Restoration of Hardware Function of Spectral Colorimeters Using Regularization Methods

The problem of determining the spectral characteristic of a controlled sample under conditions of limited a priori information using regularization methods is considered in the paper. A change in the state of the surface of optical elements significantly increases the light scattering, so it is necessary regularly to take into account the amount of scattered light in the light flux reflected from the surface and the measured and comparative samples. The conversion of the light flux into the electrical signal of the photodetector can also occur non-linearly. This requires the development of such measurement method that considers both the scattered light and various non-linearities of the measuring circuit. It is known that the mathematical model of measurement is described by the Fredholm integral equation of the first kind, its solution under the accepted assumptions is recommended to be sought in the form of a matrix equation using a recurring procedure. With regard to the fact that the estimation of the initial data errors in the equation is associated with certain difficulties, in the case under consideration, it is advisable to determine the regularization parameter based on the method of quasi-optimality. A characteristic disadvantage of the known analytical and experimental methods for determining the hardware function of a spectral device is that they do not take into account its change during operation. Since the actual hardware function of the device usually differs from the Gaussian curve, the use of hardware functions in the form of analytical dependencies does not always give the desired result, and for experimental methods, special equipment with a quasi-monochromatic radiation source is required. An algorithm for restoring the hardware function of a spectral device based on regular methods for solving ill-posed problems is proposed. The estimation of the matrix operator of the hardware function is proposed to be obtained on the basis of explicit least squares estimation algorithms. The expediency of choosing a value of the regularization parameter that minimizes the accepted characteristic of the accuracy of the solution is indicated.

EXAMINATION OF DISINFECTANTS USING AN AUTOMATED SPECTROMETER OPERATING IN THE VISIBLE RANGE OF THE SPECTRUM

The paper highlights a modern spectral device for measuring the optical parameters of solid-state materials in liquid-phase. The development of these devices is promising for optical instrumentation and science in general, since these devices are informative, highly accurate and provide reliable information. In the paper the appearance, block diagram and lighting system of the spectrometer are presented. The spectral dependences of the transmission on the wavelength in the visible range of the spectrum for disinfectants Like, Grand, Aqualite (1% solutions) are obtained. For the analysis of the studied substances, specialized cuvettes with a working length from 0.1 to 0.5 mm and leucosapfir optical pads were used. The cuvettes were 0.05 mm thick. The spectrometer provided measurement of the transmission of disinfectants in the wavelength range of 380–760 nm with an error not worse than ΔТ ≤ 2%.

Geologi, Karakteristik Alterasi Hidrotermal dan Mineralisasi Bijih pada Pit Purnama Martabe, Kabupaten Tapanuli Selatan, Provinsi Sumatera Utara

Tingginya angka kebutuhan logam berupa emas, perak, dan tembaga serta keterdapatannya yang terbatas menyebabkan pemahaman mengenai kondisi geologi, karakteristik alterasi, dan mineralisasi bijih diperlukan dalam proses eksplorasi yang berkelanjutan. Penelitian ini bertujuan untuk mengetahui kondisi geologi, karakteristik dan persebaran alterasi serta mineralisasi bijih di Pit Purnama Martabe berdasarkan hasil pemetaan, deskripsi intibor dan pengambilan sampel yang kemudian dianalisis dengan XRF (X-Ray Fluorescenes), ASD (Analytical Spectral Device), petrografi, dan mikroskopi bijih. Litologi di daerah penelitian tersusun satuan lava andesit, satuan kubah intrusi diorit, dan satuan breksi freatomagmatik polimiktik. Berdasarkan analisis ASD, zona alterasi yang berkembang terdiri atas alterasi silika vuggy-masif, zona alterasi silika+dikit±alunit, ilit+smektit, dan smektit+klorit. Berdasarkan analisis mineragrafi dan ditunjang oleh data XRF, dapat diketahui bahwa mineralisasi di daerah penelitian berupa pirit, enargit, hematit, goetit, dan jarosit. Kondisi geologi yang mengontrol persebaran alterasi dan mineralisasi yang terjadi adalah adanya struktur berarah timur laut – barat daya berupa urat kuarsa dan barat laut – tenggara, serta litologi yang memiliki porositas bervariasi.

High-Resolution Aerial Detection of Marine Plastic Litter by Hyperspectral Sensing

An automatic custom-made procedure is developed to identify macroplastic debris loads in coastal and marine environment, through hyperspectral imaging from unmanned aerial vehicles (UAVs). Results obtained during a remote-sensing field campaign carried out in the seashore of Sassari (Sardinia, Italy) are presented. A push-broom-sensor-based spectral device, carried onboard a DJI Matrice 600 drone, was employed for the acquisition of spectral data in the range 900−1700 nm. The hyperspectral platform was realized by assembling commercial devices, whereas algorithms for mosaicking, post-flight georeferencing, and orthorectification of the acquired images were developed in-house. Generation of the hyperspectral cube was based on mosaicking visible-spectrum images acquired synchronously with the hyperspectral lines, by performing correlation-based registration and applying the same translations, rotations, and scale changes to the hyperspectral data. Plastics detection was based on statistically relevant feature selection and Linear Discriminant Analysis, trained on a manually labeled sample. The results obtained from the inspection of either the beach site or the sea water facing the beach clearly show the successful separate identification of polyethylene (PE) and polyethylene terephthalate (PET) objects through the post-processing data treatment based on the developed classifier algorithm. As a further implementation of the procedure described, direct real-time processing, by an embedded computer carried onboard the drone, permitted the immediate plastics identification (and visual inspection in synchronized images) during the UAV survey, as documented by short video sequences provided in this research paper.

A Studying the Possibility of Estimating Soil Organic Carbon of Soils Under PINUS BRUTIA and QUERCUS AEGILOPS L. Trees in Sarke-Duhok By Using ASD FieldSpec 3 Spectroradiometer

Visible and Near-infrared (VNIRS) spectroscopy is a very fast non-destructive and environmentally friendly analytical technique. It has been suggested as an alternative to conventional methods for assessing and monitoring soil quality. Accurate VNIRS prediction of soil organic carbon (SOC) has been reported by many researchers in different world regions. Sixteen surface soil samples (0-30cm depth) from Sarke - Duhok were collected, eight samples under Zawita Pine (Pinus brutia) and the other eight-under oak (Quercus aegilops L.) trees. Soil colour was measured in the field and soil samples were air-dried and sieved by using a 2.0 mm sieve and analyzed in the laboratory to estimate the PH, EC, CaCo3, texture, and SOC according to Walkley and Black methods. Laboratory reflectance spectra were acquired for each sample from 350 to 2500 nm by using the Analytical Spectral Device (ASD) FieldSpec 3spectroradiometer for each of the different spectrum bands (410, 570, 660, 849, 1543 and 2187nm). Results showed that the reflectivity values of soil under both Oak and Pine trees in the IR region (849, 1543, 2187nm) were almost more than that at the visible portion (410,570, 660nm). Also, the determination coefficient (R2) results indicated that the bands 570, 1543 and 2187nm showed significant relationships between soil reflectivity and SOC% under Oak trees, R2 was 58.2 %, 89.9%, and 93.9% respectively. While under the Pine tree, the only band that showed a significant relationship was band 1543nm, its R2 was 58.3%. From the current results, as the main objectives, it is obvious that the ASD FieldSpec 3 spectroradiometer is quite an efficient and un-destructive tool that can be used for SOC estimation under Oak & pine trees especially at the IR spectrum (band 1543nm). The relationship between the variables was moderately strong; R2 was 89.88 and 58.3 alternatively. The standard error was low (0.0399, 0.0185), which indicates that the predicted values are close to the real values. Besides that, under Oak trees results indicated that there was a high R2 between the variables at bands 570 & 2187 nm, the R2 values were 58.21 and 93.92, alternatively.