Search results for "production [top]"
showing 10 items of 128 documents
Determinants of elimination decisions in the activity scheduling process
2016
[EN] This paper presents an analysis on the determinants related to a particular rescheduling decision in the activity-travel scheduling process: elimination decisions, which consist in the non-execution of pre-planned activity-travel episodes. Data used come from an in-depth computer-assisted telephone interview (CATI) follow up survey carried out during the implementation of the first wave of an activity scheduling process panel survey. Open-ended answers related to the reasons associated to changes between pre-planned and executed agenda are studied. First, an interpretative qualitative method based on analytic induction (AI) is used to cope with the complex nature of the rescheduling de…
Changes in the Scheduling Process According to Observed Activity-travel Flexibility
2014
Abstract In this work we analyze the reasons for changing pre-planned activities and travels episodes considering the type of modification observed during the scheduling process. Specifically we selected a small sample from those pre-planned episodes that are no executed at all as a pilot study. The data analyzed was collected in the first wave of a weekly activity-travel panel survey carried out in Valencia (Spain) in 2010. Each survey wave consisted on a face-to-face interview to generate a pre-planned activity agenda for the following week, an activity-travel diary implemented on mobile phones to collect activities and travels as they are executed, and in-depth telephone interviews to in…
Identification of linear parameter varying models
2003
We consider the problem of identifying discrete-time linear parameter varying models of nonlinear or time-varying systems. We assume that inputs, outputs and the scheduling parameters are measured, and a form of the functional dependence of the coefficients on the parameters. We show how the identification problem can be reduced to a linear regression, and we give conditions on persistency of excitation in terms of the inputs and parameter trajectories.
Simultaneous optimization of harvest schedule and data quality
2015
In many recent studies, the value of forest inventory information in harvest scheduling has been examined. In a previous paper, we demonstrated that making measurement decisions for stands for which the harvest decision is uncertain simultaneously with the harvest decisions may be highly profitable. In that study, the quality of additional measurements was not a decision variable, and the only options were between making no measurements or measuring perfect information. In this study, we introduce data quality into the decision problem, i.e., the decisionmaker can select between making imperfect or perfect measurements. The imperfect information is obtained with a specific scenario tree fo…
Power dispatching techniques as a finite state machine for a standalone photovoltaic system with a hybrid energy storage
2020
Standalone photovoltaic system (SPVS) is usually embedded with an energy storage unit to overcome the intermittency of photovoltaic (PV) generation as well as to address load variations in off-grid operation. In SPVS energy systems, batteries can serve as the long term energy storage and contributing to the large portion of the energy demand but to overcome the load intermittency, it necessitates a fast response energy storage embedded with the battery as a hybrid energy storage (HES) for dynamic loads (e.g., Electric Vehicle loads, emergency power management). In this work, Lead-Acid (LA) battery and supper capacitor (SC) array are used as the HES. HES helps not only in increasing more uti…
Negotiation mechanisms for capacity allocation in distributed enterprises
2003
Abstract The paper proposes an agent based approach for the capacity allocation in distributed enterprises, characterized by complex and articulated organizations and by geographically distributed production capacities contended by many product families. In such a scenario the process of allocating the production capacity to the single customer order is one the major bottlenecks of the production planning activity as far as many organizational decisional levels are involved and market turbulence implies a continuous retuning of the capacity allocation plan. A high grade of reactiveness is needed. Agent based approaches and negotiation models, by decentralizing the decisional control and sim…
Possibilistic Programming and Gas for Aggregate Production Planning under Vague Information
1999
In production planning activities, aggregate planning is surely the phase where the lack of information is more relevant. The reasons for that can be summarised in: a) the planning product is an aggregate one, very often not corresponding to actual products; b) the delay from the actual production is relevant so that information regarding actual production resources availability and performances are vague; c) the planning activity is often based on forecasts. On the other hand, all the subsequent production planning activities are based on the result of aggregate planning. In the paper a research going on at the Workgroup for Soft Computing Application in Manufacturing is presented. A Decis…
Economic lot scheduling on multiple production lines with resource constraints
2003
Abstract This paper deals with the multiple production line economic lot scheduling problem, where some items cannot be produced concurrently since they compete for some discrete resources. In particular, cyclic schedules are sought for a problem where identical production lines are present, lost sales are allowed, and minimization of the long-range production, setup, inventory, and shortage penalty costs are required. A heuristic procedure for this problem is introduced, a numerical example is worked out and some computational experiments are presented.
IM-5 zeolite for steam catalytic cracking of naphtha to produce propene and ethene. An alternative to ZSM-5 zeolite
2013
Steam catalytic cracking of naphtha in smaller FCC units can be considered an option to produce more ethene and propene. These units will operate at high reaction temperatures and in the presence of steam. The profitability of these units could be improved with the use of new catalysts with higher activity and hydrothermal stability, without compromising the selectivity to light olefins. We have explored the possibilities of IM-5 zeolite for high temperature steam catalytic cracking (SCC) of a naphtha, as an alternative to commonly used ZSM-5 zeolite. So, we compare the catalytic activity, the effect of operating variables of the process and the yields of interest products between the two z…
Algorithm for workcells design
2021
The paper presents a methodology for the design of the manufacturing cells, covering all the necessary steps, from the analysis of the customers’ needs, to part families for group technologies, process engineering, control procedures, production rate, production planning (push or pull workflow), supply in the manufacturing cell, workcell configuration, work standardisation. The necessary tools through each stage are presented. Also, there are presented links to major company systems. For each design stage, deliverables are specified. this design approach is not linear. At each stage it is possible (and indicated) to go back and analyse the previously established parameters. The methodology …