Multiobjective scheduling for semiconductor manufacturing plants

Scheduling of semiconductor wafer manufacturing system is identified as a complex problem, involving multiple and conflicting objectives (minimization of facility average utilization, minimization of waiting time and storage, for instance) to simultaneously satisfy. In this study, we propose an efficient approach based on an artificial neural network technique embedded into a multiobjective genetic algorithm for multi-decision scheduling problems in a semiconductor wafer fabrication environment

Development of Neurofuzzy Architectures for Electricity Price Forecasting

In 20th century, many countries have liberalized their electricity market. This power markets liberalization has directed generation companies as well as wholesale buyers to undertake a greater intense risk exposure compared to the old centralized framework. In this framework, electricity price prediction has become crucial for any market player in their decision‐making process as well as strategic planning. In this study, a prototype asymmetric‐based neuro‐fuzzy network (AGFINN) architecture has been implemented for short‐term electricity prices forecasting for ISO New England market. AGFINN framework has been designed through two different defuzzification schemes. Fuzzy clustering has been explored as an initial step for defining the fuzzy rules while an asymmetric Gaussian membership function has been utilized in the fuzzification part of the model. Results related to the minimum and maximum electricity prices for ISO New England, emphasize the superiority of the proposed model over well‐established learning‐based models

A novel technique for load frequency control of multi-area power systems

In this paper, an adaptive type-2 fuzzy controller is proposed to control the load frequency of a two-area power system based on descending gradient training and error back-propagation. The dynamics of the system are completely uncertain. The multilayer perceptron (MLP) artificial neural network structure is used to extract Jacobian and estimate the system model, and then, the estimated model is applied to the controller, online. A proportional–derivative (PD) controller is added to the type-2 fuzzy controller, which increases the stability and robustness of the system against disturbances. The adaptation, being real-time and independency of the system parameters are new features of the proposed controller. Carrying out simulations on New England 39-bus power system, the performance of the proposed controller is compared with the conventional PI, PID and internal model control based on PID (IMC-PID) controllers. Simulation results indicate that our proposed controller method outperforms the conventional controllers in terms of transient response and stability

Reinforcement Learning on Job Shop Scheduling Problems Using Graph Networks

This paper presents a novel approach for job shop scheduling problems using deep reinforcement learning. To account for the complexity of production environment, we employ graph neural networks to model the various relations within production environments. Furthermore, we cast the JSSP as a distributed optimization problem in which learning agents are individually assigned to resources which allows for higher flexibility with respect to changing production environments. The proposed distributed RL agents used to optimize production schedules for single resources are running together with a co-simulation framework of the production environment to obtain the required amount of data. The approach is applied to a multi-robot environment and a complex production scheduling benchmark environment. The initial results underline the applicability and performance of the proposed method.Comment: 8 pages, pre-prin

The Estimation of Product Standard Time by Artificial Neural Networks in the Molding Industry

Determination of exact standard time with direct measurement procedures is particularly difficult in companies which do not have an adequate environment suitable for time measurement studies or which produce goods requiring complex production schedules. For these companies new and special measurement procedures need to be developed. In this study, a new time estimation method based on different robust algorithms of artificial neural networks (ANNs) is developed. For the proposed method, the products that have similar production processes were chosen from among the whole product range within the cleansing department of a molding company. While using ANNs, to train the network, some of the chosen products' standard time that had been previously measured is used to estimate the standard time of the remaining products. The different ANN algorithms are trained and four of them, which are converged the data, are stated and compared in different architectures. In this way, it is concluded that this estimation method could be applied accurately in many similar processes using the relevant algorithms

Governance in niche development for a transition to a new mobility regime

Urban mobility is a difficult sustainability challenge; measures to reduce transport impacts produce only marginal reductions in overall energy use and CO2 emissions. Even fuel switch to electric vehicles and measures to manage traffic produce insufficient improvements. Seeking transport sustainability within the existing socio-technical regime involves policy approaches for dense cities to provide high-capacity, corridor-based public transport, expecting people to arrange their lives around such transport systems. Yet this socio-technical regime ill-fits modern mobility needs. The reluctance to use public transport stems much from this 150 year old regime configuration. The social-technical landscape has shifted significantly: travel patterns are increasingly dispersed in space and time – not funnelled into traditional corridor peak-hour movements. The key is not getting people to return to travel patterns of 100 years ago, but in a transition to a socio-technical transport regime that delivers sustainability compatible with the 21st century social-technical landscape. An opportunity may be emerging for socio-technical configurations in niche environments to effect transitions to alternate mobility futures. Autonomous vehicles are rapidly approaching market application. Since 2011, small autonomous pods have operated on segregated tracks at Heathrow Airport. In 2014 a similar system opened at the Suncheon Bay tourist area in South Korea. Since 2011 there have been public street trials of autonomous vehicles in the USA and in 2015 they became street legal in the UK. The Milton Keynes (MK) ‘Pathfinder’ project focuses on two-seat pods which do not need segregated tracks, but will run on cycleways and footpaths, mixing with cyclists and pedestrians. Trials will start in 2015, on short distance links from the railway station to destinations in Central Milton Keynes. This project forms part of the wider Milton Keynes Future Cities Programme and Open University-led MK:Smart project. This paper draws on these trials in MK to show through case study research how autonomous vehicles applications are moving beyond protected niches and, along with other developments, hold the potential to stimulate a major transition in public transport systems. The vehicles are small and each journey is individual to the passenger(s). Services do not run along corridor routes, like buses and trams, but are based on alternate rule-sets to the existing regime with individual journeys customised for each user. Such developments may therefore stimulate transition to totally different sorts of public transport systems and ultimately, socio-technical mobility regimes, by offering much more to users than any corridor system can provide. Rather than people adjusting their behaviour to bus routes, schedules and operating times, they travel directly, whenever they want, on services running 24/7. Thus these new regimes could be more compatible with lifestyle and economic trends that comprise 21st century socio-technical landscapes. As such, they provide credible alternatives to the private car, and so hold potential to deliver major sustainability gains. But such transitions face major challenges from entrenched actors within the existing regime. Taxis, minicabs and bus operators would be threatened. If the Uber cab app is being blocked by incumbent actors, they look likely to be powerful opponents of autonomous vehicle based cab services. However, MK provides an interesting innovation context where there are several overlapping smart transport niches in different stages of development. As well as autonomous pods, demand responsive minibuses are planned and inductive changed electric buses are in service. If these projects build links to each other (niche accumulation), demonstrate economic value and reproduced beyond their original experimental spaces (niche proliferation), there is potential for them to overcome incumbent resistance. In Milton Keynes, these processes could be getting close to reaching critical mass, opening up the possibility of moving closer to radical regime transitions