952 resultados para Waiting time
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The total time a customer spends in the business process system, called the customer cycle-time, is a major contributor to overall customer satisfaction. Business process analysts and designers are frequently asked to design process solutions with optimal performance. Simulation models have been very popular to quantitatively evaluate the business processes; however, simulation is time-consuming and it also requires extensive modeling experiences to develop simulation models. Moreover, simulation models neither provide recommendations nor yield optimal solutions for business process design. A queueing network model is a good analytical approach toward business process analysis and design, and can provide a useful abstraction of a business process. However, the existing queueing network models were developed based on telephone systems or applied to manufacturing processes in which machine servers dominate the system. In a business process, the servers are usually people. The characteristics of human servers should be taken into account by the queueing model, i.e. specialization and coordination. ^ The research described in this dissertation develops an open queueing network model to do a quick analysis of business processes. Additionally, optimization models are developed to provide optimal business process designs. The queueing network model extends and improves upon existing multi-class open-queueing network models (MOQN) so that the customer flow in the human-server oriented processes can be modeled. The optimization models help business process designers to find the optimal design of a business process with consideration of specialization and coordination. ^ The main findings of the research are, first, parallelization can reduce the cycle-time for those customer classes that require more than one parallel activity; however, the coordination time due to the parallelization overwhelms the savings from parallelization under the high utilization servers since the waiting time significantly increases, thus the cycle-time increases. Third, the level of industrial technology employed by a company and coordination time to mange the tasks have strongest impact on the business process design; as the level of industrial technology employed by the company is high; more division is required to improve the cycle-time; as the coordination time required is high; consolidation is required to improve the cycle-time. ^
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Surface defects on steel parts borne costs of smelting industries due to the need of rework. Sand molds are frequently used in foundry industries and largely responsible for providing surface defects. This study aims to optimize the levels of the molding process variables to minimize the occurrence of surface defects in steel castings in silica sand molds chemically linked by cold cure process. The methodology used the experimental design with split plot, being considered in the study the resin percentage factors in the mold formulation, addition of iron oxide, type of paint, the paint application method, amount of ink layers, use of hot air along the lines and waiting time of the mold before casting. They were analyzed as response variables erosion defects, sand inclusion, penetration, porosity and surface finish. Tensile strength tests were performed to evaluate the influence of factors on mechanical parameters and the microstructural parameters were carried out the analysis of X-ray diffraction, scanning electron microscopy (SEM) and thermal analysis (TG / DSC / dilatometry). The results elucidate that for the faulty erosion, the only significant factor with a 95% confidence level was the type of ink and the ink alumina-based superior results obtained. For the sand inclusion of defect, there were three significant factors, with best results obtained with alumina-based paint and spray applied using hot air in the mold before casting the metal. For the defect penetration, there were four significant factors, the best results being achieved with 0.8% of resin and addition of iron oxide in the molding formulation, the paint being applied by brush and standby time of 24 hours before leak. For the defect porosity with a 95% confidence level, no significant factors. For the defect surface finish, the best results were achieved with the 0.8% formulation of the resin in the mold and application of the paint brush. To obtain the levels of the factors that optimize all defects simultaneously, we performed a weighted average of the results of each type of fault, concluding that the best levels of the factors were: 0.8% resin and addition of iron oxide in the formulation of the template, application of two coats of paint applied with a brush or spray, using hot air in the mold before casting and 24 hours of waiting ready the mold before casting. These levels of the optimized factors were used in an experiment to confirm that ratified the results, helping to reduce rework and consequently reducing costs of cast steel parts.
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The consumption of a product is directly linked to its quality, and are required to comply with quality standard regulations. In chicken "griller" which comes from industrial strains, selected for best growth performance, shot with up to 35 days old and weighing 1,400kg, they have not been reported in the literature a number of quality aspects This study aimed determine the muscle transformation time in the flesh in chickens "griller" incidence of meat defects, "PSE" (pale, soft and exdudative) and "DFD" (dark, firm and dry) and their correlation between different window times slaughter (total time between beginning of the fasting and the time of slaughter) and pH curve, four different times post mortem. The base data for the study was composed of information of 208 chickens, collected between August and September 2014, in a slaughterhouse slaughtering chickens in the middle region of Triangulo Mineiro and Alto Paranaíba. We used the Minitab 17.1.0 program for the development of descriptive statistical analysis and Pareto charts. The Pearson correlation was used to evaluate the linear relationship between two variables and Excel 2013, Microsoft Office®, to produce tables and graphs. The analysis consisted of 11 chickens cities and the distance to the poultry slaughterhouse ranged from 24.5 km to 123 km. It was observed that the pH curve decays gradually until time 5horas after slaughter, and its increase was 24, indicating the transformation of the muscle meat. The incidence of regular meat was 39.9%, "DFD" 30.3% and "PSE" 29.8%. For "DFD" meat, it was observed that factors: low ambient temperature, longer transportation and fast window and mileage at dirt road, contributed to its occurrence (p <0.05). For "PSE" meat, it was observed that lower body weight factors, longer transport favored frequency (p <0.05) of the meat defect. There was no significant correlation in variance analysis between distance, waiting time at rest shed and humidity related to meat defects (p> 0.05). This high incidence of defects meat may be due to pre-slaughter stress factors.
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Background: Rates of self-harm are high and have recently increased. This trend and the repetitive nature of self-harm pose a significant challenge to mental health services. Aims: To determine the efficacy of a structured group problem-solving skills training (PST) programme as an intervention approach for self-harm in addition to treatment as usual (TAU) as offered by mental health services. Method: A total of 433 participants (aged 18-64 years) were randomly assigned to TAU plus PST or TAU alone. Assessments were carried out at baseline and at 6-week and 6-month follow-up and repeated hospital-treated self-harm was ascertained at 12-month follow-up. Results: The treatment groups did not differ in rates of repeated self-harm at 6-week, 6-month and 12-month follow-up. Both treatment groups showed significant improvements in psychological and social functioning at follow-up. Only one measure (needing and receiving practical help from those closest to them) showed a positive treatment effect at 6-week (P = 0.004) and 6-month (P = 0.01) follow-up. Repetition was not associated with waiting time in the PST group. Conclusions: This brief intervention for self-harm is no more effective than treatment as usual. Further work is required to establish whether a modified, more intensive programme delivered sooner after the index episode would be effective.
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Providing good customer service, inexpensively, is a problem commonly faced by managers of service operations. To tackle this problem, managers must do four tasks: forecast customer demand for the service; translate these forecasts into employee requirements; develop a labor schedule that provides appropriate numbers of employees at appropriate times; and control the delivery of the service in real-time. This paper focuses upon the translation of forecasts of customer demand into employee requirements. Specifically, it presents and evaluates two methods for determining desired staffing levels. One of these methods is a traditional approach to the task, while the other, by using modified customer arrival rates, offers a better means of accounting for the multi-period impact of customer service. To calculate the modified arrival rates, the latter method reduces (increases) the actual customer arrival rate for a period to account for customers who arrived in the period (in earlier periods) but have some of their service performed in subsequent periods (in the period). In an experiment simulating 13824 service delivery environments, the new method demonstrated its superiority by serving 2.74% more customers within the specified waiting time limit while using 7.57% fewer labor hours.
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Background Infant mortality in rural areas of Nigeria can be minimized if childhood febrile conditions are treated by trained health personnel, deployed to primary healthcare centres (PHCs) rather than the observed preference of mothers for patent medicine dealers (PMDs). However, health service utilization/patronage is driven by consumer satisfaction and perception of services/product value. The objective of this study was to determine ‘mothers’ perception of recovery’ and ‘mothers’ satisfaction’ after PMD treatment of childhood febrile conditions, as likely drivers of mothers’ health-seeking behaviour, which must be targeted to reverse the trend. Methods Ugwuogo-Nike, in Enugu, Nigeria, has many PMDs/PHCs, and was selected based on high prevalence of childhood febrile conditions. In total, 385 consenting mothers (aged 15–45 years) were consecutively recruited at PMD shops, after purchasing drugs for childhood febrile conditions, in a cross-sectional observational study using a pre-tested instrument; 33 of them (aged 21–47 years) participated in focus group discussions (FGDs). Qualitative data were thematically analysed while a quantitative study was analysed with Z score and Chi square statistics, at p < 0.05. Results Most participants in FGDs perceived that their child had delayed recovery, but were satisfied with PMDs’ treatment of childhood febrile conditions, for reasons that included politeness, caring attitude, drug availability, easy accessibility, flexibility in pricing, shorter waiting time, their God-fearing nature, and disposition as good listeners. Mothers’ satisfaction with PMDs’ treatment is significantly (p < 0.05) associated with mothers’ perception of recovery of their child (χ2 = 192.94, df = 4; p < 0.0001; Cramer’s V = 0.7079). However, predicting mothers’ satisfaction with PMDs’ treatment from a knowledge of mothers’ perception of recovery shows a high accord (lambda[A from B] = 0.8727), unlike when predicting mothers’ perception of recovery based on knowledge of mothers’ satisfaction with PMDs’ treatment (lambda[A from B] = 0.4727). Conclusions Mothers’ satisfaction could be the key ‘driver’ of mothers’ health-seeking behaviour and is less likely to be influenced by mothers’ perception of recovery of their child. Therefore, mothers’ negative perception of their child’s recovery may not induce proportionate decline in mothers’ health-seeking behaviour (patronage of PMDs), which might be influenced mainly by mothers’ satisfaction with the positive attributes of PMDs’ personality/practice and sets an important agenda for PHC reforms.
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Des contraintes d’accessibilité aux services de physiothérapie en clinique externe ont été rapportées dans les établissements publics au Canada. Celles-ci se traduisent souvent par un temps d’attente élevé avant d’obtenir des services. Différentes stratégies ont été proposées afin de gérer les listes d’attente, mais leur impact sur le temps d’attente est méconnu, notamment dans le contexte des services de physiothérapie au Québec. Le but de cette étude était de documenter l’accessibilité aux services de physiothérapie en clinique externe dans les centres hospitaliers au Québec. Les objectifs spécifiques étaient de 1) décrire les caractéristiques organisationnelles en lien avec l’accessibilité aux services de physiothérapie, 2) quantifier le temps d’attente pour accéder aux services et 3) explorer l’association entre les caractéristiques organisationnelles et le temps d’attente. Une enquête a été réalisée dans les cliniques externes de physiothérapie des centres hospitaliers publics du Québec offrant des services à des adultes souffrant de troubles musculosquelettiques. Des données ont été obtenues auprès de 97 (99%) centres hospitaliers. Au moment de l’enquête, 18 245 personnes étaient sur les listes d’attente. Le temps d’attente médian était de plus de six mois dans 41% des centres hospitaliers. Parmi les pratiques organisationnelles et les stratégies de gestion de listes d’attente évaluées, les politiques en cas d’annulation ou d’absence (99%) et la priorisation des demandes (96%) étaient les plus utilisées. Selon les résultats d’analyses multivariées, seule l’utilisation d’une méthode de priorisation comprenant une rencontre d’évaluation et une intervention initiale était associée au temps d’attente (p=0,008). Les résultats de cette étude démontrent qu’une grande quantité de personnes sont inscrites sur les listes d’attente des services de physiothérapie et que le temps d’attente peut être très élevé. D’après nos résultats, l’implantation d’une méthode de priorisation comprenant une évaluation et une intervention pourrait permettre d’améliorer l’accès en temps opportun aux services de physiothérapie.
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Resource allocation decisions are made to serve the current emergency without knowing which future emergency will be occurring. Different ordered combinations of emergencies result in different performance outcomes. Even though future decisions can be anticipated with scenarios, previous models follow an assumption that events over a time interval are independent. This dissertation follows an assumption that events are interdependent, because speed reduction and rubbernecking due to an initial incident provoke secondary incidents. The misconception that secondary incidents are not common has resulted in overlooking a look-ahead concept. This dissertation is a pioneer in relaxing the structural assumptions of independency during the assignment of emergency vehicles. When an emergency is detected and a request arrives, an appropriate emergency vehicle is immediately dispatched. We provide tools for quantifying impacts based on fundamentals of incident occurrences through identification, prediction, and interpretation of secondary incidents. A proposed online dispatching model minimizes the cost of moving the next emergency unit, while making the response as close to optimal as possible. Using the look-ahead concept, the online model flexibly re-computes the solution, basing future decisions on present requests. We introduce various online dispatching strategies with visualization of the algorithms, and provide insights on their differences in behavior and solution quality. The experimental evidence indicates that the algorithm works well in practice. After having served a designated request, the available and/or remaining vehicles are relocated to a new base for the next emergency. System costs will be excessive if delay regarding dispatching decisions is ignored when relocating response units. This dissertation presents an integrated method with a principle of beginning with a location phase to manage initial incidents and progressing through a dispatching phase to manage the stochastic occurrence of next incidents. Previous studies used the frequency of independent incidents and ignored scenarios in which two incidents occurred within proximal regions and intervals. The proposed analytical model relaxes the structural assumptions of Poisson process (independent increments) and incorporates evolution of primary and secondary incident probabilities over time. The mathematical model overcomes several limiting assumptions of the previous models, such as no waiting-time, returning rule to original depot, and fixed depot. The temporal locations flexible with look-ahead are compared with current practice that locates units in depots based on Poisson theory. A linearization of the formulation is presented and an efficient heuristic algorithm is implemented to deal with a large-scale problem in real-time.
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Kidney transplantation is the preferred treatment for many end stage renal disease patients; however, the small number of organs for transplantation does not allow all patients to have access to this scarce resource. An allocation system for deceased donor kidneys should be anchored to transparent policies and rules. It should take into account the relationship between supply and demand, hence seeking a balance between the higher net benefit of survival that can be provided by a particular organ and the transplant candidates’ waiting time (as well as the probability of being transplanted).
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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2015.
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Automotive producers are aiming to make their order fulfilment processes more flexible. Opening the pipeline of planned products for dynamic allocation to dealers/ customers is a significant step to be more flexible but the behaviour of such Virtual-Build-To-Order systems are complex to predict and their performance varies significantly as product variety levels change. This study investigates the potential for intelligent control of the pipeline feed, taking into account the current status of inventory (level and mix) and of the volume and mix of unsold products in the planning pipeline, as well as the demand profile. Five ‘intelligent’ methods for selecting the next product to be planned into the production pipeline are analysed using a discrete event simulation model and compared to the unintelligent random feed. The methods are tested under two conditions, firstly when customers must be fulfilled with the exact product they request, and secondly when customers trade-off a shorter waiting time for compromise in specification. The two forms of customer behaviour have a substantial impact on the performance of the methods and there are also significant differences between the methods themselves. When the producer has an accurate model of customer demand, methods that attempt to harmonise the mix in the system to the demand distribution are superior.
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Background: Levels of endoscopic demand and capacity in West Africa are unclear. Objectives: This paper aims to: 1. describe the current labor and endoscopic capacity, 2. quantify the impact of a mixed-methods endoscopy course on healthcare professionals in West Africa, and 3. quantify the types of diagnoses encountered. Methods: In a three-day course, healthcare professionals were surveyed on endoscopic resources and capacity and were taught through active observation of live cases, case discussion, simulator experience and didactics. Before and after didactics, multiplechoice exams as well as questionnaires were administered to assess for course efficacy. Also, a case series of 23 patients needing upper GI endoscopy was done. Results: In surveying physicians, less than half had resources to perform an EGD and none could perform an ERCP, while waiting time for emergency endoscopy in urban populations was at least one day. In assessing improvement in medical knowledge among participants after didactics, objective data paired with subjective responses was more useful than either alone. Of 23 patients who received endoscopy, 7 required endoscopic intervention with 6 having gastric or esophageal varices. Currently the endoscopic capacity in West Africa is not sufficient. A formal GI course with simulation and didactics improves gastrointestinal knowledge amongst participants.
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Uma das áreas de aplicação da optimização é a Engenharia Biomédica, pois a optimização intervém no estudo de próteses e implantes, na reconstrução tomográfica, na mecânica experimental, entre outras aplicações. Este projecto tem como principal objectivo a criação de um novo programa de marcação de exames médicos a fim de minimizar o tempo de espera na realização dos mesmos. É efectuada uma breve referência à teoria da optimização bem como à optimização linear e não-linear, aos algoritmos genéticos, que foram usados para a realização deste trabalho. É também apresentado um caso de estudo, formulado como um problema de optimização não linear com restrições. Com este estudo verificou-se que o escalonamento de exames médicos nunca poderá ser optimizado a 100por cento devido à quantidade de variáveis existentes, sendo que algumas delas não são passíveis de prever com antecedência.
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A saúde em Portugal encontra-se no caminho da mudança, rumo à excelência, pois questiona-se o sistema, a sua estrutura, os seus processos e os resultados. Uma das condições que mais influencia a competitividade entre instituições da saúde é a qualidade. Sendo a sociedade cada vez mais exigente, medi-la e avalia-la é um imperativo da época actual. O presente estudo teve como objectivo, contribuir para a realização de um diagnóstico de um processo de melhoria implementado num hospital privado de Lisboa - Hospital CUF Descobertas (HCD), no Serviço de Atendimento Permanente (SAP), à luz dos princípios da qualidade total. O procedimento da Triagem de Manchester é um processo que tem como principal objectivo o estabelecimento de prioridades, ou seja, identificar critérios de gravidade, de forma objectiva e sistematizada, que indicam a prioridade clínica com que o cliente deve ser atendido e o respectivo tempo de espera alvo recomendado até observação médica. Não se trata de estabelecer diagnósticos. Para o efeito, utilizou-se uma abordagem metodológica, suportada pelo modelo de auto-avaliação, designado Modelo Common Assessment Framework (CAF). Neste sentido, privilegiando-se a utilização dos critérios de meios deste modelo. Foi aplicado um questionário aos colaboradores do Serviço de Atendimento Permanente do Hospital CUF Descobertas. O Tratamento de dados estatísticos foi realizado com o apoio do SPSS, versão 16.0 e do Microsoft Excel. Os resultados deste estudo culminam com a identificação de pontos fortes, pontos fracos e sugestões de melhorias para o serviço em estudo. Neste sentido, este trabalho serviu de diagnóstico para se poder identificar em que ponto se situa e que rumo se deve seguir para se atingir um patamar de excelência relativamente à qualidade. Abstract: Health in Portugal finds itself on the path toward change, trying to find excellence while challenging the system and its structure, processes, and results. One of the conditions that most influences the competitiveness between the institutes of health is quality because society is becoming more demanding. Measuring and evaluating this change is happening in this current time. The present study has the objective of contributing and establishing a diagnostic tool relative to the process of improvement. This tool was used in a private hospital in Lisbon, Hospital CUF Descobertas, in the Emergency Room, in looking at the principles of total quality. This process designed through the Manchester Triage System has the main objective of the establishment of priorities through which we want to identify criteria of seriousness in an objective and systematic way that indicate a clinical priority with which the client is attended to in respect to the waiting time, giving a recommended time until medical observation. ln this sense, we do not diagnose patients in triage. For this effect, we used a methodological overview supported by the model of self-evaluation, the Common Assessment Framework (CAF}, in which we used the criteria: Leadership, Planning and Strategy, People, Resources and Processes. To arrive at this, a questionnaire was used by the collaborators of the emergency room of Hospital CUF Descobertas. The statistical analysis of the data was performed using SPSS version 16.0 and Microsoft Excel. The results of this study culminated with the identification of strong points, weak points, and suggestions for improvements for the work in study. ln this way, with this study, we can identify in where an organization finds itself and the path it should take in order to achieve a high level of quality excellence.
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We investigate key characteristics of Ca²⁺ puffs in deterministic and stochastic frameworks that all incorporate the cellular morphology of IP[subscript]3 receptor channel clusters. In a first step, we numerically study Ca²⁺ liberation in a three dimensional representation of a cluster environment with reaction-diffusion dynamics in both the cytosol and the lumen. These simulations reveal that Ca²⁺ concentrations at a releasing cluster range from 80 µM to 170 µM and equilibrate almost instantaneously on the time scale of the release duration. These highly elevated Ca²⁺ concentrations eliminate Ca²⁺ oscillations in a deterministic model of an IP[subscript]3R channel cluster at physiological parameter values as revealed by a linear stability analysis. The reason lies in the saturation of all feedback processes in the IP[subscript]3R gating dynamics, so that only fluctuations can restore experimentally observed Ca²⁺ oscillations. In this spirit, we derive master equations that allow us to analytically quantify the onset of Ca²⁺ puffs and hence the stochastic time scale of intracellular Ca²⁺ dynamics. Moving up the spatial scale, we suggest to formulate cellular dynamics in terms of waiting time distribution functions. This approach prevents the state space explosion that is typical for the description of cellular dynamics based on channel states and still contains information on molecular fluctuations. We illustrate this method by studying global Ca²⁺ oscillations.