A rough-cut capacity planning model with overlapping

In the early phases of projects, capacity planning is performed to assess the feasibility of the project in terms of delivery date, resource usage and cost. This tactical approach relies on an aggregated representation of tasks in work packages. At this level, aggressive project duration objectives are achieved by adopting work package overlapping policies that affect both workload and resource usage. In this article, we propose a mixed-time MILP model for project capacity planning with different possibilities for overlapping levels between work packages. In the model, the planning time horizon is divided into time buckets used to evaluate resource usage, while starting and ending times for work packages are continuous. The model was tested on a benchmark of 5 sets of 450 theoretical instances each. More than half of the tested instances were solved to optimality within 500 s. Results also show that, while overlapping is more beneficial for accelerating project delivery times, it can still have a positive impact on project cost by allowing a better distribution of workload. Finally, overlapping options seem to have less influence on the performance of the model than project slack or number of work packages

A rough-cut capacity planning model with overlapping

In the early phases of projects, capacity planning is performed to assess the feasibility of the project in terms of delivery date, resource usage and cost. This tactical approach relies on an aggregated representation of tasks in work packages. At this level, aggressive project duration objectives are achieved by adopting work package overlapping policies that affect both workload and resource usage. In this article, we propose a mixed-time MILP model for project capacity planning with different possibilities for overlapping levels between work packages. In the model, the planning time horizon is divided into time buckets used to evaluate resource usage, while starting and ending times for work packages are continuous. The model was tested on a benchmark of 5 sets of 450 theoretical instances each. More than half of the tested instances were solved to optimality within 500 s. Results also show that, while overlapping is more beneficial for accelerating project delivery times, it can still have a positive impact on project cost by allowing a better distribution of workload. Finally, overlapping options seem to have less influence on the performance of the model than project slack or number of work packages

Un modèle de planification tactique avec chevauchement

RÉSUMÉ : La gestion de projets est une discipline complexe, qui requiert des outils efficaces pour aider les gestionnaires dans la prise de décision. En construction, cette discipline emploie des techniques de fast tracking, similaires à celles de l’ingénierie simultanée, afin de réaliser les projets en régime accéléré. Une des techniques couramment employées est le chevauchement des lots de travaux, consistant à exécuter en parallèle deux lots normalement séquentiels, en commençant le lot aval tout en se basant sur des informations préliminaires du lot amont. Des outils de planification de projet avec chevauchement existent mais concernent uniquement le niveau opérationnel. À notre connaissance, les praticiens ne disposent pas d’outils les aidant dans leur choix de chevauchement lors de la planification tactique. Compte tenu de l’importance de ces pratiques dans le milieu industriel d’aujourd’hui, ce mémoire traite de la planification tactique de projet avec des possibilités de chevauchement entre les lots de travaux. Un modèle de planification agrégée, connue aussi sous le nom de Rough-Cut Capacity Planning, avec chevauchement est proposé sous forme de programme linéaire en nombres entiers. Ce modèle combine des représentations discrète et continue du temps et considère plusieurs modes de chevauchement possibles pour les lots. Le modèle a été testé sur 5 séries de 450 instances chacune et permet de résoudre plus de la moitié en moins de 500 secondes. Moins que le tiers de ces instances n’a pas été résolu à l’optimum dans un délai inférieur à 10000 secondes. Les résultats montrent que le chevauchement, initialement une technique d’accélération de projet, permet également la réduction des coûts en autorisant une meilleure distribution des charges. Cependant, certaines limitations ont été soulevées à notre modèle, concernant surtout son applicabilité à la pratique. En particulier, le modèle requiert des entrées qui peuvent être difficilement accessibles pour un projet réel et la résolution exacte nécessite de long temps de calcul pour des projets de grande ampleur. Afin de contourner la deuxième limite, une alternative a été envisagée en construisant une heuristique basée sur le modèle exact. Cette heuristique semble donner des résultats encourageants. D’autres limitations ont également été soulignées concernant le caractère aléatoire des données, le type des liens d’antériorité et les fonctions objectifs considérées. Ces limitations, ainsi que les résultats prometteurs obtenus par la solution alternative, ouvrent plusieurs voies de recherche pertinentes. Les principales avenues sont le développement d’une heuristique basée sur le modèle exact, la prise en compte de l’incertitude et la généralisation des liens d’antériorité.----------ABSTRACT : Project management is a complex discipline that requires strong tools in order to help the managers make the best decisions. In construction, fast tracking techniques, similar to Concurrent Engineering techniques, are commonly employed in order to accelerate project execution. One of these techniques is the overlapping of work packages, consisting in executing in parallel two normally sequential work packages, by starting the successor before the end of the predecessor based on preliminary information. While some planning tools with overlapping exist for the operational level, to our knowledge, no such tools are dedicated for the tactical level. Thus, practitioners do not have a tool that helps them make overlapping decisions at a tactical planning. Motivated by a true need, this study focuses on tactical project planning with the possibility of overlapping for work packages. A mixed integer linear programming model for the Rough-Cut Capacity Planning problem with overlapping is proposed. The model combines continuous and discrete representations of time, and considers several possible overlapping modes for work packages. The model was tested on 5 sets of 450 instances each, and manages to solve more than half of instances within 500 seconds, while less than one third of the instances were not solved to optimality when reaching the time limit of 10000 seconds. Results show that overlapping can reduce project cost by allowing a better distribution of workload, even though it is primarily a technique for accelerating projects. The model has several limitations mostly concerning its fitness to real projects applications. In fact, the model requires inputs that can be challenging to obtain in real projects, and it requires long solving times for big projects. In order to address that second limitation, a heuristic based on the exact model was proposed as an alternative solution, and gives very encouraging preliminary results. Other limitations were also raised concerning the stochastic nature of the problem, the type of precedence relations, and the considered objectives. These limitations, as well as the promising results of the alternative solution, offer interesting prospects for the future. Possible research avenues include development of heuristics based on the exact model, consideration of uncertainty, and generalization of precedence relations

Track Allocation in Freight-Train Classification with Mixed Tracks

We consider the process of forming outbound trains from cars of inbound trains at rail-freight hump yards. Given the arrival and departure times as well as the composition of the trains, we study the problem of allocating classification tracks to outbound trains such that every outbound train can be built on a separate classification track. We observe that the core problem can be formulated as a special list coloring problem in interval graphs, which is known to be NP-complete. We focus on an extension where individual cars of different trains can temporarily be stored on a special subset of the tracks. This problem induces several new variants of the list-coloring problem, in which the given intervals can be shortened by cutting off a prefix of the interval. We show that in case of uniform and sufficient track lengths, the corresponding coloring problem can be solved in polynomial time, if the goal is to minimize the total cost associated with cutting off prefixes of the intervals. Based on these results, we devise two heuristics as well as an integer program to tackle the problem. As a case study, we consider a real-world problem instance from the Hallsberg Rangerbangård hump yard in Sweden. Planning over horizons of seven days, we obtain feasible solutions from the integer program in all scenarios, and from the heuristics in most scenarios

A Republic of the Mind: Cognitive Biases, Fiscal Federalism, and Section 164 of the Tax Code

In its efforts to guide money to the states, our federal government annually passes up more than $75 billion in potential revenue under a single provision of the Tax Code. That provision, section 164 of the Code, allows itemizing taxpayers to deduct the cost of the state and local income, property, and (to a limited extent) sales taxes they paid during the tax year. The eye-popping size of that number makes section 164 a perennial issue in tax policy circles, and as one of the deductions omitted from the Alternative Minimum Tax\u27s (AMT) parallel tax universe, the section is also a key component of debates about the AMT. Indeed, the President\u27s Advisory Panel on Tax Reform recommends eliminating the deduction to pay for its proposed AMT reform

Design For Manufacturing (Dfm) untuk Meminimasi Biaya Produksi dan Kualitas (Studi Kasus Pallet Box Fabrication Section PT Saptaindra Sejati)

PT. XYZ is manufacturing of automotive spare parts and non-automotive company, which produces several products such as Oil Seal, Tensioner, Gasket, Rubber Only and other products. To fulfill the commitment to the company, one of the ways is to eliminate waste in the production process in the company, is Rubber. From the rubber scrap, the largest percentage is Rubber chips expired. So related to the purpose of this research is to identify the presence of waste on the rubber, improvements in production planning and compare MRP, RCCP and CRP. The method that used in this research is the FTA (Fault Tree Analysis) and RCCP (Rough Cut Capacity Planning) with CPOF technique (Capacity Planning Overall Factors). The result is able to minimize the rubber chip is wasted due to past the shelf (expired)

A Funder Journey: Scaling Up the Stone Family Foundation

This report follows the journey of one foundation from its inception to the present day. It highlights the work of an effective funder, and shares lessons that can be applied to funding more widely. The Stone Family Foundation is an example of how a relatively new and mid-sized foundation has looked to scale up and develop how it works and what it funds. The lessons learned from implementing the major grants program influenced the shape of its subsequent WASH funding. While this exact journey may be specific to the Stone Family Foundation, the general process -- starting out, planning, delivering, learning and then adapting -- will be relevant to other funders grappling with the same questions about how to become an effective funder

Algebra of Tankers

The Air Force\u27s aerial refueling tanker aircraft provide essential support for deployment and employment of combat and combat support aircraft, by extending their endurance and enhancing fighting efficiency. As the lead command for air refuelers, Air Mobility Command (AMC) must frequently examine the capability of current and proposed tanker fleets to meet mission requirements due to limited tanker resources. Analysts in AMC primarily use the Combined Mating and Ranging Plans System to provide actual tanker/receiver aircraft schedules and flight plans that take into account numerous system constraints. However, this tool can take weeks to run. Even recently developed quick look tools, aimed at optimization of the fleet, can take 1/2 hour or more. Additionally, most of these more recent studies and tools assess the feasibility of deployments. Less attention has been given to the employment phase of missions. AMC lacks a quick look tool to quickly perform rough cut capacity analysis for tanker use and assess the feasibility of proposed employment of tankers. To develop a feasibility quick look tool, the basic formulae for computing tankers missions must be understood. While the airlift community has defined million ton miles per day as their keystone metric, the tanker community -- concerned with being on time, on target, with fuel -- lacks such a definitive metric. This thesis describes fundamental algebraic relations that characterize employment of air refueling aircraft, employing rough cut capacity planning to determine feasibility of tanker employment with a given amount of resources. The Tanker Employment Model provides AMC with an efficient tool for quickly assessing tanker employment capabilities