Increase In Slice Thickness Research Articles

Tailoring the vibration characteristics of carbon fiber-reinforced polylactic acid in fused filament fabrication process

The Fused Filament Fabrication (FFF) process has gained significant attention for its ability to manufacture parts using advanced polymeric materials, such as carbon fiber-reinforced polylactic acid (CF-PLA). By adjusting the printing process parameters of the CF-PLA, the optimized mechanical properties can be achieved with less chances of flaws. Structural integrity of the components plays an important role in analyzing the durability of the product which can be analyzed using modal analysis. This research study focuses on analyzing the effect of process parameters on the vibration damping characteristics of CF-PLA components produced by the FFF process. The Taguchi method is used to model the relationship between process parameters and vibration performance metrics. Based on the vibration study, the optimal process parameters were determined as 60% infill density, 0.08 mm slice thickness, and hexagonal pattern. This study shows that the natural frequency and damping increases with increase in infill percent but decreases with increase in slice thickness. The closely aligned values between the predicted and experimental results suggest that the developed model is effective in predicting the vibration characteristics of CF-PLA composites. By accurately adjusting the process parameters, the study’s findings—such as frequencies and damping ratio—provide manufacturers with important and dependable CF-PLA Fused Deposition Modeling components.

갑상선 CT에서 스캔 파라메터 변화에 따른 선속 경화 현상 저감에 관한 연구

The beam hardening artifact arising from complex shoulder structures in thyroid CT makes it difficult to capture anatomical fine details. Thus, the purpose of our study was to know appropriate scan parameters to reduce artifacts without significantly increasing the radiation dose. We utilized the GE Revolution APEX equipment for this study. We conducted the thyroid CT examinations by varying the thickness to 0.625 mm, 1.25 mm, and 2.5 mm, and adjusting the maximum mA to 300 mA, 600 mA, and 900 mA while applying auto exposure control system. The radiation dose was measured using a glass dosimeter placed at the thyroid location of the RANDO phantom. We measured signal to noise ratio (SNR) and contrast to noise ratio (CNR) of the experimental images to analyze the image quality of the thyroid area. As the slice thickness increases, the experimental dose also increases. The same pattern was observed for the maximum tube current. In terms of SNR, there is no difference between a slice thickness of 0.625 mm and 1.25 mm. However, there is a difference between measurements of 0.625 mm and 2.5 mm, and the same for 1.25 mm and 2.5 mm. No difference was observed in terms of tube current variations. The analysis of CNR reveals that there is not a significant difference as slice thickness and maximum tube current change. To improve quality of the images in complex shoulder structures, adjusting the scan parameters of thyroid CT affects not only SNR but also patient's radiation dose. Analyzing image quality through SNR showed that increasing the slice thickness improved the image quality. However, We should carefully use changes in parameters because the increase in slice thickness also involves an increase in radiation dose.

Determining the effective diffusivity coefficient and activation energy in thin-layer drying of Haj Kazemi peach slices and modeling drying kinetics using ANFIS

Abstract This study investigated the moisture changes in Haj Kazemi peach slices during drying in a thin-layer dryer at five temperature levels (40, 50, 60, 70, and 80°C), three levels of inlet air velocity (1, 1.5, and 2 m/s), and three slice thicknesses (2, 4, and 6 mm). The relative moisture content during drying was calculated, and an adaptive neuro fuzzy inference system (ANFIS) was used to predict the drying process of peach slices. The results indicated that slice thickness had a greater impact on drying time than air velocity. Moreover, an almost direct relationship was observed between changes in slice thickness and drying time. The effective moisture diffusivity coefficient in peach slices increased with an increase in slice thickness, temperature, and air velocity and ranged from 9.57 × 10^-10 to 4.33 × 10^-9 m^2/s under different experimental conditions. The calculated activation energy for drying peach slices under experimental conditions ranged from 16.74 to 20.48 kJ/mol. The designed model for simulating the drying conditions was based on an adaptive neuro fuzzy inference system (ANFIS) with input and output membership functions of triangular and linear shapes and a hybrid learning algorithm. The model could simulate the drying process with a correlation coefficient of 0.979.

Moisture Sorption Behavior and Effects of Temperature, Slice Thickness, and Loading Density on Drying Kinetics of a Local Sweet Potato Cultivar Grown in Bangladesh

This study is aimed at investigating the moisture sorption behavior and thin-layer drying kinetics of local sweet potato sada (LSPS) variety slices. The sweet potato tubers were sliced at 3, 5, and 7 mm and dried at temperatures of 45, 55, and 62°C at a constant air velocity of 0.6 m/sec in a laboratory-scale cabinet dryer. The BET (Brunauer, Emmet, and Teller) and GAB (Guggenheim-Anderson-De Bore) models were applied to fit the sorption data. Fick’s diffusion equation was used to calculate the drying rate constant and effective moisture diffusivity. Our current result reveals that LSPS exhibited an isotherm with a sigmoid (type II) shape, and the GAB model was more goodness of fit than the BET model to clarify the adsorption isotherm of LSPS. The drying time increased with increasing slice thickness but reduced with increasing drying temperature. The drying rate constant for thin-layer drying decreased with an increase in slice thickness but increased with increasing drying temperature. The loading density with two different shapes (French cut and cube cut) also affected the drying rate constant, which decreased with the increase in loading density. Using statistical parameters, five thin-layer drying models were applied to fit the drying data. The findings indicated that the logarithmic model for 45-55°C and the Page model for 62°C were the most suitable models for explaining the drying behavior of LSPS slices. The effective moisture diffusivity increased with increasing slice thickness and drying temperature, ranging from 7.10 × 10 − 11 to 1.55 × 10 − 10 m2/s over the temperature range studied. The activation energy also increased with increasing slice thickness, and the values were 5.55 and 7.39 kJ/mol for 3 and 5 mm slices, respectively. The findings suggested that slice thickness, drying temperature, and sample loading density on cabinet dryer trays affect the drying kinetics of sweet potato slices.

Evaluation of energy consumption in drying African oil bean seeds using response surface methodology

This research was set out to evaluate the specific energy consumption (SEC) in drying African oil bean seed using convective hot air and microwave oven dryers. The process parameters investigated in thin-layer drying were temperature (40, 50, 60, 70 °C), microwave power (450, 720, 900 W), slice thickness (2, 3, 5 mm) and treatment (untreated (UT), brine pretreated (BT) and sucrose pretreated (ST)). Response surface methodology (RSM) was used to evaluate the effect of oven temperature, microwave power, slice thickness, and treatment on the SEC of African oil bean seed. The result revealed that the SEC for African oil bean seed ranged from 21.12 to 57.33 k Wh kg−1 and 90.76 to 261.23 k Wh kg−1 for microwave and oven drying, respectively. The study also found that the SEC decreases with increase in slice thickness in both microwave and oven dryer. The microwave oven method reduced SEC of African oil bean seed by 22% compared to convective hot air oven drying method. The optimum SEC was obtained at 4 mm material thickness, 53.57 °C hot air oven temperature and 814.32 W microwave power. Among the treatments, BT sample is comparatively the best treatment for AOB in order to save drying energy consumption.

Experimental investigation on mechanical properties of additively manufactured anti‐tetrachiral cellular auxetic structures under shear and flexural loading

AbstractThe present paper describes an experimental study on mechanical properties of additively manufactured anti‐tetrachiral auxetic structures under shear and flexural loading. Specimens of ABS material are fabricated using material extrusion technique of additive manufacturing. Experiments are planned using central composite design method. Three process factors, namely, slice thickness, print speed, and contour width, are considered to study their influence on modulus, strength, and specific energy absorption (SEA) of fabricated structures. To perform shear testing on specimen, a novel fixture is designed and fabricated. Flexural properties are measured using three‐point bending test on universal testing machine. It is found that all three process factors significantly affect modulus, strength, and SEA of the structure under shear and flexural loading. Mechanical properties improve with increase in slice thickness, print speed, and contour width. Regression models are developed to predict the response characteristics. In addition, optimized values of process factors are determined to maximize the mechanical properties of the structure.

Comparison of virtual monoenergetic imaging between a rapid kilovoltage switching dual-energy computed tomography with deep-learning and four dual-energy CTs with iterative reconstruction.

To assess the spectral performance of rapid kV switching dual-energy CT (KVSCT-Canon) equipped with a Deep-Learning spectral reconstruction algorithm on virtual-monoenergetic images at low-energy levels and to compare its performances with four other dual-energy CT (DECT) platforms equipped with iterative reconstruction algorithms. Two CT phantoms were scanned on five DECT platforms: KVSCT-Canon, fast kV-switching CT (KVSCT-GE), split filter CT, dual-source CT (DSCT), and dual-layer CT (DLCT). The classical parameters of abdomen-pelvic examinations were used for all phantom acquisitions, and a CTDIvol close to 10 mGy. For KVSCT-Canon, virtual-monoenergetic images were reconstructed with a clinical slice thickness of 0.5 and 1.5 mm to be close to other platforms. Noise power spectrum (NPS) and task-based transfer function (TTF) were evaluated from 40 to 80 keV of virtual-monoenergetic images. A detectability index (d') was computed to model the detection task of two contrast-enhanced lesions as function of keV. For KVSCT-Canon, the noise magnitude and average NPS spatial frequency (fav) decreased from 40 to 70 keV and increased thereafter. Similar noise magnitude outcomes were found for KVSCT-GE but the opposite for fav. For the other DECT platforms, the noise magnitude decreased as the keV increased. For split filter CT, DSCT and DLCT, the fav values increased from 40 to 80 keV. For all DECT platforms, TTF at 50% (f50) decreased as the keV increased, decreasing spatial resolution. For KVSCT-Canon, d' values peaked at 60 and 70 keV for both simulated lesions and from 50 to 70 keV for KVSCT-GE. d' decreased between 40 and 70 keV for DSCT, DLCT and split filter CT. For KVSCT-Canon, the increase in slice thickness decreases noise magnitude, fav and f50 and increases d' values. The highest d' values were found for DLCT at 40 and 50 keV and for KVSCT-Canon at 1.5 mm for other keV. For KVSCT-Canon, the detectability of contrast-enhanced lesions was highest at 60 keV. The highest d' values were found for DLCT at 40 and 50 keV and for KVSCT-Canon at 1.5 mm for other keV.

Drying kinetics, performance, and quality assessment for banana slices using heat pump–assisted drying system (HPADS)

AbstractIn the present work, fresh banana slices were dehydrated at various drying air temperatures (35, 40, and 45°C) using novel heat pump–assisted drying system (HPADS) operating in a close loop. Drying air temperature significantly influences the drying time; as the drying temperature increases, drying time is reduced linearly. Increase in slice thickness of the sample increases drying time. Verma et al.'s model was considered to select the best fit model and describe the actual data. Effective moisture diffusivity varied from 1.05 × 10−10 to 1.56 × 10−10 m2/s at temperatures 35 and 45°C, respectively. Arrhenius equation was used to correlate the dependency of moisture diffusivity with temperature and activation energy found to be 42.58 kJ/mol. Water activity (Aw) varied from 0.750 to 0.577 at temperatures 35 and 45°C, respectively. Hence, for Aw < 0.6 at 45°C drying temperature, micro‐organisms can no longer extract water for their growth, and enzymes become inactive. Specific moisture removal ratio and coefficient of performance of system were found to be 0.230 kg/kWh and 3.168, correspondingly, at maximum temperature (45°C). Therefore, a developed novel HPADS is recommended for small farmers and cottage industries.Practical ApplicationsIt is more reliable to dry agricultural products with high moisture content inside the novel heat pump assisted drying system. The developed drying system is recommended for small farmers or cottage industries. This study will be constructive for further research work on such drying systems.

The Physico-Chemical and Sensory Characteristics of Coloured-Flesh Potato Chips: Influence of Cultivar, Slice Thickness and Frying Temperature

Coloured potato chips, due to a higher concentration of bioactive compounds, may be healthier compared to traditional chips. This study examined the effect of cultivar and different slice thicknesses and frying temperatures on the physico-chemical and sensory characteristics of coloured potato chips. Potatoes chips were prepared from three coloured potato cultivars. Frying experiments were conducted at 160 and 180 °C using potato slices with thicknesses of 1.00 and 2.00 mm. The quality of the raw potatoes tubers and chips were estimated. A principal component analysis was applied to describe the differences in the physico-chemical characteristics between the potato chip samples processed with different conditions. The results showed that, significantly (p < 0.05), the highest amounts of total phenolic content, total anthocyanins, dry matter and starch were accumulated in raw tubers of potato cv. Blaue Anneliese. The highest amount of total phenolic content and anthocyanins was found in 1 mm chips of cv. Blaue Anneliese fried at 160 °C. An increased frying temperature significantly (p < 0.05) decreased the content of these compounds. The amount of fat in the chips was higher when they were fried at 160 °C than at 180 °C. Chips processed from potatoes cvs. Blaue Anneliese and Rosemarie showed a typical colour as a raw material. The hardness of the chips significantly (p < 0.05) increased with an increase in slice thickness. The flavour, odour and colour of the 1 mm chips of cv. Blaue Anneliese fried at 180 °C gained the highest rating.

Drying kinetics and sorption behavior of two varieties banana (sagor and sabri) of Bangladesh

The study was concerned with determining the drying kinetics and sorption behavior of two varieties ripe banana of Bangladesh namely, Sagor and Sabri. The fresh ripe banana collected from the local market were sliced into three different thicknesses (4 mm, 6 mm and 8 mm) and dried at 45°C, 55°C and 65°C in a cabinet dryer. The result showed that the drying rate increases with the increase in temperature and decreases with the increase in slice thickness. The sorption properties of dried banana were studied over a wide range of water activity (0.11-0.93). The BET and GAB models were fitted to the sorption data. It was found that both varieties gave sigmoid (type II) shape isotherm and GAB equation gave the much higher value of monolayer moisture content compared to BET equation. The chemical compositions of fresh and dried banana were determined. The dried products gave substantially higher solid content as well as protein, ash and carbohydrate.
 SAARC J. Agri., 16(2): 181-193 (2018)

Process Optimization for Development of Vacuum Fried Papaya (Carica papaya) Chips Using Response Surface Methodology

The effect of frying temperature, time and thickness of the slices on the quality of vacuum fried papaya chips was studied using the response surface methodology and following the central composite rotatable design. The results showed that moisture content, oil uptake, firmness, browning index and overall acceptability of fried papaya chips were significantly (p < 0.0001) influenced by all the independent variables. The browning index and overall acceptability of fried papaya chips were positively correlated with an increase in thickness of slices, whereas moisture content, fat content and firmness value were affected negatively with an increase in slice thickness. An increase in temperature positively affected all the response values except browning index, which was higher when slices were fried at high temperatures. The optimal vacuum frying condition for papaya chips was found to be 100 °C, 28 min and 3.1 mm slice thickness. The high correlation coefficients (95.55–98.70%) obtained for the responses indicate adequately fitness of the regression models.

Effect of Microwave Blanching on Slice Thickness and Quality Analysis of Star Fruit

Star fruit (Averrhoa carambola L.) is one of the underutilized tropical fruits and is a good source of vitamins and minerals. Peroxidase (POD) is the most heat stable enzyme which is used as an indicator for adequacy of blanching process. Blanching is a prerequisite for the preservation of fruits and vegetables. Hot water blanching is having disadvantages like wastewater production and loss of valuable nutrients by leaching. Microwave blanching is one of the emerging and clean technology which seems to provide a better nutrient retention due to shorter heating time and zero wastewater production. Therefore, the present investigation was carried out to identify a suitable blanching method (hot water blanching and microwave blanching) for different slice thickness (5, 10 and 15 mm) of star fruit that ensures enzyme inactivation and maximum retention of therapeutic value (ascorbic acid and oxalic acid). It was observed that blanching at 600, 480, 240 and 120 W power level for a slice thickness of 5, 10 and 15 mm required blanching time of 30-60 s, 40-70 s, 60-80 s, 80-150 s and 300-720 s respectively. For a given slice thickness, the moisture content of samples decreased with increase in power level. The moisture content was reduced to 84-88% w.b. from an initial value of 90% w.b. depending on power level and blanching time combinations. At the same time, the oxalic acid decreased significantly with increase in slice thickness and a decrease in power level. The change in ascorbic acid also showed a similar trend but the influence of slice thickness was not significant (p&gt;0.05).

Analysis of Fluctuation in Cerebral Venous Oxygenation Using MR Imaging: Quantitative Evaluation of Vasomotor Function of Arterioles.

Purpose:Cerebral arteriolar vasomotor function plays an important role in brain health. Since respiratory changes in the partial arterial pressure of CO2 (PaCO2) cause arterioles to vasodilate or vasoconstrict, resting-state arteriolar vasomotion results in the fluctuation of venous blood oxygenation, which can be monitored by observing magnetic resonance (MR) signals. Focusing on the superior sagittal sinus as the largest cerebral vein, we developed a method to elucidate the respiratory fluctuation of cerebral venous oxygenation that may reflect the vasomotor function.Methods:Single slices of varying thickness (7–15 mm) taken perpendicular to the superior sagittal sinus of five volunteers were imaged by spin-echo echo-planar imaging using a 1.5-T MR system. The time series of the signal intensity at the superior sagittal sinus was Fourier-transformed, and the spectral fluctuation intensity (SFI) at respiratory frequency was obtained. The amplitude of the respiratory fluctuation in the cerebral venous oxygenation was calculated from the gradient of the relation between the SFI and the average signal intensity, which increased proportionally with an increase in slice thickness. The amplitude of the fluctuation in cerebral venous oxygenation at low (<0.1 Hz) and cardiac pulsation frequencies was also calculated for comparison with the respiratory fluctuation.Results:The amplitude of respiratory fluctuation in the cerebral venous oxygenation was quantified as 1.2%, demonstrating the validity of our method via the highest significant correlation (r = 0.82) in the plot of SFI and average signal intensities; the correlations at low and cardiac pulsation frequencies were 0.60 and 0.63, respectively.Conclusion:We have successfully demonstrated cerebral venous oxygenation fluctuation at respiratory frequencies in the resting state. This fluctuation was non-invasively evaluated as 1.2%, representing the control value for the arteriolar vasomotor function of a healthy human.

SU-E-J-02: Accuracy of Fiducial Marker Localization Using Axial and Helical CT, Cone-Beam CT and KV Imaging.

To determine localization errors of fiducial markers using axial (ACT) and helical CT (HCT), cone beam CT (CBCT) and kV imaging. A thorax phantom containing markers of various sizes (2.5, 5, 10, 20mm) was imaged using ACT, HCT, CBCT and kV imaging. The phantom was imaged with and without motion (15mm amplitude, 15 cycles/min). CT images were reconstructed at 0.625, 1.25, 2.5 and 5mm thickness. Marker location and length were measured using axial and coronal imaging. The measured marker size increased almost linearly with increased slice thickness used in CT reconstruction with ACT for the stationary phantom. In HCT, the marker size varied non-linearly with increase in slice thickness. Motion of the phantom induced further blurring and shifts of the center of the marker with different sizes. The 10 mm marker was elongated up to 13.5 mm and 16.2 mm in the ACT and HCT, respectively. The markers were elongated up to nearly 26 mm using axial and helical scanning modes by phantom motion. The displacement of maker center was more prominent in the HCT with a shift up to 2 mm due to slice thickness for stationary phantom. The marker center was displaced by up to 18 and 22 mm using ACT and HCT, respectively, which was even higher than 15 mm motion amplitude. KV imaging produced the sharpest marker image with the least difference between actual and measured marker sizes. Increase in slice thickness enlarged the apparent marker size and displaced the maker center in ACT and HCT. Motion led to further enlargement in the maker size and displacement of maker center that depended on the motion amplitude. These effects should be considered in CT-based image-guided radiation therapy to ensure accurate tumor localization and patient positioning with implanted markers.

Effects of tomographic motion, slice thickness, and object thickness on film density

The experiment used the computer-aided CommCat model IS 2000 tomographic machine (Imaging Sciences International, Roebling, N.J.). The objective of the experiment was to study the influence of tomographic tube motion, tomographic slice thickness, and object thickness on film density. The experiment was conducted by x-radiating an aluminum step-wedge placed along the x-axis. Exposures were made for different tube motions and for different slice thicknesses. In linear horizontal and linear vertical motions, an increased slice thickness decreased film density. Slice thickness had a stronger effect on film density when the object to be x-radiated was thinner. In circular, elliptical, spiral, and hypocycloidal motions, changes in slice thickness had no noticeable effect on film density because the manufacturer had programmed the machine to produce approximately similar exposure times by increasing the x-ray tube velocity thickness had a greater effect on film density for circular, elliptical, spiral, and hypocycloidal tube motions than for linear horizontal and linear vertical tube motions. Clinical observation showed that except for the linear vertical motion (motion that was oriented in the same direction as that of the tube travel) all other motions produced a zone of diffusion along the edges of the steps of the step-wedge. An increase in slice thickness had an effect on film density. Slice thickness had a noticeable effect on film density in linear but not in multidirectional tomography. Object thickness had a greater effect on film density in multidirectional than in linear tomography.

In vitro metabolism of [ 3H]2,6-dinitrotoluene by human and rat liver

Liver slice tissue culture was used to compare human and rat liver metabolism of 2,6-dinitrotoluene (2,6-DNT). Oxidative metabolism of the 2,6-DNT side-chain methyl moiety produced 2,6-dinitrobenzylalcohol and the glucuronide conjugate of 2,6-dinitrobenzylalcohol, and reductive metabolism of the 2,6-DNT nitro groups produced 2-amino-6-nitrotoluene. Metabolites derived from side-chain oxidation accounted for 90–95% of the 2,6-DNT metabolites produced by rat liver slices under ambient oxygen concentrations of 25–100%; however, under 0% oxygen (100% nitrogen) atmospheres 2-amino-6-nitrotoluene accounted for 96% of the total metabolites. An increase in slice thickness from 0.3 to 0.8 mm decreased the ratio of oxidized to reduced 2,6-DNT metabolites produced by rat liver from 9:1 to 1:1. Under 100% oxygen and in liver slices approximately 0.3 mm thick, average rates of 2,6-DNT oxidative metabolism by human (five subjects) and rat liver were 1.0 and 2.1 nmol/min/g liver, respectively. K m and V max for the oxidative metabolism of 2,6-DNT by rat liver slices were 0.38 m m and 12 nmol/min/g liver, respectively. The average K m and V max for the oxidative metabolism of 2,6-DNT by two human subjects were 0.019 m m and 0.91 nmol/min/g liver, respectively.

Machine error in X-ray computer tomography and its relevance to prediction of in vivo body composition

An X-ray computer-assisted tomograph (Siemens Somatom 2) was used to evaluate the effects of instrumental settings on pure machine error (noise). A pig carcass was repeatedly scanned just posterior to the last rib using 24 combinations of voltage, current, slice thickness and projections. Each combination was used four times in succession and noise was assessed as the difference between scans taken with the same rotational direction. The experiment was replicated four times. Rotation had no effect and was omitted from the final model. All other factors had significant effects on the standard deviation of differences between individual pixel values and between attenuation value class frequencies of width two, ten and twenty, but had no effect on the mean attenuation value of the target. Theoretical predictions were confirmed by the data. The relationship between noise at 4 and 8 mm slice thicknesses was 0.708 compared to an expected value of 0.707 ( 1 2 ), and between the highest and lowest current levels was 0.509 compared to an expected value of 0.5 ( 1 4 ). Noise was, however, most sensitive to voltage; a 30% voltage increase resulted in a 37.5% reduction in noise, about three times the reduction that would have been produced by an equivalent increase in slice thickness or current. The results are discussed in relation to the optimum use of the tomograph for predicting in vivo composition.