Radon concentration in compressed natural gas and liquefied petroleum gas and its release range in residential houses

Radon (222Rn) exposure in the environment is an important issue, and many pathways exist for radon exposure to humans. One of these pathways is 222Rn release through the consumption of natural gas. The issues of 222Rn concentration measurement techniques and worldwide concentration distribution were reviewed in natural gas, with emphasis on performing an active method to determine 222Rn concentration in LPG and CNG gases used in Cyprus. The obtained results were compared with 222Rn concentration in natural gas worldwide and UNSCEAR reports. The average 222Rn concentration value in LPG gas was observed higher than CNG gas. Also, the 222Rn concentration in LPG and CNG gases was less than the UNSCEAR reported value.

Study on a Heuristic Wheelset Structure without Rail Corrugation on Sharply Curved Tracks

Rail corrugation on low rails of sharp railway curves is still a difficult problem to solve worldwide. Nearly all low rails of the sharp railway curves incur rail corrugation. In the present study, an active method to remedy rail corrugation was studied. From the viewpoint of the frictional self-excited oscillation of a wheelset-track system causing rail corrugation, the effect of wheelset structures on rail corrugation was studied. Three frictional self-excited oscillation models of wheelset-track systems with different wheelset structures were established, which include a heuristic wheelset structure and two being used in the railway industry. The incidence trends of the self-excited oscillations of these three wheelset-track systems were studied. It was found that the wheelset structure has an important effect on rail corrugation, and that the heuristic wheelset structure can restrain or get rid of rail corrugation. With the parameter sensitivity analysis, it was found that when the friction coefficient between the wheel and rail, rail gauge, rail cant, and sleeper span changes to some extent, the heuristic wheelset structure is robust enough to prevent rail corrugation. The proposed heuristic wheelset structure can be used as a potential solution to rail corrugation on sharply curved tracks.

Perbandingan Tingkat Kadar Gas SO2 dan NO2 di Udara Ambien Antara Metode Pasif dan Metode Aktif (Studi Kasus: Kota Jakarta)

ABSTRACT A comparison of the measurement results between the active method and the passive method was carried out to see the correlation between the resulting concentrations. The passive method used CSIRO passive sampler, while the active method used the Air Quality Monitoring System (AQMS). Sampling was conducted at AQMS Bundaran HI Jakarta Station, belonging to the Environment Laboratory of DLH DKI Jakarta. The sampling period was February - April 2019 for SO2 and NO2 parameters, with a sampling duration of three days for each data. Data was proceed using the correlation method. Data filtering with boxplot was used to filter outlier data from the passive sampler and AQMS measurements. Meteorological factors were included in the correlation calculations because of their effect on gas absorption that occurred in the passive sampler. Meteorological factors used were temperature, humidity, and wind direction. The AQMS concentration value prediction was calculated using the correlation equation between the passive sampler and the AQMS. The results showed that the correlation coefficient value between the passive sampler and AQMS was 0.67 for SO2 and NO2 of 0.79. Multivariate correlation using meteorological data, to improve the correlation value, obtained correlation values of 0.97 for SO2 and 0.94 for NO2. The predictive value of AQMS used a regression equation, with an average bias value of 4.4% for SO2 and 9.9% for NO2, while the RMSE values were 0.89 for SO2 and 4.41 for NO2. The results showed that the concentration of SO2 and NO2 gas measurement results from the passive and active methods had a good and significant correlation. Keywords: passive method, active method, SO2, NO2, AQMS ABSTRAK Perbandingan hasil pengukuran antara metode aktif dan metode pasif dilakukan untuk melihat korelasi konsentrasi yang dihasilkan antara metode aktif dan metode pasif. Metode pasif menggunakan passive sampler CSIRO, sedangkan metode aktif menggunakan Air Quality Monitoring System (AQMS). Sampling dilakukan di Stasiun Pemantauan Kualitas Udara (SPKU) DKI 1 Bundaran HI milik Laboratorium Lingkungan Hidup DLH DKI Jakarta. Periode sampling dilakukan dari bulan Februari – April 2019 untuk parameter SO2 dan NO2, dengan durasi sampling per tiga hari untuk satu data. Pengolahan data dilakukan dengan metode korelasi. Filter data dilakukan dengan menggunakan boxplot untuk memfilter data outlier dari pengukuran passive sampler dan AQMS. Faktor meteorologi dimasukkan dalam perhitungan korelasi karena pengaruhnya pada penyerapan gas yang terjadi di passive sampler. Faktor meteorologi yang digunakan adalah temperatur, kelembapan, dan arah angin. Prediksi nilai konsentrasi AQMS dihitung dengan menggunakan persamaan korelasi antara passive sampler dengan AQMS. Hasil yang diperoleh menunjukkan nilai koefisien korelasi antara passive sampler dengan AQMS sebesar 0,67 untuk SO2 dan NO2 sebesar 0,79. Korelasi multivariat menggunakan data meteorologi untuk memperbaiki nilai korelasi diperoleh nilai korelasi 0,97 untuk SO2 dan 0,94 untuk NO2. Nilai prediksi AQMS menggunakan persamaan regresi, dengan nilai rata-rata bias 4,4% untuk SO2 dan 9,9% untuk NO2, sedangkan nilai RMSE sebesar 0,89 untuk SO2 dan 4,41 untuk NO2. Hasil penelitian menunjukkan bahwa konsentrasi hasil pengukuran gas SO2 dan NO2 metode pasif dan metode aktif mempunyai korelasi yang baik dan signifikan. Kata kunci: metode pasif, metode aktif, SO2, NO2, AQMS

How Do Adolescents Obtain Health Information

Adolescent health literacy is a promising innovation in health education. This article reports the findings of research in the experience of adolescents in the methods they used in obtaining health information. A phenomenographic research approach was used to understand how adolescents conceptualized health information obtaining. The study examined data provided by 24 adolescents aged 13 to 16 living in Latvia. The data was collected through qualitative interviews. Phenomenographic data analysis uncovered five categories of description by adolescents in the way they perceived health information obtaining: 1. An opportunity to find out “things” regarding health; 2. The use of different sources of information to obtain health information; 3. The use of multimodal texts to obtain health information; 4. A passive method of obtaining information; and 5. An active method of obtaining information. It is important to integrate the experience of adolescents into health education research to develop a deeper understanding of the pedagogical phenomenon and to enhance health education programmes.