On the Saturation (or Not) of Geomagnetic Indices

Most geomagnetic indices are associated with processes internal to the magnetosphere-ionosphere system: convection, magnetosphere-ionosphere current systems, particle pressure, ULF wave activity, etc. The saturation (or not) of various geomagnetic indices under various solar-wind driver functions (a.k.a. coupling functions) is explored by examining plots of the various indices as functions of the various driver functions. In comparing an index with a driver function, “saturation” of the index means that the trend of stronger geomagnetic activity with stronger driving weakens in going from mid-range driving to very strong driving. Issues explored are 1) whether the nature of the index matters (i.e., what the index measures and how the index measures it), 2) the relation of index saturation to cross-polar-cap potential saturation, and 3) the role of the choice of the solar-wind driver function. It is found that different geomagnetic indices exhibit different amounts of saturation. For example the SuperMAG auroral-electrojet indices SME, SML, and SMU saturate much less than do the auroral-electrojet indices AE, AL, and AU. Additionally it is found that different driver functions cause an index to show different degrees of saturation. Dividing a solar-wind driver function by the theoretical cross-polar-cap-potential correction (1+Q) often compensates for the saturation of an index, even though that index is associated with internal magnetospheric processes whereas Q is derived for solar-wind processes. There are composite geomagnetic indices E(1) that show no saturation when matched to their composite solar-wind driver functions S(1). When applied to other geomagnetic indices, the composite S(1) driver functions tend to compensate for index saturation at strong driving, but they also tend to introduce a nonlinearity at weak driving.

Tingkat Korosivitas Air Terhadap Infrastruktur Sumber Daya Air Berbahan Semen atau Mortar dengan fc’ ≤ 30 MPa pada 9 Waduk di Indonesia

Abstrak. Korosi atau kerusakan yang terjadi di infrastruktur sumber daya air terutama yang berbahan semen atau mortar dengan fc’ atau dengan nilai kuat tekan ≤ 30 Mpa, dapat menimbulkan banyak kerugian. Kerugian yang ditimbulkan antara lain kerugian secara materiil karena korosi menggerogoti semua aset infrastruktur dan tentunya kerugian dalam hal keamanan karena dapat mengancam keselamatan manusia. Korosi merupakan permasalahan yang sangat penting dan tidak akan ada habisnya, karena peristiwa korosi terjadi secara terus-menerus dan berkelanjutan. Peristiwa korosi tidak dapat terjadi dengan sendirinya, tetapi karena adanya berbagai faktor-faktor tertentu yang dapat menyebabkan terjadinya korosi. Tujuan dari studi ini adalah untuk menentukan tingkat korosivitas air terhadap infrastruktur sumber daya air berbahan semen atau mortar dengan fc’ atau dengan nilai kuat tekan ≤ 30 MPa pada 9 waduk di Indonesia, sehingga akan diketahui rekomendasi yang tepat untuk pencegahan dan pengendalian korosivitas air terhadap infrastruktur sumber daya air berbahan semen atau mortar dengan fc’ atau dengan nilai kuat tekan ≤ 30 MPa, karena semen merupakan salah satu material yang paling banyak digunakan saat ini. Studi ini menggunakan data-data primer kualitas air. Metode pengambilan, penyimpanan, dan pengawetan sampel air dilakukan dengan mengikuti ketentuan dari Standar Nasional Indonesia Nomor 6989.57:2008. Pengujian kualitas air dilakukan oleh laboratorium yang terakreditasi. Metode perhitungan menggunakan rumus Langelier Saturation Index (LSI) A, B, C, D, dan rumus Saturation Index (SI) dari Standard Method APHA-AWWA-WEF. Hasil perhitungan LSI A, B, C, D, dan SI Standard Method APHA-AWWA-WEF menunjukkan bahwa tingkat korosivitas air di 9 waduk berpotensi menyebabkan korosi terhadap infrastruktur sumber daya air berbahan semen atau mortar dengan fc’ atau dengan nilai kuat tekan ≤ 30MPa. Kata kunci: infrastruktur sumber daya air, Langelier Saturation Index, Saturation Index, tingkat korosivitas air. Abstract. Water Corrosivity Level Againts the Water Resources Infrastructure Made of Cement or Mortar with fc' ≤ 30 MPa in 9 Reservoirs in Indonesia. Corrosion or damage that occurs in the infrastructure of water resources, especially those made of cement or mortar with fc' or with a compressive strength value of ≤ 30 MPa will be able to engender losses. Losses incurred, in the form of losses materially because of corrosion gnaw off all infrastructure assets and of course in losses terms of security, because it can threaten the safety of a human. Corrosion is a very important problem and will not be endless, as corrosion events occur continuously and sustainably. Corrosion events cannot occur by themselves, but because of certain factors that may cause corrosion. The purpose of this study is to determine the level of water corrosivity to the infrastructure of water resources made from cement or mortar with fc' or with a compressive strength value of ≤ 30 MPa in 9 reservoirs in Indonesia, to develop appropriate recommendations for the prevention and control of the water corrosivity to the infrastructure of water resources made from cement or mortar with fc' or with a compressive strength value of ≤ 30 MPa because cement is one of the most used materials today. This study uses water quality primary data. The methods of capturing, storing, and preserving water samples are carried out following the provisions of Indonesian national standard number 6989.57:2008. Water quality testing is done by accredited laboratories. The method of calculation uses the Langelier Saturation Index (LSI) A, B, C, D, and the formula Saturation Index (SI) of the Standard Method APHA-AWWA-WEF. Calculation results of LSI A, B, C, D, and SI Standard Method APHA-AWWA-WEF show that the level of water corrosivity in 9 reservoirs has the potential to cause corrosion of water resources infrastructure made of cement or mortar with fc' or with a compressive strength value of ≤ 30 MPa. Keywords: Langelier Saturation Index, Saturation Index, water corrosivity level, water resource infrastructure.

Development of a functional cake formulation with purple carrot powder dried by different methods

In this study, it was aimed to enhanced cake formula-tion with purple carrot pow-der (PCP) dried 3 different methods (hot-air (HPC), microwave (MPC) and vac-uum (VPC) dried) and used at 5 different ratios (0, 5, 10, 15, 20%). The effects of purple carrot powder (PCP) on chemical, physical and sensory properties of cake samples were investigated. HPC substituted cake sam-ples had lower batter densi-ty and weight values. PCP usage significantly affected the crust and crumb color value of cake samples (p<0.05). Samples contain-ing MPC had higher firm-ness and lower springiness than others. Lower firmness, volume index, saturation index and higher springiness values were determined with increasing PCP rate. The highest total phenolic content and antioxidant ac-tivity were found in cake samples containing HPC and VPC, respectively. When all cake samples evaluated, the higher overall acceptability scores were obtained with HPC added cake samples at 15 and 20% substitution level compared to control sample.