The article investigates four automatic gravimeters Scintrex CG-5. With reference to the measurements of the gravimetric calibration base set up in Lithuania, linear scale coefficients and the ...character of changes in the linear scale coefficients of gravimeters were estimated. The paper examines the vertical gradient of gravity acceleration in the eight-floor building, evaluates the range of changes into gravimeter drifts under laboratory conditions and describes daily gravimeter drift during gravimetric measurements.
Santrauka
Atlikti keturių Scintrex CG-5 gravimetrų tyrimai. Remiantis gravimetrinės bazės, įrengtos Lietuvos teritorijoje, matavimų duomenimis, nustatyta gravimetrų kalibravimo koeficientai ir jų kitimo pobūdis. Atlikti sunkio pagreičio vertikaliojo gradiento aštuonių aukštų pastate tyrimai. Laboratorinėmis sąlygomis nustatytas gravimetrų paros nulio slinkties kitimo diapazonas. Atlikti gravimetrų nulio slinkties matavimų metu tyrimai.
Резюме
Проведены исследования четырех гравиметров Scintrex CG-5. На основании измерений гравиметрической базы, находящейся на территории Литвы, получены коэффициенты калибровки гравиметров. Проведены исследования вертикального градиента ускорения силы тяжести в восьмиэтажном здании. Определен диапазон изменения лабораторного суточного смещения нуль-пункта гравиметров. Также оценено смещение нуль-пункта гравиметров во время измерений гравиметрической базы.
Estimation of the 1:200 000 scale gravimetric map of Bouguer anomalies of the Lithuanian territory was done. It based on gravity measurements at the Lithuanian gravimetric network points. Totally the ...gravity accelerations of 686 points were used for the estimation. Their accuracy is betetr than 9 μGal. It was detected areas in which gravity acceleration, calculated from the map, has the sistematic errors. The average difference between Potsdam gravity system, used in the map, and IGSN 71 system, defined by the absolute gravity measurements in the Lithuanian gravimetric network, was obtained. Article in Lithuanian Lietuvos teritorijos gravimetrinio žemėlapio tikslumo vertinimas Santrauka. Remiantis matavimų, atliktų Lietuvos gravimetrinio tinklo punktuose, duomenimis, įvertintas Lietuvos teritorijos 1:200 000 mastelio Bouguer anomalijų gravimetrinio žemėlapio tikslumas. Vertinimui naudota 686 gravimetrinių punktų sunkio pagreičio reikšmės, kurių vidutinė kvadratinė paklaida neviršija 9 μGal. Nustatytos teritorijos, kuriose sunkio pagreitis, apskaičiuotas pagal žemėlapį, turi sistemingąsias paklaidas. Gautas vidutinis skirtumas tarp žemėlapyje taikomos Potsdamo sunkio sistemos ir IGSN 71 sistemos, apibrėžtos Lietuvos gravimetriniame tinkle atliktais absoliučiaisiais gravimetriniais matavimais. Reikšminiai žodžiai: gravimetrinis žemėlapis, gravimetrinių žemėlapių tikslumas, sunkio sistemos, gravimetriniai matavimai.
The decrease of the pH of the concrete due to the interaction with the CO
2 contained in the air creates an electrolyte in the pores with a pH
<
8 that destroys the passive film. Also the presence of ...chloride ions at the rebar surface in alkaline media making susceptible to the aggression of the chlorides as pollutant in marine environment. The inhibiting efficiency of Na
3PO
4 against corrosion of carbon steel in alkaline medium simulating the interstitial solution of the concrete (pH 12.5) polluted with chloride ions were carried out. Two manners for adding the Na
3PO
4 were examined: one where the inhibitor was added into the pore solution also containing the aggressive solution, and other where the rebar was first pre-treated by immersion in the inhibitor solution. The protective effectiveness of these two procedures for the inhibitor addition was evaluated by means of several electrochemical techniques, EIS, polarisation curves and microbalance.
The results allow concluding that:
•
The pre-passivation procedure is more effective for the rebar protection.
•
The impregnation duration of steel in phosphate solution and the electrode rotation speed influence considerably the phosphate-based film resistance against corrosion.
Moisture uptake of a benzocyclobutene (BCB) film has been investigated by using the capacitance-time (C-t) measurement method. The change in the permittivity at 80% relative humidity (RH) at room ...temperature in saturation is about 1.54%. To derive the absolute amount of water molecules from the change in capacitance an appropriate electrical model is required. For the direct measurement of the amount of water molecules in the BCB film gravimetric measurements have been performed at the same environmental conditions by using a quartz crystal microbalance (QCM). In saturation the change in mass induced by the moisture uptake is only about 0.14%. However, the application of the Debye equation using the dipole moment of water vapor yielded an excellent agreement between electrical and physical measurements.
Based on gravimetric measurements, a model describing the interdependence between the ammonia and water sorption in polyacrylic acid (PAA) is developed. The starting point is the fact that PAA-coated ...quartz microbalances (QMBs) show significant frequency shifts under exposure to ammonia and humidity. The response of the devices suggests that the mass increase under ammonia exposure, in humid air, is due to both the absorbed ammonia and the additionally absorbed water. At low humidity levels the ammonia changes the polymer matrix so that more water molecules can be absorbed. If the humidity is increased a glassy-to-rubbery state transition occurs that leads to a complex response of PAA-QMBs.
Effect of peracetylated β-cyclodextrin on the solubility of diphenyl(4-phenylphenyl)phosphine in supercritical carbon dioxide medium has been investigated. As shown by gravimetric measurements, the ...presence of cyclodextrin (CD) (1 equivalent) allows to increase the solubility of phosphine (P) in supercritical carbon dioxide (scCO
2) (40
°C, 35.2
MPa, nominal system density 0.89
g/mL). This solubility enhancement was attributed to host–guest interactions in scCO
2 as the P was recovered in the form of an inclusion complex. Furthermore, a diffuse reflectance spectroscopy study on the samples recovered after the experiments and on various CD/P solid mixtures obtained by co-grinding indicates that the (4-phenylphenyl) group of the P was included in the host cavity of the peracetylated β-CD.
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