Long-term Measurement Data Research Articles

Error performance analysis and modeling of narrow-band PLC technology enabling smart metering systems

This paper presents an error performance analysis and a model of a narrow-band power line carrier (PLC) system for smart metering. Our work is founded on complex analysis based on the probability theory using limited, long-term measurement data of a rural 400 V distribution grid during operation. To obtain confident results, the analysis and modeling of the error performance were done in two steps. In the first step, the Neyman contagious distribution, originally derived in the fields of entomology and bacteriology, was applied to describe the probability distribution of errors in messages in consideration of the impulsive noise in the PLC channel and the influence of forward error correction techniques. In the second step, assuming the bit error rate (BER) was a random variable, where errors are randomly distributed in the sample rather than clustered into messages, the confidence interval of the true BER was calculated for different SNR values. The results served as a foundation for the error performance model proposed in this paper. The presented work is crucial for the research of upper layer communication protocols performance incorporating advanced phenomena at the physical layer.

PREDICTING THE ENERGY PRODUCTION OF A ROOFTOP PV PLANT BY USING DIFFERENTIAL EVOLUTION ALGORITHM

In this study, a simple and plain closed-form mathematical expression has been obtained to precisely estimate the monthly production of a rooftop photovoltaic (PV) plant installed in Adana, Turkey. The proposed model is developed by utilizing the Differential Evolution (DE) optimization algorithm based on the PV plant’s 5-year (August 2013 – July 2018) real measurement data. The PV plant is a grid-connected rooftop solar PV system located at Kıvanç Textile in Adana, Turkey. The PV system is equipped with an online monitoring system that provides real time data. The study shows the actual energy production is 730 MWh/year on average for 5 years. In order to test the robustness and precision of the present model, it has been compared with the long-term real measurement data of the PV system. The key benefit of the model is giving a convincing prediction of the future production of the PV panel in a simple way. It also does not require any further information other than time. Average percentage error was reached as small as 7.4% for 5-year data.

Effect of under-ice light intensity and convective mixing on chlorophyll a distribution in a small mesotrophic lake

Data of long-term measurements of under-ice solar radiation, water temperature, and chlorophyll a are analyzed in four phytoplankton groups (green, diatoms, blue-green, and cryptophyte algae) in a small mesotrophic Vendyurskoe Lake (Karelia) in the period of spring under-ice convection. It is shown that, after thawing away of snow cover from lake surface, under-ice illumination increases, water temperature rises, the depth of convectively mixed layer (CML) increases, and microalga photosynthesis intensifies. In the daytime, chlorophyll a extremums appear in the CML, and, unlike the homogeneous characteristics (water electric conductivity, mineralization, etc.), the cells of different phytoplankton species can be used as tracers in studying convective mixing. A prognostic equation is obtained, reflecting an inverse dependence of the coefficients of variation of chlorophyll a concentration in CML on solar radiation fluxes, penetrating under ice bottom surface. A direct relationship was shown to exist between the increase in chlorophyll concentration in CML and its thickness.

Effect of Under-Ice Light Intensity and Convective Mixing on Chlorophyll a Distribution in a Small Mesotrophic Lake

Data of long-term measurements of under-ice solar radiation, water temperature, and chlorophyll a are analyzed in four phytoplankton groups (green, diatoms, blue-green, and cryptophyte algae) in a small mesotrophic Vendyurskoe Lake (Karelia) in the period of spring under-ice convection. It is shown that, after thawing away of snow cover from lake surface, under-ice illumination increases, water temperature rises, the depth of convectively mixed layer (CML) increases, and microalga photosynthesis intensifies. In the daytime, chlorophyll a extremums appear in the CML, and, unlike the homogeneous characteristics (water electric conductivity, mineralization, etc.), the cells of different phytoplankton species can be used as tracers in studying convective mixing. A prognostic equation is obtained, reflecting an inverse dependence of the coefficients of variation of chlorophyll a concentration in CML on solar radiation fluxes, penetrating under ice bottom surface. A direct relationship was shown to exist between the increase in chlorophyll concentration in CML and its thickness.

Indoor environmental quality of green office buildings in China: Large-scale and long-term measurement

This study aims to explore the actual indoor environmental quality (IEQ) in Chinese green office buildings, based on the large-scale and long-term measurement data. A total of 41 green office buildings throughout Cold zone, Hot-Summer-Cold-Winter (HSCW) zone and Hot-Summer-Warm-Winter (HSWW) zone were measured with 198 integrated environmental sensors from June, 2017 to August, 2018. The key findings of this study can be summarized as follows: 1) Indoor thermal comfort did not show a significant difference between climate zones in summer, while thermal environment of Cold zone was much warmer and drier than the counterpart of HSCW and HSWW zone in winter. The overall indoor thermal environment met the standard, although several thermal problems were found; 2) Indoor CO2 concentration was relatively high in summer or winter and low in transition seasons. The median values of indoor CO2 concentration were far below the threshold of 1000 ppm; 3) Indoor PM2.5 concentration was generally lower in HSWW zone and higher in winter. The median values of indoor PM2.5 concentration generally conformed to the standard guideline; 4) The median values of illuminance ranged from 340 lux to 522 lux and all of them reached the lower limit of 300 lux for common offices. The above results were compared with other findings from previous literature and several differences were illustrated. In addition, the correlations between indoor and outdoor environment were found. Other possible factors influencing IEQ were discussed qualitatively.

Operational experiences of municipal heating plants with biomass-fired ORC cogeneration units

This paper reports on operational experiences and performance of two municipal heating plants that were converted into cogeneration plants by the installation of biomass-fired modules based on the Organic Rankine Cycle technology (ORC). Two different plants of this type are presented. The text provides a review and discussion of critical issues related to implementation of the technology. Similarities, differences and operational characteristics are substantiated by the analysis of long-term measurement data. Particular attention is paid to variability of operational parameters, problems with determination of performance indicators, equipment characteristics, system sizing and its integration with existing heating plants. A special focus is put on profitability of investment projects under variable economic conditions. Finally, the technology is evaluated using Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis. The text fills the gap between the theoretical knowledge and required practical know-how. It also indicates areas of possible improvements and helps technological risk analysis in the future investment projects.

Black carbon emission and transport mechanisms to the free troposphere at the La Paz/El Alto (Bolivia) metropolitan area based on the Day of Census (2012)

Urban development, growing industrialization, and increasing demand for mobility have led to elevated levels of air pollution in many large cities in Latin America, where air quality standards and WHO guidelines are frequently exceeded. The conurbation of the metropolitan area of La Paz/El Alto is one of the fastest growing urban settlements in South America with the particularity of being located in a very complex terrain at a high altitude. As many large cities or metropolitan areas, the metropolitan area of La Paz/El Alto and the Altiplano region are facing air quality deterioration. Long-term measurement data of the equivalent black carbon (eBC) mass concentrations and particle number size distributions (PNSD) from the Global Atmosphere Watch Observatory Chacaltaya (CHC; 5240 m a.s.l., above sea level) indicated a systematic transport of particle matter from the metropolitan area of La Paz/El Alto to this high altitude station and subsequently to the lower free troposphere. To better understand the sources and the transport mechanisms, we conducted eBC and PNSDs measurements during an intensive campaign at two locations in the urban area of La Paz/El Alto from September to November 2012. While the airport of El Alto site (4040 m a.s.l.) can be seen as representative of the urban and Altiplano background, the road site located in Central La Paz (3590 m a.s.l.) is representative for heavy traffic-dominated conditions. Peaks of eBC mass concentrations up to 5 μg m−3 were observed at the El Alto background site in the early morning and evening, while minimum values were detected in the early afternoon, mainly due to thermal convection and change of the planetary boundary layer height. The traffic-related eBC mass concentrations at the road site reached maximum values of 10–20 μg m−3. A complete traffic ban on the specific Bolivian Day of Census (November 21, 2012) led to a decrease of eBC below 1 μg m−3 at the road site for the entire day. Compared to the day before and after, particle number concentrations decreased by a factor between 5 and 25 over the particle size range from 10 to 800 nm, while the submicrometer particle mass concentration dropped by approximately 80%. These results indicate that traffic is the dominating source of BC and particulate air pollution in the metropolitan area of La Paz/El Alto. In general, the diurnal cycle of eBC mass concentration at the Chacaltaya observatory is anti-correlated to the observations at the El Alto background site. This pattern indicates that the traffic-related particulate matter, including BC, is transported to higher altitudes with the developing of the boundary layer during daytime. The metropolitan area of La Paz/El Alto seems to be a significant source for BC of the regional lower free troposphere. From there, BC can be transported over long distances and exert impact on climate and composition of remote southern hemisphere.

A data-driven approach for optimal design of integrated air quality monitoring network in a chemical cluster.

The chemical industry is of paramount importance to the world economy and this industrial sector represents a substantial income source for developing countries. However, the chemical plants producing inside an industrial district pose a great threat to the surrounding atmospheric environment and human health. Therefore, designing an appropriate and available air quality monitoring network (AQMN) is essential for assessing the effectiveness of deployed pollution-controlling strategies and facilities. As monitoring facilities located at inappropriate sites would affect data validity, a two-stage data-driven approach constituted of a spatio-temporal technique (i.e. Bayesian maximum entropy) and a multi-objective optimization model (i.e. maximum concentration detection capability and maximum dosage detection capability) is proposed in this paper. The approach aims at optimizing the design of an AQMN formed by gas sensor modules. Owing to the lack of long-term measurement data, our developed atmospheric dispersion simulation system was employed to generate simulated data for the above method. Finally, an illustrative case study was implemented to illustrate the feasibility of the proposed approach, and results imply that this work is able to design an appropriate AQMN with acceptable accuracy and efficiency.

Long-term black carbon variation in the South-Eastern Baltic Region in 2008–2015

Long-term continuous measurement data of equivalent black carbon (eBC) concentration over a period of 8 years (2008–2015) from the coastal – background site in Preila, Lithuania, have been analysed. The analysis performed with Preila data has shown that the average mean of eBC concentration was 750 ng/m 3 . A seasonal pattern was also observed with the highest eBC values (1170 ng/m 3 ) in winter gradually declining to the minimum concentration (380 ng/m 3 ) in summer. The frequency distribution of the data was fitted with lognormal modes. Cold and warm seasons were parameterised with three and two modes, respectively. Both the parametric and non-parametric trend analysis methods were applied in this research. A positive annual linear trend for the whole period was estimated to range from +1.97% to +5.35% per year. However, the second order trend had a maximum in 2013 and was declining during the last years of the analysed period, or, according to the t -test, had any statistically significant trend. Regional and long-range emissions of coal and biomass combustion are the main sources of the observed eBC in the Preila station during the cold seasons. This study presents the current situation of black carbon trends in the Baltic Sea region and will be helpful for assessing the policies of black carbon emissions in Europe. • Long-term measurement data of eBC concentration over a period of 2008–2015 in the SE Baltic Sea region have been analysed. • The concentration frequency count in cold and warm seasons were parameterised with three and two modes, respectively. • A second order trend for the whole period showed decrease inBC mass concentration for the second part of the period. • Increase in black carbon mass concentration during autumn season was found.

On the Development of Models for Height Profiles of the Wind Speed in the Atmospheric Surface Layer

The reliability of the known models of a height profile of the wind speed V(h) in the atmospheric boundary layer (ABL) and near-surface layer (NSL) is analyzed using the data of long-term ABL measurements accumulated in Russia in the state network of meteorological and aerological stations and the data of multilevel measurements at mast wind-measuring complexes. A new multilayer semiempirical model of V(h) is proposed which is based on aerodynamic and physical representations of the ABL vertical structure and relies on the hypothesis that wind-speed profiles providing the minimum wind friction on the ground and satisfying the conditions of profile smoothness are feasible in the ABL. This model ensures the best agreement with the data of meteorological, aerological, and mast wind measurements.

Evaluation of Electricity Generation According to Installation Type of Photovoltaic System in Residential Buildings

The types of installation of the photovoltaic system applied to domestic residential buildings are classified as follows: Mounted modules with air circulation, semi-integrated modules with air duct behind, integrated modules with fully insulated back. In order to study generation characteristics of PV system, we verified the validity of interpretation program based on long-term measurement data of demonstration house installed in BAPV form and also analyzed the generation characteristics and performance of each installation type. The results are as follows. First, the RMSE of amount of generation and simulation according to annual daily insolation of demonstration system located in Daejeon was 0.98 kWh and the range of relative error of monthly power generation was -5.8 to 3.1. Second, the average annual PR of mounted modules was 82%, semi-integrated modules 76.1% and integrated modules 71.9%. This differences were attributed to temperature loss. Third, the range of operating temperature of annual hourly photovoltaic modules was –6.5 to 61.0°C for mounted modules, –6.0~73.9°C for semi-integrated modules and –5.5 to 88.9°C for integrated modules. The temperature loss of each installation type was –14.0 to 16.1%, –13.8 to 21.9%, and –13.6 to 28.5%, respectively.

Water pipe network as a heat source for heat pump integrated into a district heating

The paper will present a technical analysis of the performance of the Heat Pumps (HP) installed in the domestic water pipe network for a big city scale. The HP integration scheme predicts the domestic water flow as a heat source and the district heating as a heat sink. The technical factors which influence on the estimated thermal power and performance of HP unit will be identified. Additionally, the pros and cons of HP operation in water intake will be determined. The analysis will be based on long-term measurement data from Glogow city.

Climate changes in atmospheric radiation parameters from the MSU meteorological observatory data

Variations in radiation fluxes and the factors that define them and their redistribution in the atmosphere are analyzed using the data of long-term ground-based measurements at the Meteorological Observatory of Lomonosov Moscow State University. It is demonstrated that since the middle of the 1990s trends in many atmospheric radiation parameters have changed as compared to the trends observed in the previous years. For some parameters the trends are significant, are kept for a long period of time, and. hence, can be considered as climate changes. The potential effects of these changes on the regional warming are assessed.

Technical and Economic Investigation and Comparison of Photovoltaic – Wind Energy – Hybrid Systems with Battery and Heat-storage Path

The paper presents results from a technical and economic investigation of a decentralized, grid-connected photovoltaic (PV) –small wind turbine (SWT) – hybrid system with lead-acid battery, lithium-ion battery and heat-storage path. Long-term measurement data of PV, wind and electricity consumption profiles for a household application are analysed. The supplementary nature of PV and wind power is demonstrated. The self-sufficiency achievable without energy storage is determined for different ratios of installed PV and SWT power and for six different types of SWT with varying hub heights. A novel peak-shaving-/power2heat-concept is introduced. Excessive and peak power of the PV and SWT plant is converted to heat, relieving grid and battery significantly. Drastic peak-shaving is possible without tremendous loss of utilizable electricity. A hybrid battery system is added aiming for an optimization of PV and wind energy self-consumption. It is demonstrated that the self-sufficiency can be increased up to 90% with a positive profit. Simulation results are presented for the scan of a multi-dimensional vector of PV and SWT plant sizes, battery capacities, peak-shaving threshold values and energy management parameters. An economic analysis of the overall hybrid system including investment costs, avoided electricity costs, revenues from feed-in-tariffs and an estimation of the total profit is presented.

Road Surface Recognition Using Laser Radar for Automatic Platooning

This paper proposes a road surface recognition system based on a “laser radar” (LIDER), which is used to detect a lane markings for application to an automatic platooning system for trucks. To ensure the safety of automatic driving, there is a need to recognize the road surface conditions (dry, wet, etc.). This system proposes an integrated system that is not only capable of recognizing lane markings but also monitors the road surface using a laser radar scanning system. Our road surface recognition method relies on the multiple reflection intensities of laser radar and a machine learning algorithm. By using multiple reflection intensities, the recognition rate is improved. Moreover, to improve the recognition rate, an additional feature variable, called the “roughness index,” is proposed. In this paper, the concept of a road surface recognition system is proposed and six road surface conditions (dry old asphalt, moist old asphalt, flooded old asphalt, dry new asphalt, moist new asphalt, and flooded new asphalt) are recognized by the proposed algorithm. The quality of the road surface recognition is examined through comparison with long-term measurement data. The proposed method exhibits a high level of road surface recognition performance.

The corrosion rate in reinforced concrete facades exposed to outdoor environment

Outdoor concrete structures such as concrete facade panels and balcony frame panels are subjected to various environmental actions causing reinforcement corrosion problems. Long-term field measurement data on reinforcement corrosion in carbonated concrete on these structures was utilized in the creation of a corrosion rate regression model combining weather parameters such as temperature, relative humidity, wind-driven rain and solar radiation to corrosion rate. A versatile model capable of predicting the effect of varying environmental actions on the corrosion rates of carbonation induced corrosion was produced. Wind-driven rain was found to have the greatest impact on corrosion rate in tandem with the micro climate surrounding the building. Due to changes in air temperature, air relative humidity as well as in the amount of wind-driven rain and solar radiation, the corrosion rate on concrete facades and balconies is constantly changing. Despite the high seasonal and yearly variation, the average level of the modelled corrosion rate was quite steady on a longer 30-year perspective. This information is substantial for the long term service life design of concrete structures.

Estimation of mean and extreme waves in the East China Seas

Accurately estimating the mean and extreme wave statistics and better understanding their directional and seasonal variations are of great importance in the planning and designing of ocean and coastal engineering works. Due to the lack of long-term wave measurement data, the analysis of extreme waves is often based on the numerical wave hind-casting results. In this study, the wave climate in the East China Seas (including the Bohai Sea, the Yellow Sea and the East China Sea) for the past 35 years (1979–2013) is hind-casted using a third generation wave model – WAMC4 (Cycle 4 version of WAM model). Two sets of reanalysis wind data from NCEP (National Centers for Environmental Prediction, USA) and ECMWF (European Centre for Medium-range Weather Forecasts) are used to drive the wave model to generate the long-term wave climate. The hind-casted waves are then analysed to study the mean and extreme wave statistics in the study area. The results show that the mean wave heights decrease from south to north and from sea to land in general. The extreme wave heights with return periods of 50 and 100 years in the summer and autumn seasons are significantly higher than those in the other two seasons, mainly due to the effect of typhoon events. The mean wave heights in the winter season have the highest values, mainly due to the effect of winter monsoon winds. The comparison of extreme wave statistics from both wind fields with the field measurements at several nearshore wave observation stations shows that the extreme waves generated by the ECMWF winds are better than those generated by the NCEP winds. The comparison also shows the extreme waves in deep waters are better reproduced than those in shallow waters, which is partly attributed to the limitations of the wave model used. The results presented in this paper provide useful insight into the wave climate in the area of the East China Seas, as well as the effect of wind data resolution on the simulation of long-term waves.

Field Performance Evaluation of Residential Photovoltaic Systems Based on Long-Term Measurement Data

Field Performance Evaluation of Residential Photovoltaic Systems Based on Long-Term Measurement Data

Effects of Physical Environment on Health and Behaviors of Residents With Dementia in Long-Term Care Facilities: A Longitudinal Study.

The challenges in investigating the effects of the physical environment on residents with dementia include having a sample of comparable study groups and a lack of long-term follow-up evaluation. The current study attempted to address these two challenges by carefully matching residents and analyzing long-term measurement data. The aim of the study was to examine whether residents with dementia (N = 12) living in a traditional large-scale setting or a small-scale, home-like setting exhibit any difference in health and behaviors over time. Physical environmental assessment of the two care facilities was conducted using the Therapeutic Environment Screening Survey for Nursing Homes. Residents' behavioral assessments were performed using three tools at three assessments over a period of 1 year: (a) Multidimensional Observation Scale for Elderly Subjects, (b) Minimum Data Set, and (c) Dementia Care Mapping. The results suggest that older adults with dementia can have increased social interaction and engagement with the support of an optimal physical environment.

Parametric approximation of the probability density function of relative air humidity under conditions of the continental climate

Obtained is the parametric law of the probability density function of relative air humidity as a result of processing the data of long-term measurements. Revealed is the existence of two maxima of the long-term probability density function of relative air humidity under conditions of the continental climate. It is demonstrated that it is possible to distinguish the components of the probability density function of air humidity.