Temperature-coupled field analysis of LPG tank under fire based on wavelet finite element method

The temperature-coupled field analysis of liquefied petroleum gas (LPG) tank under fire is carried out based on wavelet finite element method. The wavelet finite element model is constructed through combing the heat conduct equation model and B-spline wavelet scale function. The temperature changing rules of LPG tank were obtained based on ANSYS software, wavelet finite element program, and test, respectively. The temperature changing rules of LPG and tank wall are obtained, and the effectiveness of the wavelet finite element method is verified.     

Investigations with the finite element method on the Cyber 205

We are trying to investigate systematically the application of the finite element method (FEM) for solving the Schrödinger equation. The present paper is devoted to the calculation of vibrational transition probabilities for the collinear reactive system A + BC (i.e. H+H₂ and their isotopes). The calculations are fully two-dimensional and the results are compared with earlier FEM calculations and conventional basis set expansion methods using the the R-matrix or S-matrix propagation.We made extensive analysis of FEM on the vector-computer Cyber 205 and developed a vector code for the efficient use in two dimensions, so that in the near future applications even in three dimensions will be possible.For the hydrogen exchange reactions we investigated the following isotope combinations: (a) H + H₂, b) H + DH, D + HD and H + MuH (symmetric reaction), (c) D + HH, H + DD and Mu + DD (asymmetric reaction). We calculated the transition probabilities for up to five open vibrational channels and found excellent agreement with known exact values.     

H2 solved by the finite element method

We report on the solution of the Hartree-Fock equations for the ground state of the H₂ molecule using the finite element method. Both the Hartree-Fock and the Poisson equations are solved with this method to an accuracy of 10⁻⁸ using only 26 × 11 grid points in two dimensions. A 41 × 16 grid gives a new Hartree-Fock benchmark to ten-figure accuracy.     

Application of the finite element method to molecular quantum mechanics

We present a general formalism of the finite element method and its computational aspects that influence the solution accuracy of spectral quantum mechanical problems. The possibilities of the method are demonstrated using as an example inversion vibrational spectra of structurally non-rigid complexes.High Energy Physics Institute, Protvino. I. V. Kurchatov, Atomic Energy Institute, Moscow. Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 27, No. 4, pp. 442–446. July–August, 1991. Original article submitted April 4, 1991.     

Thermal analysis model of scroll compressor with clearance leakage based on multiple scale method

Journal of Thermal Analysis and Calorimetry - The leakage of scroll compressor can reduce the working efficiency and cause risk, it is significant to study it in depth, thermal analysis of leakage...     

An appreciation of usability of the finite element method for the thermal analysis of stripe-geometry diode lasers

An appreciation of usability of the finite element technique for the thermal analysis of stripe-geometry diode lasers is carried out in the present work. Thye technique appears to be very exact and surprisingly speed using even a standard IBM PC/AT microcomputer.As an example, a finite-element thermal analysis of the diffused-stripe doubleheterostructure GaAs/(AlGa)As diode laser is carried out. A system of isotherms obtained for the above laser enables us to discuss the heat spreading process within its structure and to compare relative contributions of all heat sources.

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Zusammenfassung Es wurde die Anwendbarkeit der Elementenmethode bei der Thermoanalyse von Diodenlaser des Streifentypes dargestellt. Dieses Verfahren zeigte sich als sehr genau und unter Anwendung eines IBM PC/AT der Standardausführung auch als überraschend schnell.Als Beispiel wurde die Elementenmethode bei der Thermoanalyse eines doppelt heterostrukturellen GaAs/(AlGa)As Diodenlasers vom Diffusionsstreifentyp durchgeführt. Eine für den obengenannten Laser erhaltene Schar von Isothermen ermöglicht die Diskussion der Wärmeausdehnung innerhalb der Konstruktion sowie den Vergleich der relativen Beiträge aller Wärmequellen.

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The work was carried out under the Polish Central Program for Fundamental Research, CPBP 01.06, 6.04.     

Hydrophobicity modification of woven cotton fabric by hydrophobic fumed silica coating

Water repellency of woven cotton fabric was achieved by coating with the aqueous dispersion containing organosilane agent (HDTMS) and fumed silica. The coating agents were applied using padding method and then followed by batching the coated fabric at the ambient temperature for 24 h to allow the condensation reaction between HDTMS silanol group and fumed silica silanol group, rendering silica particles hydrophobic. An ultrasonicator was employed to prepare the homogenous coating dispersion. The water repellency evaluated by water contact angle determination which showed the contact angle over 110° was obtained with low amount of applied HDTMS of 1 wt%. The effect of fumed silica addition on an increase in fiber surface roughness geometry showed the influential result in improving the water contact angle. From durability to washing test, the hydrophobic coatings evidenced from SEM and ATR/FTIR remained adhering to fiber surface, indicating the durability. After washing, the coating on the fabric with fumed silica addition appeared to be scatter particles which made a contribution to the higher contact angle value when compared to sheet-like layer coating in case of HDTMS coating alone.     

Hybrid finite element and Brownian dynamics method for diffusion-controlled reactions

Diffusion is often the rate determining step in many biological processes. Currently, the two main computational methods for studying diffusion are stochastic methods, such as Brownian dynamics, and continuum methods, such as the finite element method. This paper proposes a new hybrid diffusion method that couples the strengths of each of these two methods. The method is derived for a general multidimensional system, and is presented using a basic test case for 1D linear and radially symmetric diffusion systems.     

Generalized finite element method applied to the calculation of continuum states

A new method for the calculation of continuum energy eigenfunctions in one dimension is presented. It is based on a numerical coupling method first exploited in the so-called finite element method which does not require explicit fitting of boundary conditions. Results from simple test calculations for square well and Morse potentials show the method to be highly accurate and efficient.     

Formation and finite element analysis of tethered bilayer lipid structures

Rapid solvent exchange of an ethanolic solution of diphytanoyl phosphatidylcholine (DPhyPC) in the presence of a mixed self-assembled monolayer (SAM) [thiolipid/β-mercaptoethanol (βME) (3/7 mol/mol) on Au] shows a transition from densely packed tethered bilayer lipid membranes [(dp)tBLMs], to loosely packed tethered bilayer lipid membranes [(lp)tBLMs], and tethered bilayer liposome nanoparticles (tBLNs) with decreasing DPhyPC concentration. The tethered lipidic constructs in the aqueous medium were analyzed by atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). Finite element analysis (FEA) was applied to interpret spectral EIS features without referring to equivalent circuit modeling. Using structural data obtained earlier from neutron reflectometry and dielectric constants of lipid bilayers, we reproduced experimentally observed features of the electrochemical impedance (EI) spectra of complex surface constructs involving small pinhole defects, large membrane-free patches, and bound liposomes. We demonstrated by FEA that highly insulating (dp)tBLMs with low-defect density exhibit EI spectra in the shape of a perfect semicircle with or without low-frequency upward "tails" in the Cole-Cole representation. Such EI spectra were observed at DPhyPC concentrations of >5 × 10(-3) mol L(-1). While AFM was not able to visualize very small lateral defects in such films, EI spectra unambiguously signaled their presence by increased low frequency "tails". Using FEA we demonstrate that films with large diameter visible defects (>25 nm by AFM) produce EI spectral features consisting of two semicircles of comparable size. Such films were typically obtained at DPhyPC concentrations of <5 × 10(-3) mol L(-1). At DPhyPC concentrations of <1.0 × 10(-3) mol L(-1) the planar bilayer structures were replaced by ellipsoidal liposomes with diameters ranging from 50 to 500 nm as observed in AFM images. Despite the distinct surface morphology change, the EI curves exhibited two semicircle spectral features typical for the large size defects in planar tBLMs. FEA revealed that, to account for these EI features for bound liposome systems (50-500 nm diameter), one needs to assume much lower tBLM conductivities of the submembrane space, which separates the electrode surface and the phospholipid bilayer. Alternatively, FEA indicates that such features may also be observed on composite surfaces containing both bound liposomes and patches of planar bilayers. Triple semicircular features, observed in some of the experimental EI curves, were attributed to an increased complexity of the real tBLMs. The modeling demonstrated that such features are typical for heterogeneous tBLM surfaces containing large patches of different defectiveness levels. By integrating AFM, EIS, and FEA data, our work provides diagnostic criteria allowing the precise characterization of the properties and the morphology of surface supported bilayer systems.     

Numerical simulation for the temperature changing rule of the crude oil in a storage tank based on the wavelet finite element method

In order to study the temperature changing rule of the crude oil in the storage tank, the wavelet finite element method, the traditional finite element method and the test were used to carry out the numerical simulation. Firstly, the thermal wavelet finite element was put forward established based on thermal finite element theory and the wavelet theory. And the computational model and three boundary conditions were established. And then the temperature changing rule of the crude oil in the storage tank in 24 h for three boundary conditions was obtained by using three methods, and the results showed that the wavelet finite element method had advantages in the numerical analysis of the temperature changing rule of the crude oil in the storage. And then the temperature distribution rule of the crude oil in the storage tank under different conditions in 5 h was obtained. And the temperature changing mechanism of the crude oil was summarized finally.     

Field distribution in an electrospray ionization source determined by finite element method

Three‐dimensional computer models of electrospray ionization sources were constructed in COMSOL Multiphysics? to solve the static electric fields using finite element methods. The magnitude of the electric field strength for onset of electrospray and optimum signal was calculated under various conditions. The modification of the electric field distribution in the ion source by an atmospheric pressure ion lens was also investigated by plotting the equipotential surfaces, electric field lines and trajectories of charged droplets. Both the calculated and the experimental results demonstrate that the changes in the ion signal detected by the mass spectrometer are attributable to the focusing effect of the ion lens when appropriate voltages are applied on the sprayer and ion lens. The optimum signal was found by setting the sprayer voltage from 3000 to 5000 V while scanning the ion lens voltage. The calculated strengths of the electric field at the sprayer tip for optimum signals are similar although the applied voltages at the sprayer and ion lens are significantly different. Copyright © 2009 John Wiley & Sons, Ltd.     

基于元素分析的污泥焚烧处置综合性评估

污泥的无害化处置和资源化利用是目前社会关注的重点,对污泥泥质的综合性评估是污泥处置和利用的前提。采用8个地区的出厂污泥,基于元素分析结果,综合考虑其碳排放量和风险性,对污泥“焚烧+灰渣利用”处置方式进行综合性评估。污泥的工业分析发现地区1、7、8污泥中的干基低位发热量均值分别为11.60 MJ/kg、10.39 MJ/kg和12.04 MJ/kg,有机物含量均值为53.98%、51.23%和54.97%,发热量和有机成分显著较高,发热量和有机成分存在显著正相关关系（p<0.05）。而地区1、2、6污泥的重金属含量较高,8个地区的污泥浸出液中镍、铜、锌所占比例较大,占总体约90%。从碳排放和风险性分析可得,地区1、7、8的碳补偿量分别为958.59 kgCO2/t、909.08 kgCO2/t和963.39 kgCO2/t,碳补偿量较大,总碳排放量较小,但地区1污泥在采用制砖、水泥熟料处置时综合污染指数分别为0.72和0.71,在污染警戒范围（0.7~1.0）。结果表明,地区1、7、8的出厂污泥宜采用“焚烧+灰渣利用”处置方式,但地区1污泥处置时需关注重金属污染风险。污泥的元素分析能为污泥的焚烧处置提供科学性指导。     

Thermal analysis of phenolic resin based pyropolymers

The formation and thermal behaviour of pyropolymers based on novolak resin synthesized under carefully controlled processing conditions have been studied by various thermoanalytical techniques. A suitable reaction scheme has been proposed for the formation of these pyropolymers. Only a small (3–8%) weight loss has been observed up to 800 °C in static air. DTA curves confirmed multistage exothermic processes predominantly due to two different linkages which control their thermo/thermo-oxidative stability. Hot metal filtration (700 °C) in an inert atmosphere exhibited only negligible weight loss.

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Zusammenfassung Mittels verschiedener thermoanalytischer Verfahren wurde Bildung und thermisches Verhalten von Pyropolymeren auf Novolackbasis unter streng geregelten Reaktionsbedingungen untersucht. Zur Bildung dieser Pyropolymere wurde ein geeignetes Reaktionsschema entwickelt. In unbewegter Luftatmosphäre kann bis 800 °C nur ein geringer (3–8%) Gewichtsverluft beobachtet werden. Die DTA-Kurven zeigen einen exothermen Mehrstufenprozeß, der hauptsächlich auf zwei verschiedene Verkettungen zurückzuführen ist, welche die thermische/thermisch-oxidative Stabilität bestimmen.

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Thermal analysis of soybean oil based polyols

Soybean oil based polyols (5-OH polyol, 10-OH polyol and 15-OH polyol) were synthetised from epoxidized soybean oil. The melting peak of polyols and the relationship between melting peak and the number-average functionality of hydroxyl in polyols were investigated by differential scanning calorimetry (DSC). The thermal decomposition of polyols and some of their thermal properties by thermogravimetry (TG) and derivative thermogravimetry (DTG) were also studied. The thermal stability of polyols in a nitrogen atmosphere was very close hence they had a same baseplate of triglyceride for polyols. The extrapolated onset temperature of polyols in their thermal mass loss, first step had a decreasing order: 5-OH polyol>10-OH polyol>15-OH polyol due to the difficulty in forming multiple elements ring of them had the same order. The thermal behavior of polyols under non-isothermal conditions using Friedman’s differential isoconversional method with different heating rates indicated that the 5-OH polyol had the lowest activation energy in thermal decomposition amongst these polyols according to the same fractional mass loss because of the weakest intramolecular oligomerization. The 15-OH polyol was prior to reach the mass loss region because the six-member ring is more stable than the three-member ring from 10-OH polyol and more easily formed.