# Grapevine Downy Mildew Warning System Based on NB-IoT and Energy Harvesting Technology
## 1 Introduction
### Related Work  
A review of the related works on the two research areas, downy mildew models and the warning and forecasting systems, is provided in this section. Early downy mildew warning system models were based on incubation methods. After the conditions for primary infection are met (e.g., as indicated by the 3-10 method [3]), [PERSON]'s incubation method [14] can be used to estimate the incubation period of time (number of days). This incubation method resulted from many decades of research in central Europe [15]. The incubation curve is interpreted in the form of a table in order to enable the estimation of the incubation period based on average daily temperatures. The main drawback of this method is that it predicts the duration of the incubation period from the average daily temperature at the time of the beginning of incubation. A more precise method has been developed [15] to account for daily averages. It can be given by Equation (1), which corrects the estimation of the incubation period on a per-day basis. Note that [PERSON]'s method does not take into account days with average daily temperatures below 12 \({}^{\circ}\)C:  
\[c=\frac{a}{b}-b \tag{1}\]  
where \(c\) is the number of days before the incubation is completed, \(b\) is the number of days that have passed after the infection started (the days with average daily temperatures below 12 \({}^{\circ}\)C are not taken into account), and \(a\) is the sum of the estimated duration of incubation period for every day that has passed after the infection started. A similar method is that of [PERSON]'s incubation method, in which the incubation time is taken as a daily ratio based on the average daily temperature. When the daily ratios sum up to 100%, the incubation period can be considered completed. Only days with a new temperature threshold (8 \({}^{\circ}\)C, instead of 12 \({}^{\circ}\)C) qualify for the estimation. The actual daily add-ons to the sum based on the average daily temperature are given in a table in [15]. Russian scientists [PERSON] and [PERSON] found that the incubation period calculated as a sum of effective temperatures could be considered during the period when the sum was 61 \({}^{\circ}\)C. Here, the temperature threshold is set to 8 \({}^{\circ}\)C.  
The Goidanich index (GI) [16] is applied where the 3-10 requirements are met, and an observation of the evolution of primary infection can start. Unlike the early methods that only use average daily temperatures, the GI is based on monitoring the average daily temperature (Tm), the average relative humidity (Hm), and precipitation. In addition, low and high humidity values are distinguished with the GI. The Goidanich table-based model [16] can be described as a more practical version of the two equations [17]. One of the early mechanical models [18] (we designate it as mechanical model 1) simulated the monitoring of the entire infestation spread during the season. To calculate the incubation period, the hydro-thermal time from the temperature, humidity, and precipitation data including hourly monitoring was used. A more recent simulation model [19] of downy mildew epidemics was based on a complex set of parameters to simulate epidemics throughout the entire season. However, the incubation period was set to two discrete values in correlation with the levels of temperature (cold and warm) and humidity (wet, partly wet, dry, and very dry). Temperature is considered cold at below 13 \({}^{\circ}\)C and warm at above 13 \({}^{\circ}\)C. The daily precipitation is added for the wet and partly wet parts in the next model [20] (we designate it as mechanical model 2). Present early warning systems (EWSs) for the disease forecasting generally consist of (1) a module for collecting environmental and weather information (from on-site sensors or meteorological services); (2) a model for disease prediction; (3) a hardware and communication module; and optionally (4) a cloud-based platform service. The early EWS was designed to operate offline on a desktop computer [21; 22].