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Background: The limited spatial resolution in SPECT images leads to partial volume effect (PVE), degrading the subsequent dosimetric accuracy. We aim to quantitatively evaluate PVE and partial volume corrections (PVC), i.e., recovery coefficient (RC)-PVC (RC-PVC), reblurred Van-Cittert (RVC) and iterative Yang (IY), in 177Lu-PSMA-617 SPECT images. Methods: We employed a geometrical cylindrical phantom containing five spheres (diameters ranging from 20 to 40 mm) and 40 XCAT phantoms with various anatomical variations and activity distributions. SIMIND Monte Carlo code was used to generate realistic noisy projections. In the clinical study, sequential quantitative SPECT/CT imaging at 4 time-points post 177Lu-PSMA-617 injections were analyzed for 10 patients. Iterative statistical reconstruction methods were used for reconstruction with attenuation, scatter and geometrical collimator detector response corrections, followed by post-filters. The RC-curves were fit based on the geometrical phantom study and applied for XCAT phantom and clinical study in RC-PVC. Matched and 0.5-2.0 voxels (2.54–10.16 mm) mismatched sphere masks were deployed in IY. The coefficient of variation (CoV) was measured on a uniform background on the geometrical phantom. RCs of spheres and mean absolute activity error (MAE) of kidneys and tumors were evaluated in simulation data, while the activity difference was evaluated in clinical data before and after PVC. Results: In the simulation study, the spheres experienced significant PVE, i.e., 0.26 RC and 0.70 RC for the 20 mm and 40 mm spheres, respectively. RVC and IY improved the RC of the 20 mm sphere to 0.37 and 0.75 and RC of the 40 mm sphere to 0.96 and 1.04. Mismatch in mask increased the activity error for all spheres in IY. RVC increased noise and caused Gibbs ringing artifacts. For XCAT phantoms, both RVC and IY performed comparably and were superior to RC-PVC in reducing the MAE of the kidneys. However, IY and RC-PVC outperformed RVC for tumors. The XCAT phantom study and clinical study showed a similar trend in the kidney and tumor activity differences between non-PVC and PVC. Conclusions: PVE greatly impacts activity quantification, especially for small objects. All PVC methods improve the quantification accuracy in 177Lu-PSMA SPECT. [ABSTRACT FROM AUTHOR]

Abstract Introduction This study aims to evaluate the use of CT-based whole kidney parenchyma (WKP) segmentation in 177Lu-DOTATATE dosimetry. Specifically, it investigates whether WKP volumes change during treatment and evaluates the accuracy of applying a single delineated WKP volume for dosimetry. Furthermore, it aims to determine the cause of WKP volume changes—whether caused by radiation or amino acid infusion—by comparing them with spleen volume changes as a marker for radiation-induced alterations. Methods SPECT/CT images of 18 patients were acquired over the abdomen approximately 4 h (h) (D0), 24 h (D1), 48 h (D2) and 168 h (D7) post-administration of 177Lu-DOTATATE. CT guided WKP volumes were measured before (baseline) and during treatment. Kidney activity concentrations at each time point were derived from CT-segmented WKP overlaid on SPECT scans. The accuracy of using WKP segmentation from a single CT for all time points was assessed against the gold standard of segmenting each WKP individually. Time-integrated activity calculations were based on a tri-exponential curve fit of the kidney activity concentration over time. Kidney absorbed doses were estimated under the assumption of local energy deposition. Additionally, the impact of various partial volume correction methods on dosimetry was evaluated. Results Whole-kidney parenchyma (WKP) volumes, ranging from 31 to 243 mL, showed a gradual increase from baseline (mean ± SD = 130.6 ± 46.1 mL) at the initial time points D0 (138.5 ± 44.7 mL) and D1 (139.4 ± 41.6 mL), followed by a slight decrease at D2 (132.8 ± 44.5 mL) and a further decrease at D7 (129.2 ± 42.7 mL). The volume increase at D0 and D1 was statistically significant. Spleen volume did not change during treatment, suggesting that amino acid infusion rather than irradiation effects caused WKP volume changes. Bland-Altman analysis revealed WKP volume biases of 8.77% (D0 vs. BL), 10.77% (D1 vs. BL), 1.10% (D2 vs. BL), and 1.10% (D7 vs. BL), with corresponding uncertainties of 24.4%, 23.6%, 25.4%, and 25.4%, respectively. When WKP segmentation from a single CT is applied across all SPECTs, these WKP volume changes could overestimate the activity concentration and mean absorbed doses up to 4.3% and 2.5%, respectively. The absorbed dose uncertainties using a recovery coefficient (RC) of 0.85 for single-time-point WKP delineation increase the absorbed dose uncertainty by 4% compared to the use of patient-specific RCs and time specific segmentation of WKP volumes. Conclusions Kidney volume exhibited significant variation form D0 to D7, affecting the precision of dosimetry calculation, primarily due to errors in whole-kidney parenchyma (WKP) delineation. Notably, using WKP segmentation from a single CT scan applied to sequential SPECT images introduce further uncertainty and may lead to an overestimation of the absorbed dose. The fluctuations in kidney volume are most likely attributable to amino acid infusion.

Abstract Background Unilateral condylar hyperplasia (UCH) of the mandible is a rare condition characterized by asymmetric growth of the mandibular condyles. Bone scintigraphy with SPECT(/CT) is commonly used to diagnose UCH and guide treatment. Still, varying results have been reported using the traditional threshold of 55%:45% in relative tracer uptake. While absolute quantification of uptake on SPECT/CT could improve results, optimal correction and reconstruction settings are currently unknown. Methods Three anthropomorphic phantoms representing UCH were developed from patient CT volumes and produced using 3D printing technology. Fillable spherical inserts of different sizes (Ø: 8–15 mm) were placed in the condylar positions representing symmetrical and asymmetrical distributions. Recovery coefficients were determined for SPECT/CT using various reconstruction corrections, including attenuation and scatter correction (ACSC), resolution modeling (RM), and partial volume correction (PVC) using phantom measurements. Uptake ratios between condyles and condyle to clivus were evaluated. Finally, the impact of these correction techniques on absolute activity and diagnostic accuracy was assessed in a retrospective patient cohort for the diagnostic threshold of 55%:45%. Results The activity was only partially recovered in all spherical inserts (range: 22.5–64.9%). However, RM improved relative recovery by 20.2–62.3% compared to ACSC. In the symmetric phantoms, the 95% confidence interval (CI) of condyle ratios included the diagnostic threshold (57.6%:42.4%) for UCH when using ACSC potentially leading to false positives, but not for ACSCRM datasets. Partial volume corrections coefficients from the NEMA IQ phantom was positionally dependent, with improvements seen performing PVC using coefficients derived from anthropomorphic phantoms. Retrospective application in a patient cohort showed only a weak linear correlation (R²: 0.25–0.67) and large limits of agreement (9.6–12.5%) between different reconstructions. Up to 44% of patients were reclassified using the 55%:45% threshold. Using clinical outcome data, ACSCRM had highest sensitivity (91%; 95% CI 59–100%) and specificity (66%; 95% CI 47–81%), significantly improving specificity (P = 0.038). Conclusions Anthropomorphic phantoms were shown to be essential in determining optimal settings for acquisition, reconstruction, and analysis. SPECT/CT reconstructions with attenuation and scatter correction and resolution modeling are recommended and could improve specificity when using the 55%:45% threshold to assess condylar growth.

Introduction: This study aims to evaluate the use of CT-based whole kidney parenchyma (WKP) segmentation in 177Lu-DOTATATE dosimetry. Specifically, it investigates whether WKP volumes change during treatment and evaluates the accuracy of applying a single delineated WKP volume for dosimetry. Furthermore, it aims to determine the cause of WKP volume changes—whether caused by radiation or amino acid infusion—by comparing them with spleen volume changes as a marker for radiation-induced alterations. Methods: SPECT/CT images of 18 patients were acquired over the abdomen approximately 4 h (h) (D0), 24 h (D1), 48 h (D2) and 168 h (D7) post-administration of 177Lu-DOTATATE. CT guided WKP volumes were measured before (baseline) and during treatment. Kidney activity concentrations at each time point were derived from CT-segmented WKP overlaid on SPECT scans. The accuracy of using WKP segmentation from a single CT for all time points was assessed against the gold standard of segmenting each WKP individually. Time-integrated activity calculations were based on a tri-exponential curve fit of the kidney activity concentration over time. Kidney absorbed doses were estimated under the assumption of local energy deposition. Additionally, the impact of various partial volume correction methods on dosimetry was evaluated. Results: Whole-kidney parenchyma (WKP) volumes, ranging from 31 to 243 mL, showed a gradual increase from baseline (mean ± SD = 130.6 ± 46.1 mL) at the initial time points D0 (138.5 ± 44.7 mL) and D1 (139.4 ± 41.6 mL), followed by a slight decrease at D2 (132.8 ± 44.5 mL) and a further decrease at D7 (129.2 ± 42.7 mL). The volume increase at D0 and D1 was statistically significant. Spleen volume did not change during treatment, suggesting that amino acid infusion rather than irradiation effects caused WKP volume changes. Bland-Altman analysis revealed WKP volume biases of 8.77% (D0 vs. BL), 10.77% (D1 vs. BL), 1.10% (D2 vs. BL), and 1.10% (D7 vs. BL), with corresponding uncertainties of 24.4%, 23.6%, 25.4%, and 25.4%, respectively. When WKP segmentation from a single CT is applied across all SPECTs, these WKP volume changes could overestimate the activity concentration and mean absorbed doses up to 4.3% and 2.5%, respectively. The absorbed dose uncertainties using a recovery coefficient (RC) of 0.85 for single-time-point WKP delineation increase the absorbed dose uncertainty by 4% compared to the use of patient-specific RCs and time specific segmentation of WKP volumes. Conclusions: Kidney volume exhibited significant variation form D0 to D7, affecting the precision of dosimetry calculation, primarily due to errors in whole-kidney parenchyma (WKP) delineation. Notably, using WKP segmentation from a single CT scan applied to sequential SPECT images introduce further uncertainty and may lead to an overestimation of the absorbed dose. The fluctuations in kidney volume are most likely attributable to amino acid infusion. [ABSTRACT FROM AUTHOR]

Introduction: A newly developed clinical organ-targeted Positron Emission Tomography (PET) system (also known as Radialis PET) is tested with a set of standardized and custom tests previously used to evaluate the performance of Positron Emission Mammography (PEM) systems. Methods: Imaging characteristics impacting standardized uptake value (SUV) and detectability of small lesions, namely spatial resolution, linearity, uniformity, and recovery coefficients, are evaluated. Results: In-plane spatial resolution was measured as 2.3 mm ± 0.1 mm, spatial accuracy was 0.1 mm, and uniformity measured with flood field and NEMA NU-4 phantom was 11.7% and 8.3% respectively. Selected clinical images are provided as reference to the imaging capabilities under different clinical conditions such as reduced activity of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (18F-FDG) and time-delayed acquisitions. SUV measurements were performed for selected clinical acquisitions to demonstrate a capability for quantitative image assessment of different types of cancer including for invasive lobular carcinoma with comparatively low metabolic activity. Quantitative imaging performance assessment with phantoms demonstrates improved contrast recovery and spill-over ratio for this PET technology when compared to other commercial organ-dedicated PET systems with similar spatial resolution. Recovery coefficients were measured to be 0.21 for the 1 mm hot rod and up to 0.89 for the 5 mm hot rod of NEMA NU-4 Image Quality phantom. Discussion: Demonstrated ability to accurately reconstruct activity in tumors as small as 5 mm suggests that the Radialis PET technology may be well suited for emerging clinical applications such as image guided assessment of response to neoadjuvant systemic treatment (NST) in lesions smaller than 2 cm. Also, our results suggest that, while spatial resolution greatly influences the partial volume effect which degrades contrast recovery, optimized count rate performance and image reconstruction workflow may improve recovery coefficients for systems with comparable spatial resolution. We emphasize that recovery coefficient should be considered as a primary performance metric when a PET system is used for accurate lesion size or radiotracer uptake assessments. [ABSTRACT FROM AUTHOR]

Abstract Background Q.Clear, a Bayesian penalized likelihood reconstruction algorithm, has shown high potential in improving quantitation accuracy in PET systems. The Q.Clear algorithm controls noise during the iterative reconstruction through a β penalization factor. This study aimed to determine the optimal β-factor for accurate quantitation of dynamic PET scans. Methods A Flangeless Esser PET Phantom with eight hollow spheres (4–25 mm) was scanned on a GE Discovery MI PET/CT system. Data were reconstructed into five sets of variable acquisition times using Q.Clear with 18 different β-factors ranging from 100 to 3500. The recovery coefficient (RC), coefficient of variation (CVRC) and root-mean-square error (RMSERC) were evaluated for the phantom data. Two male patients with recurrent glioblastoma were scanned on the same scanner using 18F-PSMA-1007. Using an irreversible two-tissue compartment model, the area under curve (AUC) and the net influx rate Ki were calculated to assess the impact of different β-factors on the pharmacokinetic analysis of clinical PET brain data. Results In general, RC and CVRC decreased with increasing β-factor in the phantom data. For small spheres (

IntroductionA newly developed clinical organ-targeted Positron Emission Tomography (PET) system (also known as Radialis PET) is tested with a set of standardized and custom tests previously used to evaluate the performance of Positron Emission Mammography (PEM) systems.MethodsImaging characteristics impacting standardized uptake value (SUV) and detectability of small lesions, namely spatial resolution, linearity, uniformity, and recovery coefficients, are evaluated.ResultsIn-plane spatial resolution was measured as 2.3 mm ± 0.1 mm, spatial accuracy was 0.1 mm, and uniformity measured with flood field and NEMA NU-4 phantom was 11.7% and 8.3% respectively. Selected clinical images are provided as reference to the imaging capabilities under different clinical conditions such as reduced activity of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (18F-FDG) and time-delayed acquisitions. SUV measurements were performed for selected clinical acquisitions to demonstrate a capability for quantitative image assessment of different types of cancer including for invasive lobular carcinoma with comparatively low metabolic activity. Quantitative imaging performance assessment with phantoms demonstrates improved contrast recovery and spill-over ratio for this PET technology when compared to other commercial organ-dedicated PET systems with similar spatial resolution. Recovery coefficients were measured to be 0.21 for the 1 mm hot rod and up to 0.89 for the 5 mm hot rod of NEMA NU-4 Image Quality phantom.DiscussionDemonstrated ability to accurately reconstruct activity in tumors as small as 5 mm suggests that the Radialis PET technology may be well suited for emerging clinical applications such as image guided assessment of response to neoadjuvant systemic treatment (NST) in lesions smaller than 2 cm. Also, our results suggest that, while spatial resolution greatly influences the partial volume effect which degrades contrast recovery, optimized count rate performance and image reconstruction workflow may improve recovery coefficients for systems with comparable spatial resolution. We emphasize that recovery coefficient should be considered as a primary performance metric when a PET system is used for accurate lesion size or radiotracer uptake assessments.

Abstract Background This study evaluated, as a snapshot, the variability in quantification and image quality (IQ) of the clinically utilized PET [18F]FDG whole-body protocols in Finland using a NEMA/IEC IQ phantom permanently filled with 68Ge. Methods The phantom was imaged on 14 PET-CT scanners, including a variety of models from two major vendors. The variability of the recovery coefficients (RCmax, RCmean and RCpeak) of the hot spheres as well as percent background variability (PBV), coefficient of variation of the background (COVBG) and accuracy of corrections (AOC) were studied using images from clinical and standardized protocols with 20 repeated measurements. The ranges of the RCs were also compared to the limits of the EARL 18F standards 2 accreditation (EARL2). The impact of image noise on these parameters was studied using averaged images (AVIs). Results The largest variability in RC values of the routine protocols was found for the RCmax with a range of 68% and with 10% intra-scanner variability, decreasing to 36% when excluding protocols with suspected cross-calibration failure or without point-spread-function (PSF) correction. The RC ranges of individual hot spheres in routine or standardized protocols or AVIs fulfilled the EARL2 ranges with two minor exceptions, but fulfilling the exact EARL2 limits for all hot spheres was variable. RCpeak was less dependent on averaging and reconstruction parameters than RCmax and RCmean. The PBV, COVBG and AOC varied between 2.3–11.8%, 9.6–17.8% and 4.8–32.0%, respectively, for the routine protocols. The RC ranges, PBV and COVBG were decreased when using AVIs. With AOC, when excluding routine protocols without PSF correction, the maximum value dropped to 15.5%. Conclusion The maximum variability of the RC values for the [18F]FDG whole-body protocols was about 60%. The RC ranges of properly cross-calibrated scanners with PSF correction fitted to the EARL2 RC ranges for individual sphere sizes, but fulfilling the exact RC limits would have needed further optimization. RCpeak was the most robust RC measure. Besides COVBG, also RCs and PVB were sensitive to image noise.

Background: Q.Clear, a Bayesian penalized likelihood reconstruction algorithm, has shown high potential in improving quantitation accuracy in PET systems. The Q.Clear algorithm controls noise during the iterative reconstruction through a β penalization factor. This study aimed to determine the optimal β-factor for accurate quantitation of dynamic PET scans. Methods: A Flangeless Esser PET Phantom with eight hollow spheres (4–25 mm) was scanned on a GE Discovery MI PET/CT system. Data were reconstructed into five sets of variable acquisition times using Q.Clear with 18 different β-factors ranging from 100 to 3500. The recovery coefficient (RC), coefficient of variation (CVRC) and root-mean-square error (RMSERC) were evaluated for the phantom data. Two male patients with recurrent glioblastoma were scanned on the same scanner using 18F-PSMA-1007. Using an irreversible two-tissue compartment model, the area under curve (AUC) and the net influx rate Ki were calculated to assess the impact of different β-factors on the pharmacokinetic analysis of clinical PET brain data. Results: In general, RC and CVRC decreased with increasing β-factor in the phantom data. For small spheres (< 10 mm), and in particular for short acquisition times, low β-factors resulted in high variability and an overestimation of measured activity. Increasing the β-factor improves the variability, however at a cost of underestimating the measured activity. For the clinical data, AUC decreased and Ki increased with increased β-factor; a change in β-factor from 300 to 1000 resulted in a 25.5% increase in the Ki. Conclusion: In a complex dynamic dataset with variable acquisition times, the optimal β-factor provides a balance between accuracy and precision. Based on our results, we suggest a β-factor of 300–500 for quantitation of small structures with dynamic PET imaging, while large structures may benefit from higher β-factors. Trial registration: Clinicaltrials.gov, NCT03951142. Registered 5 October 2019, https://clinicaltrials.gov/ct2/show/NCT03951142. EudraCT no 2018-003229-27. Registered 26 February 2019, https://www.clinicaltrialsregister.eu/ctr-search/trial/2018-003229-27/NO. [ABSTRACT FROM AUTHOR]

The influence of various structural types of smart dispersion-filled polymer composite materials (DFPCMs) on such shape-memory effect (SME) parameters as the shape fixation and recovery coefficients (Rf and Rr) and SME kinetics characterized by the rate of the initial shape recovery (υr) was studied for the first time, with the polyurethane + modified silicon carbide (SiC) particles as example. The main dependences describing the relationship of the shape fixation and recovery coefficients (Rf and Rr) and of the shape recovery rate (υr) with the generalized parameter Θ, DFPCM structural type, and surface morphology of SiC particles were found. The contribution of the specific surface area of dispersed SiC particles (SBET from 3 to 45 m2 g–1) to the smart properties of the disperse systems was demonstrated for the first time. [ABSTRACT FROM AUTHOR]

Curve rail grinding for metros can effectively reduce the lateral and vertical vibration acceleration of the vehicle, thereby improving the running stability of vehicles. Using the running stability measurement of vehicles, the paper proposes a vibration evaluation index to evaluate the vibration response degree of the vehicle body passing through a curve and to assess the quality of the curve equipment. To comprehensively evaluate the immediate effect and the ongoing effect of the maintenance quality, a recovery coefficient of the rail grinding operation is proposed. Furthermore, a correlation analysis model between vehicle body vibration response and the quality of the curve rail grinding operation is established. The actual data of Zhengzhou Metro Line 1 is used to verify the proposed model. The calculation results show that the model can effectively analyze the correlation between the vehicle body vibration response and the quality of rail grinding operations, and play a major role in guiding the track maintenance. [ABSTRACT FROM AUTHOR]

The bouncing process of an irregular object falling on the ground contains many interesting mechanical problems. The article investigated the bounce height of a capsule-shaped object when it falls on the ground. The variation of three physical quantities, namely the angle of the object, the linear velocity of the center of mass and the angular velocity relative to the center of mass when it fell on the ground are studied. According to the limit condition of friction, the three-dimensional phase diagram of the above three physical quantities was drawn when the fall height of the capsule-shaped object and the bounce height was equal. The movement of the capsule-shaped object is captured by using two cameras positioned perpendicular to each other. The trajectory was tracked by TRACKER software to obtain the fall height and bounce height of the capsule. When the bounce height was higher than the fall height, it was marked with a red dot. If both heights were equal, it was marked with a black dot. Otherwise, it was marked with a blue dot. Different types of experimental data points are plotted in the phase diagram. A large amount of random experimental data verifies the correctness of the theory. [ABSTRACT FROM AUTHOR]

Background: This study evaluated, as a snapshot, the variability in quantification and image quality (IQ) of the clinically utilized PET [18F]FDG whole-body protocols in Finland using a NEMA/IEC IQ phantom permanently filled with 68Ge. Methods: The phantom was imaged on 14 PET-CT scanners, including a variety of models from two major vendors. The variability of the recovery coefficients (RCmax, RCmean and RCpeak) of the hot spheres as well as percent background variability (PBV), coefficient of variation of the background (COVBG) and accuracy of corrections (AOC) were studied using images from clinical and standardized protocols with 20 repeated measurements. The ranges of the RCs were also compared to the limits of the EARL 18F standards 2 accreditation (EARL2). The impact of image noise on these parameters was studied using averaged images (AVIs). Results: The largest variability in RC values of the routine protocols was found for the RCmax with a range of 68% and with 10% intra-scanner variability, decreasing to 36% when excluding protocols with suspected cross-calibration failure or without point-spread-function (PSF) correction. The RC ranges of individual hot spheres in routine or standardized protocols or AVIs fulfilled the EARL2 ranges with two minor exceptions, but fulfilling the exact EARL2 limits for all hot spheres was variable. RCpeak was less dependent on averaging and reconstruction parameters than RCmax and RCmean. The PBV, COVBG and AOC varied between 2.3–11.8%, 9.6–17.8% and 4.8–32.0%, respectively, for the routine protocols. The RC ranges, PBV and COVBG were decreased when using AVIs. With AOC, when excluding routine protocols without PSF correction, the maximum value dropped to 15.5%. Conclusion: The maximum variability of the RC values for the [18F]FDG whole-body protocols was about 60%. The RC ranges of properly cross-calibrated scanners with PSF correction fitted to the EARL2 RC ranges for individual sphere sizes, but fulfilling the exact RC limits would have needed further optimization. RCpeak was the most robust RC measure. Besides COVBG, also RCs and PVB were sensitive to image noise. [ABSTRACT FROM AUTHOR]

Positron emission tomography (PET)/computed tomography (CT) has improved sensitivity and resolution using silicon photomultiplier as a photosensor. Previously, only a fixed setting was available for the shooting time of 1 bed, but now, the shooting time can be changed for each bed. Time can be shortened or extended depending on the target area. A few studies reported on image reconstruction conditions for head and neck cancer in whole-body PET/CT examinations. Thus, this study aimed to optimize the imaging conditions of the head and neck region during whole-body imaging. A cylindrical acrylic container with a 200 mm diameter was used to simulate the head and neck area using a PET/CT system equipped with a semiconductor detector. Spheres of 6-30 mm in diameter were enclosed in the 200 mm diameter cylindrical acrylic vessel. Radioactivity in 18F solution (Hot:BG ratio 4:1) was enclosed in a phantom following the Japanese Society of Nuclear Medicine (JSNM) guidelines. Background radioactivity concentration was 2.53 kBq/mL. List mode acquisition of 1,800 s was collected at 60-1,800 s with the field of view of 700 mm and 350 mm. The image was reconstructed by resizing the matrix to 128 128, 192 192, 256 256, and 384 384, respectively. The imaging time per bed in the head and neck should be at least 180 s, and the reconstruction conditions should be a field of view (FOV) of 350 mm, matrix sizes of ≥ 192, and a Bayesian penalized likelihood (BPL) reconstruction with a β-value of 200. This allows detection of > 70% of the 8-mm spheres in the images. [ABSTRACT FROM AUTHOR]

This article describes the procedure of analysis and control of energy efficiency of continuous heating furnace based on establishment of direct functional dependence of specific fuel flowrate for metal heating on furnace structural and technological parameters. Using this procedure, it is possible to arrange lines of power consumptions of industrial furnaces in order to solve the issues of normalization of fuel flowrate, compilation of gas balance, diagnostics of furnace state, verification of reasonability of selected parameters of temperature rate mode. At the stage of furnace designing, this procedure allows to determine structural parameters allowing to achieve the preset level of specific fuel flowrate. [ABSTRACT FROM AUTHOR]

Abstract Background Single-photon emission computed tomography (SPECT) can cause an over- or underestimation of tissue activity concentration due to limitations in spatial resolution compared to the structures under study. This is commonly referred to as partial volume effect (PVE). Ideally, the PVE should be controlled for and corrected. One such correction method involves determining recovery coefficients (RC) from phantom measurements. In the literature, several studies applying simplified geometries are available. In this study, we aimed to determine kidney PVE for realistic kidney geometries. Furthermore, we proposed a new surrogate metric for predicting the extent of PVE in kidneys. Material and methods Based on patients’ CT data, we manufactured fillable phantoms using a 3D-printer. Nine cortex-only and ten whole-parenchyma phantoms were obtained, and one ellipsoidal phantom for comparison. To measure PVE, we placed the phantoms in a torso phantom and filled them with a specified activity concentration. The phantoms’ RCs were determined from fully quantitative SPECT/CT acquisitions at three different target-to-background ratios (TBRs). Additionally, the surface area-to-volume (SA:V) ratio was determined for all phantoms and correlated with RCs. Results For SPECT reconstructions with 36 iterations, average RC ± one standard deviation at a 10-to-1 TBR was 76.3 ± 1.5% and 48.4 ± 8.3% for whole-parenchyma and cortex-only phantoms, respectively. The RC for the ellipsoidal phantom was 85.4%. The RC for whole-parenchyma was significantly higher than for cortex-only phantoms (p

The movement of sand particles on the desert is the primary mechanism resulting in the development of sandstorms. Scientists have found that the physicochemical environments of terrestrial planets can cause the surface of sand particles to form a peelable covering layer, which may shed gradually during the movement of sand particles and affect the collision process between sand particles and bed surface, and finally affect aeolian sand transport itself. However, only a few studies have investigated these microscopic physical processes and conducted quantitative analysis of the relationship between covering layer mass and its coefficient of restitution (COR) when a particle impact desert surface. In this study, we collected four types of natural sand particles from the Badain Jaran, Mu Us, and Taklimakan deserts and the shoreside of the Yellow River respectively. A hydrochloric acid solution was used to dissolve the surface‐covering layer of sand particles, and high‐speed photography was used to capture the process of particle‐bed collision. The motion characteristics of the sand particles under different covering layers were analyzed using statistical analysis, and the quantitative formula between the COR and the covering layer mass was provided. This calculation result was further incorporated into an aeolian sand transport model to evaluate the effect of the covering layer on sand flux. Considering the ubiquity of covering layer on sand particle, the methodology proposed in this study can be used to simulate sand drift on Earth, Mars, and other terrestrial planets more accurately. Plain Language Summary: Aeolian sand on Earth, Mars, and other terrestrial planets is an important process that affects substance transport, landform evolution, and climate change. The sand grains are generally considered to be composed of only a single substance, and the material property affects their collision behavior and computational accuracy when assessing the sand hazards such as sandstorms. However, recent researches show that the surfaces of sand particles on terrestrial planets have 1–10 μm thick covering layers made out of metal oxides, which are different from the internal material and could be break off due to continuous collision and consequently change the collision behavior of sand particles. In this study, we collected natural sand particles from four different study areas. Chemical reagent was used to dissolve the covering layer and high‐speed photography was used to capture the process of collision. The motion characteristics of the sand particles were analyzed and a formula was proposed to describe this complex process. We built an improved calculation method for aeolian sand transport and may be used to simulate aeolian sand on Earth, Mars, and other terrestrial planets more accurately. Key Points: The collision processes between natural sand particles in four study areas and bed surface were recordedThe quantitative formula between the coefficient of restitution and the covering layer mass was providedThe methodology proposed in this study can be used to simulate sand drift on Earth, Mars, and other terrestrial planets more accurately [ABSTRACT FROM AUTHOR]

Abstract Background The digital cadmium–zinc–telluride (CZT)-based SPECT system has many advantages, including better spatial and energy resolution. However, the impacts of different acquisition and reconstruction parameters on CZT SPECT quantification might still need to be validated. This study aimed to evaluate the impacts of acquisition parameters (the main energy window and acquisition time per frame) and reconstruction parameters (the number of iterations, subsets in iterative reconstruction, post-filter, and image correction methods) on the technetium quantification of CZT SPECT/CT. Methods A phantom (PET NEMA/IEC image quality, USA) was filled with four target-to-background (T/B) ratios (32:1, 16:1, 8:1, and 4:1) of technetium. Mean uptake values (the calculated mean concentrations for spheres) were measured to evaluate the recovery coefficient (RC) changes under different acquisition and reconstruction parameters. The corresponding standard deviations of mean uptake values were also measured to evaluate the quantification error. Image quality was evaluated using the National Electrical Manufacturers Association (NEMA) NU 2–2012 standard. Results For all T/B ratios, significant correlations were found between iterations and RCs (r = 0.62–0.96 for 1–35 iterations, r = 0.94–0.99 for 35–90 iterations) as well as between the full width at half maximum (FWHM) of the Gaussian filter and RCs (r = − 0.86 to − 1.00, all P values 0.05) were found between the 15% and 20% energy windows except for the 32:1 T/B ratio (P value = 0.023) or between the 10 s/frame and 120 s/frame acquisition times except for the 4:1 T/B ratio (P value = 0.015) in terms of RCs. Conclusions CZT-SPECT/CT of technetium resulted in good quantification accuracy. The favourable acquisition parameters might be a 15% energy window and 40 s/frame of acquisition time. The favourable reconstruction parameters might be 35 iterations, 20 subsets, the AC + SC + RR correction combination, and no filter.

• Experimental study of droplets rebounding completely from non-superhydrophobic surfaces (polydimethylsiloxane, PDMS). • Droplet oscillation in free fall motion affects the complete rebound. • Fluctuating recovery coefficient of droplet with increasing the Weber number. • A theoretical model of oscillating droplet rebound for interpreting the fluctuating recovery coefficient. Oscillating droplets rebounding completely from non-superhydrophobic surfaces (polydimethylsiloxane, PDMS) were experimentally studied and theoretically interpreted. The new experimental finding is that, with increasing the droplet impact Weber numbers (W e), the recovery coefficient of droplet velocity, which is defined as the ratio of the rebounding velocity over the impact velocity, has an overall trend of decrease but in a fluctuating manner. Physically, a sufficiently large droplet freely falling under gravity has an inevitable oscillation, which makes the impacting droplet shape slightly deviate from being spherical and in turn affects the interaction between the droplet and the surface. The fluctuating recovery coefficient is the result of the periodically varying phase of droplet oscillation with increasing W e , and increasing the droplet viscosity can suppress the droplet oscillation and then the fluctuation amplitude of the recovery coefficient. A theoretical model of oscillating droplet rebound is proposed and well fits the present experiments over a wide range of W e. [Display omitted] [ABSTRACT FROM AUTHOR]

Titanium materials are widely used in aviation; their poor wear resistance and easy high-temperature oxidation defects limit their further application. Cold spraying technology is an excellent way to solve these defects, has essential significance for its surface research. This study reports the deposition mechanism of Aluminium (Al) + Titanium (Ti) mixed powders deposited onto Ti6Al4V by cold spraying technology using Abaqus/Explicit. Because of its high surface hardness, it is not easy to obtain effective deposition by direct spraying with pure Al powder. Hence, Ti powder as the intermediate coating was proposed between Ti6Al4V and pure Al powder. Since there are few reports on numerical simulation of mixed particles, most studies focus on single or multi-particles of the same material. The critical process of numerical simulation of mixed powders is emphasized in detail. Using the recovery coefficient is defined to determine the critical speed. The results show that it is feasible to determine the critical velocity of mixed powder through the smaller value of recovery coefficient from the perspective of energy. In this paper, the recommended critical speed of mixed powder is 500 m/s-900 m/s. It will provide theoretical guidance for researchers and is of great significance to further expand the application of other mixed powders. [ABSTRACT FROM AUTHOR]

Background: Single-photon emission computed tomography (SPECT) can cause an over- or underestimation of tissue activity concentration due to limitations in spatial resolution compared to the structures under study. This is commonly referred to as partial volume effect (PVE). Ideally, the PVE should be controlled for and corrected. One such correction method involves determining recovery coefficients (RC) from phantom measurements. In the literature, several studies applying simplified geometries are available. In this study, we aimed to determine kidney PVE for realistic kidney geometries. Furthermore, we proposed a new surrogate metric for predicting the extent of PVE in kidneys. Material and methods: Based on patients' CT data, we manufactured fillable phantoms using a 3D-printer. Nine cortex-only and ten whole-parenchyma phantoms were obtained, and one ellipsoidal phantom for comparison. To measure PVE, we placed the phantoms in a torso phantom and filled them with a specified activity concentration. The phantoms' RCs were determined from fully quantitative SPECT/CT acquisitions at three different target-to-background ratios (TBRs). Additionally, the surface area-to-volume (SA:V) ratio was determined for all phantoms and correlated with RCs. Results: For SPECT reconstructions with 36 iterations, average RC ± one standard deviation at a 10-to-1 TBR was 76.3 ± 1.5% and 48.4 ± 8.3% for whole-parenchyma and cortex-only phantoms, respectively. The RC for the ellipsoidal phantom was 85.4%. The RC for whole-parenchyma was significantly higher than for cortex-only phantoms (p < 0.01). The RC variance was significantly higher for cortex-only phantoms (p < 0.01). A highly significant correlation of the SA:V ratio and RC was found for all phantoms. (R2 of linear regression was between 0.96 and 0.98.) Conclusion: Changes in the specific shape of the kidneys cause large changes in PVE magnitude. Therefore, RCs derived from more simple phantoms are most likely insufficient to correct the PVE in patient images. Furthermore, one should account for the fact that intra-renal activity distribution significantly influences the extent of PVE. Additionally, we found that the SA:V ratio excellently models kidney RCs; potentially, this approach could also be applied to other geometries and represents an alternative to full imaging process simulations to determine the extent of PVE. [ABSTRACT FROM AUTHOR]

Background: The digital cadmium–zinc–telluride (CZT)-based SPECT system has many advantages, including better spatial and energy resolution. However, the impacts of different acquisition and reconstruction parameters on CZT SPECT quantification might still need to be validated. This study aimed to evaluate the impacts of acquisition parameters (the main energy window and acquisition time per frame) and reconstruction parameters (the number of iterations, subsets in iterative reconstruction, post-filter, and image correction methods) on the technetium quantification of CZT SPECT/CT. Methods: A phantom (PET NEMA/IEC image quality, USA) was filled with four target-to-background (T/B) ratios (32:1, 16:1, 8:1, and 4:1) of technetium. Mean uptake values (the calculated mean concentrations for spheres) were measured to evaluate the recovery coefficient (RC) changes under different acquisition and reconstruction parameters. The corresponding standard deviations of mean uptake values were also measured to evaluate the quantification error. Image quality was evaluated using the National Electrical Manufacturers Association (NEMA) NU 2–2012 standard. Results: For all T/B ratios, significant correlations were found between iterations and RCs (r = 0.62–0.96 for 1–35 iterations, r = 0.94–0.99 for 35–90 iterations) as well as between the full width at half maximum (FWHM) of the Gaussian filter and RCs (r = − 0.86 to − 1.00, all P values < 0.05). The regression coefficients of 1–35 iterations were higher than those of 35–90 iterations (0.51–1.60 vs. 0.02–0.19). RCs calculated with AC (attenuation correction) + SC (scatter correction) + RR (resolution recovery correction) combination were more accurate (53.82–106.70%) than those calculated with other combinations (all P values < 0.05). No significant statistical differences (all P values > 0.05) were found between the 15% and 20% energy windows except for the 32:1 T/B ratio (P value = 0.023) or between the 10 s/frame and 120 s/frame acquisition times except for the 4:1 T/B ratio (P value = 0.015) in terms of RCs. Conclusions: CZT-SPECT/CT of technetium resulted in good quantification accuracy. The favourable acquisition parameters might be a 15% energy window and 40 s/frame of acquisition time. The favourable reconstruction parameters might be 35 iterations, 20 subsets, the AC + SC + RR correction combination, and no filter. [ABSTRACT FROM AUTHOR]

Abstract Absolute quantification of radiotracer distribution using SPECT/CT imaging is of great importance for dosimetry aimed at personalized radionuclide precision treatment. However, its accuracy depends on many factors. Using phantom measurements, this multi-vendor and multi-center study evaluates the quantitative accuracy and inter-system variability of various SPECT/CT systems as well as the effect of patient size, processing software and reconstruction algorithms on recovery coefficients (RC). Methods Five SPECT/CT systems were included: Discovery™ NM/CT 670 Pro (GE Healthcare), Precedence™ 6 (Philips Healthcare), Symbia Intevo™, and Symbia™ T16 (twice) (Siemens Healthineers). Three phantoms were used based on the NEMA IEC body phantom without lung insert simulating body mass indexes (BMI) of 25, 28, and 47 kg/m2. Six spheres (0.5–26.5 mL) and background were filled with 0.1 and 0.01 MBq/mL 99mTc-pertechnetate, respectively. Volumes of interest (VOI) of spheres were obtained by a region growing technique using a 50% threshold of the maximum voxel value corrected for background activity. RC, defined as imaged activity concentration divided by actual activity concentration, were determined for maximum (RCmax) and mean voxel value (RCmean) in the VOI for each sphere diameter. Inter-system variability was expressed as median absolute deviation (MAD) of RC. Acquisition settings were standardized. Images were reconstructed using vendor-specific 3D iterative reconstruction algorithms with institute-specific settings used in clinical practice and processed using a standardized, in-house developed processing tool based on the SimpleITK framework. Additionally, all data were reconstructed with a vendor-neutral reconstruction algorithm (Hybrid Recon™; Hermes Medical Solutions). Results RC decreased with decreasing sphere diameter for each system. Inter-system variability (MAD) was 16 and 17% for RCmean and RCmax, respectively. Standardized reconstruction decreased this variability to 4 and 5%. High BMI hampers quantification of small lesions (

Existing studies on the trajectory of the rockfall all regard the slope as a semi-infinite and uniform slope, but in actual working conditions, the slope is composed of heterogeneous materials.According to the different motion modes of rockfall, the slope surface is simplified to the structure of multi-layer rocks and soil materials.In the rolling stage, based on Hertz contact theory, the movement characteristics of falling rocks under different slope conditions are obtained, and the calculation formula for the tangential friction coefficient of the rockfall under the condition of the slope layering is given.In the collision phase, based on the law of conservation of energy, the normal recovery coefficient formula obtained by the quasi-static contact mechanics theory is used.The analytical solutions of the normal and tangential recovery coefficients of the rockfall under the condition of the arbitrary rock and soil material structure slope are derived, and then the motion parameters of the rockfall after the collision are obtained, According to the relationship between the speed of the rockfall and the amount of rebound after the collision, the judgment conditions for the transition of the motion mode of the rockfall after the collision are given.Finally, combined with the kinematics theorem, the motion trajectory of the falling rock under any layered slope condition in three motion modes is obtained. The theoretical formula is applied to the prediction of the motion trajectory of a rolling rock in a mountainous area, which verifies the applicability and validity of the theoretical formula.

To accurately simulate the motion process of the particle-wall collision, collision experiments were conducted on the spherical particles and non-spherical regular particles. The rebound angles of the normal and tangent plane, the model factor, and the particle shape factor were proposed. Based on the rebound angle distribution functions and model factor functions, the collision recovery coefficient distribution functions were obtained, and a three-dimensional non-spherical regular particle-wall collision model was established. The experimental results show that as the shape factor increases, the normal and tangential collision recovery coefficients increase, the distribution becomes more concentrated, and the prediction and experimental errors significantly decrease. The model has high accuracy in predicting the mean of the collision recovery coefficients, the prediction and experimental error of the mean normal collision recovery coefficient is less than 10.5%, and the prediction and experimental error of the mean tangential collision recovery coefficient is less than 6.8%. [Display omitted] • The rebound angles of the normal and tangent planes were introduced to analyze the particle-wall collision process. • The shape factor was proposed to quantify the particle shape characterization. • The rebound angle distribution functions and model factor functions were obtained based on the shape factor. • The normal and tangential collision recovery coefficient distribution functions were obtained. • Based on experimental and model simulation data, the accuracy of the collision model was verified. [ABSTRACT FROM AUTHOR]

The edges and corners of non-spherical particles cause random bounces in three-dimensional space after the particle-wall collision. To study the collision behaviors, four kinds of non-spherical regular particles are prepared, and the collision test system with a dual-camera is built. The collision process is characterized by introducing the lateral velocity and lateral angle. The rebound angle, lateral angle, and recovery coefficients under different particle diameters and impact angles are obtained. The results show that the rebound angle, lateral angle, and recovery coefficients of non-spherical regular particles are highly dispersed. The mean rebound angles of non-spherical regular particles are significantly smaller than that of spherical particles. The particle diameter, impact angle, and recovery coefficients are in negative correlation. The normal recovery coefficients of non-spherical particles are greatly reduced, and the tangential recovery coefficients change slightly. The recovery coefficients can be applied to multi-phase flow simulations to improve the simulation accuracy. [Display omitted] • The random bouncing behaviors of the particles in three-dimensional space were observed by dual-camera. • Lateral velocity and lateral angle were introduced to characterize the collision process. • The effects of the particle shape and diameter on the rebound angle and lateral angle were obtained. • The effects of the particle shape and diameter on the normal and tangential recovery coefficient were obtained. • The normal and tangential recovery coefficients at different impact angles were obtained. [ABSTRACT FROM AUTHOR]

The paper analyses the behavior to creasing of some woven materials made from yarns type wool used for ready-made clothes. Factors like fibrous composition, properties of constituent fibers, wovens structure parameters, mechanical properties of warp and weft yarns and finishing treatments that influenced the recovery capacity from crease/folding were investigated experimentally through several tests which revealed their importance in the process. The creasing of woven materials made from combed yarns type wool used for ready-clothes is an undesired deformation effect with temporary or permanent character, which is caused by a composed strain of bending and compression during utilization, processing or maintenance. It is manifested by the appearance of wrinkles, folds or stripes on the surface of wovens materials, thus diminishing their qualitative appearance and also their practical value. Creasing is the result of irreversible changes created through the reciprocal sliding of structural fiber components when exposed to a bending strain. Creasing is specific to oriented structures with high crystallinity (cellulosic fibers). The sliding appears because of hydrogen bond breaking which can, however, reform easy in other positions conferring a permanent character to creasing.Functional apparel will be subjected to a wide range of end uses such that a garment will be affected by intern (fibres, yarn fineness warp/weft, fabric density, thickness, fabric count) and external factors (external environment - exposure to sunlight, wind, rain, cold weather conditions, fabric/human body interaction). These factors affect the performance and behaviour of functional.

Functional imaging with 68Ga prostate-specific membrane antigen (PSMA) and positron emission tomography (PET) can fulfill an important role in treatment selection and adjustment in prostate cancer. This article focusses on quantitative assessment of 68Ga-PSMA-PET. The effect of various parameters on standardized uptake values (SUVs) is explored, and an optimal Bayesian penalized likelihood (BPL) reconstruction is suggested. PET acquisitions of two phantoms consisting of a background compartment and spheres with diameter 4 mm to 37 mm, both filled with solutions of 68Ga in water, were performed with a GE Discovery 710 PET/CT scanner. Recovery coefficients (RCs) in multiple reconstructions with varying noise penalty factors and acquisition times were determined and analyzed. Apparent recovery coefficients of spheres with a diameter smaller than 17 mm were significantly lower than those of spheres with a diameter of 17 mm and bigger (p < 0.001) for a tumor-to-background (T/B) ratio of 10:1 and a scan time of 10 min per bed position. With a T/B ratio of 10:1, the four largest spheres exhibit significantly higher RCs than those with a T/B ratio of 20:1 (p < 0.0001). For spheres with a diameter of 8 mm and less, alignment with the voxel grid potentially affects the RC. Evaluation of PET/CT scans using (semi-)quantitative measures such as SUVs should be performed with great caution, as SUVs are influenced by scanning and reconstruction parameters. Based on the evaluation of multiple reconstructions with different β of phantom scans, an intermediate β (600) is suggested as the optimal value for the reconstruction of clinical 68Ga-PSMA PET/CT scans, considering that both detectability and reproducibility are relevant.

Absolute quantification of radiotracer distribution using SPECT/CT imaging is of great importance for dosimetry aimed at personalized radionuclide precision treatment. However, its accuracy depends on many factors. Using phantom measurements, this multi-vendor and multi-center study evaluates the quantitative accuracy and inter-system variability of various SPECT/CT systems as well as the effect of patient size, processing software and reconstruction algorithms on recovery coefficients (RC). Methods: Five SPECT/CT systems were included: Discovery™ NM/CT 670 Pro (GE Healthcare), Precedence™ 6 (Philips Healthcare), Symbia Intevo™, and Symbia™ T16 (twice) (Siemens Healthineers). Three phantoms were used based on the NEMA IEC body phantom without lung insert simulating body mass indexes (BMI) of 25, 28, and 47 kg/m2. Six spheres (0.5–26.5 mL) and background were filled with 0.1 and 0.01 MBq/mL 99mTc-pertechnetate, respectively. Volumes of interest (VOI) of spheres were obtained by a region growing technique using a 50% threshold of the maximum voxel value corrected for background activity. RC, defined as imaged activity concentration divided by actual activity concentration, were determined for maximum (RCmax) and mean voxel value (RCmean) in the VOI for each sphere diameter. Inter-system variability was expressed as median absolute deviation (MAD) of RC. Acquisition settings were standardized. Images were reconstructed using vendor-specific 3D iterative reconstruction algorithms with institute-specific settings used in clinical practice and processed using a standardized, in-house developed processing tool based on the SimpleITK framework. Additionally, all data were reconstructed with a vendor-neutral reconstruction algorithm (Hybrid Recon™; Hermes Medical Solutions). Results: RC decreased with decreasing sphere diameter for each system. Inter-system variability (MAD) was 16 and 17% for RCmean and RCmax, respectively. Standardized reconstruction decreased this variability to 4 and 5%. High BMI hampers quantification of small lesions (< 10 ml). Conclusion: Absolute SPECT quantification in a multi-center and multi-vendor setting is feasible, especially when reconstruction protocols are standardized, paving the way for a standard for absolute quantitative SPECT. [ABSTRACT FROM AUTHOR]

The fittings such as diffusers and reducers are essential flow elements in a piping system, which play a role to connect the different sized pipes or to branch a part of main stream to other piping. However, their central role is to convert the dynamic energy (velocity) of a flow into the static energy (pressure), or vice versa. When designing a piping system, the pressure drop calculation is very important due to the estimation of power consumption for maintaining a required flowrate. For this reason, many coefficient values of the standard sized fitting products are usually provided by manufacturers or by engineering handbooks. In this study, some analytical calculations were performed to find the optimum angles of non-standard reducers and diffusers based on a dimensionless aspect ratio (length/diameter). The results showed that the optimum angles decreased exponentially as the aspect ratio increased and vice versa. Especially, the optimum angle of a diffuser converged to about 5° when the aspect ratio is over 10. Furthermore, these results were verified through the CFD calculations and the previous reported data. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to correct for partial volume effect in positron emission imaging studies which is the most influential factors using three-dimensional (3D) representation of the recovery coefficients (RCs) to improve standardized uptake value (SUV) calculations.Methods: Several phantom studies were conducted at significantly wide range of lesion contrast, range 2:1 up to 15:1. It was then classified into two groups: one for generating 3D function taking into consideration the sphere size as well lesion contrast whereas the other group was used for functions validation. A segmentation threshold algorithm for lesion delineation and volume determination was generated based on lesion contrast and lesion size. In addition, five 3D functions of the RC of the SUV were formulated considering lesion size and lesion contrast. Validation of the new algorithms has considered both phantom and clinical studies.Results: The error in threshold 3D function was well below 10%. For lesions ≤ 2 cm in diameter, there was no statistical difference of the functions developed for SUVmax as well as those functions generated for SUVmean. However, the median SUVmax has increased significantly when compared with data before correction. For SUVmean, the increase in median value was also significantly high.Conclusion: It has been successful to generate 3D mathematical formulations of the SUV RC taking into consideration the most influential factors including lesion size and lesion contrast. Validation studies were suggestive of the good performance of the new mathematical algorithms generated to correct for PVE. However, further studies are underway to ensure the performance of the proposed algorithms in clinical PET studies. [ABSTRACT FROM AUTHOR]

According to the new quantitative model for original total organic carbon (TOCo) evolution and recovery of source rocks, The TOCo evolution of muddy source rocks with different TOCs (MSRDTOC) (0.5% < TOC ≤ 1.5%, 2.5% < TOC ≤ 3.5% and 4.0% < TOC ≤ 6.0%, and their average values were 1.0%, 3.0% and 5.0%, respectively) and type III kerogen were investigated in the Western Sichuan Depression (WSD) of Sichuan Basin, China, finally recovery coefficients of TOCo were calculated. Studies showed that TOCo evolution of the MSRDTOC have similarities and differences. The similarities reveal that with the increase of thermal evolution level, varied TOC all reduce gradually and the sharp reduction occurs at the stage of a large number of hydrocarbon generation and expulsion (0.7% ≤ vitrinite reflectance (VR) ≤ 1.3%). The differences indicate that the starting time and decrease range for varied TOC are different. For TOCo = 1.0%, 3.0% and 5.0%, their starting time of TOC reduction are VR = 1.05%, 0.80% and 0.60%, respectively. When VR reaches to 3.0%, their TOC decrease ranges are 30.54%, 38.52% and 44.00% and their recovery coefficients are 1.44, 1.63 and 1.79, respectively. The higher the TOC is, the earlier the starting time of TOC reduction is, the bigger the range of TOC reduction and recovery coefficient are. It must restore TOCo when we evaluate source rocks at high-over mature stage and predict oil and gas resources. The MSRDTOC and their TOCo recovery should be evaluated, respectively. [ABSTRACT FROM AUTHOR]

• A model-based equation for the mean RC is derived for large objects of any shape. • For smaller objects an equation with one added empirical parameter is presented. • Numerical simulations confirm the accuracy of these equations for the mean RC. • The equations are superior to EANM's logistic function and others. • The model-based equation was verified on SPECT and PET NEMA body phantom data. In NM-imaging, theoretical curves for the recovery coefficient (RC) of the signal maximum and mean are known for spheres and cubes, if a 3D Gaussian PSF is assumed. The RC of the maximum is also known for cylinders. For these and other shapes empirical equations with one or two fit-parameters have been utilized. An equation for the RC for large objects of arbitrary shape is derived and generalized into an empirical equation for smaller objects, which is verified by numerical simulations. The proposed equation is compared to published results on SPECT kidney phantom measurements and to PET measurements on the NEMA IEC PET body phantom with six spheres. The signal loss (1- RC) for large spheres is inversely proportional to the radius, where the slope is proportional to the FWHM of the spatial resolution. For non-spherical shapes the generalized instead of the volume equivalent radius should be utilized. For smaller objects, an equation with one added empirical fit-parameter is presented. It is demonstrated that the EANM-guidelines' two-parameter logistic function results in a poor fit if the theoretical slope and inverse proportionality are forced and it gives a suboptimal fit when both parameters are fitted. A novel model-based equation for the mean RC -curve is derived. It can be used for arbitrary shapes as long as the sphericity is taken into account and it is accurate down to RC = 10 %. One parameter is directly related to the spatial resolution, while the other is a shape depending fit-parameter. [ABSTRACT FROM AUTHOR]

Highlights • Quantitative imaging is of foremost importance in Molecular Radionuclide Therapies. • Partial Volume Effect (PVE) is one of the most important source of error in quantitative imaging. • To date, methods developed do not correct completely for PVE and are more or less easy to apply in clinics. • PVE correction based on Recovery Coefficients derived from phantom measurements is a rough but simple method. Abstract Background At present activity quantification is one of the most critical step in dosimetry calculation, and Partial Volume Effect (PVE) one of the most important source of error. In recent years models based upon phantoms that incorporate hot spheres have been used to establish recovery models. In this context the goal of this study was to point out the most critical issues related to PVE and to establish a model closer to a biological imaging environment. Methods Two different phantoms, filled with a 177Lu solution, were used to obtain the PVE Recovery Coefficients (RCs): a phantom with spherical inserts and a phantom with organ-shaped inserts. Two additional phantoms with inserts of various geometrical shapes and an anthropomorphic phantom were acquired to compare the real activities to predicted values after PVE correction. Results The RCs versus volume of the inserts produced two different curves, one for the spheres and one for the organs. After PVE correction, accuracy on activity quantification averaged over all inserts of three test phantoms passed from −26% to 1.3% (from 26% to 10% for absolute values). Conclusion RCs is a simple method for PVE correction easily applicable in clinical routine. The use of two different models for organs and lesions has permitted to closely mimic the situation in a living subject. A marked improvement in the quantification of activity was observed when PVE correction was adopted, even if further investigations should be performed for more accurate models of PVE corrections. [ABSTRACT FROM AUTHOR]

A model of the dynamics of the particles-spheroids carried by a gas flow over a cross cylindrical body and rebounding from it has been developed. In this model, the gas flow around the particles is assumed to be viscous, and the reverse action of the particles on the gas and the collisions between them are not taken into account. The coefficients of recovery of the velocity components of the particles rebounded from the cylinder were determined on the basis of the heuristic theory in which the physical and mechanical properties of colliding bodies are considered. The influence of the ratio between the axes of particles-spheroids on the coefficient of wetting of the cylinder by them, the distributions of the mass-flow density of the particles and their velocity components over the cylinder surface, and the spatial distribution of the indicated quantities of the rotating particles rebounded from the cylinder was investigated numerically. The model proposed can be used for estimating the action of ice microcrystals and particles of volcanic ash emissions and dust storms on the structural elements of aircraft engines and small-size flying vehicles. [ABSTRACT FROM AUTHOR]

Obtaining accurate quantitative measurements in preclinical Positron Emission Tomography/Computed Tomography (PET/CT) imaging is of paramount importance in biomedical research and helps supporting efficient translation of preclinical results to the clinic. The purpose of this study was two-fold: (1) to investigate the effects of different CT acquisition protocols on PET/CT image quality and data quantification; and (2) to evaluate the absorbed dose associated with varying CT parameters.Methods: An air/water quality control CT phantom, tissue equivalent material phantom, an in-house 3D printed phantom and an image quality PET/CT phantom were imaged using a Mediso nanoPET/CT scanner. Collected data was analyzed using PMOD software, VivoQuant software and National Electric Manufactures Association (NEMA) software implemented by Mediso. Measured Hounsfield Unit (HU) in collected CT images were compared to the known HU values and image noise was quantified. PET recovery coefficients (RC), uniformity and quantitative bias were also measured.Results: Only less than 2 and 1% of CT acquisition protocols yielded water HU values < −80 and air HU values < −840, respectively. Four out of 11 CT protocols resulted in more than 100 mGy absorbed dose. Different CT protocols did not impact PET uniformity and RC, and resulted in

The flying gangue is a kind of special derivative disaster in the steeply dipping coal seam, which seriously endangers the safety of the working face equipment and personnel. It is essential to discuss the disaster mechanism to establish the protection system in longwall face along strike when mining the steeply dipping coal seam. Laboratory simulation was carried out on the basis of disaster measurement of (lying gangue, the impact energy and energy recovery coefficient were used to characterize the flying gangue’ s hazard, impact energy were recorded and acquired by HDV and pressure sensors. The evolution characteristics of impact energy under different working conditions were analyzed by statistical principle. The risk discrimination model of flying gangue was established according to the curve of impact energy and energy recovery coefficient, and the damage level of flying gangue were divided. Then taking the energy of equipment (personnel) as the control object, the energy absorption steep point and extreme point as the boundary, the flying gangue damage risk discrimination model was established to divide the damage level. The mechanism of flying gangue disaster was discussed on the basis of above discussion. The results show that the hazard of flying gangue by the impact energy and energy recovery coefficient reaches to the corresponding hazard level under the coupling of collision path and mode. The disaster process is the accumulation of impact energy in the state of free fall, splash, rolling and sliding, meets the movement, height, collision position and contact with the equipment. The impact energy can be converted into the elasticity of the device and the vibration damping between the components, resulting in the deformation of the component is greater than its ultimate deformation when the damage occurs. Lastly, the rationality of the energy recovery coefficient in the studies of theory and experiment were verified by simulation method. [ABSTRACT FROM AUTHOR]

The modern development of the industry, new technologies and a lot of harmful substances more than 2500 names attracts a lot of attention to industrial ventilation systems. The subject of this paper is analysis and generalization of foreign experience within the limits of proposed theory. In this paper, as a continuation of the previous papers the basics of designing effective industrial ventilation systems by optimizing air flow were described.An integrated exponential power dependence for defining the recovery effectiveness of different harmful substances by different local exhaust devices was proposed. The conception of equivalent effective velocity was proposed and substantiated.The method of optimal air exchange calculation and engineering design techniques were proposed.