Using interval graphs in an order processing optimization problem

In this paper we address an order processing optimization problem known as minimization of open stacks (MOSP). We present an integer pro gramming model, based on the existence of a perfect elimination scheme in interval graphs, which finds an optimal sequence for the costumers orders.

A mathematical model for supermarket order picking

Order picking consists in retrieving products from storage locations to satisfy independent orders from multiple customers. It is generally recognized as one of the most significant activities in a warehouse (Koster et al, 2007). In fact, order picking accounts up to 50% (Frazelle, 2001) or even 80% (Van den Berg, 1999) of the total warehouse operating costs. The critical issue in today’s business environment is to simultaneously reduce the cost and increase the speed of order picking. In this paper, we address the order picking process in one of the Portuguese largest companies in the grocery business. This problem was proposed at the 92nd European Study Group with Industry (ESGI92). In this setting, each operator steers a trolley on the shop floor in order to select items for multiple customers. The objective is to improve their grocery e-commerce and bring it up to the level of the best international practices. In particular, the company wants to improve the routing tasks in order to decrease distances. For this purpose, a mathematical model for a faster open shop picking was developed. In this paper, we describe the problem, our proposed solution as well as some preliminary results and conclusions.

Expatriates’ influence on knowledge sharing: an empirical study with International portuguese companies

Despite the abundant literature in knowledge management, few empirical studies have explored knowledge management in connection with international assignees. This phenomenon has a special relevance in the Portuguese context, since (a) there are no empirical studies concerning this issue that involves international Portuguese companies; (b) the national business reality is incipient as far as internationalisation is concerned, and; (c) the organisational and national culture presents characteristics that are distinctive from the most highly studied contexts (e.g., Asia, USA, Scandinavian countries, Spain, France, The Netherlands, Germany, England and Russia). We examine the role of expatriates in transfer and knowledge sharing within the Portuguese companies with operations abroad. We focus specifically on expatriates’ role on knowledge sharing connected to international Portuguese companies and our findings take into account organizational representatives’ and expatriates’ perspectives. Using a comparative case study approach, we examine how three main dimensions influence the role of expatriates in knowledge sharing among headquarters and their subsidiaries (types of international assignment, reasons for using expatriation and international assignment characteristics). Data were collected using semi‐structured interviews to 30 Portuguese repatriates and 14 organizational representatives from seven Portuguese companies. The findings suggest that the reasons that lead Portuguese companies to expatriating employees are connected to: (1) business expansion needs; (2) control of international operations and; (3) transfer and knowledge sharing. Our study also shows that Portuguese companies use international assignments in order to positively respond to the increasingly decaying domestic market in the economic areas in which they operate. Evidence also reveals that expatriation is seen as a strategy to fulfill main organizational objectives through their expatriates (e.g., business internationalization, improvement of the coordination and control level of the units/subsidiaries abroad, replication of aspects of the home base, development and incorporation of new organizational techniques and processes). We also conclude that Portuguese companies have developed an International Human Resources Management strategy, based on an ethnocentric approach, typically associated with companies in early stages of internationalization, i.e., the authority and decision making are centered in the home base. Expatriates have a central role in transmitting culture and technical knowledge from company’s headquarters to the company’s branches. Based on the findings, the article will discuss in detail the main theoretical and managerial implications. Suggestions for further research will also be presented.

Power Law Behavior and Self-similarity in Modern Industrial Accidents

Advances in technology have produced more and more intricate industrial systems, such as nuclear power plants, chemical centers and petroleum platforms. Such complex plants exhibit multiple interactions among smaller units and human operators, rising potentially disastrous failure, which can propagate across subsystem boundaries. This paper analyzes industrial accident data-series in the perspective of statistical physics and dynamical systems. Global data is collected from the Emergency Events Database (EM-DAT) during the time period from year 1903 up to 2012. The statistical distributions of the number of fatalities caused by industrial accidents reveal Power Law (PL) behavior. We analyze the evolution of the PL parameters over time and observe a remarkable increment in the PL exponent during the last years. PL behavior allows prediction by extrapolation over a wide range of scales. In a complementary line of thought, we compare the data using appropriate indices and use different visualization techniques to correlate and to extract relationships among industrial accident events. This study contributes to better understand the complexity of modern industrial accidents and their ruling principles.

Discrete fractional order system vibrations

A theory of free vibrations of discrete fractional order (FO) systems with a finite number of degrees of freedom (dof) is developed. A FO system with a finite number of dof is defined by means of three matrices: mass inertia, system rigidity and FO elements. By adopting a matrix formulation, a mathematical description of FO discrete system free vibrations is determined in the form of coupled fractional order differential equations (FODE). The corresponding solutions in analytical form, for the special case of the matrix of FO properties elements, are determined and expressed as a polynomial series along time. For the eigen characteristic numbers, the system eigen main coordinates and the independent eigen FO modes are determined. A generalized function of visoelastic creep FO dissipation of energy and generalized forces of system with no ideal visoelastic creep FO dissipation of energy for generalized coordinates are formulated. Extended Lagrange FODE of second kind, for FO system dynamics, are also introduced. Two examples of FO chain systems are analyzed and the corresponding eigen characteristic numbers determined. It is shown that the oscillatory phenomena of a FO mechanical chain have analogies to electrical FO circuits. A FO electrical resistor is introduced and its constitutive voltage–current is formulated. Also a function of thermal energy FO dissipation of a FO electrical relation is discussed.

Strange Dynamics in a Fractional Derivative of Complex-Order Network of Chaotic Oscillators

We study the peculiar dynamical features of a fractional derivative of complex-order network. The network is composed of two unidirectional rings of cells, coupled through a "buffer" cell. The network has a Z3 × Z5 cyclic symmetry group. The complex derivative Dα±jβ, with α, β ∈ R+ is a generalization of the concept of integer order derivative, where α = 1, β = 0. Each cell is modeled by the Chen oscillator. Numerical simulations of the coupled cell system associated with the network expose patterns such as equilibria, periodic orbits, relaxation oscillations, quasiperiodic motion, and chaos, in one or in two rings of cells. In addition, fixing β = 0.8, we perceive differences in the qualitative behavior of the system, as the parameter c ∈ [13, 24] of the Chen oscillator and/or the real part of the fractional derivative, α ∈ {0.5, 0.6, 0.7, 0.8, 0.9, 1.0}, are varied. Some patterns produced by the coupled system are constrained by the network architecture, but other features are only understood in the light of the internal dynamics of each cell, in this case, the Chen oscillator. What is more important, architecture and/or internal dynamics?

O presente e o futuro da supervisão das instituições financeiras em Portugal

Dissertação de Mestrado apresentada ao Instituto Superior de Contabilidade e Administração do Porto para a obtenção do grau de Mestre em Contabilidade e Finanças sob orientação do Doutor Armindo Licínio da Silva Macedo “Esta versão contém críticas e sugestões dos elementos do júri”.

Blood Donation in the Hospital de S. José. A 11-Year Retrospective Analysis of Deferrals and Exclusions

Background: Approximately 5% of the population donates blood each year in developed countries. Recruiting and maintaining a pool of altruistic and healthy blood donors is a challenging task. Blood donation as a dynamic process must naturally co-exist with the arguably essential deferrals. Aims: To analyse a 11-year cohort of donors and blood donations in order to determine the profile of the average donor and the typical donation. Characterize the donor’s population in terms of gender, age, number of donations, most common causes for deferral and exclusion and the possible relationships between them. Establish the tendency flow of donations per year. Methods: Analysis of 95861 blood donations from 31550 donors collected between 2000 and 2010 (11 years) in the Immunohemotherapy Department of the ‘‘Centro Hospitalar Lisboa Central - Hospital de Sa˜o Jose´’’ (Lisboa, Portugal). Prior to blood donation, donors were required to fill out a form of informed consent, a questionnaire of 21 ‘‘yes or no’’ questions and were submitted to a clinical assessment and physical examination including: measurement of weight, blood pressure, pulse and capillary hemoglobin levels. Post-donation, the collected blood was tested for ALT elevation and blood-borne viral agents (HBV, HCV, HIV 1 and 2 and HTLV 1 and 2) and other infections (Treponema pallidum). Blood donors and donations were registered in a database and statistically studied in terms of: gender and age distribution, number of donations, most common causes for deferral and exclusion. The frequency of blood donations throughout the period of observation was analyzed and statistically significant relationships between the collected variables were investigated. Results: From the population of 31550 donors 61% were male and a mean age of 41.5 years (± 12.5 years) was found. From the total of 95682 blood donations collected 78% were successful while the most common causes for deferral were: donation incompatible hemoglobin levels (5% of the blood donations and 22% of deferrals), ALT elevation (3% and 14%), positive blood screening test for Treponema pallidum (1% and 6%), medication (1% and 4%), positive serological blood markers for HBV (1% and 4%), endoscopy in the previous 12 months (1% and 3%), arterial hypertension (1% and 3%), infectious conditions (1% and 3%), influenza or influenza-like symptoms (1% and 2%) and positive serological blood markers for HCV (1% and 2%). Summary/Conclusions: Several factors may have contributed to a limited number of new regular donors in the population, namely: ageing population, the alienation of the individual from the community induced by modern lifestyles and job precariousness. It is of the utmost importance to refine our blood donation campaigns according to the existing population of donors. The optimization of the blood donation potential of a population of donors must be achieved through the development of reliable and consistent screening methods. In order to appeal to new donors it is important to promote blood donations considering the profile of the regular and healthy blood donor of the existing population.

Analysis of benefits of the process of certification on international standars: ISO 9001-2008 for Mapfre Assistencia Portugal

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics

Papo D’Anjo - International strategic implementation plan to Brazil

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

Corporate strategy development: International distance model for the Brazilian market

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

Relatório de estágio na Caixa Geral de Depósitos

This report will describe the activities undertaken during my internship at the Personnel Department (DPE-UPE4.1) in Caixa Geral de Depósitos (CGD), Lisbon, between September 22, 2014, and February 28, 2015. I consider that it is important to note from the outset i) that the subject of my training was suggested by my supervisor in the DPE and accepted by me; and ii) that the internship consisted essentially of carrying out research and information gathering into the different social systems that coexist within the bank and the application of each legal system in solving concrete situations of the CGD employees. The research and analysis of information was important not only for my study but for the CGD itself, as it enables the department to have such an important matter, full of specific characteristics, condensed into a single document, i.e. this report. This is a complex reality. The various welfare systems differ according to the contractual agreement linking the employee to the employer at the date when the labour contract is signed, and also the unique/singular characteristics of the CGD. In the early stage I started by trying to understand the financial institution and its organization and role and the department where I worked. So I analyzed the CGD Statutes and the legal measures that crystallized the scheme for its employees and I also researched its domestic and international operations. The first month was devoted to the research and analysis of such legislation to understand the creation of the CGD and its path to date. In the second and third months I studied the legal social systems that are applied to different groups of CGD workers. This period was quite important to identify and understand the differences between those regimes of CGD employees as well as the procedure inherent in each case. I highlighted the non-implementation of “the social protection regime of convergence” to the workers of this institution; the differences regarding the allocation of sickness subsidies paid to workers who belong to Social Security and CGA contributors, as well as the enforcement of internal rules to all the workers when a work-related accident happens. Then I focused on to assessing and examining external legislation and several internal regulations in order to obtain solutions to questions raised and situations involving by the workers, in order to understand how the DPE solves these situations. Over the last three months of internship, after this more theoretical work, I began the analysis of concrete situations involving employees carrying out their duties in Portugal and abroad. Some of these situations had been received by the department before the beginning of my internship and others over this period. When I was “working” in the DPE I analyzed “cases” that had been solved and some others without a final solution because they were still in courts. As for the last ones (new cases) I was able to follow their assessment and sometimes their outcome. Some of them became study cases for me. Over these five months of my internship, several cases were analyzed and discussed by legal experts of DPE in which I could participate. I always worked hard. I know that this action contributed to elucidate me about the treatment of the issues, and allowed me to have a direct contact with some workers and be part of a dynamic work team. For these reasons, my internship report is not merely descriptive of activities. It consists of an analysis of rules (legislation) and a regulatory framework of activities and it is also a description of several specific situations solved or in a solution process. Through this work I intend to make known the particular reality of a modern Portuguese financial institution not only because of its importance in our country but also such a large number of employees work here (in Portugal and abroad). I should add that throughout my internship I was allowed to attend conferences, within the scope of the bank in order to get a broader view of some issues related to the daily life of the DPE and the CGD. So, I participated in I Jornadas Bancárias and the Conferência Internacional do Contrato a Termo, given that the CGD is a bank and the DPE deals with legal and labour relations.

Performance analysis of an SRI screen based on employment quality in high and low capital industries: International evidence

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics and Maastricht University School of Business and Economics

Internationalization strategy for MyHelpster.com with a focus on international market selection

International Market Selection is an important step towards a successful internationalization strategy. This is no different for startup companies like MyHelpster. This work project was intended to help MyHelpster with their internationalization process by completing the IMS portion of it. The IMS process presented in this paper lead to the conclusion that MyHelpster’s next market for expansion should be the USA. In order to find as much success as possible the author suggests being patient and only expanding when the company has the necessary capital, experience and credibility. Both primary and secondary data were used to compile the qualitative and quantitative analyses.

8-Phase Ring oscillator for modern receivers

The evolution of receiver architectures, built in modern CMOS technologies, allows the design of high efficient receivers. A key block in modern receivers is the oscillator. The main objective of this thesis is to design a very low power and low area 8-Phase Ring Oscillator for biomedical applications (ISM and WMTS bands). Oscillators with multiphase outputs and variable duty cycles are required. In this thesis we are focused in 12.5% and 50% duty-cycles approaches. The proposed circuit uses eight inverters in a ring structure, in order to generate the output duty cycle of 50%. The duty cycle of 1/8 is achieved through the combination of the longer duty cycle signals in pairs, using, for this purpose, NAND gates. Since the general application are not only the wireless communications context, as well as industrial, scientific and medical plans, the 8-Phase Oscillator is simulated to be wideband between 100 MHz and 1 GHz, and be able to operate in the ISM bands (447 MHz-930 MHz) and WMTS (600 MHz). The circuit prototype is designed in UMC 130 nm CMOS technology. The maximum value of current drawn from a DC power source of 1.2 V, at a maximum frequency of 930 MHz achieved, is 17.54 mA. After completion of the oscillator layout studied (occupied area is 165 μm x 83 μm). Measurement results confirm the expected operating range from the simulations, and therefore, that the oscillator fulfil effectively the goals initially proposed in order to be used as Local Oscillator in RF Modern Receivers.