Forecasting intermittent demand

Methods for forecasting intermittent demand are compared using a large data-set from the UK Royal Air Force (RAF). Several important results are found. First, we show that the traditional per period forecast error measures are not appropriate for intermittent demand, even though they are consistently used in the literature. Second, by comparing target service levels to achieved service levels when inventory decisions are based on demand forecasts, we show that Croston's method (and a variant) and Bootstrapping clearly outperform Moving Average and Single Exponential Smoothing. Third, we show that the performance of Croston and Bootstrapping can be significantly improved by taking into account that each lead time starts with a demand

Bootstrapping motives in nonfinancially constrained firms: A case study

The purpose of this paper is to examine the reasons or motives for firms with enough capital investment, thus not financially incapacitated, but still utilizing some form of financial bootstrapping in their daily operations. This paper uses the empirical findings on techniques and motives for bootstrapping according to Winborg and Landström (2001) and Winborg (2009) as a basis for analysis to evaluate the various bootstrapping methods and motives. Two case studies in southern Sweden were carefully selected, a manufacturing company in operation for four years and an IT company with three years in operation. Each company has adequate financial support internally and externally, but still bootstrapping in various ways. The results indicate that bootstrapping in not a form of cheap finance for firms lacking financial capital since even financially fit companies bootstrap to lower their day to day operating costs. Results also show that companies will not use customer-oriented bootstrapping techniques for fear of being too strict to make customers pay on time while risking losing them to their competitors. Joint utilization bootstrapping techniques are widely used and save a lot of time and money in the long run. The findings do not support the use of customer-oriented bootstrapping techniques as observed in previous research as the customer is the means for the firm’s survival, if threatened can move to obtain an alternative product or service from competitors. As far as bootstrapping is said to save money, this study’s findings show that it wastes time in return especially in projects that are short-lived or need to be launched within a limited period. Meaning that bootstrapping will take a lot of time to develop a product or service although may lower the overall cost. Practical implications for this study could assist business owners to understand why they bootstrap, and to carefully evaluate a project before bootstrapping since it is important to decide whether it is worth it to save time or save money. This study is among the few studies which have gone further to explore the empirical findings of bootstrapping in a case study approach, hence obtaining in-depth information of bootstrapping in specific companies operating in capital-intensive industries

Methodology for Determining the Acceptability of Given Designs in Uncertain Environments

Managers wish to verify that a particular engineering design meets their require- ments. This design's future environment will differ from the environment assumed during the design. Therefore it is crucial to determine which variations in the envi- ronment may make this design unacceptable. The proposed methodology estimates which uncertain environmental parameters are important (so managers can become pro-active) and which parameter combinations (scenarios) make the design unac- ceptable. The methodology combines simulation, bootstrapping, and metamodeling. The methodology is illustrated through a simulated manufacturing system, includ- ing fourteen uncertain parameters of the input distributions for the various arrival and service times. These parameters are investigated through sixteen scenarios, selected through a two-level fractional-factorial design. The resulting simulation In- put/Output (I/O) data are analyzed through a first-order polynomial metamodel and bootstrapping. A second experiment gives some outputs that are indeed un- acceptable. Polynomials fitted to the I/O data estimate the border line (frontier) between acceptable and unacceptable environments.Uncertainty modeling;Risk analysis;Robustness and sensitivity analysis;Simulation;Bootstrap

The development of a demand forecasting web application for Spare Parts Management \\ using Bootstrapping Method

The forecast has been recognized as one of the most essential parts of spare part management, which often impacts inventory costs and performance to a large degree. In the case study, the demand pattern of spare parts from a subsea maintenance service provider is characterized as intermittent demand. This demand pattern is common among spare parts which accounts for a large portion of inventory costs. As a means of predicting its intermittent demand, there is a method called WSS bootstrapping method, described in the literature. We developed a web application based on the WSS bootstrapping model by Willemain et al. (2004) and an adapted jittering method by Rego and Mesqutia (2015). The computational results show that the results of the bootstrapping model often contain true value when using the 99\% confidence interval. The error of the model is lower than our analysis criterion. Therefore, the performance of the bootstrapping model is satisfying

Demonstration of Zero-touch Device and L3-VPN Service Management using the TeraFlow Cloud-native SDN Controller

We demonstrate zero-touch device bootstrapping, monitoring, and L3-VPN service management using the novel TeraFlow OS SDN controller prototype. TeraFlow aims at producing a cloud-native carrier-grade SDN controller offering scalability, extensibility, high-performance, and high-availability features

In-band control, queuing, and failure recovery functionalities for openflow

In OpenFlow, a network as a whole can be controlled from one or more external entities (controllers) using in-band or out-of-band control networks. In this article, we propose in-band control, queuing, and failure recovery functionalities for OpenFlow. In addition, we report experimental studies and practical challenges for implementing these functionalities in existing software packages containing different versions of OpenFlow. The experimental results show that the in-band control functionality is suitable for all types of topologies. The results with the queuing functionality show that control traffic can be served with the highest priority in in-band networks and hence, data traffic cannot affect the communication between the controller and networking devices. The results with the failure recovery functionality show that traffic can be recovered from failures within 50 ms