Prof. Dr.-Ing. habil. Peter Nyhuis

Function:
Managing partner
Phone:
+49 (0)511 279 76-119
E-Mail:
info@iph-hannover.de
vCard:
vCard
ResearchGate:
http://www.researchgate.net/profile/Peter_Nyhuis

Publications

During the assembly of large-scale products, disruptions often occur. To reduce these disruptions, a straightforward approach to their systematic processing is needed. This should automatically identify similar disruptions and independently suggest sensible corrective measures. For this, the disruptions are first collected and characterized and a model for practical information flows is created. Then, in a multi-stage similarity search, similar disruptions are identified, and suitable corrective measures are derived.

Disruption management, single and small batch assembly, large scale products, similarity search

Since free?aces for new buildings are limited or not available at all, redensification is a promising approach to generate new living space. This can be both the extension of existing buildings by further storeys and the vertical extension or change of use of other building structures. Modular house construction takes this objective into account because a large part of the added value is generated before construction begins. Its advantages are now set against the logistical challenges of post-densification.

Modular house construction, post-densification, construction sites, production planning and control

On inner-city construction sites, there is usually only a limited amount of space available. This increases the complexity in the implementation of corresponding construction projects and at the same time the risk of postponements. Both the composition of the demand for specific types of space and the development of demand during the construction period should be taken into account in the course of scheduling. One way of assessing the demand for space is to introduce the potential for conversion as an indicator of the property of a specific space to be able to adapt flexibly in the event of possible short-term changes in the construction project. This can be used to create an evaluation basis that initially provides decision support for project planners and can subsequently be integrated into optimising procedures for scheduling. This will have a positive influence on the quality of a schedule in connection with its robustness.

Scheduling, construction management, project planning, production planning, construction sites

In the production of stock goods, manufacturing companies are faced with uncertain customer demand. In order to counter uncertainties, an increased inventory is necessary in order to be able to meet customer demand. The costs incurred are influenced by the ordering behaviour given the forecast uncertainty. Ordering behaviour is largely determined by the ordering policy. Therefore, the influence of forecast uncertainty and ordering policy on the resulting storage costs was investigated by means of sensitivity analyses. Accordingly, forecast uncertainties require larger inventories under the (t, S) policy than under the (s, q) policy.

stock planning, ordering policy, forecasting

Software for an Automated Multidimensional Factory Layout Optimisation: Layout planning is a complex planning task in the context of factory planning, which up to now has usually needed to be carried out manually. Although many optimisation methods for the underlying problem have been developed in the past, they were only applicable to a small group of experts, mostly from universities. Therefore, an easy-touse software for layout planning was developed in a research project to provide companies with access to these optimisation methods.

Factory planning, facility layout planning, optimization, operations research, software

In current approaches to factory planning, the influences of transport systems are not taken into account in the layout planning process. Means of transport selection and transportation network planning takes place downstream of layout planning. The effects of transport system selection on the design of the factory layout are therefore only considered at the end of the factory planning process. The selection of certain transportation systems can therefore require extensive adjustments to the layout. This article describes a concept for an expert system that integrates transportation network planning into the layout planning process in addition to transportation system selection. The expert system should interpret the expert knowledge for the selection of transport systems on the basis of fuzzy logic and generate the later factory layout, as well as the transport networks, automatically on the basis of defined input data.

factory planning, layout planning, transport systems, fuzzy logic

Resource depletion and climate change are the main drivers for the rapid change of power generation structures. The energy transformation is causing an increase in energy prices for manufacturing small and medium-sized enterprises (SMEs). Within the last decade energy prices in Germany have doubled and are expected to grow even further . Metal processing SMEs are already attributing 4.5 percent of their gross production value to electricity costs. The paper shows the possible savings potential of the use of inventory levels as energy storage and provides approaches to an efficient solution of the associated optimization problems.

production program planning, energy costs, inventory level, energy storage

In average, more than 1,275 wind turbines were installed annually since 1997 in Germany and more than 27,000 wind turbines are in operation today. The technical and economic life time of wind turbines is around 20 to 25 years. Consequently, dismantling of aging wind turbines will increase significantly in upcoming years due to repowering or decommissioning of wind farms and lead to millions of costs for operators. An option to supersede the costly and time-consuming dismantling of wind turbines entirely on-site is to establish a dismantling network in which partly dismantled wind turbines are transported to specialized dismantling sites for further handling. This network requires an optimization model to determine optimal locations and an appropriate distribution of disassembly steps to dismantling sites. The challenge is to consider the networks dependency on the trade-off between transportation and dismantling costs which, in turn, depends on the selection of dismantling depths and sites. Building on the Koopmans-Beckmann problem, we present a mathematical optimization model to address the described location planning and allocation problem. To permit a proof-of-concept, we apply our model to a case-study of an exemplary wind farm in Northern Germany. Our results show that the model can assist dismantling companies to arrange efficient dismantling networks for wind turbines and to benefit from emerging economic advantages.

dismantling, wind turbine, optimization model

Currently used methods for factory layout planning are limited in their evaluation methods. Factory evaluation is either qualitative or quantitative, but limited to a few objectives. These deficits were overcome by the development of a quantitative, multidimensional ad hoc factory evaluation method. On this basis, it is now possible to develop a method for factory layout planning that reduces the planning effort and significantly increases the quality of the solution.

facility layout planning, factory planning, operations research, mathematical modelling

Rising and increasingly volatile energy prices resulting from increased power feeds from renewable sources such as solar and wind energy are confronting manufacturers with new challenges. If these companies procure their power supplies at ?uctuating short-term prices from electricity exchanges or through energy purchasing pools, they can in?uence the result-ing energy costs through production control via its actuating variables while energy consumption remains constant. A form of sequencing that decides at short notice which order will be processed next shows particularly high potential. The energy price-oriented sequencing rule that is introduced in this article prioritises orders with a high energy requirement at times when energy prices are low and gives precedence to orders that require less energy at times when energy prices are high, without neglecting the scheduled completion deadline. However, this sequencing rule can only be applied e?ectively under certain preconditions. These are elaborated in this article by means of a simulation study that will con?rm the way the rule functions.

production planning and control, manufacturing control, sequencing, energy costs

As a result of the increasing feed-in of renewable energies, the volatility of the electricity price rises. Considering this, manufacturers can save energy costs by applying an energy price-oriented sequencing rule. Since the application of this sequencing rule does not only have an impact on the energy costs, a potential analysis is presented in this article which, in addition to the energy costs, also considers the schedule compliance cost of production orders.

cost accounting, manufacturing control, production planning and control

Work-related illnesses and their results may pose a threat to businesses' productivity. This may as well affect businesses' competitiveness for the worse. A workplace designed by methods of ergonomic workplace-design may counter some of the caused issues. But companies often lack knowledge or fear required financial resources to restructure workplaces. With this article technical requirements to an automated ergonomics assesment system are described.

ergonomics, evaluation, optimization, workplace design

The volatility of electricity prices is steadily increasing due to the growing expansion of renewable energies. This is particularly observable at the electricity exchange. Small and medium-sized enterprises (SMEs) in the manufacturing sector can save energy costs due to these fluctuations through targeted load management methods. To increase this potential, SMEs need to use smart meters and obtain their electricity at pricest as close to those at the electricity exchange as possible.

power procurement, electricity exchange, load management, electricity costs

The forecast of sales volumes represents a challenge for the production planning. Above all, sales forecasts that are difficult to predict, such as those caused by promotions, are obstructive. Often, additional information from macroeconomic indexes is not topical, the level of detail of products to be forecast too low and the forecast expenditure too high. Aim of a research project therefore is to develop a model based on search engine data to forecast sales volumes at product level. By the use of complementary application of search engine data to the sales forecast is expected that the forecast mistake can be reduced compared with conventional forecast models upon product level. In general it should be clarified whether and in which extend the logistical efficiency of an enterprise can be improved by search engine data based forecast of sales volumes in the production planning.

production planning, sales forecast, search engine data, forecast model

In production, product-based failure costs can be reduced by focusing the production factor „human“. Therefore, human performance fluctuations during the course of day have to be considered in the production planning and control. This paper presents an approach for quality-orientated flexible job shop scheduling, taking into account human performance fluctuations during the day.

production planning and control, performance curve, quality

Assembling large-scale products involves frequent process interruptions why in order to reduce the impact of interruptions, a short-term response is necessary to reduce delivery delays and idle times of resources. An approach to challenge this represents the flexibility of a production system. Regarding the environment of large-scale product assembly, it has to be shown which potentials of flexibility are able to be used in a short-term manner.

assembly, production management, disruption management

Considering production planning and control, lot sizing is a very important task. Lot sizes are usually resorted to lot size dependent order and storage costs. However, models for lot sizes ignore the aspect of lot size dependent maintenance costs. For forging companies the tool wear has a great economic importance, because the tooling costs represents a major factor in production costs.

production planning and control, lot sizing, process stability

Rising electricity prices for industrial companies result in increasing energy costs and thus lower international competitiveness. Due to increasing electricity price fluctuations, savings in energy costs without capital-intensive investments are possible by implementing specific organizational methods to process energy-intensive orders at times of low prices and energy-low orders at times of high prices.

energy costs, energy price, manufacturing control, sequencing

Disassembling of large-scale products (e. g. wind energy plants, crane and conveyor systems which are known as XXL-Products) becomes increasingly important, as the operating time is limited. The challenge is to optimize the positioning of the complex and expensive disassembling on the operation site on the one hand and the costly transportation of modules to the disassembling factories. For this reason the location and allocation problem will be pictured in a mathematical model within the research project “DemoNet”. This model supports companies to create a XXL-disassembly-network. The research hypothesis assumes: a disassembly under ecological, economical and logistical aspects constitutes the optimum. The extension of a location planning tool forms the basis of the mathematical optimization model for the disassembly of XXL-Products. For solving the problem a genetic algorithms will be used. The result helps companies to arrange disassembling networks for XXL-Products efficiently.

dismantling planing, dismantling networks, impact model

Controlling the time synchronicity of supply processes for assembly requires a quantitative measure. An existing controlling instrument, the supply diagram, already provides an effective way of assessing the supply situation. It incorporates different key figures which allow for an evaluation of a company’s supply process coordination. However, it lacks a key figure for describing the level of time synchronicity. Therefore, a quantitative evaluation of actions to improve the time synchronicity in supply processes is not possible. Based on an existing approach of approximating the completion of full assembly orders, a key figure for describing the level of time synchronicity is developed in this article: the synchronicity factor. As this new key figure is dependent on the average number of components required for one assembly order for the regarded time period, a second measure, the relative synchronicity factor, accounts for this number and can thereby be used to compare different time periods. As the numerical calculation of the synchronicity factors is a complex problem, the possibility of applying a simple hill climbing algorithm to accurately determine the synchronicity factor for a certain supply situation is examined.

Production planning and control, supply chain management, supply diagram, time synchronicity