Optimization of the time series surface deformation analysis using machine learning algorithms on the interferogram simulation data

<p>Time-series InSAR techniques, such as Stanford Method for Persistent Scatterers (StaMPS) are commonly used to measure time-series surface deformation. This study presents a novel approach of optimized time series deformation analysis based on a support vector regression (SVR) algorithm and optimization Hot-Spot Analysis on persistent scatterers (PS). To examine the performances of the optimized process in time-series, we generated a synthetic interferogram using a Mogi model equation to construct a simulated surface deformation phase. Topography errors simulated orbital error and atmospheric error phases have been added to synthetic interferogram construction. All the synthetic interferogram based on Sentinel-1 SAR Image acquisition dates over Seoul, Korea. An SVR algorithm was used to find an optimum measurement point and reduce error points in time-series analysis. Then, the OHSA approach was implemented on the optimum measurement point through the analysis of Getis-Ord Gi* statistics. As the result, the optimization measurement point indicates refined results in the mean velocity deformation map and time-series graph. In addition, the detection accuracy can be improved by more than 10% with synthetic data. Then, the correlation coefficient between the optimization result and the deformation model shows a good correlation (> 0.8). Also, the standard deviation of time-series results can be reduced by more than 7% after optimizing the process. The proposed method is useful to detect a low deformation rate and can be implemented for several deformation cases.   </p>

An Amperometric Biosensor For Hg(II) Based On Urease/Alginate–Chitosan Membrane Modified Screen Printed Carbon Electrode

A screen-printed three-electrode system is fabricated to prepare a novel screen-printed biosensor for rapid determination of Hg(II) in aqueous solution. The amperometric biosensor is prepared by entrapping urease in alginate–chitosan membrane to modify the screen-printed carbon electrode. The urease/alginate–chitosan membrane for Hg(II) had optimum measurement conditions at work potential of -0.15 V, pH of 7, urea concentration of 75 mM, response time of 8 seconds, inhibition time of 7 minutes and temperature of 25 °C. The resulted biosensor characteristic were found to have the range concentration of Hg(II) ion between 40-90 ppb with the detection limit I10% was 66.45 ppb, the coefficient of variance (Cv) was 0.8%, and reactivation was 5 times reuse.

Studi Metode Diffusive Gradient In Thin Film dengan Binding Gel Titanium Dioksida-Chelex untuk Penyerapan Logam Besi(II) dan Fosfat Secara Simultan

Tingginya konsentrasi fosfor sebagai fosfat ke dalam sistem akuatik mengakibatkan eutrofikasi yang berujung pada terjadinya algae blooming. Input fosfat dalam sistem akuatik ini dicurigai dipengaruhi oleh pelepasan fosfat yang terikat pada besi(III) hidroksida ketika tereduksi menjadi besi(II) di sedimen, sehingga diperlukan pengukuran fosfat dan besi(II) secara simultan. Teknik diffusive gradient in thin film (DGT) merupakan salah satu metode pengukuran in-situ yang dikembangkan untuk pengukuran fosfat dan logam.Teknik DGT diteliti menggunakan binding gel campuran TiO2-Chelex. Metode baru ini memperkenalkan penggunakan TiO2 hasil sintesis melalui metode sol-gel sebagai agen pengikat fosfat dan resin Chelex-100 sebagai agen pengikat logam Fe(II). DGT yang terdiri dari diffusive layer dan binding layer diuji kemampuannya dalam menyerap logam labil besi(II) dan fosfat secara terpisah, kemudian diuji homogenitasnya. DGT dengan binding gel TiO2-Chelex diuji pada sejumlah variasi waktu pengukuran, konsentrasi larutan, dan pH.Hasil analisis menggunakan spektrofotometer AAS untuk logam besi dan spektrofotometer UV-Vis untuk fosfat menunjukkan bahwa waktu optimum untuk pengukuran DGT adalah 24 jam. DGT dengan binding gel TiO2-Chelex optimum mengukur fosfat pada larutan dengan pH 5.2 dan pH 6 dan optimum mengukur besi(II) pada pH netral (pH 7). DGT TiO2-Chelex memiliki kapasitas pengukuran 5.86 mg/L untuk fosfat dan 53.41 mg/L untuk logam besi(II). Sehingga dapat disimpulkan bahwa, binding gel campuran TiO2-Chelex yang telah dibuat dalam sistem DGT dapat menyerap logam Fe(II) dan fosfat secara simultan dengan baik. The high phosphorus as phosphate input into aquatic systems causes eutrophication which leads to the occurrence of algae blooming. Phosphate input in aquatic systems is influenced by the release of suspected phosphate bound to iron(III) when reduced to iron(II) in the sediment. Diffusive gradients in thin films (DGT) technique is one of the in-situ measurement methods developed for the measurement of phosphate and metals. DGT technique was studied using gel bindings mixture of TiO2-Chelex. This new method introduces the use synthesis of TiO2 via sol-gel method and resin Chelex-100 as phosphate and iron(II) binding agents, respectively. DGT composed of diffusive and binding layer was tested for their ability to absorb iron(II) and phosphate separately, and homogeneity. DGT with bindings TiO2-Chelex gel was tested at various measurement time, solution concentration, and pH. The results of the analysis using AAS for iron and UV - Vis spectrophotometer for phosphate showed that the optimum time for DGT measurement is 24 hours. Optimum measurement of DGT with bindings gel TiO2-Chelex was reached at pH around pH 5.2 and 6 for phosphate, and neutral (pH 7) for iron(II). TiO2-Chelex DGT measurement capacity was 5.86mg/L and 53.41 mg/L for phosphate and iron (II), respectively. In conclusion, the TiO2-Chelex mixed binding gel that was made can absorb iron (II) and phosphate simultaneously.

A Target Indirect Thrust Measurement Method of Pulse Detonation Engine

An indirect thrust measurement method based on impulse of a target plate was developed, and a new thrust measurement system (TMS) was successfully designed and constructed. A series of multi-cycle experiments on thrust measurement were conducted to investigate the feasibility of this method with the newly-built indirect TMS. The thrust measurement of PDE was made at different plate target axial positions and operating frequencies. All the experiments were conducted using gasoline as fuel and air as oxidant. The experimental results implied that the thrust of PDE by using the indirect impulse method was a function of the target plate axial position, and there existed an optimum measurement position for PDE with a diameter of 60 mm. The optimum target plate position located at 3.33. According to the experimental results, the thrusts obtained by using indirect TMS were less than the actual values, and so the observed value of thrust was modified in order to make the thrust more reliable. A relative accurate calibration formula depending on the operating frequency was found.