, and nursing staff workload. Lean-based strategies, such as standardized triage and improved care pathways, are essential to reducing delays and enhancing both patient care and staff satisfaction in the post-pandemic healthcare environment.

Background and AimsMater Dei Hospital in Malta provides a 24-hour neuraxial analgesia service in its delivery suite. The Royal College of Anaesthetists (RCoA) recommends that in such set-ups, an anaesthetist...

PurposeThis paper aims to deal with the problems of failure dependence and common cause failure (CCF) that arise in reliability analysis of complex systems.Design/methodology/approachFirstly, a dynamic fault tree (DFT) is used to capture the dynamic failure behaviours and converted into an equivalent generalized stochastic petri net (GSPN) for quantitative analysis. Secondly, an efficient decomposition and aggregation (EDA) theory is combined with GSPN to deal with the CCF problem, which exists in redundant systems. Finally, Birnbaum importance measure (BIM) is calculated based on the EDA approach and GSPN model, and it is used to take decisions for system improvement and fault diagnosis.FindingsIn this paper, a new reliability evaluation method for dynamic systems subject to CCF is presented based on the DFT analysis and the GSPN model. The GSPN model is easy to capture dynamic failure behaviours of complex systems, and the movement of tokens in the GSPN model represent the changes in the state of the systems. The proposed method takes advantage of the GSPN model and incorporates the EDA method into the GSPN, which simplifies the reliability analysis process. Meanwhile, simulation results under different conditions show that CCF has made a considerable impact on reliability analysis for complex systems, which indicates that the CCF should not be ignored in reliability analysis.Originality/valueThe proposed method combines the EDA theory with the GSPN model to improve the efficiency of the reliability analysis.

We consider a deterministic queueing system in which N ≥ 2 servers of different speeds operate in parallel. Each service in queue i takes the deterministic time Si. Identical customers arrive exactly one per time unit, and it is desirable to route them to the queues so that the average waiting time (we consider as waiting time the time a customer waits in the buffer of a queue, and thus the service time is not included in this) is minimized. We provide an algorithm to compute lower and upper bounds on this quantity. The upper bound is found by showing that there is a periodic policy for which the average waiting time is no greater than the lower bound plus (N / 2) − 1. Thus, the bounds coincide when N = 2. For obtaining the lower bound, we give explicit formulae for the average waiting time in case of regular routing to a deterministic queue.

A single-server subject to random breakdowns (or preemptive interruptions) insure the service of customers who arrive in the system according to a homogeneous Poisson process. The customer who arrive when the server is blocked (out of order or busy) is admitted to repeat his call until the server can provide his service. The purpose of this paper is to provide a simple approach to compute the stationary probability distribution of the customer's sojourn time in the system. We also obtain the probability distribution of the work which is different from the sojourn time contrary to the classical FIFO discipline. We show how mean performance measures such as mean waiting time and mean sojourn time can be obtained. Finally, we obtain asymptotic distributions of the waiting and sojourn times in heavy traffic and in the case of low retrial rate.

44 Background: Intravenous hydration (IVH) is frequently administered to oncology patients in outpatient chemotherapy infusion units. High demand for IVH often leads to capacity restraints in the chemotherapy infusion unit, negatively impacting the availability of infusion chairs for cancer-directed therapy, causing long wait times and patient dissatisfaction. This feasibility study aimed to expand the capacity for IVH and chemotherapy at a regional site of an academic medical center, through a dedicated hydration station outside of the conventional infusion chairs. Methods: A mobile space adjacent to a nurses’ station, within the chemotherapy infusion unit, was designated and converted to accommodate two patients simultaneously for IVH. Privacy screens separated this area from the rest of the infusion unit. Patients were directly scheduled into hydration station chairs. One nurse provided patient monitoring within the hydration station. The hydration rate was standardized to 1 liter per hour, subject to change at the discretion of treating physicians. Outcomes collected included the number of patients treated, total hours of hydration, wait times, and patient satisfaction, which was ascertained by a survey administered during February 2023 of the pilot phase. Results: Over a six-month period from December 2022 through May 2023, a total of 784 patients received IVH in the hydration station. This equates to 11 hours of IVH per day, and a cumulative total of 1,590 hours over the course of six months. The average wait time from check-in to starting IVH was 7 minutes. During the same period, the average wait time for chemotherapy was halved to 16 minutes. Among 28 patients who completed the satisfaction survey and had previously received IVH in a conventional infusion chair, 24 (86%) reported that the hydration station was either better or equivalent to their prior hydration experience. 23 (82%) patients reported a shorter or similar wait time compared to the conventional process. Overall, 84% were satisfied with their experience. Importantly, no patient safety issues were reported during the six-month period. Conclusions: IVH can be safely and effectively administered outside the conventional infusion chair, resulting in decreased wait times and high patient satisfaction. This IVH model increased the capacity for cancer-directed therapy in the chemotherapy infusion unit, with no reported safety issues. It is being standardized and implemented across other infusion units across our institution.

To evaluate the use of an audio/visual (A/V) system in pediatric patients as an alternative to sedation in magnetic resonance imaging (MRI) in terms of wait times, image quality, and patient experience. Pediatric MRI examinations from April 8 to August 11, 2008 were compared to those 1 year prior to the installation of the A/V system. Data collected included age, requisition receive date, scan date, and whether sedation was used. A posttest questionnaire was used to evaluate patient experience. Image quality was assessed by two radiologists. Over the 4 months in 2008 there was an increase of 7.2% (115; P < 0.05) of pediatric patients scanned and a decrease of 15.4%, (67; P = 0.32) requiring sedation. The average sedation wait time decreased by 33% (5.8 months) (P < 0.05). Overall, the most positively affected group was the 4-10 years. The questionnaire resulted in 84% of participants expressing a positive reaction to the A/V system. Radiological evaluation revealed no changes in image quality between A/V users and sedates. The A/V system was a successful method to reduce patient motion and obtain a quality diagnostic MRI without the use of sedation in pediatric patients. It provided a safer option, a positive experience, and decreased wait times.

SummaryRecently, the deployment of novel smart network concepts, such as the Internet of things (IoT) or machine‐to‐machine communication, has gained more attention owing to its role in providing communication among various smart devices. The IoT involves a set of IoT devices (IoTDs) such as actuators and sensors that communicate with IoT applications via IoT gateways without human intervention. The IoTDs have different traffic types with various delay requirements, and we can classify them into two main groups: critical and massive IoTDs. The fundamental promising technology in the IoT is the advanced long‐term evolution (LTE‐A). In the future, the number of IoTDs attempting to access an LTE‐A network in a short period will increase rapidly and, thus, significantly reduce the performance of the LTE‐A network and affect the QoS required by variant IoT traffic. Therefore, efficient resource allocation is required.In this paper, we propose a priority‐based allocation scheme for multiclass service in IoT to efficiently share resources between critical and massive IoTD traffic based on their specific characteristics while protecting the critical IoTDs, which have a higher priority over the massive IoTDs. The performance of the proposed scheme is analyzed using the Geo/G/1 queuing system focusing on QoS guarantees and resource utilization of both critical and massive IoTDs. The distribution of service time of the proposed system is determined and, thus, the average waiting and service times are derived. The results indicate that the performance of the massive IoTDs depends on the data traffic characteristics of the critical IoTDs. Furthermore, the results emphasize the importance of the system delay analysis and demonstrate its effects on IoT configurations.

Patients' Perspectives on Wait Times and the Referral-Consultation Process While Attending a Tertiary Diabetes and Endocrinology Centre: Is Econsultation an Acceptable Option?

Surgeons have been slow to incorporate industrial reliability techniques. Process control methods were applied to surgeon waiting time between cases, and to length of stay (LOS) after colon surgery. Waiting times between surgeries were evaluated by auditing the operating room records of a single hospital over a 1-month period. The medical records of 628 patients undergoing colon surgery over a 5-year period were reviewed. The average surgeon wait time between cases was 53 min, and the busiest surgeon spent 291/2 hr in 1 month waiting between surgeries. Process control charting demonstrated poor overall control of the room turnover process. Average LOS after colon resection also demonstrated very poor control. Mean LOS was 10 days. Weibull's conditional analysis revealed a conditional LOS of 9.83 days. Serious process management problems were identified in both analyses. These process issues are both expensive and adversely affect the quality of service offered by the institution. Process control mechanisms were suggested or implemented to improve these surgical processes. Industrial reliability and quality management tools can easily and effectively identify process control problems that occur on surgical services.