Performance of state space and ARIMA models for consumer retail sales forecasting

Forecasting future sales is one of the most important issues that is beyond all strategic and planning decisions in effective operations of retail businesses. For profitable retail businesses, accurate demand forecasting is crucial in organizing and planning production, purchasing, transportation and labor force. Retail sales series belong to a special type of time series that typically contain trend and seasonal patterns, presenting challenges in developing effective forecasting models. This work compares the forecasting performance of state space models and ARIMA models. The forecasting performance is demonstrated through a case study of retail sales of five different categories of women footwear: Boots, Booties, Flats, Sandals and Shoes. On both methodologies the model with the minimum value of Akaike's Information Criteria for the in-sample period was selected from all admissible models for further evaluation in the out-of-sample. Both one-step and multiple-step forecasts were produced. The results show that when an automatic algorithm the overall out-of-sample forecasting performance of state space and ARIMA models evaluated via RMSE, MAE and MAPE is quite similar on both one-step and multi-step forecasts. We also conclude that state space and ARIMA produce coverage probabilities that are close to the nominal rates for both one-step and multi-step forecasts.

Logística e estão da cadeia de abastecimento

Relatório apresentado ao Instituto Superior De Contabilidade e Administração Do Porto para obtenção do grau de Mestre em Logística Orientado por António Jorge S. T. Duarte

Dispersion Modelling of Natural Radionuclides 238U, 232Th and 40K Released from Coal-fired Power Plants Operations

The aim of this work was to simulate the radionuclides dispersion in the surrounding area of a coal-fired power plant, operational during the last 25 years. The dispersion of natural radionuclides (236Ra, 232Th and 40K) was simulated by a Gaussian plume dispersion model with three different stability classes estimating the radionuclides concentration at ground level. Measurements of the environmen-tal activity concentrations were carried out by γ-spectrometry and compared with results from the air dispersion and deposition model which showed that the stabil-ity class D causes the dispersion to longer distances up to 20 km from the stacks.

Gestão da cadeia de abastecimento de bens de consumo baseada em modelos de previsão lineares

Dissertação apresentada ao Instituto Politécnico do Porto para obtenção do Grau de Mestre em Logística

Swordfish: an Autonomous Surface Vehicle for Network Centric Operations

The design and development of the swordfish autonomous surface vehicle (ASV) system is discussed. Swordfish is an ocean capable 4.5 m long catamaran designed for network centric operations (with ocean and air going vehicles and human operators). In the basic configuration, Swordfish is both a survey vehicle and a communications node with gateways for broadband, Wi-Fi and GSM transports and underwater acoustic modems. In another configuration, Swordfish mounts a docking station for the autonomous underwater vehicle Isurus from Porto University. Swordfish has an advanced control architecture for multi-vehicle operations with mixed initiative interactions (human operators are allowed to interact with the control loops).

Structured Light System for Underwater Inspection Operations

In this work we propose the development of a stereo SLS system for underwater inspection operations. We demonstrate how to perform a SLS calibration both in dry and underwater environments using two different methods. The proposed methodology is able to achieve quite accurate results, lower than 1 mm in dry environments. We also display a 3D underwater scan of a known object size, a sea scallop, where the system is able to perform a scan with a global error lower than 2% of the object size.

Water jet based autonomous surface vehicle for coastal waters operations

This paper presents the design of low cost, small autonomous surface vehicle for missions in the coastal waters and specifically for the challenging surf zone. The main objective of the vehicle design described in this paper is to address both the capability of operation at sea in relative challenging conditions and maintain a very low set of operational requirements (ease of deployment). This vehicle provides a first step towards being able to perform general purpose missions (such as data gathering or patrolling) and to at least in a relatively short distances to be able to be used in rescue operations (with very low handling requirements) such as carrying support to humans on the water. The USV is based on a commercially available fiber glass hull, it uses a directional waterjet powered by an electrical brushless motor for propulsion, thus without any protruding propeller reducing danger in rescue operations. Its small dimensions (1.5 m length) and weight allow versatility and ease of deployment. The vehicle design is described in this paper both from a hardware and software point of view. A characterization of the vehicle in terms of energy consumption and performance is provided both from test tank and operational scenario tests. An example application in search and rescue is also presented and discussed with the integration of this vehicle in the European ICARUS (7th framework) research project addressing the development and integration of robotic tools for large scale search and rescue operations.

Significance of Biogenic Amines in Cold-Smoked Fish and Their Relation to Microbiological Characteristics of Products Available in Portuguese Retail Markets

Studies on microbial characterization of cold-smoked salmon and salmon trout during cold storage were performed on samples available in the Portuguese market. Samples were also classified microbiologically according to guidelines for ready-to-eat (RTE) products. Further investigations on sample variability and microbial abilities to produce tyramine and histamine were also performed. The coefficient of variation for viable counts of different groups of microorganisms of samples collected at retail market point was high in the first 2 wk of storage, mainly in the Enterobacteriaceae group and aerobic plate count (APC), suggesting that microbiological characteristics of samples were different in numbers, even within the same batch from the same producer. This variation seemed to be decreased when storage and temperature were controlled under lab conditions. The numbers of Enterobacteriaceae were influenced by storage temperature, as indicated by low microbial numbers in samples from controlled refrigeration. Lactic acid bacteria (LAB) and Enterobacteriaceae were predominant in commercial products, a significant percentage of which were tyramine and less histamine producers. These results might be influenced by (1) the technological processes in the early stages of production, (2) contamination during the smoking process, and (3) conditions and temperature fluctuations during cold storage at retail market point of sale.

Sistema de apoio à decisão na localização de peças

A globalização, nas suas diversas dimensões, está a tornar o mundo cada vez mais pequeno, alterando as nossas vidas e transformando a forma como as empresas fazem negócios. Estamos cada vez mais expostos aos traços e práticas das outras culturas à medida que a tecnologia diminui os custos da comunicação global e das viagens. A globalização está a obrigar as empresas a serem mais competitivas ao mesmo tempo que os países reduzem as barreiras ao comércio internacional e ao investimento estrangeiro. A competitividade das empresas obriga-as a serem mais eficientes e eficazes, logo a pensarem os seus processos internos de forma a procurarem a sua otimização e melhorarem a sua produtividade, com a notória consequência na satisfação do cliente. Para a satisfação do cliente é necessário que as operações dentro do sistema de distribuição, nomeadamente as realizadas no armazém, sejam otimizadas. Esta otimização é atingida quando as encomendas dos clientes estiverem completas e prontas a serem despachadas em tempo útil e todos os processos necessários para o efeito tenham ocorrido no menor espaço de tempo possível e com o mínimo de recursos. O planeamento das operações no armazém tem de determinar o tempo e a ordem das operações bem como os recursos necessários de forma a não acontecerem congestionamentos. A Caetano Parts, uma empresa de revenda de peças de substituição automóvel, identificou um congestionamento na localização de peças que chegavam pela primeira vez ao seu armazém, o que suscitou a necessidade do desenvolvimento de uma ferramenta que permitisse proceder à localização destas peças de uma forma mais expedita, permitindo ganhos significativos de tempo na arrumação das peças e consequentemente no tempo gasto na sua procura/separação e posterior envio para os clientes. A ferramenta desenvolvida consiste num programa em Visual Basic for Applications (VBA) cuja conceção, desenvolvimento e descrição das funcionalidades serão abordados ao longo do trabalho. Os testes realizados ao longo do desenvolvimento validaram o correto funcionamento da ferramenta.

Reengenharia do processo de reclamações das lojas

Num contexto global de incerteza, as cadeias de abastecimento mais ágeis e os clientes com mais exigências manifestam uma constante preocupação com a melhoria contínua da eficiência das operações logísticas. O presente projeto foi desenvolvido na empresa Sonae Modelo Continente Hipermercados, S.A, uma das duas principais empresas do retalho da grande distribuição alimentar em Portugal. Sendo a logística um fator chave de sucesso, uma das atividades críticas de uma empresa, é identificada a oportunidade de melhoria operacional do processo de negócio, a partir das reclamações dos clientes internos. O tratamento destas reclamações, incidências, é de grande complexidade e responsabilidade para a área do Logistics Customer Service. O projeto desenvolvido, a ‘Reengenharia do processo de reclamações das Lojas’, surgiu da necessidade de criar um modelo e processo de negócio de melhoria contínua, que solucione falhas operacionais com implicação na Logística, Supply Chain e em outras áreas da empresa. A procura dessa melhoria é o objetivo deste trabalho. Pretende-se, com a proposta aqui apresentada, a interligação e automatização da cadeia abastecimento, para superar as ocorrências operacionais, elevar a qualidade do serviço, aumentar a capacidade do processo e incorporar uma monitorização das atividades de input (Lojas) e output (Entrepostos), para futura rastreabilidade das operações, através da integração da cadeia de abastecimento, para a satisfação do cliente interno. Para a elaboração do novo modelo de processo foi seguida a orientação da reengenharia de processos de negócio, nas suas linhas orientadoras: identificação do modelo de processo atual e das suas necessidades; definição dos objetivos norteadores do projeto a apresentar; redesenhar novo modelo de processo de negócio, de modo a dar resposta às necessidades detetadas nos clientes internos.