Conversion from dose-length product to effective dose in computed tomography venography of the lower extremities

For radiation dose assessement of computed tomography (CT), effective dose (ED) is often estimated by multiplying the dose-length product (DLP), provided automatically by the CT scanner, by a conversion factor. We investigated such conversion in CT venography of the lower extremities performed in conjunction with CT pulmonary angiography. The study subjects consisted of eight groups imaged using different scanners and different imaging conditions (five and three groups for the GE and Siemens scanners, respectively). Each group included 10 men and 10 women. The scan range was divided into four anatomical regions (trunk, proximal thigh, knee and distal leg), and DLP was calculated for each region (regional DLP). Regional DLP was multiplied by a conversion factor for the respective region, to convert it to ED. The sum of the ED values for the four regions was obtained as standard ED. Additionally, the sum of the four regional DLP values, an approximate of the scanner-derived DLP, was multiplied by the conversion factor for the trunk (0.015 mSv/mGy/cm), as a simplified method to obtain ED. When using the simplified method, ED was overestimated by 32.3%−70.2% and 56.5%−66.2% for the GE and Siemens scanners, respectively. The degree of overestimation was positively and closely correlated with the contribution of the middle and distal portions of the lower extremities to total radiation exposure. ED/DLP averaged within each group, corresponding to the conversion factor, was 0.0089−0.0114 and 0.0091−0.0096 mSv/mGy/cm for the GE and Siemens scanners, respectively. In CT venography of the lower extremities, ED is greatly overestimated by multiplying the scanner-derived DLP by the conversion factor for the trunk. The degree of overestimation varies widely depending on the imaging conditions. It is recommended to divide the scan range and calculate ED as a sum of regional ED values.

Addition of Ginseng (Withania Somnifera) To the Diet and Its Effect on Productive Performance for Broilers Raised with Two Different Densities: إضافة الجينسنغ (Withania somnifera) إلى العليقة وتأثيره في الأداء الإنتاجي لفروج اللحم المربى بكثافتين مختلفتين

The study was conducted to find out the effect of adding ginseng root powder (Withania somnifera) at (0, 1.5 and 3.0) g/kg under two densities of breeding (12 and 17) birds/m2 on performance, economic indicators. Chicks were raised from the age 1 day-42 and distributed to the treatments at the second week in T1:12 bird\m2 +0%, T2:12 bird\m2 +1.5%,T3:12 bird\m2 +0.3%,T4:17bird\m2+0%,T5:17bird\m2+ 1.5%,T6:17 bird \m2 +0.3%.The statistical analysis showed that there was no significant difference in density in body weight, weight gain, relative growth, feed conversion factor, production index, production coefficient,while the density was 12 birds/ m2 superior in consumption The feed density of 17 birds/m2 gave a higher productivity in kg/m2 compared to 12 birds/m2. The addition of ginseng did not affect the weight gain, relative growth, conversion factor, index, production coefficient, productivity yield in kg/m2, while there was a superiority of adding (1.5 and 3.0) g of ginseng compared with no addition in live body weight and in Feed consumption and production factor and in the effect of the interaction there were no significant differences in the weight gain, growth, feed consumption, evidence and production factor, while we note that the interaction(12 birds/ m2+1.5 gm ginseng) gave the highest body weight and a significant improvement in the feed conversion factor for the addition of (1.5 and 3.0) gm under the influence of breeding density 17 birds/m2 and the productivity yield exceeded kg/m2.

Developing and Investigating the Analyzers of Kinematic Viscosity and Density of Petroleum Products on Throttle Bridge Transducers

Measuring the viscosity and density of petroleum products is important for their proper production, transportation and application. Viscosity and density are the main parameters determining the composition and structure of petroleum products. Therefore, in the industry, to control the quality of petroleum products during various technological processes, automatic and non-automatic devices are used for their measurement. The accuracy of measuring the viscosity and density of petroleum products is an important factor. The authors analyzed different methods of measuring the viscosity and density of petroleum products and synthesized three versions of throttle bridge transducers. These versions implement differential measurement methods and have different numbers of laminar and turbulent throttles. The authors obtained new equations of static conversion functions by channels of measuring the kinematic viscosity and density of petroleum products of the proposed throttle bridge transducers. The authors developed a block diagram and designed measuring equipment to study experimentally the static characteristics of the throttle bridge transducers. The authors determined that the maximal relative deviations of the results of experimental studies from numerical calculations of a static conversion factor by channels of kinematic viscosity and density were 5.88% and 8.76%, respectively. The authors developed two versions of automatic devices for measuring the kinematic viscosity and density of petroleum products based on the proposed throttle bridge transducers. The first version is an automatic analyzer with tracking astatic balancing. The second version is an automatic analyzer with deployment balancing. The authors developed constructions of both versions of automatic analyzers and obtained the results of experimental measuring of the kinematic viscosity and density of petroleum products in different ranges.

Energy/Exergy Conversion Factors of Low-Enthalpy Geothermal Heat Plants

From the system perspective, a geothermal heat plant is not only a source of heat, but, in case of liquid producing wells producing liquid brine, also a sink for relevant amounts of electricity, consumed mainly by the pump(s). This electricity demand is usually not given much attention, although being decisive for operation costs and offering chances for demand side management as a variable consumer. From the perspective of an integrated energy system, geothermal installations basically move energy from the electricity sector into the heat sector. So do electrical compression heat pumps, whose performance is rated by the COP, the ratio between useful heat and invested energy and useful heat, the COP. This study transfers the COP concept to geothermal sites, by defining and determining the energy conversion factor quantity (i.e. relative auxiliary energy or operating cost of heat provision expressed in electricity) for a selection of mostly German geothermal sites. Based on heterogenous data consisting of operational values for some sites and theoretical estimations for others, the calculated ε range from 12 to 116. In analogy, the concept is extended to the exergy conversion factor ζ, which is calculated to range from 1 to 36. A comparison with alternative heat provision technologies, such as heat pumps (COP ≤ 6) or simple electric heating (ε ≈ 1), quantifies the potential service geothermal plants can render to the grid by converting electrical energy into useful heat. This study aims at quantifying the potential benefit of geothermal plants on for the electric grid.

Исследование градуировочной характеристики турбинных преобразователей расхода жидкости типа MVTM

Most of the failures of turbine flow converters (TFC) used in the Russian system of main oil pipelines and oil product pipelines are caused by abrupt changes in the viscosity of the transported medium. In studies related to determination of the influence of the rheological properties of the pumped oil on the metrological characteristics of TFC that have a calibration curve in the form of a piecewise approximation without taking into account the correlation of TFC rotor speed with the viscosity of the pumped liquid in the flow rate subrange, the instability of the metrological characteristics in the operating range is observed. Taking into account the tendency to increase the volume of production and pumping of high-viscosity oils it can be assumed that the irregularity of the metrological characteristics of TFC, expressed in the change in the conversion factor will remain, which will negatively affect the reliability of accounting operations using oil quality control system (OQCS). Accordingly there is a need to maintain the error of TFC within the set limits in the subranges and throughout the entire range of flow rates. According to the results of the study performed by the authors it was confirmed that for the TFC of MVTM type the use of the calibration curve in the form of a piecewise-parabolic approximation with the dependence of the conversion factor on the ratio of TFC pulse frequency to the oil viscosity makes it possible to minimize the effect of changes in the parameters of the pumped medium on the measurement accuracy and as a consequence to stabilize the metrological characteristics of TFC in the recalibration interval, eliminate the costs of performing out-of-turn verifications, increase the accuracy and metrological reliability of the OQCS. Большинство отказов турбинных преобразователей расхода (ТПР), используемых в российской системе магистральных нефтепроводов и нефтепродуктопроводов, обусловлено резкими изменениями вязкости транспортируемой среды. В исследованиях по определению влияния реологических свойств перекачиваемой нефти на метрологические характеристики ТПР, имеющих градуировочную характеристику в виде кусочно-линейной аппроксимации без учета корреляции частоты вращения ротора ТПР с вязкостью перекачиваемой жидкости в поддиапазоне расхода, отмечается нестабильность метрологических характеристик в рабочем диапазоне. Учитывая тенденцию увеличения объема добычи и перекачки высоковязких нефтей, можно предположить, что непостоянность метрологических характеристик ТПР, выражаемая в изменении коэффициента преобразования, сохранится, что негативно скажется на достоверности учетных операций с применением систем измерений количества и показателей качества нефти (СИКН). Соответственно, возникает потребность в поддержании погрешности ТПР в установленных пределах в поддиапазонах и во всем диапазоне расходов. По результатам проведенного авторами исследования подтверждено, что для ТПР типа MVTM использование градуировочной характеристики в виде кусочно-параболической аппроксимации с зависимостью коэффициента преобразования от отношения частоты импульсов ТПР к вязкости нефти позволяет минимизировать влияние изменений параметров перекачиваемой среды на точность измерений и, как следствие, стабилизировать метрологические характеристики ТПР в межповерочном интервале, исключить затраты на выполнение внеочередных поверок, повысить точность и метрологическую надежность СИКН.

Surface EMG-based Quantification of Inspiratory Effort: A Quantitative Comparison with Pes

Background Inspiratory patient effort under assisted mechanical ventilation is an important quantity for assessing patient-ventilator interaction and recognizing over and under assistance. An established clinical standard is respiratory muscle pressure Pmus, derived from esophageal pressure (Pes), which requires the correct placement and calibration of an esophageal balloon catheter. Surface electromyography (sEMG) of the respiratory muscles represents a promising and straightforward alternative technique, enabling non-invasive monitoring of patient activity. Methods A prospective observational study was conducted with patients under assisted mechanical ventilation, who were scheduled for elective bronchoscopy. Airway flow and pressure, esophageal/gastric pressures and sEMG of the diaphragm and intercostal muscles were recorded at four levels of pressure support ventilation. Patient efforts were quantified via the Pmus–time product (PTPmus), the transdiaphragmatic pressure–time product (PTPdi) and the EMG–time products (ETP) of the two sEMG channels. To improve the signal-to-noise ratio, a method for automatically selecting the more informative of the sEMG channels was investigated. Correlation between ETP and PTPmus was assessed by determining a neuromechanical conversion factor KEMG between the two quantities. Moreover, it was investigated whether this scalar can be reliably determined from airway pressure during occlusion maneuvers, thus allowing to quantify inspiratory effort based solely on sEMG measurements. Results In total, 62 patients with heterogeneous pulmonary diseases were enrolled in the study, 43 of wich were included in the data analysis. The ETP of the two sEMG channels was well correlated with PTPmus (r=0.79±0.25 and r=0.84±0.16 for diaphragm and intercostal recordings, respectively). The proposed automatic channel selection method improved correlation with PTPmus (r=0.87±0.09). The neuromechanical conversion factor obtained by fitting ETP to PTPmus varied widely between patients (KEMG=4.32±3.73 cmH2O/μV) and was highly correlated with the scalar determined during occlusions (r=0.95, p<.001). The occlusion-based method for deriving PTPmus from ETP showed a breath-wise deviation to PTPmus of 0.43±1.73 cmH2Os across all datasets. Conclusion These results support the use of surface electromyography as a reliable non-invasive alternative for monitoring breath-by-breath inspiratory effort of patients under assisted mechanical ventilation.