First national intercomparison of solar ultraviolet radiometers in Italy

A blind intercomparison of ground-based ultraviolet (UV) instruments has been organized for the first time in Italy. The campaign was coordinated by the Environmental Protection Agency of Aosta Valley (ARPA Valle d'Aosta) and took place in Saint-Christophe (45.8 degrees N, 7.4 degrees E, 570 m a.s.l.), in the Alpine region, from 8 to 23 June 2010. It involved 8 institutions, 10 broadband radiometers, 2 filter radiometers and 2 spectroradiometers. Synchronized measurements of downward global solar UV irradiance at the ground were collected and the raw series were then individually processed by the respective operators on the base of their own procedures and calibration data. A radiative transfer model was successfully applied as an interpretative tool. The input parameters and output results are described in detail. The comparison was performed in terms of global solar UV Index and integrated UV-A irradiance against a well-calibrated double monochromator spectroradiometer as reference. An improved algorithm for comparing broadband data and spectra has been developed and is discussed in detail. For some instruments, we found average deviations ranging from -16% up to 20% relative to the reference and diurnal variations as large as 15% even in clear days. Remarkable deviations were found for the instruments calibrated in the manufacturers' facilities and never involved in field intercomparison. Finally, some recommendations to the UV operators based on the campaign results are proposed

Impedance Mathing Improvement of Half-Cut Broadband Printed Monopole Antenna with Microstrip Feeding

The requirement of wireless access networks and user equipments to support coexistence of many communication standards and frequency bands poses challenge on antenna to be broadband and small. The application of half-cut technique to broadband printed monopole with microstrip feeding worsens the resulted antenna’s impedance. To improve the half-cut antenna impedance mathing, two methods were investigated in this paper: (1) monopole and ground extension, (2) the application of microstrip line transformer and ground extension. The first approach only produces limited improvement, whereas method #2 can enhance the return loss significantly. The application of the second approach potentially produces antenna pair that has low mutual coupling, good return loss, and small size. Considering its radiation pattern, the antenna is suitable for diversity and MIMO. Its application in broadband microwave-photonic access point need special arrangement due to radiation null at 5 GHz band at right side.DOI:http://dx.doi.org/10.11591/ijece.v3i5.337

A review of recent advances in metaheuristic maximum power point tracking algorithms for solar photovoltaic systems under the partial-shading conditions

Several maximum power point (MPP) tracking algorithms for solar power or photovoltaic (PV) systems concerning partial-shading conditions have been studied and reviewed using conventional or advanced methods. The standard MPPT algorithms for partial-shading conditions are: (i) conventional; (ii) mathematics-based; (iii) artificial intelligence; (iv) metaheuristic. The main problems of the conventional methods are poor power harvesting and low efficiency due to many local maximum appearances and difficulty in determining the global maximum tracking. This paper presents MPPT algorithms for partial-shading conditions, mainly metaheuristics algorithms. Firstly, the four classification algorithms will be reviewed. Secondly, an in-depth review of the metaheuristic algorithms is presented. Remarkably, 40 metaheuristic algorithms are classified into four classes for a more detailed discussion; physics-based, biology-based, sociology-based, and human behavior-based are presented and evaluated comprehensively. Furthermore, the performance comparison of the 40 metaheuristic algorithms in terms of complexity level, converter type, sensor requirement, steady-state oscillation, tracking capability, cost, and grid connection are synthesized. Generally, readers can choose the most appropriate algorithms according to application necessities and system conditions. This study can be considered a valuable reference for in-depth works on current related issues

Does solar ultraviolet radiation play a role in COVID-19 infection and deaths? An environmental ecological study in Italy

A significantly stronger impact in mortality and morbidity by COVID-19 has been observed in the northern Italian regions compared to the southern ones. The reasons of this geographical pattern might involve several concurrent factors. The main objective of this work is to investigate whether any correlations exist between the spatial distribution of COVID-19 cases and deaths in the different Italian regions and the amount of solar ultraviolet (UV) radiation at the Earth's surface. To this purpose, in this environmental ecological study a mixed-effect exponential regression was built to explain the incidence of COVID-19 based on the environmental conditions, and demographic and pathophysiologic factors. Observations and estimates of the cumulative solar UV exposure have been included to quantify the amount of radiation available e.g., for pre-vitamin D3 synthesis or SARS-CoV-2 inactivation by sunlight. The analysis shows a significant correlation (p-value <5 × 10−2) between the response variables (death percentage, incidence of infections and positive tests) and biologically effective solar UV radiation, residents in nursing homes per inhabitant (NHR), air temperature, death percentage due to the most frequent comorbidities. Among all factors, the amount of solar UV radiation is the variable contributing the most to the observed correlation, explaining up to 83.2% of the variance of the COVID-19 affected cases per population. While the statistical outcomes of the study do not directly entail a specific cause-effect relationship, our results are consistent with the hypothesis that solar UV radiation impacted on the development of the infection and on its complications, e.g. through the effect of vitamin D on the immune system or virus inactivation by sunlight. The analytical framework used in this study, based on commonly available data, can be easily replicated in other countries and geographical domains to identify possible correlations between exposure to solar UV radiation and the spread of the pandemic

STUDI KONSUMSI ENERGI LISTRIK MOTOR INDUKSI SATU FASA PENGGERAK POMPA AIR PADA PENGISIAN TANDON SECARA BERTINGKAT

Salah satu aplikasi motor induksi adalah sebagai pompa yang dapat digunakan untuk mengalirkan fluida. Dalam industri, sering dibutuhkan suatu sistem untuk mengatur beberapa pompa yang bekerja secara simultan atau sekuensial sehingga durasi operasi dan dan daya total sistem akan mempengaruhi energi yang dibutuhkan. Pada Tugas Akhir ini dibuat suatu plant pengisian tandon air secara bertingkat yang terdiri dari tiga buah motor pompa dan empat buah tandon air dengan kapasitas yang berbeda. Plant ini digunakan untuk mencari metode dan skema operasi yang paling efisien dari tiga motor pompa air yang disusun bertingkat dan diatur oleh PLC OMRON CPM1A ditinjau dari segi daya motor pompa, durasi operasi dan konsumsi energi listrik. Dari hasil pengujian didapatkan bahwa proses pengisian tandon 2 sangat mempengaruhi energi dan durasi operasi. Pengukuran menunjukkan bahwa metode 1 merupakan metode yang paling efisien bila dibandingkan dengan kedua metode yang lain. Secara lebih spesifik lagi, skema operasi yang paling efisien pada metode satu adalah skema operasi 1 hingga 8. Perbedaan konsumsi energi antara skema-skema operasi dalam suatu metode dipengaruhi oleh durasi dan urutan operasi Kata Kunci : motor pompa, metode, skema operasi, efisien, PL

INVERTER MULTI LEVEL TIPE JEMBATAN SATU FASA TIGA TINGKAT DENGAN MIKROKONTROLER AT89S51

Inverter is a power electronics circuit which is used to convert DC voltage and current to AC voltage andcurrent. In conventional inverter, most commonly used, only has three level voltage, those are +Vdc, -Vdc,and zero. Meanwhile both square inverters and SWPM inverter has big harmonic distortion. In SPWMinverter scheme, high frequency switching must be used to minimize total harmonic distortion (THD). Multilevel inverter is a type of inverter that has more than one level of voltage and current output.The major advantages of multi level inverters are a good voltage waveform, small harmonic dirtortion,switching component operated under low frequency, and it can supply a big power.This paper will discuse the construction of single phase three level multi level inverters, hardware testinginclude output waveform THD, and the comparisson of multilevel inverter with other conventional invertersscheme suc as PWM inverters modulation, and square waveform inverter. Atmel’s AT89S51 microcontrollerused to control switching scheme in this multi level inverter. By this power electronic circuit, it is expected alow cost and reliable multi level inverters prototipe