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This study deals with the performance of PV2-state model in intra-hour forecasting of photovoltaic (PV) power. The PV2-state model links an empirical model for estimating the PV power delivered by a PV system under clear-sky with a model for forecasting the relative position of the Sun and clouds. Sunshine number (SSN), a binary quantifier showing if the Sun shines or not, is used as a measure for the Sun position with respect to clouds. A physics-based approach to intra-hour forecasting, processing cloud field information from an all-sky imager, is applied to predict SSN. The quality of SSN prediction conditions the overall quality of PV2-state forecasts. The PV2-state performance was evaluated against a challenging database (high variability in the state-of-the-sky, thin cloud cover, broken cloud field, isolated passing clouds) comprising radiometric data and sky-images collected on the Solar Platform of the West University of Timisoara, Romania. The investigation was performed from two perspectives: general model accuracy and, as a novelty, identification of characteristic elements in the state-of-the-sky which fault the SSN prediction. The outcome of such analysis represents the basis of further research aiming to increase the performance in PV power forecasting.

Teaching activities in the Instrumentation and Measurement (I&M) field, for both undergraduate and postgraduate students in the engineering domains, should be correlated with the industry requirements [1]—[3]. In this way, students can understand actual industry needs and gain skills in solving I&M problems occurring in associated activities.

The state-of-the-art in the accuracy of solar resources forecasting is obtained by using results reported in 1705 accuracy tests reported in several geographic regions (North America, Europe, Asia, Australia). There is a tendency in literature to avoid reporting model performance assessments in places, or on time-horizons, where it is known that the models have low performance. Usual bias and spreading statistical indicators are useful tools but taking proper decision by managers of funding agencies and policy makers requires usage of additional error measures. Several classes of forecasting models have been compared: persistence, classical statistics, machine learning, cloud-motion tracking, numerical weather prediction and hybrid models (combining classical statistics with machine learning approach and/or exogenous inputs). Forecasting errors increase by increasing the time-horizon. Forecasting model performance depends on time-horizon and climate. Machine learning and hybrid models have the best performance for intra-hour performance in all climates. The best intra-hour forecasts are provided in all climates by machine learning and classical statistics models while the hybrid models perform well in tropical and snow climates. For day-ahead forecasts the hybrid models have very good performance in all climates. Generally, the hybrid models have the best performance. The accuracy of the forecasting models significantly increased in the last decade. The normalized MBE and RMSE have been reduced by two thirds and one third, respectively.

Forecasting the solar energy production is a key issue in the large-scale integration of the photovoltaic plants into the existing electricity grid. This paper reports on the research progress in forecasting the solar energy production at the West University of Timisoara, Romania. Firstly, the experimental facilities commissioned on the Solar Platform for testing the forecasting models are briefly described. Secondly, a new tool for the online forecasting of the solar energy production is introduced. Preliminary tests show that the implemented procedure is a successful trade-off between simplicity and accuracy.

This paper presents the design, implementation and testing of the automation component for a prototype machinery destined for cutting, sorting and bundling of harvested SRC crops for planting purposes. The device has been developed under the name Rod Picker and is the result of collaboration between six partners from four different countries. The Rod Picker project includes mechanical, automation, hydraulics and sensor measurement concepts. It operates according to conditions imposed by the beneficiaries - Short Rotation Coppice (SRC) farm owners, agricultural machinery and energy crops species producers. Freshly harvested material is cut (obeying diameter and length restrictions), sorted and bundled into packages ready for distribution. The process is automated, requiring little intervention on behalf of the operator. The cutting accuracy and speed of execution are two features which underline the efficiency of this device when compared against manual rod processing methods. Measurement errors of under ±2% are obtained between what the machine indicates and the manually calculated length. Functionality tests performed over several weeks, in both laboratory and industrial conditions, confirm that this system was properly designed and implemented. Regarding the economical evaluation the conclusion is that working with this machinery can decrease overall processing costs approximately five times when compared to manual labor.

The theoretical performance of a photovoltaic (PV) module is typically evaluated by using models based on equivalent circuits whose parameters are derived from data listed in manufacture's datasheet. Few manufactures provide detailed enough datasheets to allow using highly accurate models. In many cases simplified models have to be used due to missing information. This paper proposes a new procedure to evaluate PV modules performance. The procedure is based on the four-parameter model, which can be used with input data provided by most manufactures. Firstly, the parameters extraction in standard test conditions is discussed. Secondly, an algorithm for PV module performance estimation under real weather conditions is proposed. The procedure is validated on a commercial PV module. Estimations and field-test data are found to be in good agreement. The difference between the response time of the pyranometer (tens of seconds) and the response time of the PV module (almost instantaneous) is found to be an important source of errors. This aspect has not been previously discussed in literature with sufficient detail. The proposed procedure represents a feasible tool for calculating the performance of PV modules described by a limited set of data, operating in arbitrary weather conditions.

a multicopter is a coaxial flight system using two or more spinning propellers. This paper is focused on how the weight and thickness of the multicopter power wires affects the flight time keeping in mind that the flight time is directly related to the weight of the multirotor. A high diameter wire can lower the energy loss but will increase the weight of the system resulting shorter flight time. The author had developed an application who analyze the multirotor configuration and give a graphical estimation of the best wire to use.

Holography is a well-developed method with a large range of applications, including dentistry. This study uses holographic methods for the study of total dental prosthesis. The issue is that the transformation of wax denture base in polymethylacrylate causes dimensional alterations and retractions in the final dental constructs. These could cause the failure of the stability of the complete denture in the oral cavity. Thus, the aim of this study is to determine and to compare using holography, total prosthesis obtained using three different manufacturing methods: pressing, injection, and polymerization. Each of the three types of dentures thus produced were recorded over the previously wax complete base holographic plates. The dimensional alterations that appear after using the different activation methods were thus determined. The most significant modification was remarked in the custom press technology, while the smallest variations were detected in the injection alternative.

The periodontal disease is one of the most common pathological states of the teeth and gums system. The issue is that its evaluation is a subjective one, i.e. it is based on the skills of the dental medical doctor. As for any clinical condition, a quantitative evaluation and monitoring in time of the retraction of the gingival margins is desired. This phenomenon was evaluated in this study with a holographic method by using a He-Ne laser with a power of 13 mW. The holographic system we have utilized – adapted for dentistry applications - is described. Several patients were considered in a comparative study of their state of health – regarding their oral cavity. The impressions of the maxillary dental arch were taken from a patient during his/her first visit and after a period of six months. The hologram of the first model was superposed on the model cast after the second visit. The retractions of the gingival margins could be thus evaluated three-dimensionally in every point of interest. An evaluation of the retraction has thus been made. Conclusions can thus be drawn for the clinical evaluation of the health of the teeth and gums system of each patient.

In our days, almost all of the electrical equipment has been equipped with switching supplies which can cause disturbances in the electrical power network. In order to reduce or even eliminate this disturbances, an electrical power network monitoring is required. The disturbances presents in the system must be recorded and analyzed in order to take the right decision to eliminate them.

This paper presents a system for monitoring the electrical disturbances which are present every day in electrical power distribution networks. A simple solution for detecting the disturbances using a low power microcontroller (MSP 430) was developed. The system was devised to work with 230V 50Hz electrical power networks in Europe.

This paper introduces the first station in Romania (Eastern Europe) outfitted for systematic monitoring of solar irradiance on tilted surfaces. The resulted database is in many aspects unique for Romania, allowing for the first time to derive specific parameters like diffuse fraction or sunshine number. Also for the first time, the data collected on tilted surfaces can be used to test models reported in literature and to recommend the most fitting for the region, as is detailed in the paper.