Investigation on the plastic work-heat conversion coefficient of 7075-T651 aluminum alloy during an impact process based on infrared temperature measurement technology

The plastic work-heat conversion coefficient is one key parameter for studying the work-heat conversion under dynamic deformation of materials. To explore this coefficient of 7075-T651 aluminum alloy under dynamic compression, dynamic compression experiments using the Hopkinson bar under four groups of strain rates were conducted, and the temperature signals were measured by constructing a transient infrared temperature measurement system. According to stress versus strain data as well as the corresponding temperature data obtained through the experiments, the influences of the strain and the strain rate on the coefficient of plastic work converted to heat were analyzed.The experimental results show that the coefficient of plastic work converted to heat of 7075-T651 aluminum alloy is not a constant at the range of 0.85–1 and is closely related to the strain and the strain rate. The change of internal structure of material under high strain rate reduces its energy storage capacity, and makes almost all plastic work convert into heat.

Study on Purchasing Power Conversion Coefficient at Par

The basic theory of the purchasing power at par refers to the rate of one country＇s currency to U.S. dollar while purchasing ＂a basket＂ goods and services in the same quantity and quality respectively in this country and U.S.A. This paper gives out calculation method of purchasing power conversion coefficient at par and how to calculate the non-base year purchasing power at par.

Study on the conversion coefficient between ACH_(50)and ACH in typical zones of public buildings

The air infiltration of buildings is closely related to its indoor and outdoor environment and energy consumption.However,measuring air infiltration of a building under natural conditions is time-consuming,easily affected and expensive,so it’s often inferred based on building airtightness in practical engineering.Empirical models can nevertheless make a rapid prediction without building parameters,which are widely applied in practical engineering.At present,most of the existing empirical models take residential buildings as objects,therefore they are difficult to be applied to public buildings.Hence,it is imperative to build an empirical model applicable to public buildings.In this study,the conversion coefficients between the airtightness(air change rate under the pressure difference of 50Pa)and the air infiltration rates under natural conditions of four typical zones of public buildings were analyzed.Firstly,the airtightness of four zones of public buildings in the cold region of China was measured.Secondly,their air infiltration rates under 1800 combined conditions of wind pressure and stack effect pressure were simulated based on the airtightness measured results.Finally,calculation and statistical analysis of the conversion coefficient were carried out based on the measured and simulated results,and the recommended value of conversion coefficient was proposed.Analysis results show that the CC of each zone is significantly affected by outdoor meteorological conditions and varies in a wide range(1#zone:3.21 to 188.44).It is advised to ignore the extreme data and take the mean value of the CC corresponding to 95%of the data volume as the recommended value(22.2).This study can provide theoretical basis for the formulation of standards for the performance evaluation of building airtightness.

Determination of Conversion Coefficient to Evaluate Couple-year of Protection (CYP) for Tubectomy and Vasectomy in Urban and Rural Regions of Iran:IMES Study

Objective To calculate couple-year of protection （CYP） by conversion coefficient （F） of tubectomy and vasectomy in urban and rural regions of Iran. Methods A total of 103 450 married women aged 10-49 years in 2005 across urban and rural regions of lran were sampled by multi stage cluster sampling. The data were collected by household survey and direct interview and analyzed by STATA8.0 software and survey analysis commands. Results Mean age of the women at the time of tubectomy estimated 31.9 years and conversion coefficient of tubectomy was 17.1 ±0.1. Mean age of women at the time of her husband vasectomy estimated 31.48 years and its conversion coefficient was 17. 5 ± 0. 1. Cluster analysis defined different regions of Iran on the basis of evaluated conversion coefficients of tubectomy and vasectomy which both of them presented seven clusters. Literacy of women and total coverage of family planning in a region had a direct relationship with this conversion coefficient （P〈0.05）. Conclusion The variations observed in the conversion coefficients and their dissimilarity among different regions of Iran may be due to a variety of fundamental factors of which literacy and culture are of important factors.

Regulation of Power Conversion in Fuel Cells

Here we report a regulation about power conversion in fuel cells. This regulation is expressed as that total power produced by fuel cells is always proportional to the square of the potential difference between the \{equilibrium\} potential and work potential. With this regulation we deduced fuel cell performance equation which can describe the potential vs.the current performance curves, namely, polarization curves of fuel cells with three power source parameters: equilibrium potential E_0; internal resistance R; and power conversion coefficient K. The concept of the power conversion coefficient is a new criterion to evaluate and compare the characteristics and capacity of different fuel cells. The calculated values obtained with this equation agree with practical performance of different types of fuel cells.

Mechanical model for failure modes of rock and soil under compression

The failure modes of rock and soil under compression are complex phenomena that have not been explained in a mechanical perspective. However, large amounts of studies indicate that the failure modes of rock and soil samples can be categorized into eight types. In this work, the inner tensile stress and the dissipation and conversion of energy of rock and soil under compression are analyzed, then the effective conversion coefficient of energy is deduced, thus the tensile failure criterion of rock and soil under compression is established. Combined with the shear strength criterion of Mohr–Coulomb, a tensile joint shear strength criterion for rock and soil under compression is built. Therefore, a mechanical criterion model concerning the failure modes of rock and soil under compression is established and verified by tests. This model easily explains the test results in the existing literature and many natural phenomena, such as collapse.

Estimating the costs of one hectare of poplar planting and supplying wood required for producing various types of paper in Iran

In Iran, due to abundant restrictions on harvesting wood from northern forests by implementing the preservation project and also lack of possibility for sufficient wood production, development of the area of planting poplar is quite inevitable. Poplar wood properties have special importance to produce many wood production, particularly pulp and paper. Paper factories are the major consumers of poplar wood at the global level and this is because of unique morphological, physical, mechanical and technological properties of poplar wood. Therefore, regarding the importance of using this species in making various printing and writing paper, packaging or carton, cardboard and newsprint, in this study, costs of poplar production in one hectare including planting and harvesting were examined and determined. Then, based on conversion coefficients of FAO, required round wood, productivity and the cost of poplar wood were calculated for the producing various kinds of paper. The results indicate that carton and cardboard paper or packaging allocate the lowest cost and highest return, while printing and writing paper had highest cost and lowest return in terms of poplar wood supply needed for paper production.

Enhanced piezoelectric properties in low-temperature sintered Pb(Zr,Ti)O_(3)-based ceramics via Yb_(2)O_(3)doping

Pb(Mg_(0.5)W_(0.5))O_(3)–Pb(Ni_(1/3)Nb_(2/3))O_(3)–Pb(Zr_(0.5)Ti_(0.5))O_(3)(PNN–PMW–PZT)piezoceramics were sintered at a low temperature of 900℃by the mixed metal oxide powder solid-state reaction route.CaCO_(3)and Li_(2)CO_(3)as sintering aids and Yb_(2)O_(3)as a dopant were added into the PNN–PMW–PZT ceramic system for low-temperature sintering and enhancement of electrical properties,respectively.The effects of different Yb_(2)O_(3)doping amounts on the microstructure,dielectric,piezoelectric and ferroelectric properties of the samples were systematically investigated.The piezoceramics doped with 0.1 mol%Yb_(2)O_(3)have optimal electrical properties(d_(33)=563 pC/N,k_(p)=0.66,ε_(r)=2728(1 kHz),tanδ=0.0176(1 kHz),and T_(C)=301℃).While the piezoceramics doped with 0.3 mol%Yb_(2)O_(3)have optimal energy conversion properties:the piezoelectric voltage coefficient g_(33)=26.7×10^(-3)Vm/N and the effective piezoelectric energy conversion coefficient d_(33)×g_(33)=14366×10^(-15)m^(2)/N.

A hierarchical spatiotemporal adaptive fusion model using one image pair

Image fusion techniques that blend multi-sensor characteristics to generate synthetic data with fine resolutions have generated great interest within the remote sensing community.Over the past decade,although many advances have been made in the spatiotemporal fusion models,there still remain several shortcomings in existing methods.In this article,a hierarchical spatiotemporal adaptive fusion model(HSTAFM)is proposed for producing daily synthetic fine-resolution fusions.The suggested model uses only one prior or posterior image pair,especially with the aim being to predict arbitrary temporal changes.The proposed model is implemented in two stages.First,the coarse-resolution image is enhanced through super-resolution based on sparse representation;second,a pre-selection of temporal change is performed.It then adopts a two-level strategy to select similar pixels,and blends multi-sensor features adaptively to generate the final synthetic data.The results of tests using both simulated and actual observed data show that the model can accurately capture both seasonal phenology change and land-cover-type change.Comparisons between HSTAFM and other developed models also demonstrate our proposed model produces consistently lower biases.

Quantitative characterization of pore structure of the CarboniferousePermian tight sandstone gas reservoirs in eastern Linqing depression by using NMR technique

Micro-nano scale pores can accurately and fastly be measured by the nuclear magnetic resonance(NMR)technique,which provides a new method to quantitatively characterize pore structures in tight sandstone.Based on the method of calibration of mercury pressure data for NMR T_(2) spectrum,for the measurement inaccuracy due to the mercury saturation less than 100%in tight sandstone,the mercury pressure curve and T_(2) spectrum is used to cumulate from the maximum pore on the right boundary to the small pores in the left,the range of pore-throat radius measured by the mercury injection in the leftward cumulative curve is selected as a comparable interval of NMR pore-throat radius,and the longitudinal interpolation method and the least square method are utilized to construct the distribution curve of pore-throat radius transformed by T_(2) spectrum.The modified method is used to obtain NMR T_(2) spectrum,conversion coefficient of pore-throat radius and pore-throat radius distribution of the Carboniferous-Permian tight sandstone gas reservoirs in the eastern Linqing depression,and characteristics of reservoir pore structures are quantitatively investigated;in addition,in combination with analysis of thin section and scanning electron microscopy,the reservoir effectiveness and cause of the pore structure variability in the tight sandstone are also well studied.The results show that the NMR pore-throat radius curve obtained by the modified method has a high consistency with the mercury injection curve,and the NMR test accuracy of tight sandstone is significantly improved.In the study area,the pore-throat radius of the Carboniferous-Permian tight sandstone mainly ranges from 0.002 to 2 mm,the pore is generally submicro-nano scale,but the pore-throat radius distribution of different types of sandstone varies significantly.The lithic quartz sandstone is rich in siliceous matter and poor in plastic detritus and matrix,generally dominated by submicro-scale pore-throats including micro-scale porethroats;lithic feldspar sandstone and quartz-rich feldspar lithic sandstone are rich in quartz and poor in plastic detritus and matrix,dominated by submicro-nano scale pore-throats(nano-scale pore-throats predominantly);the lithic fragment-rich feldspar lithic sandstone and lithic sandstone are poor in quartz and rich in plastic detritus and matrix,mainly dominated by nano-scale pore-throats smaller than 0.05 mm.Micropetrographic components are key factors to control pore structure difference and reservoir effectiveness,and the reservoir quality may be macroscopically controlled by sedimentary microfacies;the lithic quartz sandstones of coarse-and fine-grained point bar/riverbed microfacies are the most favorable reservoirs;the lithic feldspar sandstone of fine-grained point bar microfacies,the quartzrich feldspar lithic sandstone of fine-grained distributary channel and barrier bar microfacies are relatively favorable reservoirs,while both lithic fragment-rich feldspar lithic sandstone and lithic sandstone of tidal-flat facies are ineffective reservoirs with very poor porosity and permeability.

Ca^2+ doping effects in(K,Na,Li)(Nb0.8Ta0.2)O3 lead-free piezoelectric ceramics

Lead-free(K0.5-x/2Na0.5-x/2Lix)(Nb0.8Ta0.2)O3(KNLNT)and(K0.49-x/2Na0.49-x/2-LixCa0.01)(Nb0.8Ta0.2)O3(KNLNT-Ca)ceramics were prepared by a conventional ceramic processing.Structural analysis shows that the Ca^2+ doping takes the A site of ABO3 perovskite and decreases the phase transition temperature.Property measurements reveal that as a donor dopant,the Ca^2+ doping results in higher room-temperature dielectric constant,lower dielectric loss,and lower mechanical quality factor.In addition,the Ca^2+ doping does not change the positive piezoelectric coefficient d33,but increases the converse piezoelectric coefficient d 33*significantly.This is likely due to the increase in the relaxation,as well as the appearance of(CaNa/K·-VNa/K’)defect dipoles.