Conversion Curves Research Articles

Application of logistic function to describe kinetics of non-isothermal dehydroxylation of fullerol

A sample of fullerol C60(OH)24 was synthesized. The basic physicochemical characterization of the synthesized fullerol was done. The non-isothermal kinetics of C60(OH)24 dehydroxylation has been investigated. The thermogravimetric curves have been recorded at different heating rates ranging from 5 to 25 K min−1. By application of the Kissinger–Akahira–Sunose isoconversion method, it was found that the activation energy complexly changes with the dehydroxylation degree. The possibility of mathematical description of the kinetics of fullerol dehydroxylation by logistic function was investigated. Fullerol dehydroxylation conversion curves were completely mathematically described by the linear combination of two logistic functions at all of the investigated heating rates. The changes in the values of parameters of logistic functions with heating rate were established. It was shown that complex kinetics of C60(OH)24 dehydroxylation consists of two consecutive dehydroxylation reactions (low-temperature and high-temperature components). The values of the kinetic parameters for two components of dehydroxylation process were calculated. A model for fullerol dehydroxylation has been discussed.

Effect of computed tomography number-relative electron density conversion curve on the calculation of radiotherapy dose and evaluation of Monaco radiotherapy treatment planning system.

The accuracy of a computed tomography (CT)-relative electron density (RED) curve may have an indirect impact on the accuracy of dose calculation by a treatment planning system (TPS). This effect has not been previously quantified for input of different CT-RED curves from different CT-scan units in the Monaco TPS. This study aims to evaluate the effect of CT-RED curve on the dose calculation by the Monaco radiotherapy TPS. Four CT images of the CIRS phantom were obtained by different CT scanners. The accuracy of the dose calculation in the three algorithms of the Monaco TPS (Monte Carlo, collapse cone, and pencil beam) is also evaluated based on TECDOC 1583. The CT-RED curves from the CT scanners were transferred to the Monaco TPS to audit the different algorithms of the TPS. The dose values were measured with an ionization chamber in the CIRS phantom. Then, the dose values were calculated by the Monaco algorithms in the corresponding points. For the Monaco TPS and based on TECDOC 1583, the accuracy of the dose calculation in all the three algorithms is within the agreement criteria for most of the points evaluated. For low dose regions, the differences between the calculated and measured dose values are higher than the agreement criteria in a number of points. For the majority of the points, the algorithms underestimate the calculated dose values. It was also found that the use of different CT-RED curves can lead to minor discrepancies in the dose calculation by the Monaco TPS, especially in low dose regions. However, it appears that these differences are not clinically significant in most of the cases.

In situ Raman analyses of the soot oxidation reaction over nanostructured ceria-based catalysts

To reduce the emissions of internal combustion engines, ceria-based catalysts have been widely investigated as possible alternatives to the more expensive noble metals. In the present work, a set of four different ceria-based materials was prepared via hydrothermal synthesis, studying the effect of Cu and Mn as dopants both in binary and ternary oxides. In situ Raman analyses were carried out to monitor the behaviour of defect sites throughout thermal cycles and during the soot oxidation reaction. Despite ceria doped with 5% of Cu featured the highest specific surface area, reducibility and amount of intrinsic and extrinsic defects, a poor soot oxidation activity was observed through the standard activity tests. This result was confirmed by the calculation of soot conversion curves obtained through a newly proposed procedure, starting from the Raman spectra collected during the in situ tests. Moreover, Raman analyses highlighted that new defectiveness was produced on the Cu-doped catalyst at high temperature, especially after soot conversion, while a slight increase of the defect band and a total reversibility were observed in case of the ternary oxide and pure/Mn-doped ceria, respectively. The major increment was related to the extrinsic defects component; tests carried out in different atmospheres suggested the assignment of this feature to vacancy-free sites containing oxidized doping cations. Its increase at the end of the tests can be an evidence of peroxides and superoxides deactivation on catalysts presenting excessive oxygen vacancy concentrations. Instead, ceria doped with 5% of Mn exhibited the best soot oxidation activity, thanks to an intermediate density of oxygen vacancies and to its well-defined morphology.

Regularised patient-specific stopping power calibration for proton therapy planning based on proton radiographic images

Proton transmission imaging has been proposed and investigated as imaging modality complementary to x-ray based techniques in proton beam therapy. In particular, it addresses the issue of range uncertainties due to the conversion of an x-ray patient computed tomography (CT) image expressed in Hounsfield Units (HU) to relative stopping power (RSP) needed as input to the treatment planning system. One approach to exploit a single proton radiographic projection is to perform a patient-specific calibration of the CT to RSP conversion curve by optimising the match between a measured and a numerically integrated proton radiography.In this work, we develop the mathematical tools needed to perform such an optimisation in an efficient and robust way. Our main focus lies on set-ups which combine pencil beam scanning with a range telescope detector, although most of our methods can be employed in combination with other set-ups as well. Proton radiographies are simulated in Monte Carlo using an idealised detector and applying the same data processing chain used with experimental data. This approach allows us to have a ground truth CT-RSP curve to compare the optimisation results with.Our results show that the parameters of the CT-RSP curve are strongly correlated when using a pencil beam based set-up, which leads to unrealistic variation in the optimised CT-RSP curves. To address this issue, we introduce a regularisation procedure which guarantees a plausible degree of smoothness in the optimised CT-RSP curves. We investigate three different methods to perform the numerical projection operation needed to generate a proton digitally reconstructed radiography. We find that the approximate and computationally faster method performs as well as the more accurate but more demanding method. We perform a Monte Carlo experiment based on a head and neck patient to evaluate the range accuracy achievable with the optimised CT-RSP curves and find an agreement with the ground truth expectation of better than . Our results further indicate that the region in the patient in which the proton radiography is acquired does not necessarily have to correspond to the treatment volume to achieve this accuracy. This is important as the imaged region could be freely chosen, e.g. in order to spare organs at risk.

Fabrication and modeling of catalytic membrane for removing water in esterification

In this study, homogeneous catalyst “poly(styrenesulfonic acid)” and crosslinking agent “3-amino propyl methyl diethoxy silane” were added into the Polyvinyl alcohol to prepare the catalytic composite membrane (CCM). And the separation layer was prepared by blending polyvinyl alcohol and sodium alginate. Poly(styrenesulfonic acid) (PSSA) loaded CCM have been used to synthesize ethyl propionate in a pervaporation catalytic membrane reactor. The CCM was characterized by the SEM, FTIR and XRD. The pervaporation and catalytic performance of CCM were investigated under varying conditions (mass ratio of PSSA to PVA, 3-amino propyl methyl diethoxy silane content, heat treatment time). When the mass ratio of PSSA to PVA was 5:5, content of SCA-A10F was 20.0% to PSSA, the esterification conversion reached 91.6% after 12 h. The permeation flux and separation factor were 260 g m−2 h−1 and 91 respectively. Then the reaction kinetic model and separation kinetic model were established by Python least square method for the first time. Meanwhile, the theoretical maximum conversion curve and the PV coupling model conversion curve were proposed by combining the two models. It was found that the conversion of the actual coupling reaction was between the two model curves.

Kinetics Study of the Solid State Reaction of Iron(III)Citrate Leading to Hematite Nanoparticles

Background: Thermal decomposition of iron-bearing organic complexes is a useful way to prepare iron oxides. Iron(III)citrate, FeC6H5O7, is a precursor for hematite (α-Fe2O3) synthesis by thermal decomposition technique. However, there is no information available on the nature of the mechanism of the reaction. Objective: Kinetic analysis of the solid-state thermal reaction of Iron(III)citrate, which decomposes to hematite under oxidative reaction atmosphere, has been studied in order to understand the reaction process. Method: Non-isothermal thermogravimetry under multiple heating rates has been employed. The obtained data are analyzed using model-free iso-conversional kinetic techniques in order to estimate the activation energy of reaction and reaction rate. Master plot method has been employed to determine the most-probable reaction mechanism. Reaction rate has been used to estimate the thermodynamic parameters (ΔS*, ΔH* and ΔG*). Decomposed material has been studied by XRD and TEM. Observations: Thermal decomposition of Iron(III)citrate is a three-step process and is completed by ~600 K. The decomposed product obtained is hematite nanomaterial. The estimated activation energy and reaction rate values are strongly dependent on the extent of conversion. The initial two steps of thermal decomposition reaction may involve ‘threedimensional diffusion’ and ‘random nucleation’, whereas the third step may be assigned again to ‘three-dimensional diffusion’. Simulated conversion curves justify the estimated kinetic parameters. A reaction pathway has also been predicted. Keywords: Iron(III)citrate, iso-conversional method, kinetics, thermal decomposition, thermogravimetry, thermal energy.

Gasification mechanism and kinetics analysis of coke using distributed activation energy model (DAEM)

This work studied the gasification reaction of four different metallurgical cokes (Coke-A, Coke-B, Coke-C, Coke-D) with CO2 by the thermogravimetric analysis. The physical, chemical and structure features were also analyzed systematically. It is found that with increasing the heating rate, the conversion curves move to high temperature for all these four cokes, and the maximum gasification rate also increases. Meanwhile, at the same heating rate, the gasification reactivity of these four cokes is ordered as: Coke-D > Coke-C > Coke-B > Coke-A. According to the component and structural analysis, the gasification reactivity was mainly due to the microcrystalline structure of the carbon in the coke, and the gasification reactivity of coke increases when the content of amorphous carbon increases. Comparing with the single-step global model, the distributed activation energy model (DAEM) is more accurate to characterize the gasification kinetics for the studied cokes, and the activation energies are in the range of 159.8–254.1 kJ/mol.

Electrospun YMn2O5 nanofibers: A highly catalytic activity for NO oxidation

Nanofiber catalysts are potentially promising to be equipped in the lean-burned vehicle exhaust emission system considering its facile synthesis, low-cost, long durability in contrast to the traditionally complicated powder based catalyst. Here, via electrospinning method, we synthesized YMn2O5 nanofibers (average diameter: ˜93 nm) including nanowire stacked with particles, and hollow tubes with or without inside nanowires. The morphologies remained even after hydrothermal aging at 800 ℃ for 10 h with 10% H2O stream. X-ray photoelectron spectrum revealed Mn4+/Mn3+ ratio 0.589 on the surface of YMn2O5 catalyst (YMO), indicating the existence of oxygen vacancies. The highest conversion of electrospun mullite fibers at 310 ℃ is ˜18% higher than powder-based YMO at 352 ℃ in the presence of 5% H2O at WHSV = 240,000 ml g−1 h−1. The extracted activation energy from NO-to-NO2 conversion curves of YMO nanofiber (61.68 kJ/mol) is slightly lower than that of powder-based mullite (91.45 kJ/mol), consistent with calculated 68.16 kJ/mol on the fiber YMO surface (121) with a rate-limiting step of the NO2 desorption. The catalytic activity can be attributed to the unit occupy of the eg (dz2 and dx2-y2) orbitals of Mn-dimer atoms around fermi level based on the combination of the theoretical calculations and DRIFTS spectra analysis. Importantly, after the hash hydrothermal-aging, the highest NO oxidation conversion of powder-based mullite is less than 50%, while the fiber maintains a conversion of 62%. Moreover, the fresh YMO fiber maintained superior oxidation stability for 12 h at its maximum conversion of 66%. This work provides the possibility for mullite oxide fibers to replace powder-based precious metal catalyst coating on monolith converter.

DAEM kinetics analysis and finite element simulation of thermal debinding process for a gelcast SiAlON green body

Thermal debinding is an important step in a gelcasting process, and the proper selection of the debinding technique is crucial for the quality of a green body. In this work, the pyrolysis characteristics of an N,N-dimethylacrylamide/N,N′-methylenebisacrylamide gel system in a thermal debinding process of a gelcast SiAlON green body were investigated through nonisothermal thermogravimetric analysis and a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy analysis. In addition, the pyrolysis kinetics of the thermal debinding process of the gelcast SiAlON green body were described by using a three-parallel-distributed activation energy model. The results showed that the conversion (α) and reaction rate (dα/dT) curves predicted by the kinetic model agreed well with the experimental data. The kinetic parameters (E0,i, k0,i, and σi) of the global thermal debinding process were 116.0–158.0 kJ/mol, 9.31 × 108 s−1 and 2.19–20.52 kJ/mol, respectively. Finally, a solid–fluid–thermal–mechanical coupling numerical model of the thermal debinding process was established through finite element methods on the basis of theories of the porous medium seepage and thermodynamics. The distributions of the residual content of the gel polymer, the temperature, the pressure, and the stress in the green body throughout the entire thermal debinding process were evaluated using this model. It was shown that a high heating rate leads to a high temperature gradient and von Mises stress inside the green body. Moreover, a reasonable debinding technique was proposed to effectively prevent and eliminate defects caused by excessive stress or a temperature gradient inside the green body. In a given DMAA/MBAM gel system, the strongest stress peak can be effectively eliminated by holding at 310 °C for no less than 2 h at a heating rate of 1 °C/min. This work aims to provide a theoretical basis for studying thermal debinding kinetics and optimizing debinding techniques for the gelcasting of various materials.

Catalytic effect of nanosized ZnO and TiO2 on thermal degradation of poly(lactic acid) and isoconversional kinetic analysis

Thermal features and thermal decomposition of poly(lactic acid) (PLA) hybridized with nanosized ZnO and TiO2 have been investigated in inert nitrogen by means of multiple heating-rate thermogravimetric analysis. Experimental results show that PLA hybrids become thermally destabilized as compared to pure PLA and ZnO exhibits stronger effect than TiO2. Evolutional FTIR spectra demonstrate that PLA and its two hybrids exhibit relatively different thermal dependences. Isoconversional kinetic analysis has been performed with various differential and integral methods and the activation energies thus calculated over the whole pyrolysis range suggest that the metal oxide added has led to greatly decreased activation energy for PLA to undergo pyrolysis and resulted in substantially higher decomposition rate constant. Such catalytic effect is found to be more considerable for ZnO than TiO2. By using the Coats-Redfern method, the D3 model is determined to be the most probable reaction model for PLA decomposition. Using the isoconversional activation energy, pre-exponential factor and D3 model, the temperature-dependent mass conversion curves under different heating rates have been successfully recast, leading to very satisfactory calculation performances for the description of pyrolysis decomposition of PLA and its two metal oxide hybrids.

Effects of Light on Catalytic Activities and Lifetime of Plasmonic Au Catalysts in the CO Oxidation Reaction

The catalytic oxidation of CO to CO2 allows for the removal of poisonous CO to improve indoor and outdoor air quality. Currently, industrial CO oxidation catalysts are not effective at low temperatures. A group of the most promising choices, Au catalysts supported on Mg(OH)2 and MgO, are highly active even at −70 °C, but show decreased activity between 20 and 100 °C. These catalysts also have short lifetimes. Here, we utilize knowledge of plasmonic catalysis in the study of the CO oxidation reaction over plasmonic Au catalysts. We hypothesized that light interacting with catalysts via surface plasmon resonances has the potential to dramatically improve such catalytic reactions. Initial experiments demonstrated a significant improvement of the catalytic activity and lifetime under light. Using the particular features in the temperature dependent conversion curve of this catalyst, we developed a method to separately examine the thermal and nonthermal contributions of light. Detailed studies on the relations...

38 Evaluation of an artifact correction algorithm and influence on dose calculation in photon and proton therapy

Introduction The Centre Antoine Lacassagne is equipped with a Discovery CT590 RT scanner from GE Healthcare with the smart Metal Artifact Reduction technology (MAR). MAR is a reconstruction algorithm which improves CT data quality in the presence of high Z-metal such as prosthesis or screws for example. This correction of Hounsfield CT number (UH) has potentially an influence on the dose calculation in and around material with high density. The purpose of this study is to evaluate the impact of this reconstruction on photon and proton dose calculation and to propose a methodology to optimize the artifact correction protocol according to the treatment modality. Methods Phantoms containing different metallic implants (dental sealing and hip prostheses for photontherapy and titanium screw for protontherapy) were built. CT images were acquired with the inserts, and each set of images was reconstructed twice: once with and once without MAR. Different plans were made on the different Treatment Planning System (TPS) according to the technique: Isogray (Dosisoft) with collapsed cone dose calculation for photon and Raystation (Raysearch) with pencil beam and Monte Carlo dose calculation for protontherapy. Dose measurements were made with ionization chambers in the phantom (cylindrical chamber for photon and plane parallel chamber for proton). Then, experimental measurements were compared to the TPS dose calculation for each protocol: - For plan with CT Scan and UH generated with MAR algorithm, - For plans with CT scan and UH without MAR, - For plan with artifact override density in the CT scan with density close to surrounding tissues. Results The first results show that in protontherapy there is a difference between the doses obtained with or without MAR and therefore it was necessary to adopt 2 different calibration curves. More measurements are in progress. In protontherapy measurements of the equivalent water thickness and the impact on the range in 1D and 2D have to be made. In photontherapy, the observed differences do not significantly affect the dosimetric calculation but play an important role during the contouring phase. Measurements with other dose calculation algorithm have to be made also. Conclusion This work proposes a methodology to optimize CT protocol and HU-to-density conversion curve when using Metal artifact correction. The methodology has to be adapted according the localization but also the treatment modality and dose calculation algorithm.

Applicability and repeatability in angiography systems of statistical method for the low contrast detectability

Purpose The aim of this study is to evaluate the applicability and repeatability of the Low Contrast Detectability (LCD) statistical method in angiography systems [1] , [2] . Methods A phantom consisting of a square aluminum target and a 5-step-wedge (0.2–1 mmAl) was built according to Radice et al. [2] . Different acquisition protocols were used (low, normal and high dose fluoroscopy; abdomen and cerebtal fluorography), and measurements were repeated for several thicknesses of PolyMethylMethAcrylate (PMMA). A Matlab software automatically calculates LCD values in terms of Pixel Value (PV) and contrast threshold (Ct); it also converts PV in mmAl (Fig. 1), providing the LCD(mmAl) [2] . The short- and long-term repeatability were evaluated by repeating acquisitions five times for every session and monthly (for six months) respectively. Results The Coefficients of Variation CV(%) reported in Table 1 are always higher for LCD(mmAl) than for LCD(PV) and LCD(Ct), especially in case of long-term measurements which consequently are not repeatable. This difference is related to unstable conversion from PV to mmAl; indeed, the image noise makes difficult to select the steps of the wedge. To overcome the problem, it would be possible to extend the step-wedge up to 2 mmAl, to introduce the point (0,0) in the conversion curve and to use only the curves with R2 > 0.8. Conclusions The LCD statistical method is easy to implement and provides consistent results for LCD(PV) and LCD(Ct). However, the LCD(mmAl) values seem to be not repeatable because of the instability of PV-mmAl conversion; the suggested solutions can improve the conversion, leading to more robust LCD (mmAl) values.

Catalytic effect of zeolite LTA on thermal degradation of polysulfone and kinetic analysis

AbstractThermal stability of polysulfone (PSF) and its zeolite LTA hybrids with two different zeolite contents has been investigated by using differential thermal analysis (DTA) and thermogravimetric (TG) analysis measurements, and the thermal experiments in air were conducted at a constant heating rate in the span of 5–30 K/min. The thermal characteristics were evaluated based on TG and DTA results. Two‐stage thermal decomposition is seen to mainly occur in the range of 700–970 K and the zeolite LTA added has considerably influenced the thermal behavior of PSF. Two isoconversional model‐free Flynn–Wall–Ozawa and Coats–Redfern methods are employed to perform kinetic analysis of the mass loss versus temperature data, resulting in activation energy and pre exponential factor values. The activation energies obtained over the whole conversion range for two zeolite composites are considerably lower than those of pure PSF, possibly related to the catalytic effect of zeolite LTA added. The materials conversion functions D5 and D3 are found to more appropriately describe thermal degradation of PSF and its zeolite LTA hybrids. Using the kinetic parameters and conversion functions, the temperature‐dependent thermal conversion curves under different heating rates have been successfully recast, leading to excellent calculation results.

A procedure for deriving wind turbine noise limits by taking into account annoyance

With the increasing installation of wind farms, the attention of citizens towards wind turbine noise (WTN) has grown. Differently from some national legislations, the scientific community has promptly responded, increasing the studies and the social surveys in order to better understand the cause of disturbance and the indicators that relate to it. At first, the paper underlines the importance of low WTN levels for indirect health effects such as sleep disturbance and annoyance. The importance to consider noise annoyance in legislation is also discussed, as WTN is more disturbing than other most common noise sources. Then, conversion curves for equally highly annoyed are introduced considering the annoyance perceived by population in relation with the type of source. Finally, a specific limit value of 43 dB(A) for WTN is derived and suggested, comparable with British and Danish standards.

P269] Absorbed dose calculation based on CBCT data for head and neck cancer patients

Purpose In a radiotherapy magnetic resonance imaging (MRI) only workflow, a synthetic CT (sCT) data set is generated from the MRI data as a substitute to the computed tomography (CT). Since no CT scan will be acquired, no such data is available for quality control (QC) of the sCT. It has been suggested to use kV-cone beam CT (CBCT) data for QC in the head region [1] . The aim of this study is to evaluate the possibility to use CBCT for QC of the sCT for head and neck (H&N) cancer by comparing H&N treatment plans calculated using the CT and CBCT data, respectively. Methods Five patients with one CT and two CBCT data sets each, were evaluated. All CBCT data sets were deformably registered to the CT data, remediating errors originating from repositioning and/or anatomical changes between the imaging sessions. The CBCT and CT data were adjusted to the same field of view (FOV) in the longitudinal direction. A clinical treatment plan was created based on the CT data for each patient. Treatment volumes, organs-at-risk (OAR) and treatment plan were copied from the CT to the deformable registered CBCT. The treatment plan was then recalculated, with the standard CT HU-RED conversion curve. Dosimetric differences between the dose distributions for the treatment plans were calculated and evaluated by comparing dose-volume constrains. Results The mean local difference for the mean absorbed dose to the clinical target volume (CTV) was 0.41% with a maximum and minimum value of 1.37% and 0.15% respectively. The CTV D 98 % criteria had a difference of 0.19% and CTV D 2 % criteria a difference of 0.38%. The planning OAR volume (PRV) of the spinal cord had a difference of 0.39% and the parotid right and left a difference of 0.36% and 0.08%, respectively. Conclusions The dosimetric difference between the dose distributions for treatment plans calculated based on CT and CBCT data were minor. This indicates that CBCT data could be a good candidate for QC of sCT data in an MRI only workflow for H&N cancer patients.

The Enhancement of 3 MHz Ultrasonic Echo Signal for Conversion Curve Development for Acoustic Impedance Estimation by Using Wavelet Transform

Ultrasonic technology has already been used for many applications. Most of them are mainly used for object measurement. Some techniques have been widely applied to particular measurement by utilizing a very specific component. In this research, the previous technique to develop a conversion curve to obtain the acoustic impedance of the target is adopted. Then, we propose a 3 MHz concave shaped ultrasonic transducer for measuring liquids and a confirmation is needed to confirm if the system used is correct. Therefore, several saline solutions which property has been known are used. A low voltage of 10 Volt pulse is used to trigger the transducer. The ultrasonic wave is then transmitted through the multilayered mediums, which is pure water, clear acrylic, and the target. The echo from the interface between the acrylic and the target is then received by the same transducer. Some parameters such as peak and RMS are used to develop the conversion curve. A peak detection and comparison between the original echo and the processed one by using Wavelet transform (UWT and DWT) is then performed. Some analysis of the echo signal by using multiresolution and time-frequency analysis is also proposed. The result obtained from the measurement is then compared to that from the theoretical calculation. Based on the result, in terms of developing the calibration graph, only the RMS value (UWT) which has the closest trend to the result of the calculation, with the mean percentage error of 0.65512%, which is the smallest value among all parameters.

Effects of view angle and measurement distance on electrical equipment UV corona discharge detection

A UV radiation detecting platform is set up to evaluate the influence of view angle and measurement distance in UV detection technology, then a coordinate conversion equation is proposed to compensate the influencing factors. Since the photon number of dischargeable power equipment changes with the varied external factors including distance, angle, humidity, and wind force, the research studies the effects of both view angle and distance while others are invariant. Results show that the variation of view angle and distance has an impact on UV detection. Given that different observation points have different view angle and observation distance, photon numbers at different points could be calibrated to the optimal position in accordance with the proposed equation. In addition, the 3-D simulation and conversion curves also verify the validity of proposed theory. Accordingly, the results of this study can provide a reference to improve the effectiveness and application of UV imager in fault diagnosis.

Pyrolysis of Corn Residues: Kinetic Analysis using Discrete Distributed Activation Energy Model

Agro-residues are usually generated in large amount. These biomass materials may be utilized as renewable energy source via thermochemical conversion processes. Knowledge on kinetic of thermal decomposition behavior of biomass is important in reactor design and thermal process optimization. In this work, thermogravimetric (TG) data (35 to 900°C, at heating rates of 5 to 50°C/min) from pyrolysis of corn residues was analyzed using discrete distributed activation energy model (DAEM). Prediction accuracy of the simulated data was verified by comparing experimental with calculated data of conversion at selected heating rates. Kinetic parameters including activation energy and pre-exponential factor obtained from this method were found to give correct conversion curves for different heating rates simultaneously with correlation coefficients greater than 0.99, within the ranges considered. According to the discrete DAEM, variation in activation energy with conversion implied changes in mechanism during pyrolysis process. The activation energies were observed to be in the range of 100 – 120 and 80 – 180 kJ/mol for the macro-TG and typical TG analysers, respectively.

Using a Somatosensory Controller to Assess Body Size for Size-Specific Dose Estimates in Computed Tomography.

Computed tomography (CT) has been widely used in the healthcare environment. Presently, the radiation dose in CT is determined using the size-specific dose estimate (SSDE). Accurate assessment of individual's body size is essential for dose estimation. In this study, we integrated a somatosensory controller with a CT scanner to measure patient's anterior-posterior diameter (APD) and lateral diameter (LATD) and calculate the corresponding effective diameter (ED). A total of 108 individuals with an average age of 38.6 years were enrolled in this study. Microsoft Kinect was used to acquire the depth image of subjects. A grayscale-to-surface height conversion curve was created using acrylic sheets for APD estimation. The APD, LATD, and ED were measured and compared with the results obtained using F ruler and CT images. The mean absolute differences for APD, LATD, and ED between Kinect and F ruler measurements were 5.2%, 1.3%, and 2.5%, respectively, while those between Kinect and CT measurements were 8.8%, 2.6%, and 5.0%, respectively. Kinect can replace CT or F ruler for real-time body size measurements. The use of the somatosensory controller has the advantages of simple, low cost, no radiation, and automatic calculation. It can accurately estimate patient's APD, LATD, and ED for SSDE.