MemComputing Integer Linear Programming

Integer linear programming (ILP) encompasses a very important class of optimization problems that are of great interest to both academia and industry. Several algorithms are available that attempt to explore the solution space of this class efficiently, while requiring a reasonable compute time. However, although these algorithms have reached various degrees of success over the years, they still face considerable challenges when confronted with particularly hard problem instances, such as those of the MIPLIB 2010 library. In this work we propose a radically different non-algorithmic approach to ILP based on a novel physics-inspired computing paradigm: Memcomputing. This paradigm is based on digital (hence scalable) machines represented by appropriate electrical circuits with memory. These machines can be either built in hardware or, as we do here, their equations of motion can be efficiently simulated on our traditional computers. We first describe a new circuit architecture of memcomputing machines specifically designed to solve for the linear inequalities representing a general ILP problem. We call these self-organizing algebraic circuits, since they self-organize dynamically to satisfy the correct (algebraic) linear inequalities. We then show simulations of these machines using MATLAB running on a single core of a Xeon processor for several ILP benchmark problems taken from the MIPLIB 2010 library, and compare our results against a renowned commercial solver. We show that our approach is very efficient when dealing with these hard problems. In particular, we find within minutes feasible solutions for one of these hard problems (f2000 from MIPLIB 2010) whose feasibility, to the best of our knowledge, has remained unknown for the past eight years

Integrating nurse and surgery scheduling.

Scheduling; Surgery scheduling; International; Theory; Applications; Euro; Researchers;

"You have to get wet to learn how to swim" applied to bridging the gap between research into personnel scheduling and its implementation in practice

Personnel scheduling problems have attracted research interests for several decades. They have been considerably changed over time, accommodating a variety of constraints related to legal and organisation requirements, part-time staff, flexible hours of staff, staff preferences, etc. This led to a myriad of approaches developed for solving personnel scheduling problems including optimisation, meta-heuristics, artificial intelligence, decision-support, and also hybrids of these approaches. However, this still does not imply that this research has a large impact on practice and that state-of-the art models and algorithms are widely in use in organisations. One can find a reasonably large number of software packages that aim to assist in personnel scheduling. A classification of this software based on its purpose will be proposed, accompanied with a discussion about the level of support that this software offers to schedulers. A general conclusion is that the available software, with some exceptions, does not benefit from the wealth of developed models and methods. The remaining of the paper will provide insights into some characteristics of real-world scheduling problems that, in the author’s opinion, have not been given a due attention in the personnel scheduling research community yet and which could contribute to the enhancement of the implementation of research results in practice. Concluding remarks are that in order to bridge the gap that still exists between research into personnel scheduling and practice, we need to engage more with schedulers in practice and also with software developers; one may say we need to get wet if we want to learn how to swim

Formalisation and use of competencies for industrial performance optimisation : a survey.

For many years, industrial performance has been implicitly considered as deriving from the optimisation of technological and material resources (machines, inventories,...), made possible by centralized organisations. The topical requirements for reactive and flexible industrial systems have progressively reintroduced the human workforce as the main source of industrial performance. Making this paradigm operational requires the identification and careful formalisation of the link between human resource and industrial performance, through concepts like skills, competencies or know-how. This paper provides a general survey of the formalisation and integration of competence-oriented concepts within enterprise information systems and decision systems, aiming at providing new methods and tools for performance management

ÇKKV ve Tamsayılı Programlama Yöntemleri ile Bir Üretim İşletmesinde Uzaktan Çalışma Modelinin Oluşturulması

Tüm dünyada etkisini sürdüren Covid-19, iş hayatında çalışma koşullarının değişmesinde büyük rol oynamıştır. Covid-19’un ortaya çıkmasından sonra birçok işletme uygun bir bilgi işlem altyapısı varsa uzaktan çalışma ya da dönüşümlü çalışma modeline geçmeyi tercih etmişlerdir. Bilgi işlem altyapısı eksik olan işletmeler ise altyapılarını geliştirmeye ve uzaktan çalışma modeline geçmek için gerekli şartları sağlamaya çalışmıştır. Bu süreçte ofiste bulunan çalışan sayısının azaltılması ve temasın mümkün olduğunca azaltılabilmesi açısından uzaktan çalışma modeli bir ihtiyaç haline gelmiştir. Bu çalışmada, Denizli’de faaliyet gösteren bir üretim işletmesinde, ofiste bulunan çalışan sayısını azaltmak amacıyla öncelikle uzaktan çalışmaya uygunluğa yönelik kriterlerin ağırlıkları MACBETH (Measuring Attractiveness by a Categorical Based Evaluation Technique) yöntemiyle belirlenmiş, sonrasında TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) yöntemi ile çalışanlar uzaktan çalışma modeline uygunluğa göre sıralanmış ve işletmenin uzaktan çalışma modeline göre belirlediği kurallar dikkate alınarak tamsayılı programlama yöntemi ile çalışanların uzaktan çalışma ve ofisten çalışmasına yönelik dönüşümlü çalışma modeli oluşturulmuştur. Bu çalışmada önerilen yöntemler yardımıyla, manuel olarak oluşturulan çizelgelere göre daha adil ve işveren taleplerini karşılayan bir çalışma modeli oluşturulmuştur

Solving Challenging Real-World Scheduling Problems

This work contains a series of studies on the optimization of three real-world scheduling problems, school timetabling, sports scheduling and staff scheduling. These challenging problems are solved to customer satisfaction using the proposed PEAST algorithm. The customer satisfaction refers to the fact that implementations of the algorithm are in industry use. The PEAST algorithm is a product of long-term research and development. The first version of it was introduced in 1998. This thesis is a result of a five-year development of the algorithm. One of the most valuable characteristics of the algorithm has proven to be the ability to solve a wide range of scheduling problems. It is likely that it can be tuned to tackle also a range of other combinatorial problems. The algorithm uses features from numerous different metaheuristics which is the main reason for its success. In addition, the implementation of the algorithm is fast enough for real-world use.Siirretty Doriast

Effect of individual resources and team-member exchange on service quality

While workplace resources are generally viewed as positively affecting performance, some studies indicate that not all resources increase performance. This study addresses the controversial disparate effects of workplace resources on performance by exploring functionally classified workplace resources in self-managing service teams and their relative impacts on team service quality. Considering membership dynamics and consequences between members, a field experiment was conducted in a cafeteria, with data collected through a working diary for workplace resources and a customer survey to evaluate service quality. Results suggest that efficacy-resources in self-managing teams should be controlled with caution as they may adversely affect team service quality. Supporting the person-situation interactionism perspective, workplace resources interact dynamically with individual employees and with situations. Esteem-resources were found to increase team service quality, while team-member exchange (TMX) not only improved team service quality but also moderated the impact of esteem-resources on team service quality

Manpower planning optimization in three different real world areas: container terminals, hospitals and retail stores

Problems related to the optimization of human resources in working areas have been extensively studied in the literature with the major goal of guaranteeing the greatest benefits from the efforts of workers, while taking into account their personal skills and requirements. In particular, in this thesis we focus on short-term and long-term manpower planning problems. The main goal consists in appropriately assigning shifts to workers in a given time horizon, taking into account their own requirements, their contractual rules, and the quality and efficiency of the work environment. In this thesis the manpower planning problem is studied in three different working areas, namely container terminals, hospitals and retail stores. Different solutions are proposed based on mathematical models that allow to describe in linear algebraic terms the set of feasible solutions. An optimal scheduling is then computed using linear integer programming. The proposed policies have been validated on three different real case studies in Cagliari, Italy