Introduction
Various ICTs have been applied in forestry and forest industry to improve collection and analysis of data, and management and monitoring of WSCs [
1] providing products and services to consumers which are produced by forest-based industry. However, the forest related supply chains remain at a rather general level without focus on logistics or even wood procurement by the forest industry. Furthermore, the upstream logistics part of these supply chains is seen differently in various countries, partly based on historical reasons. In this regard, there are two generic types of forest supply chain management schemes related to the integrated material and energy industry (IMEI): Wood supply chains (WSCs) and wood procurement chains (WPCs). WSCs are managed by decentralized Enterprise Resource Planning (ERP) schemes, whereas WPCs are managed by more centralized schemes. In Finland, IMEIs managed all forest information by using the centralized ERP systems (i.e., as WPC) until the 2010′s [2•], whereas in eastern EU countries the WPC is still applied. Contrary, in western EU countries the WSC have been introduced since the 2000′s [
3]. Finland provides a very good example as a basic reference with both supply schemes implemented to analyze changes in information systems triggered by digitalization. Furthermore, Finland appears even as an example for prospects because of current modern comprehensive data transmission networks is operating well also in forest operations far from urban areas.
Traditionally, the WPC scheme has been described by integrating data from forests’ wood resources, which are related to monetary flows, wood flows and information flows related to mills’ wood demand [4•]. In addition, IMEI’s ERP database systems collect information from wood purchasing, wood harvesting, wood storing, wood transportation and mills’ woodyard. Currently in Finland, wood resources are mainly owned and managed (70% from forest growth) by private forest owners [
5]. Furthermore, over 80% of wood purchased and used by Finnish forest industry comes from these forests. The industry only owns 9% from forests while in Sweden it owns or manages over 50%. Therefore, wood purchasing is only partly in IMEI’s hands, and hasn’t been outsourced to WSC organizations. Recently, some subprocesses of the WSC like wood harvesting and transportation have been outsourced to suppliers in Finland [2•,6], and therefore can be seen as WSC operations [
3]. Under the WSC scheme typically small and medium sized enterprises collect and manage more supply chain information themselves than under the WPC scheme. This characterizes the recent outsourcing trend driven by the development to a WSC, which creates the need to integrate separated decentralized information systems of a WSC and to share digital data between the involved stakeholders [7•].
Digitalized data-driven modeling can improve information management and the performance of DSSs in the WSC management scheme of forest industry. In this study, this aspect will be highlighted from productivity simulations of single human-machine systems of wood harvesting to management optimizations of whole WSCs from forest to the IMEI. Data-driven systems engineering (DDSE) is seen as a key enabler for such complex DSSs. It provides suitable data to different mathematical optimization models and simulation models that are used to solve WSC management problems to assess the impacts of ecological, economic, environmental, and social changes (cf. e.g. [8••,9]). Systems’ structures differ widely from useful deterministic systems to complex stochastic systems [
10]. Despite the technical differences between WSC management systems there are common methodological problems related to data application. In this paper, actual deficits are considered in data, models and solution methods, and how the DDSE may contribute description of them toward better WSC’s management systems in the IMEI.
The organizations of IMEI should use theoretically sound dynamic models in their DSSs for an effective management of the WPC and WSC [4•]. Initially, a system based on the pull principle of wood demand of the IMEI can be formulated as a dynamic model that converts inputs to outputs. There are two types of inputs in its dynamics: stages (phases) and states. Stages describe functions of a WPC model, which are so called logistics activities (e.g., harvesting, transportation), whereas states are stocks created by stages at a single moment in time (e.g., amounts of wood storages). Stocks and flows must be synchronized regarding each other at all time moments through the entire WSC or WPC periods under consideration. Deficiencies may be present both in model components (stages, states) and in the model structure itself, which affect the system’s output. Furthermore, if understanding or accurate data is missing about the magnitude of the deficiencies, there are also systematic inaccuracies. Unfortunately, not many modelling studies include a comprehensive analysis of inaccuracies, possibly because most operations research methods of WSCs have not been standardized in respect to data used [
11].
During the last ten years, there has been a trend in operations research to base constraints of dynamics on a data-driven theory [
7]. This approach is taken in this study for consideration by combining it with WSC modelling. We aim to show that defining dynamics of WSC with data-driven model components reduces inaccuracies when new data becomes available for solving the model. The data-driven approach is known in the literature by many different names: system identification, statistical identification, direct controller identification or iterative feedback tuning. Whilst the different names refer to different applications of data-driven modelling, all share the idea of specifying time-varying parameters which are modified for models of DSS according to the rules of data-driven theory. This idea also may facilitate the comprehensive analysis of inaccuracies.
The modelling guide presented in this paper can be applied to any kind of WSC modelling and problem solving, simple or complex, static or dynamic, site-based or area-based, deterministic or stochastic. Scholtz et al. (2018) introduce several review papers of WSCs covering the use of various operations research (OR) methods: e.g., [
12,
13], and more widely to use of biomass-based supply chains: e.g., [
14,
15,
16,
17]. Furthermore, examples will be taken from literature on deterministic data-driven models (DDMs) of the WSCs in the IMEI that can be used for improving the decision support needed by IMEI [
18]. These models also belong to a class of dynamic models that simulate or optimize WSCs in the DSS [
7,
19]. Large DDMs tend to include a lot of activities and constraints and are therefore computationally demanding. We explain how model characteristics may cause problems in the application of the DDM in current dynamic multi-criteria analyses of WSC managers and which modelling approaches have been proposed so far.
The structure of the paper is as follows. The paper begins by defining key terms that will be used in the review, including ‘dynamics’ and ‘time-varying parameters’, and digital ERP concepts that are used in data descriptions of DDMs. Then, the data-driven approach is described for modeling time-varying parameters and the most common computational restrictions are explained in solution methods. After that, inaccuracies of model structure are declared and different ways of avoiding these issues are proposed. The paper finishes with a general discussion on future digital ERP solutions and prospects for data-driven modelling. In this last phase the importance of DDSE and DDM are emphasized in ERP available in group decision making of WSCs cloud-based platforms.
Terminology and Concepts
Over the last decade digitalization has produced larger, more complex data sets, especially for enterprise resource planning (ERP) data sources. This data has been characterized by big amount, variety, and velocity [
20]. Under the big data concept, such large data sets cannot be analyzed sufficiently by statistical data processing applications [
21]. For example, when a single wood-harvesting machine processes trees at two shifts during a day, it produces a record of over a million single rows in a database. This data characterizes the work of a single machine and two operators in a human-machine system [
22,
23]. Such a data set constitutes a typical data-mining problem, which is solved by transforming it into useful smaller files or databases. In the data mining process, it is necessary to use the DDSE and the DDMs to find separate patterns or/and groups within big data [
21]. The refined data can then be analyzed e.g. by statistical methods for producing meaningful information for work studies, which may be used in turn as initial data in simulation models of WSCs.
GIS data is important for modelling the WSC operations and providing sufficient information for digital wood trade (selling and purchasing). There is a need to describe the operational environment as realistically as possible using sufficient digital abstraction which can refer to both the spatial precision of the GIS data and the operations included in the WSC or WPC. Different planning needs (strategic, tactical, operative) also affect abstraction needs. For example, the locations of planned activities of IMEI, which are determined by the positions of the mills, terminals, and transportation routes, are used in strategic planning, while the list should be extended by the locations of roadside storages in tactical planning and by the locations of machines and vehicles in operative planning [24••]. Because the forest industries optimize their production by obtaining timber assortments that best fit their feedstock needs [
25] timber buyers of WPC organizations acquiring roundwood can make better pricing decisions if they have detailed spatially collected pre-harvest information [
26]. Furthermore, WSC organizations use GIS-based wood transportation planning systems in daily work. In these models both raster data (also referred as “grid-based data”) and vector data (“line-based data”) can be used [
27].
Big data has come to prominence within WPC management of IMEI as ERPs support organizations for WSC management more efficiently than common management systems. Especially Big Data Analytics streamlines the collection and distribution of digital data by using information technology (IT) [28••]. In this paper, the use of big data analytics to resolve data collection issues within organizations is called information technology operations analytics (ITOA). On the other hand, operational data analytics (ODA) as defined by [
29] relates to the studies with HPC site operational efficiency. ITOA supports IT and the management of outsourced operations by applying big data analytics to large datasets inside the scope of simulation and optimization. In addition, ITOA may offer a platform for operations management that brings separate data of the WSC operations together and enables to gain business insights in the entire dynamic system rather than from analysis of partial data. At the same time, this provides a possible approach or method for automation to retrieve, analyze, and report data for the planning of WSC operations so that regional organizations can easily optimize local WSC problems [30•]. When ITOA technologies are integrated in WSC, they might either increase revenue or reduce costs depending on selected criteria [
31].
System dynamics provides a method for modelling and analyzing the behavior of a time-dependent system consisting of moving stages of a system. WPCs and WSCs schemes are typical examples of such systems (
Figure 1). Ideally, systems’ states move from current to next states according to the dynamic method [
32]. In addition to time-related dynamics, the dynamics of the WSCs also consist of simultaneous sequential dynamics, which are described by flow and effect arrows in
Figure 1 for WPC operations [
33]. Operations analysis of WPCs can be implemented by using mathematical optimization with linear programming (LP) as the most useful method. Numerous more sophisticated methods have also been suggested by researchers [34,35•], but they are not so commonly used in DSSs of WPCs in practice. When ITOA is used for providing initial data (e.g., time-varying parameters of cost or spatial data) for LP, optimization may follow the principle of data-driven modelling of the WPC. It is an innovative technique to adjust rather general LP-models to solve local WPC situations [
36]. In cases of outsourced wood supply, data-driven modeling with optimization may also serve as an efficient technique to offer the necessary ERP or DSS to the WSC management. Another approach uses simulation in WSC management, which produces a partial analysis of the WPC problem with a restricted number of WSCs, time-related elements, and selected sequential operations.
Data-driven Approach for Modelling WSC in WPC-network
Data-driven operations analyzes with aggregated data from different wood sources of the WPC can provide IMEI valuable insights to derive comprehensive strategies for their logistics network. The analyzes can also be used to resolve operative effects of WSC-related issues in sensitivity analyzes of the network. In this work, predictive analytics accurately predict future strategic trends, forecast inventory levels, and manage available resources (cf. [35•]). Prescriptive analytics also answers “what-if” questions supporting tactical and strategic decision making for WSC management in practice. Previous studies already showed that with more accurate data in hand, analytical scenarios can be solved by optimization, which is more useful in strategic planning for WPC-network [30•]. In their work, a five-step analytics procedure with data-driven modelling was introduced for optimization of the WPC-network:
Step 1: Alternative WPC strategies,
Step 2: Identify key WPC issues,
Step 3: Data targeting to the issues,
Step 4: Analyzing data for data-driven modelling,
Step 5: Strategic insight turning into WSC-action via optimization.
When organizations are looking for new ways to optimize WSCs, they are incorporating ITOA of ERP-data or the Internet of Things (IoT) into Step 4 (Analyzing data for data-driven modelling), which supports organizations to gain in-depth insight into complex WSCs. In this respect, the amount of digital unstructured data is even greater, which makes data more complex and difficult for organizations to manage and analyze with ordinary tools. Data-driven optimization was developed for this purpose. It is defined as a systematic process that gathers ITOA outcomes-based assessment data (for example, data derived from results of statistics analysis) and merges this data e.g., with trend, forecast, or capacity data. Somehow, all this data must be incorporated systematically into a DDM before solving the optimization problem e.g. as time-varying parameters or constraints.
A study of NewVantage Partners [
37] recently reported that organizations have invested a lot to modernize their business, but 70% of these initiatives have failed because they prioritized technology investments without building a data-driven culture to support it. It seems that organizations aspire actively to a data-driven culture, while only a third of them were successful. In pursuit of developing data-driven modelling, many WPC-organizations are developing two capabilities, data proficiency and analytics agility. However, transforming the way in which an organization undertakes planning and decisions is a challenging task. Palander et al. [
38] described a group decision-making method that is used in WPC organizations. Incorporating current digital big data and its analytics into group decision-making methods and ERP could provide a promising approach. This level of transformation requires a dedicated approach to refine DDMs of the WSC for a cloud-based platform, which would have a considerably transformative impact on both WPC- and WSC-organizations.