Prediction of the thermo-elastic properties of knitted structural composites using FEM

It is a very important and complex task to estimate the thermo-elasticproperties of a textile structural composite. In this paper, the finite element method (FEM) wasused for the prediction of the orthotropic thermo-elastic properties of a composite reinforced byglass fiber knitted fabric. In order to define the final 3-D configuration of the loop reinforcingstructure, the interactions between the adjacent loops, the large displacement and the contactelements without friction were considered. The values predicted were compared with the experimentalresults.

刍议如何提高小学语文预习有效性

学好语文不仅需要教师的有效引导，还需要学生的默契配合。课前的预习是学习的重要组成部分，在语文学习中同样如此。小学生在学习语文时，教师可以为其布置有针对性的预习问题，并采用不同的预习形式来调动学生预习的积橱I生，同时重视预习成果的验收。从而不断地提高小学语文预习的有效性，降低学生在课堂上学习和接受语文知识与技能的难度。

Thermodynamic optimization for a quantum thermoacoustic refrigeration micro-cycle

A model of quantum thermoacoustic refrigeration micro-cycle(QTARMC)is established in which heat leakage is considered.A single particle contained in a one-dimensional harmonic potential well is studied,and the system consists of countless replicas.Each particle is confined in its own potential well,whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions.Based on the Schrodinger equation,the expressions of coefficient of performance(COP)and cooling rate for the refrigerator are obtained.Effects of heat leakage on the optimal performance are discussed.The optimal performance region of the refrigeration cycle is obtained by the using ofΩobjective function.The results obtained can enrich the thermoacoustic theory and expand the application of quantum thermodynamics.

The optimal performance of a generalized Carnot cycle for a generalized heat transfer law

The finite time thermodynamic performance of a generalized Carnot cycle, in which the heat transfer between the working fluid and the heat reservoirs obeys the generalized law Q∝( Δ T) m , is studied. The optimal configuration and the fundamental optimal relation between power and efficiency of the cycle are derived. Some special examples are discussed. The results can provide some theoretical guidance for the design a practical engine.

Finite element analysis for radiative heat transfer in multidimensional participating media

A finite element model is developed to simulate the radiative transfer in 2D and 3D complex-geome-tric enclosure filled with absorbing and scattering media. This model is based on the discrete ordinates method and finite element theory. The finite element formulations and detailed steps of numerical calculation are given. The discrepancy of the results produced by different space and solid angle discretization is also investigated and compared. The effect of the six-node quadric element on the accuracy is analyzed by a 2D rectangular enclosure. These results indicate that the present model can simulate radiative transfer in multidimensional complex-geometric enclosure with participating media effectively and accurately.

Effect of temperature on formability of glass mat reinforced thermoplastic sheets with ductile dummy sheets

Given the increasing use of glass mat-reinforced thermoplastic(GMT)composites,the formability of GMT sheets is currently a topic of research.A new sheet forming process for solidified GMT was developed.In this process,a GMT sheet was sandwiched by dummy metallic sheets during deep drawing.The dummy metallic sheets acted as protective materials and media for heating the GMT sheet.In this study,tensile tests of GMT specimens were carried out under different temperature conditions.The effect of temperature on the tensile deformation was analyzed.The effect of temperature on the deep drawing process of GMT sheets with dummy sheets was further investigated.Finite element method(FEM)was conducted to simulate the deep drawing process.In the drawing force rising stage,the law of drawing force with the depth of the drawing was analyzed using FEM and experiments.

Highly efficient UV-visible-infrared photothermocatalytic removal of ethyl acetate over a nanocomposite of CeO_(2) and Ce-doped manganese oxide

A unique nanocomposite of CeO_(2)nanoparticles and Ce-doped manganese oxide nanofibers having a crystalline cryptomelane-type octahedral molecular sieve(KMn_(8)O_(16)·nH_(2)O,abbreviated as OMS-2)structure(denoted CeO_(2)-CeOMS-2)was prepared by the reaction of Ce(NO_(3))3 and KMnO_(4)at 90°C.CeO_(2)-CeOMS-2 shows extremely high photothermocatalytic activity,very low selectivity for acetaldehyde(an unfavorable byproduct),and excellent durability for ethyl acetate removal under UV-visible-infrared(UV-vis-IR)irradiation.In striking contrast,pure CeO_(2),pure OMS-2,and TiO_(2)(P25)showed much lower photothermocatalytic activities and higher selectivities for acetaldehyde.The CO_(2)production rate within the first five minutes(r CO2)of reaction with CeO_(2)-CeOMS-2 was as high as 1102.5μmol g-1 min-1,which is 137,17,and 30-times higher than those of pure CeO_(2),pure OMS-2,and TiO_(2)(P25),respectively.CeO_(2)-CeOMS-2 also shows good photothermocatalytic activity under vis-IR(λ>420 or 560 nm)irradiation.Further,even under vis-IR(λ>830 nm)irradiation,efficient photothermocatalytic activity was achieved.In addition,the catalytic activity of CeO_(2)-CeOMS-2 is far superior to those of pure CeO_(2)and OMS-2,which is attributed to the fact that Ce doping significantly improves the lattice oxygen activity of OMS-2.The high photothermocatalytic activity of CeO_(2)-CeOMS-2 arises from the synergy between the photocatalytic effect of the CeO_(2)nanoparticles and light-driven thermocatalysis of the Ce-doped OMS-2.The novel photoactivation of Ce-doped OMS-2,which is unlike that of conventional photocatalysis on semiconductor photocatalysts,further promotes the catalytic activity because the surface oxygen activity of Ce-doped OMS-2 is promoted upon UV-vis-IR or vis-IR(λ>560 nm)irradiation.

Eco-friendly synthesis of high silica zeolite Y with choline as green and innocent structure-directing agent

Zeolite synthesis in contemporary chemical industries is predominantly conducted using organic structure‐directing agents(OSDAs),which are chronically hazardous to humans and the environment.It is a growing trend to develop an eco‐friendly and nuisanceless OSDA for zeolite synthesis.Herein,choline is employed as a non‐toxic and green OSDA to synthesize high silica Y zeolite with SiO2/Al2O3 ratios of 6.5–6.8.The prepared Y zeolite samples exhibited outstanding(hydro)thermal stability at ultrahigh temperature owing to the higher SiO2/Al2O3 ratio.The XRF,SEM,29Si‐NMR and 13Na+results suggested that choline plays a structure‐directing role in the synthesis of Y zeolite,while the feed molar fraction of Na+is a crucial determinant for the framework SiO2/Al2O3 ratio and the crystal morphology.

3D numerical study on flow structure and heat transfer in a circular tube with V-baffles

A 3D numerical investigation has been carried out to examine periodic laminar flow and heat transfer characteristics in a circular tube with 45°V-baffles with isothermal wall.The computations are based on the finite volume method(FVM),and the SIMPLE algorithm has been implemented.The fluid flow and heat transfer characteristics are presented for Reynolds numbers ranging from 100 to 2000.To generate main longitudinal vortex flows through the tested section,V-baffles with an attack angle of 45°are mounted in tandem and in-line arrangement on the opposite positions of the circular tube.Effects of tube blockage ratio,flow direction on heat transfer and pressure drop in the tube are studied.It is apparent that a pair of longitudinal twisted vortices(P-vortex)created by a V-baffle can induce impingement on a wall of the inter-baffle cavity and lead a drastic increase in heat transfer rate at tube wall.In addition,the larger blockage ratio results in the higher Nusselt number and friction factor values.The computational results show that the optimum thermal enhancement factor is around 3.20 at baffle height of B=0.20 and B=0.25 times of the tube diameter for the V-upstream and V-downstream,respectively.

Determination of a U-Notch Stress Concentration Factor Using Thermoelasticity

This paper uses the TSA （therrnoelastic stress analysis） technique to determine the stress concentration factor （Kt） of a U-notch in an aluminum plate, and then compares the results with those obtained from a FEA （finite elements analysis） of the same specimen. In order to do so, it devises a calculation procedure to extrapolate the thermoelastic data near the tip of the notch and then applies the resulting algorithm to seven distinct experiments that had different loading frequencies, mean loads and load ranges. The overall positive results suggest that the technique may be suitable for Kt measurements in real-world structures. A discussion about the calibration factor of the thermoelastic data is included by confronting the calibration results using independent tensile uniaxial tests and using the U-notch TSA and FEA paired specimen data.

Fracture prediction in non-isothermal viscous pressure bulging of aluminum alloy sheet using ductile fracture criterion

The failure of AA3003 aluminum alloy sheet metal was predicted for non-isothermal viscous pressure bulging (VPB). Utilizing the coupled thermo-mechanical finite element method combined with ductile fracture criterion, the calculations were carried out for non-isotherm VPB at various temperatures and the influences of the initial temperature of viscous medium on failure mode of bulge specimens were investigated. The results show that the failure modes are different for the non-isothermal VPB with different initial temperatures of viscous medium. For the non-isothermal VPB of AA3003 aluminum alloy sheet with initial temperature of 250 ℃, when the initial temperature of viscous medium ranges from 150 to 180 ℃, the formability of sheet metal can be improved to a full extent. The validity of the predictions is examined by comparing with experimental results.

Spatial Quality Evaluation of Pedestrian Streets

This paper presents an assessment of the spatial quality of a pedestrian street located in downtown Bauru, S^o Paulo State, Brazil, from the application of some urban sustainability indicators. Multi-method was used to evaluate the thermal comfort quality of users, urban accessibility and preservation of architectural heritage. The results show that the sustainability indicators, apart from being effective tools in identifying problems, can assist local managers in decision making, planning and monitoring of pedestrian public space. These indicators contribute to a broad diagnosis of the pedestrian street and also the formulation of programs, projects and municipal policies, aimed at providing a better life quality for pedestrians.

A simple analytical method for deflation prediction of inflatable structures

The static performance of inflatable structures has been well studied and the dynamic deployment simulation has received much attention. However, very few studies focus on its deflation behavior. Although there are several dynamic finite element algorithms that can be applied to the deflation simulation, their computation costs are expensive, especially for large scale structures. In this work, a simple method based on classic thermodynamics and the analytical relationship between air and membrane was proposed to efficiently analyze the air state variables under the condition of ventilation. Combined with failure analysis of static bearing capacity, a fast incremental analytical method was presented to predict both elastic and post wrinkling deflation process of inflatable structures. Comparisons between simplified analysis, dynamic finite element simulation, and a full-scale experimental test are presented and the suitability of this simple method for solving the air state and predicting the deflation behavior of inflatable structures is proved.

Fractionation of Zn,Cd and Pb in a Tropical Soil After Nine-Year Sewage Sludge Applications

A long-term field experiment was carried out in the experiment farm of the Sao Paulo State University,Brazil,to evaluate the phytoavailability of Zn,Cd and Pb in a Typic Eutrorthox soil treated with sewage sludge for nine consecutive years,using the sequential extraction and organic matter fractionation methods.During 2005-2006,maize(Zea mays L.) was used as test plants and the experimental design was in randomized complete blocks with four treatments and five replicates.The treatments consisted of four sewage sludge rates(in a dry basis):0.0(control,with mineral fertilization),45.0,90.0 and 127.5 t ha-1,annually for nine years.Before maize sowing,the sewage sludge was manually applied to the soil and incorporated at 10 cm depth.Soil samples(0-20 cm layer) for Zn,Cd and Pb analysis were collected 60 days after sowing.The successive applications of sewage sludge to the soil did not affect heavy metal(Cd and Pb) fractions in the soil,with exception of Zn fractions.The Zn,Cd and Pb distributions in the soil were strongly associated with humin and residual fractions,which are characterized by stable chemical bonds.Zinc,Cd and Pb in the soil showed low phytoavailability after nine-year successive applications of sewage sludge to the soil.

Parameterizing soil organic carbon's impacts on soil porosity and thermal parameters for Eastern Tibet grasslands

This study investigates the stratification of soil thermal properties induced by soil organic carbon (SOC) and its impacts on the parameterization of the thermal properties. Soil parameters were measured for alpine grassland stations and North China flux stations, with a total of 34 stations and 77 soil profiles. Measured data indicate that the topsoils of alpine grasslands contain high SOC contents than underlying soil layers, which leads to higher soil porosity values and lower thermal conductivity and bulk density values in the topsoils. However, this stratification is not evident at the lowland stations due to low SOC contents. Evaluations against measured data show that three thermal conductivity schemes used in land surface models severely overestimate the values for soils with high SOC content (i.e. topsoils of alpine grassland), but they are better for soils with low SOC content. A new parameterization is then developed to take the impacts of SOC into account. The new one can well estimate the soil thermal conductivity values in both low and high SOC content cases, and therefore, it is a potential candidate of thermal conductivity scheme to be used in land surface models.

Efficient and stable non-doped deep-blue organic light emitting diode based on an anthracene derivative

A new anthracene derivative 9,10-bis[3,5-di(4-tert-butylphenyl)phenyl]anthracene (BPPA) was synthesized via Suzuki coupling reaction and characterized by 1H NMR spectrum,mass spectrum,and elemental analysis.BPPA exhibits deep-blue emission both in solution and in solid thin film.This compound has a non-planar structure that results in high thermal stability and the phenomenon of polymorphism.The non-doped device based on this material shows stable deep-blue emission with the 1931 Commission international de I'Eclairage (CIE) coordinate of (0.15,0.05) under different applied voltages.The device exhibits the maximum external quantum efficiency of 2.2% at 14.9 mA/cm2 with luminance of 105 cd/m2.

Calculation Model of Effective Thermal Conductivity of a Spiral-wound Lithium Ion Battery

This paper proposed an analytical model which can calculate the effective thermal conductivity (ETC) of a spiral-wound Lithium-ion battery (Li-ion battery). It bases on a two-dimensional energy balance with both radial and spiral heat transfer, as well as internal thermal contact resistance (TCR) considered simultaneously and studies the influence of winding layers and winding tension on the ETC. Results show that the analytical data are in good agreement with the numerical results. With the winding layers decreased and the winding tension enhanced, the ETC of Li-ion battery increases gradually. The radial temperature in Li-ion battery is also investigated which demonstrates a relatively higher temperature when considering the internal TCR.

Red phosphorescent organic light-emitting diodes based on a novel host material with thermally activated delayed fluorescent properties

High cost of phosphors and significant efficiency roll-off at high brightness are the two main factors that limit the wide application of phosphorescent organic light-emitting diodes （PHOLEDs）. Efforts have been paid to find ways to reduce the phosphors＇ concentration and efficiency roll-off of PHOLEDs. In this work, we reported red emission PHOLEDs with low dopant concentration and low efficiency roll-off based on a novel host material 2,4-biscyanophenyl-6-（12-phenylindole[2,3-a]carbazole-ll-yl）-1,3,5-triazine （BCPICT）, with thermally activated delayed fluorescent （TADF） properties. The device with 1.0% dopant concentration displayed a maximum external quantum efficiency of 10.7%. When the dopant concentration was increased to 2.0%, the device displayed a maximum external quantum efficiency of 10.5% and a low efficiency roll-off of 5.7% at 1000 cd/m^2.

Mechanism study of the transmission of moxibustion heat in human acupoint tissues

Objective: To discuss the topical action characteristics of the biological transmission of moxibustion heat via temperature collection and numerical modeling. Methods: Temperature of moxibustion was measured at multiple points at a distance of 3 cm to obtain the moxibustion temperature field nephograms by the high-accuracy temperature measure array. Finite element analysis was used to imitate the three-dimensional dynamic distribution of temperature in acupoint tissues. Results: Through numerical analysis, the one-dimensional, two-dimensional and three-dimensional distributions of temperature in human acupoint tissues at 5 min of moxibustion were established. The result showed that moxibustion heat mainly tran smitted from the surface of the tissue to the internal, and the in flue nee of moxibusti on heat decreased with the depth of the tissue. The analysis of the nephograms of acupoint tissue temperature at 5,10, 15 and 20 min of moxibustion showed that with the in crease of the moxibusti on time, the temperature in acupoint tissues consta ntly rose, and the transmission depth of moxibustion heat also further expanded inside acupoint. Conclusion: By establishing the three-dimensional dynamic model of heat transmission inside acupoint tissues with the biological parameters of human tissues and the temperature values obtained, this study used finite element analysis software ANSYS 14.0 and discovered the rules in the transmission of heat in body tissues during moxibustion, and the features in moxibustion heat transmission (from the proximal to the distant) and heat penetration (from the surface to the intern al). This study provides theoretical and experime ntal support for the application of moxibusti on in clinical practice.

Thermodynamic properties and constitutive relations of crystals at finite temperature

The dynamics equation for each individual atom is established directly around the equilibrium state of the system of N atoms based on the inter-atomic potential energy of EAM model.Using the theory of lattice dynamics and periodical boundary condition,the 3N×3N stiffness matrix in eigen equations of vibration frequencies for a parallelepiped crystal is reduced to a 3n×3n matrix of eigen equations of vibration frequencies for a unit lattice.The constitutive relation of the crystal at finite temperature is extracted based on the quantum-mechanical principle.The thermodynamic properties and the stress-strain relationships of crystal Cu with large plastic deformation at different temperatures are calculated,the calculation results agree well with experimental data.