Search

Shape accuracy is an important quality measure of finished parts built by Additive Manufacturing (AM) processes. Previous work has established a generic and prescriptive methodology to represent, predict and compensate in-plane (x – y plane) shape deviation of AM built products using a limited number of test cases. However, extension to the out-of-plane (z-plane) shape deviation faces a major challenge due to intricate inter-layer interactions and error accumulation. One direct manifestation of such complication is that products of the same shape exhibit different deviation patterns when varying product sizes. This work devises an economic experimental plan and a data analytical approach to model out-of-plane deviation for improving the understanding of inter-layer interactions using a small set of training shapes. The key strategy is to discover the transition of deviation patterns from a smaller shape with fewer layers to a bigger one with more layers. This transition is established through the effect equivalence principle, which enables the model predicting a smaller shape to digitally "reproduce" the bigger shape by identifying the equivalent amount of design adjustment. In addition, a Bayesian approach is established to infer the deviation models capable of predicting deviation of complex shapes along the z-direction. Furthermore, prediction and compensation of out-of-plane deviation for two-dimensional freeform shapes are accomplished with experimental validation in a stereolithography process. [ABSTRACT FROM AUTHOR]

A series of functional microcapsules for electrophoretic display (EPD) prepared by complex coacervation technology utilising gelatin and arabic gum as a wall material are presented. The authors have investigated the Isopar M electrophoretic fluid containing blue-white, red-white and yellow-white particles modified by the physical coating as core materials of microcapsules, respectively. The mass ratio of wall/core material is a key factor influencing the yield of microcapsules. The surface of microcapsule was characterised by optical microscopy and scanning electron microscopy. The display prototypes based on the red-white, blue-white and yellow-white microencapsulated electrophoretic fluids have been prepared. The contrast ratios of prototypes were found to be 1.62, 1.67 and 1.22, respectively. [ABSTRACT FROM AUTHOR]

Algae are good sources of immature oil. A long-term (more than 5 years), low-temperature (80°C) simulation of early diagenesis of organic matter from algae was carried out. In the very early stage of the simulation, different quantities of immature oil were generated after 26 to 56 days. After one year, algae showed obvious fluorescence, and the intensity was maintained during the remainder of the simulation. From the earlier stages of the simulation to the later stages, the asphaltene fractions of the soluble extracts decreased and the polar fractions increased. Asphaltene and polar compounds play important roles in the formation of immature oil, especially under briny environments. Finally, the changes in hydrocarbons during the simulation are discussed and the algae-originated phytenes and C20bicyclic terpanes are suggested as biomarkers for immature oil. [ABSTRACT FROM PUBLISHER]

This paper presents a novel method for modeling the complexity of collaborative design systems based on their analysis and proposes a solution for reducing complexity and improving the performance of such systems. The interaction and interfacing properties among many components of a complex design system are analyzed from different viewpoints and then a complexity model for collaborative design is established accordingly. In order to simplify complexity and improve performance of collaborative design, a general solution of decomposing a whole system into sub-systems and using a unified interface mechanism between them has been proposed. This proposed solution has been tested with a case study. It has been shown that the proposed solution is meaningful and practical. [ABSTRACT FROM AUTHOR]

This work provides a summary of selected experimental capabilities being developed to support nonnuclear testing and demonstration of technology in support of microreactors under the U.S. Department of Energy's (DOE's) Microreactor Program. Major capabilities include the Single Primary Heat Extraction and Removal Emulator (SPHERE) and the Microreactor Agile Non-nuclear Experimental Test Bed (MAGNET). The SPHERE facility allows for controlled testing of the steady-state and transient heat rejection capabilities of a single heat pipe using electrical heaters that simulate nuclear heating. The facility is capable of monitoring axial temperature profiles along the heat pipe and surrounding test articles during startup, steady-state operation, and transients. Instrumentation includes noncontact infrared thermal imaging, surface thermocouples, spatially distributed fiber optic temperature and strain sensors, electrical power meters, and a water-cooled, gas-gap calorimeter for quantifying heat rejection from the heat pipe. The facility can be operated under both vacuum and inert-gas conditions. The MAGNET facility is a large-scale, 250-kW electrically heated microreactor test bed to enable nonnuclear experimental evaluation of a variety of microreactor concepts. It can be supplied to electrically heat a scaled section of a microreactor and further test the capabilities of heat rejection systems. The initial MAGNET experiments will support technology maturation and reduce uncertainty and risk associated with the design, operation, and deployment of monolithic heat pipe--based reactors. However, this test bed can broadly be applied to multiple microreactor concepts to evaluate a wide range of thermal-hydraulic and structural phenomena such as interface coupling with power conversion units and other collocated systems. MAGNET can evaluate integral thermomechanical effects during electrical heating of an array of heat pipes in a larger test article. Examples of initial testing will include thermal stresses in the monolith and the impact of debonding of a heat pipe from the core block and how that failure could impact surrounding heat pipes, i.e., understanding the potential for cascading failure. This work also discusses some modeling capabilities that can support experiment design, analysis, and interpretation, including the heat pipe code Sockeye and a comparison of thermal-structural simulations performed using ABAQUS and STAR-CCM+. [ABSTRACT FROM AUTHOR]

Source rocks generate and expel hydrocarbon with thermal evolution, which lead to a decrease of total organic carbon (TOC) content. A new quantitative model for original total organic carbon (TOCo) content evolution and recovery was proposed, and then was used to the carbonate source rocks with different TOCs (CSRDTOC) in the Tazhong area, Tarim Basin, China. Studies showed that the higher the TOC of source rocks, the bigger the range of TOC reduction and recovery coefficient. When vitrinite reflectance (VR) is equal to 2.5%, recovery coefficients of TOCo= 0.2%, 0.4%, and 1.0% are 1.43, 1.66, and 2.01, respectively. It must restore TOCowhen we evaluate source rocks at the stage of high overmaturity and predict oil and gas resources. [ABSTRACT FROM PUBLISHER]

An efficient method for wide-band analysis of antennas radiating in the presence of an electrically large conducting platform is proposed. The method is based upon the well known method of moments-physical optics (MoM-PO) hybrid formulation combined with the Maehly approximation. Compared with the asymptotic waveform evaluation (AWE) technique, the major advantage of the Maehly approximation is that it does not require the complex computation concerning dense impedance matrix, and it can be easily implemented into an existing MoM-PO computer code. Numerical results show that the proposed method is superior, in terms of CPU time, to the traditional MoM-PO. [ABSTRACT FROM AUTHOR]

The structural stability of marcasite-type FeP2 at high pressure has been studied by X-ray diffraction, Raman spectroscopy, and theoretical calculations. Experimental results show that no phase transitions happen up to 28 GPa at room temperature. The shortest axis of the marcasite-type FeP2 cell, the c-axis, is the most compressible, due to the softening of edge-shared octahedra along the c-axis. The linear pressure coefficients and Gruneisen parameters of four Raman modes are determined. Theoretical calculations further support the experimental results and indicate that FeP2 is still a semiconductor up to 35 GPa. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of endangered plants using remote sensing data. The aim of this study was to investigate and assess spatial distribution changes and temporal coverage changes of the following endangered rare plants: Tetraena mongolica, Helianthemum soongolicum, Reaumuria trigyna, Reaumuria soongorica, Potaninia mongolica, and Ammopiptanthus mongolicus, in the West Ordos Plateau National Conservation Region in Inner Mongolia, China. Using ETM+ (August 1999) remote sensing data, DEM data, and data from 25 field samples collected from Gangdeger Mountain in July 1999, digital maps highlighting endangered plant populations (1994) were processed using the ‘MPH feature extraction method’ to view the current spatial distribution pattern of the endangered plants. The ‘radiometric normalization’ and ‘vegetation change detection’ methods were then used to reveal temporal coverage changes of the endangered plants, using TM (September 1987) and ETM+ (August 1999) data. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to determine the associations among menopausal status, menopausal symptoms, and depressive symptoms in midlife women in Hunan, China.Methods: A secondary analysis involving 3199 women aged 40-55 years was performed based on data from the Women Health Needs Survey 2018 in Hunan Province, central south China. The depressive symptoms were determined using the 9-item Patient Health Questionnaire. The menopausal symptoms were assessed using the Kupperman Menopausal Index. Demographic characteristics and menopausal status were measured using self-administered questionnaires.Results: The prevalence of depressive symptoms was 19.3%. The three most common menopausal symptoms were insomnia (48.0%), fatigue (42.7%), and mood swing (39.8%). The increase in depressive symptoms was significantly associated with menopausal status and menopausal symptoms. After controlling for demographic variables, multivariate logistic regression showed that menopausal transition (odds ratio [OR] = 1.14, 95% confidence interval [95% CI] = 1.12-1.86), postmenopause (OR =1.52, 95% CI = 1.09-2.11), and four menopausal symptoms including mood swing (OR = 1.32, 95% CI = 1.03-1.70), depressive mood (OR = 2.28, 95% CI = 1.79-2.91), palpitations (OR = 1.37, 95% CI = 1.06-1.77), and urinary tract infection (OR = 1.49, 95% CI = 1.16-1.92) were associated with depressive symptoms.Conclusions: Independent of demographic variables, menopausal transition, postmenopause, and four menopausal symptoms (mood swing, depressive mood, palpitations, and urinary tract infection) increase the risk of depressive symptoms. [ABSTRACT FROM AUTHOR]

The pyrolysis kinetics of invasive plantSpartina anglicabiomass was investigated via a thermogravimetric (TG) analyzer from 50 to 800°C in an inert argon atmosphere at different heating rates of 5–30°C/min, and the kinetic parameters were deduced by Starink and master-plots methods. The results showed that three stages appeared in the thermal degradation process, and the mean value of activation energy was calculated to be 291.57 kJ/mol by the Starink method. It suggested that the most probable pyrolysis kinetic model wasg(α) = [−ln(1-α)]4deduced by the master-plots method, which meant a random nucleation and nuclei growth mechanism. These results provided fundamental useful information for describing the pyrolysis process, and the subsequent designing and running of a pyrolytic processing system usingS. anglicaas feedstock. [ABSTRACT FROM PUBLISHER]

Several grasses are among the agricultural wastes generated annually in a large quantity during farming activities. In this study, thermogravimetric analysis was used to evaluate the fuel properties of a number of grasses, includingAeluropus sinensis, Conyza canadensis, Imperata cylindrica, andSetaria viridis. The pyrolysis behavior was also compared with the other biomasses. The thermal reaction systems fitted well with the distributed activation energy model and the global kinetic model and it is obvious that the values ofEandk0calculated by the distributed activation energy model were much higher than that of the global kinetic model. [ABSTRACT FROM PUBLISHER]

The optimal reaction model for analysis of thermal decomposition of various types of biomasses is currently under debate. Four established models for the kinetic analysis ofPolygonum lapathifoliumwere employed in this study: double extrapolation method, Flynn–Wall–Ozawa method (FWO), distributed activation energy model (DAEM), and global kinetic model. The values of activation energy and frequency factor calculated by global kinetic model are much lower than that of the other three methods. Moreover, it has been demonstrated that the activation energy analyzed by FWO method and DAEM is widely distributed and is not directly related to the heating rates, which are more objective than double extrapolation method and global kinetic model. [ABSTRACT FROM PUBLISHER]

Cyanobacteria have developed various response mechanisms in long evolution to sense and adapt to external or internal changes under abiotic stresses. The signal transduction system of a model cyanobacterium Synechocystis sp. PCC 6803 includes mainly two-component signal transduction systems of eukaryotic-type serine/threonine kinases (STKs), on which most have been investigated at present. These two-component systems play a major role in regulating cell activities in cyanobacteria. More and more co-regulation and crosstalk regulations among signal transduction systems had been discovered due to increasing experimental data, and they are of great importance in corresponding to abiotic stresses. However, mechanisms of their functions remain unknown. Nevertheless, the two signal transduction systems function as an integral network for adaption in different abiotic stresses. This review summarizes available knowledge on the signal transduction network in Synechocystis sp. PCC 6803 and biotechnological implications under various stresses, with focuses on the co-regulation and crosstalk regulations among various stress-responding signal transduction systems. [ABSTRACT FROM AUTHOR]

Lead phosphate Pb3(PO4)2was investigated byin situsynchrotron radiation X-ray diffraction and X-ray absorption near-edge structure (XANES) combined with diamond anvil cell technique up to 60.9 GPa. A pressure-induced phase transition of Pb3(PO4)2was observed from monoclinic (C2/c) to trigonal () phases at about 1.7 GPa at room temperature. The high-pressure annealing experiment indicates that the trigonal phase of Pb3(PO4)2is stable at least up to 60.9 GPa. Isothermal pressure–volume relationship of trigonal Pb3(PO4)2is well described by the third-order Birch–Murnaghan equation of state withV0= 533(1) Å3,K0= 89(4) GPa andK0′= 5.8(2). In trigonal Pb3(PO4)2, thea-axis is more compressible than thec-axis, showing an anisotropy elasticity. XANES results reveal the evolution of Pb local environment, i.e. the first-shell coordination number of Pb1 changes from 9 to 12 and the average Pb–O bond length increases at the crossover ofC2/c-to-phase transition. [ABSTRACT FROM AUTHOR]

The use of non-food biomass for bio-oils production appears to be an important trend for renewable energy in China. Biomass, in the form of marine macro-algae, is becoming popular among new renewable energy sources. Fast pyrolysis is one of the most important thermal conversion processes from biomass to bio-fuel. In this work, the marine green tide macroalgaeEnteromorpha proliferawas converted into bio-oil by fast pyrolysis in a free-fall reactor at different temperatures ranging from 100 to 750°C. The bio-oil obtained was analyzed by elemental, gas chromatography-mass spectrometer, and Fourier transform infrared spectroscopy analysis. The results showed that the average heat value was 25.33 MJ kg−1and the oxygen content was 30.27 wt%. The results suggested thatE. proliferapresents as a good bio-oil feedstock candidate. [ABSTRACT FROM PUBLISHER]

The marine macroalgae green tides occurring frequently produced a great quantity of macroalgal wastes from 2007 to 2011 in China. The pyrolytic characteristics and kinetics of one kind of marine green tide macroalgae, Enteromorpha prolifera, was investigated by the thermogravimetric analysis method at heating rates of 10, 20, 30, 40, 50°C/min. The corresponding activation energy E and the pre-exponential factor A were calculated and the mechanism functions were determined by double extrapolation and Flynn-Wall-Ozawa methods based on the thermogravimetric data. The results show that the optimum mechanism can be described by the Zhuralev, Lesokin, and Tempelmen equation (G(α) = {[1/(1 − α]1/3 − 1}2) for E. prolifera in pyrolysis temperatures that range from 240 to 290°C, and the thermolysis mechanism is a three-dimensional diffusion process in the main pyrolysis process. It indicates that E. prolifera has low thermal stability for pyrolysis and is a potential biomass energy resource. [ABSTRACT FROM PUBLISHER]

The pyrolytic kinetics of Jerusalem artichoke stalk, cornstalk, and sawdust (the latter two served as control) were investigated using a thermogravimetric analysis method under an inert atmosphere at heating rates of 5, 10, 20, and 30°C/min from 50 to 800°C. For Jerusalem artichoke stalk, starting with the dehydration step between 30 and 150°C, the main thermal decomposition process showed two distinct degradation zones, corresponding to the devolatilization step between 200 and 400°C and the combustion step between 400 and 600°C. Kinetic expressions for the degradation rate in devolatilization and combustion steps have been obtained for Jerusalem artichoke stalk with Popescu, Flynn-Wall-Ozawa, and Kissinger-Akahira-Sunose methods. The results showed that the model agreed well with the experimental data and provided useful information for the design of a pyrolytic processing system using Jerusalem artichoke stalk as feedstock to produce bio-fuel. [ABSTRACT FROM PUBLISHER]

Behavioural modelling of physical systems from observations of their input/output behaviour is an important task in engineering. Such models are needed for fault monitoring as well as intelligent control of these systems. The paper addresses one subtask of behavioural modelling, namely the selection of input variables to be used in predicting the behaviour of an output variable. A technique that is well suited for qualitative behavioural modelling and simulation of physical systems is Fuzzy Inductive Reasoning (FIR), a methodology based on General System Theory. Yet, the FIR modelling methodology is of exponential computational complexity, and therefore, it may be useful to consider other approaches as booster techniques for FIR. Different variable selection algorithms: the method of the unreconstructed variance for the best reconstruction, methods based on regression coefficients (OLS, PCR and PLS) and other methods as Multiple Correlation Coefficients (MCC), Principal Components Analysis (PCA) and Cluster analysis are discussed and compared to each other for use in predicting the behaviour of a steam generator. The different variable selection algorithms previously named are then used as booster techniques for FIR. Some of the used linear techniques have been found to be non-effective in the task of selecting variables in order to compute a posterior FIR model. Methods based on clustering seem particularly well suited for pre-selecting subsets of variables to be used in a FIR modelling and simulation effort. [ABSTRACT FROM AUTHOR]