Toward digital twins for sawmill production planning and control : benefits, opportunities and challenges

Sawmills are key elements of the forest product industry supply chain, and they play important economic, social, and environmental roles. Sawmill production planning and control are, however, challenging owing to severalfactors, including, but not limited to, the heterogeneity of the raw material. The emerging concept of digital twins introduced in the context of Industry 4.0 has generated high interest and has been studied in a variety of domains, including production planning and control. In this paper, we investigate the benefits digital twins would bring to the sawmill industry via a literature review on the wider subject of sawmill production planning and control. Opportunities facilitating their implementation, as well as ongoing challenges from both academic and industrial perspectives, are also studied

Application of digital twin technologies for the optimization of the energy consumption for a wood clattering panels manufacturer

This thesis describes applications of digital twin technology for the optimization of the energy consumption profile. It is based on the electricity consumption data from a Finnish wood clattering panels manufacturer – Puucomp. The data consists of hourly records for the duration of 36 months. Production simulation was used to identify the bottleneck process with the highest energy consumption, which is perforation. The Energy Value Stream Mapping (EVSM) method may be enriched with the digital twin (DT) models and electricity data, enabling energy flow tracking at the current time. It has been determined that the highest energy consumption occurs during the morning hours, with an overall increase in consumption during the cold period. The data has not shown significant dependency on humidity, wind speed, or air pressure. The base load has been considered with the floor heating and the gap required to fulfill is 60kWh. Proposed solutions are the utilization of renewable energy sources, technological improvement of the systems, and production rerouting. The most viable solution is the energy mix, which includes renewable energy sources used with the combination of energy storage systems (ESS) in the form of batteries. The first scenario consists of the utilization of rooftop space for the solar panels, which are expected to support floor heating, while ESS is used to support the grid during peak hours. The second possible scenario includes rooftop leasing, geothermal heat pump utilization for the floor heating, and ESS as a support to the grid. Utilization of DT technologies has been seen as a viable approach to reduce energy consumption profile. However, the application of DT is limited by the availability of the data

Electricity from photovoltaic solar cells: Flat-Plate Solar Array Project final Report. Volume III: Silicon sheet: wafers and ribbons

The Flat-Plate Solar Array (FSA) Project, funded by the U.S. Government and managed by the Jet Propulsion Laboratory, was formed in 1975 to develop the module/array technology needed to attain widespread terrestrial use of photovoltaics by 1985. To accomplish this, the FSA Project established and managed an Industry, University, and Federal Government Team to perform the needed research and development. The primary objective of the Silicon Sheet Task of the FSA Project was the development of one or more low-cost technologies for producing silicon sheet suitable for processing into cost-eompetitive solar cells. Silicon sheet refers to high-purity crystalline silicon of size and thickness for fabrication into solar cells. The Task effort began with state-of-the-art sheet technologies and then solicited and supported any new silicon sheet alternatives that had the potential to achieve the Project goals. A total of 48 contracts were awarded that covered work in the areas of ingot growth and casting, wafering, ribbon growth, other sheet technologies, and programs of supportive research. Periodic reviews of each sheet technology were held, assessing the technical progress and the long-range potential. Technologies that failed to achieve their promise, or seemed to have lower probabilities for success in comparison with others, were dropped. A series of workshops was initiated to assess the state of the art, to provide insights into problems remaining to be addressed, and to support technology transfer. The Task made and fostered significant improvements in silicon sheet including processing of both ingot and ribbon technologies. An additional important outcome was the vastly improved understanding of the characteristics associated with high-quality sheet, and the control of the parameters required for higher efficiency solar cells. Although significant sheet cost reductions were made, the technology advancements required to meet the Task cost goals were not achieved. This FSA Final Report (JPL Publication 86-31, 5101-289, DOE/JPL 1012-125, October 1986) is composed of eight volumes, consisting of an Executive Summary and seven technology reports: Volume I: Executive Summary. Volume II: Silicon Material. Volume III: Silicon Sheet: Wafers and Ribbons Volume IV: High-Efficiency Solar Celis. Volume V: Process Development. Volume VI: Engineering Sciences and Reliability. Volume VII: Module Encapsulation. Volume VIII: Project Analysis and Integration. Two supplemental reports included in the final report package are: FSA Project: 10 Years of Progress, JPL Document 400-279. 5101-279, October 1985. Summary of FSA Project Documentation: Abstracts of Published Documents, 1975 to 1986, JPL Publication 82-79 (Revision 1),5101-221, DOE/JPL-1 012-76, September 1986

Flat-plate solar array project. Volume 8: Project analysis and integration

Project Analysis and Integration (PA&I) performed planning and integration activities to support management of the various Flat-Plate Solar Array (FSA) Project R&D activities. Technical and economic goals were established by PA&I for each R&D task within the project to coordinate the thrust toward the National Photovoltaic Program goals. A sophisticated computer modeling capability was developed to assess technical progress toward meeting the economic goals. These models included a manufacturing facility simulation, a photovoltaic power station simulation and a decision aid model incorporating uncertainty. This family of analysis tools was used to track the progress of the technology and to explore the effects of alternative technical paths. Numerous studies conducted by PA&I signaled the achievement of milestones or were the foundation of major FSA project and national program decisions. The most important PA&I activities during the project history are summarized. The PA&I planning function is discussed and how it relates to project direction and important analytical models developed by PA&I for its analytical and assessment activities are reviewed

Activity-based costing method in forest industry : modelling the production and costs of sawing, the pulp and paper industry, and energy production

Finnish forest industry purchases 50 million cubic meters of wood annually. This means that the economic importance of the business is significant to forest owners. Sawmills, pulp and paper industry, and energy production are most common targets of the wood raw material. It is in mutual interest of both forest owners and the industry that the wood is allocated to right use according to the highest possible value-adding. The path of wood from forest to customers can be described as a value chain where the links are formed of harvesting and forwarding, long distance transportation, wood processing and energy use, and delivery to final customers. This dissertation focuses on the links of wood processing and energy use of the wood value chain by modelling production and costs of sawmill, pulp mill, paper mill, and combined heat and power (CHP) plant. The modelling was done by using activity-based costing (ABC), where the production is divided into processes and the production costs of each process are allocated to products or services according to resource consumption. Finally, all process costs are summed for total production costs of each cost object. The production and cost models were tested with virtual mills. The processes, the resources and the necessary cost factors of production were determined for test calculations. Finally, the capital, the labor, and the energy costs were allocated to the cost objects, which were both the raw materials and the end products. When comparing different mills and their production processes, it was noticed clearly that drying was an expensive process in sawmilling, pulping and papermaking. When focusing on cost factors of each mill, it was noteworthy that the sawing pattern affects the costs of a sawmill, energy production affects the costs of pulp and paper industry, and, likewise the utilization rate affects the combined heat and power plant. Profitability analyses were also made on the pulp mill, the paper mill and the CHP plant in varied market situations. One key finding was that in papermaking, the change of market price of paper was more significant to economics of the mill than a similar change in the market price of energy. The results of this dissertation can be used in estimating the economic performance of forest industry. Process-based approach helps in finding possible bottlenecks and in developing the production systematically. The findings of this study can also be used in finding the most profitable route for wood from the forest to customers.Metsäteollisuus maksaa suomalaisille metsänomistajille noin 1,6 miljardia euroa kantorahatuloja vuosittain. Suurin osa kotimaisesta 50 miljoonan kuutiometrin raakapuumäärästä päätyy sahatavaraksi, selluksi, paperiksi sekä energiaksi. Metsäteollisuuden tavoite on ohjata ketjun puuvirtoja eri tehtaille taloudellisesti parhaimmalla mahdollisella tavalla. Puun matkaa metsästä tehtaalle voidaan kuvata arvoketjuna, jossa lenkit muodostuvat puun korjuusta metsässä, kuljetuksesta metsästä tehtaalle, jalostuksesta tehtaalla ja toimituksesta asiakkaalle. Tämä väitöskirjatutkimus keskittyi tutkimaan arvoketjun jalostuslenkkejä, eli sahan, sellutehtaan, paperitehtaan ja sähkö- ja lämpöenergian yhteistuotantolaitoksen tuotanto- ja kustannusrakenteita. Mallinnusmenetelmänä oli toimintoperusteinen kustannuslaskenta. Toimintoperusteisessa kustannuslaskennassa tutkittavan laitoksen tuotanto jaetaan osiin eli prosesseihin, joille kullekin tehdään oma kustannuslaskelma. Jokaisen prosessin kustannukset kohdistetaan tuotteille tai palveluille niiden tuotannossa kulutettujen resurssien mukaan. Lopuksi jokaisen prosessin kustannukset lasketaan yhteen ja näin tutkimuskohteille saadaan keskenään vertailukelpoiset kokonaiskustannukset. Laskentamalleja testattiin kokeellisesti niin sanotuilla virtuaalilaitoksilla. Jokaiselle laitokselle määriteltiin prosessit, joille määriteltiin pääoma-, energia- ja työvoimakustannukset, jotka lopuksi kohdistettiin sekä raaka-aineille että lopputuotteille. Vertailtaessa laitosten kustannusrakenteita keskenään voitiin huomata, että erityisesti kuivaus aiheuttaa merkittävät kustannukset sahatavaran, sellun ja paperin tuotannoissa. Laitoskohtaisista tekijöistä sahausasete vaikutti merkittävästi sahauksen, energian tuotanto sellu- ja paperiteollisuuden ja kapasiteetin käyttöaste lämpölaitoksen tuotantokustannuksiin. Laskelmissa selvitettiin myös sellun, paperin ja energian tuotantojen kannattavuutta tietyissä markkinatilanteissa. Esimerkiksi paperitehtaalla paperin markkinahinnan muutos vaikutti tehtaan kannattavuuteen enemmän kuin energian markkinahinnan vastaava muutos. Tämän väitöskirjan tulokset auttavat selvittämään metsäteollisuuden taloudellista suorituskykyä ja prosessiperusteinen kustannusanalyysi auttaa löytämään mahdollisia kehittämiskohteita tuotantolaitosten toiminnoissa. Tuloksia voidaan hyödyntää osaltaan myös puuvirtojen ohjauksen suunnittelussa

Automated array assembly

A general technology assessment and manufacturing cost analysis was presented. A near-term (1982) factory design is described, and the results of an experimental production study for the large-scale production of flat-panel silicon and solar-cell arrays are detailed

Flat-plate solar array project. Volume 3: Silicon sheet: Wafers and ribbons

The primary objective of the Silicon Sheet Task of the Flat-Plate Solar Array (FSA) Project was the development of one or more low cost technologies for producing silicon sheet suitable for processing into cost-competitive solar cells. Silicon sheet refers to high purity crystalline silicon of size and thickness for fabrication into solar cells. Areas covered in the project were ingot growth and casting, wafering, ribbon growth, and other sheet technologies. The task made and fostered significant improvements in silicon sheet including processing of both ingot and ribbon technologies. An additional important outcome was the vastly improved understanding of the characteristics associated with high quality sheet, and the control of the parameters required for higher efficiency solar cells. Although significant sheet cost reductions were made, the technology advancements required to meet the task cost goals were not achieved

Electricity from photovoltaic solar cells: Flat-Plate Solar Array Project final report. Volume VIII: Project analysis and integration

The Flat-Plate Solar Array (FSA) Project, funded by the U.S. Government and managed by the Jet Propulsion Laboratory, was formed in 1975 to develop the module/array technology needed to attain widespread terrestrial use of photovoltaics by 1985. To accomplish this, the FSA Project established and managed an Industry, University, and Federal Government Team to perform the needed research and development (R&D). PA&1 performed planning and integration activities to support management of the various FSA Project R&D activities. Technical and economic goals were established by PA&I for each R&D task within the Project to coordinate the thrust toward the National Photovoltaics Program goals. A sophisticated computer modeling capability was developed to assess technical progress toward meeting the economic goals. These models included a manufacturing facility simulation [Solar Array Manufacturing Industry Costing Standards (SAMICS)], a photovoltaic power station simulation [Lifetime Cost and Performance (LCP)] and a decision aid model incorporating uncertainty [SIMulation of Research ANd Development Projects (SIMRAND)]. This family of analysis tools was used to track the progress of the technology and to explore the effects of alternative technical paths. Numerous studies conducted by PA&I signaled the achievement of milestones or were the foundation of major FSA Project and National Program decisions. This document summarizes the most important PA&I activities during the Project's history. It discusses the PA&I planning function and how it related to Project direction and reviews important analytical models developed by PA&I for its analytical and assessment activities. The document summarizes major studies completed during the term of the Project and provides considerable insight into the role played by PA&I in supporting Project management

Internal Defect Detection in Hardwood Logs With Fast Magnetic Resonance Imaging.

Identification of defects such as knots in logs before the cutting operation would allow lumber mills to maximize the value of lumber from each log. This dissertation presented images obtained from scanning an oak log with magnetic resonance imaging (MRI). The unique characteristics of MRI images of hardwood logs were noted and were used to derive a quick algorithm to isolate defects. Defect regions had some pixels that varied considerably in intensity from their neighborhood, providing a seed for initiating the defect region. There was an overlap between the pixel gray level of the defects and clear wood. Therefore, traditional thresholding techniques did not cleanly separate these regions. In this study, region-growing methods were used to extract the defects. The algorithm grew the defect region seed until the border-pixel gray levels approached the average level of the neighborhood. The region-growing methods obtained more accurate defect regions than thresholding methods because of the simultaneous consideration of gray level and adjacency information. Two methods of MRI imaging were considered: spin-echo and echo-planar. Spin-echo imaging provided clear, detailed images but required about 20 seconds of acquisition time, which was too slow to be used in a production environment. Echo-planar images could be acquired in about 1/2 second, which was fast enough for production, but the images were fuzzy and noisy. The dissertation presented an algorithm that found the defect regions in spin-echo images. Region-growing methods use a number of parameters and the best parameters were unique for each image. However, common image statistics could be used to predict the proper parameters. The dissertation also presented an algorithm that found most of the defect regions in echo-planar images. Enhancing the echo-planar images using common general-purpose image-enhancement techniques failed because the lack of discrimination allowed the process to smooth image structures as well as noise. By taking advantage of the structure of a tree, smoothing between MRI frames accomplished the goal of smoothing along homogeneous areas and not across image structures. This z-axis smoothing enhanced the echo-planar image visually and reduced the number of false alarm defect regions