Ray Attenuation Method Research Articles

On-line measurement of ultralow mass concentration particulate based on light scattering coupled with beta ray attenuation method

Light scattering method is the most commonly used method for on-line measurement of ultralow particulate matter mass concentration. However, when the particle characteristics change, the effectiveness of the empirical relationship decreases, which would lead to a sizeable deviation. To accurately measure the mass concentration of particulate matter in real-time, a coupling measurement idea of light scattering and beta-ray attenuation is proposed. The beta-ray attenuation is little affected by particle properties and accurately reflects the average PM mass concentration in the measured period. The single calibration method (M1), periodic calibration method (M2), average calibration method (M3), and asymmetric factor calibration method (M4) are formed based on the coupling idea. The results of all methods are perfect when the particle size is unchanged. However, when the particle sizes fluctuate frequently, the results of M1, M2, and M3 deviate seriously from the actual value, and the applicable working conditions have limitations. The results of M4 are in good agreement with the actual value, and the effectiveness is not limited by the particle size. Finally, the prototype based on experimental exploration was developed and had been continuously operated for more than 528 h at a 1000 MW unit of a coal-fired power plant.

Relationships between Meteorological and Particulate Matter Concentrations (PM2.5 and PM10) during the Haze Period in Urban and Rural Areas, Northern Thailand

Meteorological parameters play a crucial role in the ambient air quality of urban and rural environments. This study aims to investigate the relationship between meteorological parameters (including temperature, relative humidity, and wind speed) and the concentrations of PM2.5 and PM10 in the urban area and the rural area, northern Thailand during the haze period (January to April) from 2016 to 2020. Statistical analyses of the Spearman-Rank correlation coefficient and the multivariate gaussian regression were used to investigate the relationships. The secondary data of ambient PM2.5 and PM10 concentration and meteorological parameters were acquired from the Thai Pollution Control Department. The measurements are obtained using the Beta Ray attenuation method. The results showed that approximately 24% to 65% of daily average PM2.5 concentrations in the urban area over the study period exceeded Thailand’s National Ambient Air Quality Standards. The average PM2.5/PM10 ratios in the urban and the rural areas over the haze period were 0.69 and 0.66, respectively. Our analysis established a significant correlation between atmospheric temperature ( r = 0.624) and relative humidity ( r = −0.722) with the concentrations of PM2.5 and PM10. In both areas, PM2.5 and PM10 concentrations were also positively correlated with temperature. In contrast, relative humidity was significantly related with the decrease of PM2.5 and PM10 concentrations. However, wind speed does not affect PM2.5 and PM10 concentrations. Additionally, the daily backward trajectories using the hybrid-single particle Lagrangian integrated trajectory model also demonstrated air mass movement in March mostly came from the southwesterly direction, which moved through the highlands, the large biomass burned areas, upwind neighboring provinces, and transboundary transports before reaching the air monitoring stations. Our findings improve the understanding of particulate matter pollution and meteorological patterns during annual haze periods in the urban and rural areas. We expect the output of this study can help improve existing haze mitigation measures for improving the prediction accuracy of air pollution under variable meteorological parameters.

On-Line Measurement of Ultralow Mass Concentration Particulate Based on Light Scattering Coupled with Beta Ray Attenuation Method

On-Line Measurement of Ultralow Mass Concentration Particulate Based on Light Scattering Coupled with Beta Ray Attenuation Method

Optimizing vertical profile measurements setup of gamma ray attenuation

Abstract: For undisturbed measurements of material properties, the gamma ray attenuation (GRA) method is a commonly used approach, e.g. in soil sciences. So far, various setups of the GRA method are applied depending on specific purposes. For accurate measurements, statistical error due to radioactive decay must be considered. In addition, a careful setting of the further involved parameters such as collimator size, the distance between source and detector as well as the measuring time need to be taken into account. In this study, a method to optimize GRA measurements is presented by relating measuring time and collimator selection to the statistical error of radiation. As a result, a method for choosing the optimum collimator size and a mathematical equation for optimizing the measuring time are derived, which is helpful for planning the vertical profile measurement in terms of required time and spatial resolution.

A new model for volume fraction measurements of horizontal high-pressure wet gas flow using gamma-based techniques

The accurate predictions of void fraction and gas volume fraction are important in characterizing wet gas flow, as they are the basic input for determining other key flow parameters, such as flow velocity and flow rate of each phase. In previous studies, empirical relationships were used to predict void fraction and gas volume fraction, which have limited applicability due to the lack of detailed structural and dynamic information involved in two-phase flow. Hence, in this work, attempts are being made to develop a model based on a simplified two-phase interfacial structure. A slip ratio based equal-diameter double-circle model is proposed to predict the void fraction and gas volume fraction using gamma ray attenuation method for high-pressure wet gas conditions. Model predictions were verified against experiments in a 172.0 mm inner diameter horizontal pipe. Nitrogen and kerosene were used as the test fluids with gas volume fractions ranging from 92% to 100%. The relative errors in the line-averaged void fraction predicted by the slip ratio based model were within ±2%. In addition, this model can be used to explain the relationship between the key flow parameters and further to predict the optimal measuring angle of the gamma rays. The line-averaged void fraction measured by the gamma ray attenuation method at a proper angle predicted by the model is equal to the gas volume fraction for these high-pressure wet gas conditions, with an average relative error of 0.2%.

Experimental and ab initio molecular dynamics study of the structure and physical properties of liquid GeTe

GeTe is a prototypical phase-change material employed in data storage devices. In this work, the atomic structure of liquid GeTe is studied by x-ray and neutron diffraction in the temperature range from 1197 to 998 K. The dynamic viscosity is measured from 1273 to 953 K, which is 55 K below the solidification point, using an oscillating-cup viscometer. The density of liquid GeTe between 1293 and 973 K is determined by the high-energy $\ensuremath{\gamma}$-ray attenuation method. The experiments are complemented with ab initio molecular dynamics (AIMD) simulations based on density functional theory (DFT). Compatibility of the AIMD-DFT models with the diffraction data is proven by simultaneous fitting of all data sets in the frame of the reverse Monte Carlo simulation technique. It is shown that octahedral order dominates in liquid GeTe, although tetrahedral structures are also present. The viscosity of the equilibrium and weakly undercooled liquid GeTe obeys the Arrhenius law with a small activation energy of the order of 0.3 eV, which is indicative of a highly fragile liquid. The calculated density of states and electronic wave functions point to the existence of a pseudogap and localized electron states within the gap in the equilibrium liquid near the melting point as well as in the undercooled liquid.

Impact of accelerated carbonation on OPC cement paste blended with fly ash

Cement is a huge carbon dioxide producer. Supplementary cementitious materials can help reduce this outcome. However, carbonation of these blended cements remains an active subject of research. Accelerated carbonation tests (10% CO2, 25°C and 62% RH) are performed on fly ash blended cement pastes. Experiments are performed at varying ages of carbonation (1 to 16weeks) to measure the evolution of the carbonation depth over time and to quantify key parameters: thermogravimetric analysis (TGA), mercury intrusion porosimetry (MIP) and gamma ray attenuation method (GRAM). The total porosity decreases with a rearrangement of the microstructure due to carbonation and the creation of big capillary pores for the paste with the highest contents of fly ash (60vol.%). The C-S-H molar volume evolution during fly ash-blended cement carbonation is calculated using a method combining MIP, TGA and GRAM formerly successfully applied to OPC paste in a paper published in the same journal.

Thermo physical properties of wrought aluminum alloys 6061, 2219 and 2014 by gamma ray attenuation method

The temperature dependence of linear attenuation coefficient, density and thermal expansion of 6061, 2219 and 2014 aluminum alloys have been studied by gamma ray attenuation technique in the temperature range 298–773K. The gamma ray attenuation studies have been carried out using a gamma ray densitometer fabricated in our laboratory. The linear attenuation coefficients (μl) for the alloys as a function of temperature and the coefficients of temperature dependence of density have been reported. The variation of density and thermal expansion of these alloys have been represented by linear equations. Volume thermal expansion coefficients have been reported.

Temperature Dependence of Density and Thermal Expansion of Wrought Aluminum Alloys 7041, 7075 and 7095 by Gamma Ray Attenuation Method

The gamma quanta attenuation studies have been carried out to determine mass attenuation coefficients of 7041, 7075 and 7095 wrought aluminum alloys. The temperature dependence of linear attenuation coefficient, density and thermal expansion of these wrought aluminum alloys in the temperature range 300 K - 850 K have been reported. The measurements were done by using a gamma ray densitometer designed and fabricated in our laboratory. The data on variation of density and linear thermal expansion with temperature have been represented by linear equations. Volume thermal expansion coefficients have been reported.

Density of Molten Terbium Chloride

The density of molten terbium chloride at 993 to 1213 K, as measured by the γ -ray attenuation method, is found to be d = [3.937±0.028−(4.76±0.25) · 10−4T] g/cm3. The characteristic state parameters of molten TbCl3 are found to be 1129 K and 78.0 ml for T* and ν*, respectively.

Volumetric effects of ZnTe, CdTe and HgTe compounds at melting and subsequent heating

The temperature dependence of the density of CdTe, ZnTe and HgTe compounds was studied by means of the γ– ray attenuation method both in solid and liquid states. A decrease in the density in the course of the crystal → melt phase transition and subsequent heating for ZnTe and CdTe is obtained. The volume effect during the HgTe melting is negative. According to our evaluations, the increase of the external pressure should result in an increase of the fusion temperature for ZnTe and CdTe. The dT/dP coefficient of the HgTe at the melting point is negative. The density of the molten HgTe compound changes along a curve with a maximum. This anomaly is explained by the thermal dissociation of the HgTe with the formation of 2 complex associates in the liquid phase. The thermal expansion of the Zn and Cd tellurides is considered on the basis of the characteristics of the interatomic bonds strength.

Localized two liquids phase and non-metal-metal transition in the liquid STe system

Molar volume has been determined on the liquid STe system using a high energy gamma ray attenuation method. Overall dependence on temperature and concentration of the volume is quite similar to that reported for the liquid SeTe system. However anomalous behaviour was observed for S 40Te 60. The volume irregularly decreases around 680° C and recovers again around 740° C to the value extrapolated from the low temperatures, where a meniscus appears in the alloy. It has been found that the two liquids phase boundary is closed. The appearance of the lower and upper critical solution temperatures is discussed in relation to the structural change and the non-metal-metal transition in the liquid S, SeTe mixtures.

Trabecular osteopenia in Colles' fracture.

Bone density was measured in 23 postmenopausal women with Colles' fracture. Trabecular spine density was measured by quantitative computed tomography. The bone mineral density in the distal radius and in the diaphysis of the radius and ulna was measured by the gamma ray attenuation method. Compared with age-matched controls, the patients were found to have reduced trabecular bone mass in the spine and distal radius, but no osteopenia in the diaphysis of the radius and ulna. The mean age-corrected decrease was 0.7 SD in the spine and 0.5 SD in the distal end of the radius. The results suggest that patients with Colles' fracture have trabecular but not cortical osteopenia.

Cadmium Content of Human Cancellous Bone

The cadmium content of human cancellous bone was related to age, sex, bone loss, physical properties, and elemental composition. Bone specimens from the anterior iliac crest were collected from 889 cadavers with a normal mineral status, and from 50 cadavers which had bone loss from chronic diseases and immobilization. The element concentrations were analyzed using atomic absorption spectrophotometry. Bone fluoride levels ere determined with the ion specific electrode, the mineral density with the gamma ray attenuation method, and the compressive strength with a strain transducer. The data were analyzed using multiple linear regression analysis. The mean cadmium content of 0.22 +/- 9.16 micrograms/g dry weight (+/- SD) in the samples did not change with age and its content was slightly greater in males than in females. Furthermore, no statistically significant relation was found in cadmium content to bone loss changes or to the calcium content of bone. The cadmium content had a high statistically significant positive correlation with the strontium and nickel content.

Lactose malabsorption and bone mineral content.

ABSTRACT Bone mineral has been measured by the Am‐241 gamma ray attenuation method in 12 men and 22 women with lactose malabsorption and in 17 men and 17 women with normal lactose absorption, and compared with previously established normal values. Although lactose malabsorption led to reduced milk consumption and calcium intake, it did not cause osteoporosis.

Bone mineral content of the forearm in a healthy population.

The bone mineral content in the distal radius, in the midshaft radius and ulna was measured in 83 healthy males and 89 females from 11 to 87 years old using the 241Am gamma ray attenuation method. The age distributions of different 'density' quantities characterizing bone mineral are presented and the usefulness of these quantities is discussed.

Bone Mineral Density in Patients with Urolithiasis

The bone mineral density (g/cm3) of the distal cancellous radius was determined in a consecutive series of 21 women and 54 men with urolithiasis with the Americium-241 gamma ray attenuation method. Bone mineral density was statistically significantly lower in both sexes compared with coeval healthy subjects. Further study is needed to examine the relationship between the bone mineral density and disturbances in calcium metabolism in patients with renal stone disease.

The Influence of Calcium and Calcium + Vitamin D2Treatment on Bone Mineral after Partial Gastrectomy

Sixty-three men and 23 women who had undergone partial gastrectomy for ulcer disease were randomized into three groups to study the effect of calcium (2 g per day) and calcium + vitamin D2 (1000 IU calciferol per day) treatment for eight months on bone mineral. The Americium-241 gamma ray attenuation method was used to measure the changes in bone mineral density. Calcium and calcium + vitamin D2 increased the bone mineral density statistically significantly in the males, but not in females. Partial gastrectomy causes bone rarefaction, and consequently these patients reach the risk level of bone mineral density for osteoporotic fractures earlier than healthy subjects. The conclusion drawn was that prophylactic treatment is needed after partial gastrectomy. Further study is required, especially of women, to find the most suitable form of treatment for disturbances in bone mineral metabolism after gastric resection.

Thenar muscle blood flow and bone mineral in the forearms of lumberjacks.

Forty lumberjacks who had used a chain saw for 0-20 years and who had no general disease affecting the bones were studied by measuring the thenar muscle blood flow of both hands by the 133-Xe local clearance method. Bone mineral in the left forearm in the region of cancellous and cortical bone was assessed by the 241-Am gamma ray attenuation method. Virbration was found to decrease the blood flow in the saw-bearing left hand compared with the right hand of the lumberjacks. The bone mineral density (g/vm-3) was lower in the forearm bones of the lumberjacks than in controls of the same age with healthy bones. Moreover the poorer the thenar muscle blood flow, the greater was the decrease in the mineral density of the distal radius. Measurement of the mineral density of the forearm bones by the gramma ray attenuation method can be used for early detection of bone lesions in traumatic vasospastic disease.

Bone Mineral after Partial Gastrectomy I

The bone mineral content estimated by gamma ray attenuation method, serum calcium, phosphorus, alkaline phosphatase, and protein was examined in three types of patients with peptic ulcer. The bone mineral content in ulcer patients before surgery did not differ from that of the control series. In patients subjected to 1/3 gastric resection and Billroth I reconstruction with or without selective vagotomy 3.3-8.5 years previously, and in patients subjected to 2/3 gastric resection with Billroth II reconstruction 15-18 years earlier, the mineral density of bone was found to be lower than in a control series of matched age and sex. The mineral loss developed sooner in women than in men. Low serum calcium values were met most often in patients examined 3.3 to 8.5 years after surgery. The serum alkaline phosphatase level increased after surgery. However, there was no difference in bone mineral density in patient groups with low calcium or high alkaline phosphatase, compared with patients with normal values. In conclusion, gastric resection of 1/3 or 2/3 of the stomach, with or without vagotomy, using gastroduodenostomy or gastroenterostomy as the reconstruction, results in a lowering of bone mineral density. This decrease, however, was not found to have caused symptoms injurious to the health of patients examined in this study.