Taylor Equation Research Articles

Wear characterisation and tool performance of sintered carbide inserts during automatic machining of AISI 1045 steel

This paper presents tool condition monitoring (TCM) of dry turning processes on automatic lathes, and describes the information generated by different measuring systems applied to the single point turning situation. The outputs measured were correlated with the state and wear rate of the cutting tools. Semi-finishing and rough-shaping tests have been carried out at different cutting speeds. Uncoated sintered carbide inserts have been used in both processes, while TiC–TiN coated inserts have only been used in the semi-finishing processes. The behaviours of the utilised power, the tool-holder shank vibrations and the surface roughness vs. pass number were studied. The main criteria used for the wear assessment, were the roughness checks on work pieces in the semi-finishing processes, the electrical input by the lathe motor together with the vibrations level in the rough-shaping processes. The life of the tool inserts was assessed for each test, and Taylor's equation was determined for the three types of inserts used. The parameters investigated show that the results are directly influenced by degree of the tool wear and also give indications when the tool insert has reached the end of its life. Coated inserts permit approximately 50% longer machining time, a higher wear mark width and a reduced applied power consumption, compared with uncoated inserts. The end of tool life in the semi-finishing processes, when compared to the rough-shaping processes, refers to the higher power range used in the latter. The established relationships can be used in the evaluation of a tool insert's life and subsequently give rise to clear indications of the opportunity for higher productivity.

Correlation between microstructure and mechanical properties of severely deformed metals

There is a correlation between the microstructure and the mechanical behavior of ultrafine-grained face centered cubic (fcc) metals processed by equal-channel angular pressing (ECAP). It is shown that the saturation yield strength is related to the maximum dislocation density according to the Taylor equation and, in addition, the value of the parameter α in the Taylor equation is strongly affected by the stacking fault energy because of different geometrical arrangements of dislocations within the grains. It is also demonstrated that the ductility of Cu processed by ECAP decreases with increasing strain but at extremely high strains the ductility is partially restored due to the recovery of the microstructure.

Glass transition temperatures of a ready to eat breakfast cereal formulation and its main components determined by DSC and DMTA

The effect of water content on the glass transition temperatures of a ready to eat cereal formulation was determined, as well as for its major components, oat flour, rice flour and an oat–rice flour blend, in the same ratio as they are present in the formulation. All samples were compression moulded at high temperature and were moisture conditioned in a 10–22% interval (dry basis). Glass transition temperatures ( T g) were measured by differential scanning calorimetry (DSC) and the main mechanical relaxation temperatures ( T α), measured by dynamic mechanical thermal analysis (DMTA). The relaxation temperatures taken at tan δ peaks, were found 20–30 °C larger than T g. Besides the plasticizing effect of water adequately described by the Gordon–Taylor equation, no differences of T g (and T α) values between the major components were obtained at a constant moisture content. The T g and T α values of the RTE formulation were found to be about 30 °C lower than its components, a result which was attributed to the plasticizing effect of the minor components in the formulation (sugar and malt extract).

Miscibility and phase behaviour of binary and ternary homoblends of poly(styrene- co-acrylic acid), poly(styrene- co- N,N-dimethylacrylamide) and poly(styrene- co-4-vinylpyridine)

The miscibility and phase behaviour of binary and ternary homoblends prepared from poly(styrene- co-acrylic acid) (SAA14), poly(styrene- co- N, N-dimethylacrylamide) (SAD25) and poly(styrene- co-4-vinylpyridine) (S4VP15) were investigated by DSC. SAA14 is miscible with both S4VP15 and SAD25 and interacts more strongly with S4VP15 than with SAD25 as evidenced by comparing their compositional variation of glass transition temperatures ( T g). Positive and negative deviations from linear average line were respectively observed with the SAA14/S4VP15 and SAA14/SAD25 blends. Several conventional theoretical approaches were used to describe these T g-composition behaviours. The one parameter Gordon–Taylor equation or the two parameters Kwei equation describe very well the behaviour of SAA14/S4VP15 system. However, the recent three parameters Brostow equation was needed to reproduce experimental T g-composition for the SAA14/SAD25 system. Reasonable agreement with the experimental values are obtained for both systems when the fitting parameter free method developed by Coleman et al. is applied to predict the composition dependence of the glass transition temperature. The experimental phase diagram of the SAA14/S4VP15/SAD25 ternary polymer blend system presents an immiscibility region due to the unbalanced interactions among the three polymer pairs.

Miscibility and interactions between 17β-estradiol and Eudragit® RS in solid dispersion

Miscibility of 17β-estradiol and Eudragit® RS in solid dispersions was determined by modulated temperature differential scanning calorimetry (MTDSC). A reduction of the 17β-estradiol melting point in Eudragit® RS solid dispersions was observed by MTDSC using heating program I in which the maximum temperature in the first heating run was lower than the 17β-estradiol melting point. The melting point depression of 17β-estradiol in solid dispersions as a function of composition could be explained by the Nishi–Wang equation indicating an interaction between 17β-estradiol and Eudragit® RS in the system. A variation of glass transition temperature (Tg) of 17β-estradiol in Eudragit® RS solid dispersion was observed by MTDSC using heating program II in which the maximum temperature in the first heating run reached the 17β-estradiol melting point. In the second heating run of heating program II, 17β-estradiol was in an amorphous form blended with Eudragit® RS. The variation in Tg of amorphous 17β-estradiol blended with Eudragit® RS could be explained by the Kwei equation, a modified version of the Gordon–Taylor equation. The parameter estimates from the Kwei equation were consistent with an interaction between 17β-estradiol and Eudragit® RS, which was due to inter-associated hydrogen bonding as deduced from the FTIR spectra of the blends.

Testing Reference Evapotranspiration Estimation Methods Using Evaporation Pan and Modeling in Maritime Region of Canada

Four methods of estimating daily reference evapotranspiration (ETo) were evaluated with the data collected from 2004 to 2006 in a Maritime weather station, the Potato Research Centre, Fredericton, N.B., Canada. We tested two models [i.e., the FAO-56 Penman–Monteith (PM) and the Priestley–Taylor (PT) equations] and two Class A pan methods (Cuenca and Snyder equations). In order to assess the Evaporation Pan methods, an automatic Class A Pan system was installed in a grassed field surrounded by potato fields and continuously measured from 2004 to 2006. The results from three growing seasons (years 2004–2006) indicated that both evaporation pan methods generated lower estimations of ETo compared to the PM and PT methods. The PT method produced the highest ETo estimation. The Snyder method showed a better agreement with the PM (r2>0.56). However, the agreement varied from year to year with an r2 value range of 0.4–0.7. Kpan coefficients (a factor to convert pan observation to ETo) varied from 0.78 to 0.94. In general, the Cuenca generated lower Kpan values (0.83) than the Snyder method (0.87). Compared to the PM, the PT method overestimated ETo, which may be related to the absence of humidity adjustment in the model. Furthermore, the research suggested that the time step played an important role in the estimation of ETo in this region. The PM method at daily time step was simple but intended to overestimate ETo by 10% compared to the hourly time-step method. In summary, when Class A Pan data are available, the Snyder equation can be used to calculate Kpan with an acceptable accuracy. If the PM method is used to estimate ETo when pan observations are unavailable, a reduction of 10% to the calculated ETo at daily time step could be applied to improve the accuracy of ETo estimation.

Physical characterization and stability of amorphous indomethacin and ranitidine hydrochloride binary systems prepared by mechanical activation

Co-milling of γ-indomethacin and ranitidine hydrochloride form 2 at various weight ratios (1:2, 1:1 and 2:1) was investigated with a particular interest in the physicochemical properties and the stability of the milled mixed amorphous form. Co-milling was carried out using an oscillatory ball mill for various periods of time up to 60 min in a cold room (4 °C). The maximum temperature of the solid material was 42 °C during co-milling in a cold room. Results showed that both indomethacin and ranitidine hydrochloride were fully converted into the amorphous state after 60 min of co-milling. In contrast individually milled drugs remained partially crystalline after co-milling under the same conditions. During co-milling, the XRPD characteristic peaks of indomethacin were found to decrease faster than those of ranitidine hydrochloride. DSC results were in agreement with XRPD, and T gs of the fully converted amorphous mixtures of 29.3, 32.5 and 34.3 °C were measured for the 1:2, 1:1 and 2:1 mixtures, respectively. These T g values were in good agreement with the predicted T gs of the mixtures using the Gordon–Taylor equation. DRIFTS spectra of the co-milled amorphous samples showed peaks at 1610, 1679 and 1723 cm −1, that were not present in the individually milled samples and that are indicative of an interaction at the carboxylic acid carbonyl (HO–C O) and benzonyl amide (NC O) of the indomethacin molecule with the aci-nitro (C N) of ranitidine hydrochloride. Upon 30 days of storage, the 1:2 mixtures were found to crystallize; however, the amorphous 2:1 and 1:1 mixtures were stable when milled for 60 min and stored at 4 °C (for the 2:1 mixture) and at 4 and 25 °C (for the 1:1 mixture), respectively. Although XRPD, DSC and DRIFTS suggested an interaction between the two drugs, co-crystal formation was not observed between indomethacin and ranitidine hydrochloride.

Thermal transitions of rice: Development of a state diagram

A state diagram of basmati rice was developed by measuring the glass line; glass transition temperature vs. solids content, freezing curve; initial freezing point vs. solids content and maximally freeze concentrated conditions by using the modulated differential scanning calorimetry (MDSC) method. In addition, a cooling curve method was used to measure the initial freezing point ( T F) and the end point of freezing ( T m ′ ). The glass transition line of the state diagram was modeled using the Gordon–Taylor and linear equations, and the pattern of freezing curve was modeled using the Chen equation which incorporated unfreezable water. The condition of maximal-freeze-concentration corresponded to X s ′ (characteristic solids content) = 0.60 and T m ′ (end point of freezing) = −3.6 °C obtained from freezing curve. The characteristics glass transition T g ′ = −7.1 °C and corresponding solids content X s ″ = 0.66 were obtained by extending the freezing curve up to glass line modeled using linear equation. The T g ′ = −11.6 °C and X s ″ = 0.82 were obtained when the glass line was modeled using Gordon–Taylor equation. Adsorption isotherms of rice were measured at room temperature by isopiestic method and data were modeled with BET and GAB equations. The BET and GAB monolayer values were found as 0.083 and 0.136 kg H 2O/kg dry solids, respectively. The state diagram and water sorption properties of basmati rice can be useful in optimizing the drying and freezing processes as well as studying the physicochemical changes during storage.

Evaluation of a MODIS-Based Potential Evapotranspiration Product at the Point Scale

Abstract This paper outlines the development of a continuous, daily time series of potential evapotranspiration (PET) using Moderate Resolution Imaging Spectroradiometer (MODIS) sensor data from the Terra satellite platform. The approach is based on the Priestley–Taylor equation, incorporating a daily net radiation model during cloudless days. A simple algorithm using “theoretical clear-sky” net radiation (incorporating daily cloud fraction and cloud optical thickness) and PET is then used to estimate net radiation and PET under cloudy conditions. The method requires minimal ground-based observations for initial calibration of regional radiation algorithm coefficients. Point-scale comparisons are undertaken at four flux-tower sites in North America covering a range of hydroclimatic conditions and biomes. Preliminary results at the daily time step for a 4-yr period (2001–04) show good correlation (R2 = 0.89) and low bias (0.34 mm day−1) for three of the more humid sites. Results are further improved when aggregated to the monthly time scale (R2 = 0.95, bias = 0.31 mm day−1). Performance at the semiarid site is less satisfactory (R2 = 0.95, bias = 2.05 mm day−1 at the daily time step). In general, the MODIS-based daily PET estimates derived in this study are promising and show the potential for use in theoretical and operational water resource studies in both gauged and ungauged basins.

Dissipative particle dynamics simulation of on-chip hydrodynamic chromatography

Separations of flexible polymers using on-chip hydrodynamic chromatography (HDC) have been studied with dissipative particle dynamic simulations, a novel computational technique that fully accounts for hydrodynamic interactions among polymer segments and with walls. The current study focuses on comparisons of simulation results on elution times with that predicted by earlier theoretical models for HDC separation. The elution times obtained in simulation are found to compare reasonably well with the theoretical prediction when chain stretching is not significant. Deviation from the theoretical prediction occurs when the chain stretching becomes significant. We observe a reversal in elution order and the reversal occurs at a Deborah number about 8, slightly larger than the Deborah number at the onset of chain stretching. The simulations also confirm the applicability of the Aris–Taylor equation for the convective dispersion of small solutes and for solutes like polymer chains, except the latter requires the use of a modified Peclet number.

New findings about the complementary relationship-based evaporation estimation methods

Summary A novel approach has been found to estimate the equilibrium surface temperature (Te) of wet environment evaporation (Ew) on a daily basis. Employing this temperature in the Priestley–Taylor equation as well as in the calculation of the slope of the saturation vapor pressure curve with pan measurements improved the accuracy of long-term mean evaporation (E) estimation of the Advection–Aridity (AA) model when validated by Morton’s approach. Complementarity of the potential evaporation (Ep) and E terms was considered both on a daily and a monthly basis with the involved terms always calculated daily from 30 yr of hourly meteorological measurements of the 1961–1990 period at 210 SAMSON stations across the contiguous US. The followings were found: (a) only the original Rome wind function of Penman yields a truly symmetric Complementary Relationship between E and Ep which makes the so-obtained Ep estimates true potential evaporation values; (b) the symmetric version of the modified AA model requires no additional parameters to be optimized; (c) for a long-term mean value of evaporation the modified AA model becomes on a par with Morton’s approach not only in practical applicability but also in its improved accuracy, especially in arid environments with possible strong convection; (d) the latter two models yielded long-term mean annual evaporation estimates with an R2 of 0.95 for the 210 stations, which is all the more remarkable since they employ very different approaches for their Ep calculations; (e) with identical apparent Ep values the two models yielded practically identical long-term mean annual evaporation rates; (f) with the proper choice of the wind function to estimate apparent Ep the long-term mean annual E estimates of the modified AA model are still very close (R2 = 0.93) to those of the Morton approach.

Conducting polymer blends prepared from polyaniline with n‐dodecylbenzenesulfonic acid zinc salt as the secondary dopant

AbstractA red‐shift of the UV–vis spectra of n‐dodecylbenzenesulfonic acid doped polyaniline (PANI (DBSA)0.5), resulting from the secondary doping of polyaniline backbones, was found in the presence of n‐dodecylbenzenesulfonic acid zinc salt (Zn(DBS)2). It is proved to behave as steric hindrance spacers to induce the extension of the conjugation length through the straightening effect on the polyaniline backbones and the obtained mixtures (PANI(DBSA)0.5 plus Zn(DBS)2) can be used as master batch materials (MB‐13) for blending with regular polypropylene polymer (PP). The thermal degradation accompanied with loss of conductivity for MB‐13 can be delayed to over 250°C when enough Zn(DBS)2 was secondarily doped on PANI(DBSA)0.5., which allow the performance of its blending with other nonconducting/regular polymers possible. Below 80 rpm, increasing shear rates would induce higher viscosity difference between the MB‐13 and PP matrix, resulting in elongation of MB‐13 in the PP matrix and higher conductivities of the polyblends. The deviation from the Taylor equation, which is used to estimate the degree of elongation for a polyblend, started when shear rate is over 80 rpm. The leakage of Zn(DBS)2 out of MB‐13 can be confirmed by comparing the DSC thermograms and X‐ray diffraction patterns with that of neat PP. Gradual deformation for the conductive fillers (MB‐13) and a well‐defined and expanded layered structure can be found when processing time is below 15 min with 60 rpm shear rate. The layers started to shrink back after 15 min of procession with the loss of the Zn(DBS)2 from MB‐13 in the PP matrix. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Mine ventilation measurements with tracer gas method and evaluations of turbulent diffusion coefficient

Tracer gas measurements have been carried out at the Pongkor underground gold mine, Indonesia, to evaluate mine ventilation flows and to investigate the effective turbulent diffusion coefficients in mine airways. The airflow routes and quantity, and the diffusion coefficient have been obtained by matching the measurements with numerical simulations using the advection-diffusion equation. Two leakages with flow quantity of 26.7 and 36.7 m3/s were detected. Reduction of leakages have been measured with the method after stopping the leakage routes. The turbulent diffusion coefficients for the simple airways have good agreement with the Taylor equation. However, for complex airways in operating mines, the coefficients show higher values (1.5 to 32 times) than that obtained by the Taylor equation and these have been compared with the data measured in the Kushiro coal mine, Japan. It is mainly affected by the ratio of airway length over equivalent diameter and airway frictions, but airflow mixing along the airway also has an effect on the diffusion coefficient.

Standardization of 125I by the coincidence method and practical applications

A new coincidence system, based on two thin NaI(Tl) crystals, 50×2 mm 2, with beryllium windows, 1.5 mg cm −2, positioned approximately symmetrically from the source holder (at various distances) was constructed. The electronic chains of a classical 4 πPC– γ system were utilized. A multichannel analyzer was employed for energy calibration, and an oscilloscope for visualization of the pulses. After calibration, the system was used for the standardization of an 125I solution. An energy window of 12–95 keV containing the entire spectrum (single and sum peak) was employed, and a simple demonstration of Taylor's equation [1967. X-ray–X-ray coincidence counting methods for the standardization of 125I and 197Hg. In: Standardization of Radionuclides: Proceedings of a International Atomic Energy Agency Symposium, Vienna, 1966, pp. 341–353, SM-79/65] for whole spectrum counting, was developed. The method and system were tested during the calibration of a LKB 2104 multi-gamma counter, by comparing the detection efficiency values obtained for this prepared standard solution and that utilized in the CIPM-CCRI(II) key comparison. The efficiency of the equipment was calculated as the mean of the two individual values. The result validates the method and demonstrates the accomplishment of the national traceability assurance in nuclear medicine for 125I.

Thermomechanical behavior of epoxy resins modified with epoxidized vegetable oils

AbstractBiobased epoxy materials were prepared from diglycidyl ether of bisphenol A (DGEBA) and epoxidized vegetable oils (EVOs) (epoxidized soybean oil and epoxidized castor oil) with a thermally latent initiator. The effects of EVO content on the thermomechanical properties of the EVO‐modified DGEBA epoxy resins were investigated using several techniques. Differential scanning calorimetry indicated that the cure reaction of the DGEBA/EVO systems proceeded via two different reaction mechanisms. Single and composition‐dependent glass transition temperature (Tg) mechanisms were observed for the systems after curing. The experimental values of Tg could be explained by the Gordon–Taylor equation [Gordon M and Taylor JS, J Appl Chem 2:493 (1952)]. The thermal stability of the systems decreased as the EVO content increased, due to the lower crosslinking density of the DGEBA/EVO systems. The coefficient of thermal expansion of the systems was found to increase linearly with increasing EVO content. This could be attributed to the fact that the degrees of freedom available for motions of the segments of the macromolecules in the network structure were enhanced by the addition of EVO. Copyright © 2008 Society of Chemical Industry

Miscibility, crystallization behavior and specific intermolecular interactions in thermosetting polymer blends of novolac epoxy resin and polyethylene glycol

AbstractThermosetting polymer blends of novolac epoxy resin (EPN) and polyethylene glycol (PEG) were studied. The miscibility and crystallization behavior of the blends before curing reaction were investigated by polarized optical microscopy and differential scanning calorimetry (DSC). Overall uncured blend compositions were homogeneous in amorphous state. Single composition‐dependent glass‐transition temperature (Tg) for each blend could be observed, and the experimental Tg's of blends with EPN content ≥40 wt% could be explained well by the Gordon–Taylor equation. Thermal properties of blends cured with 4,4′‐diaminodiphenylmethane were also determined by DSC. The capability of PEG to crystallize in cured blends was different from that in uncured ones because of the topological effect of highly crosslinking structure. On the basis of Fourier transform infrared spectroscopy results, it was judged that there were intermolecular hydrogen‐bonding interactions between EPN and PEG in both cured and uncured blends. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Examination of the concentration dependence of [formula omitted] of binary aqueous solutions

We present Differential Scanning Calorimetry (DSC) results of rapidly quenched samples of the aqueous solutions of glycerol, propylene glycol and ethylene glycol along with some of their oligomers over a wider concentration. We have critically examined the concentration dependence of glass transition temperature ( T g ) of these mixtures. Our results indicate that the Gordon–Taylor equation is not the correct description of the situation. The implication of this finding on the determination of T g of bulk water from the binary solution data, is discussed.

Microstructure and yield strength of severely deformed silver

High-purity silver was processed by equal-channel angular pressing (ECAP) to eight passes, giving an average grain size of ∼250 nm. The densities of dislocations and twins were measured and compared with reported values for other face-centered cubic metals processed by ECAP. The results show the saturation yield strength correlates to the dislocation density according to the Taylor equation, and that the value of the geometrical parameter α in the Taylor equation is strongly influenced by the stacking fault energy.

Significance of soil temperature and moisture for soil respiration in a Chinese mountain area

We measured soil CO 2 efflux rate at 11 sites with different vegetation types, elevations and soil textures in a mountain area near Taiyuan city, China, over a period of 1 year. The aim was to understand the seasonal and spatial changes of soil respiration ( R s) and its responses to soil temperature ( T s) and soil water content ( W s). During the experimental period the mean T s of the sites at 10 cm depth ranged from about 0 to 26 °C, and the mean W s of the surface 0–10 cm soil layer fluctuated between the levels of field water holding capacity (WHC) and less than 1/3 of WHC. The temporal course of R s and T s could be fitted with a three-parameter Gaussian equation, with the higher values in August and the lower values in March and December. The annual mean R s (based on daily-weighted monthly mean R s) was 3.08 ± 2.12 (mean ± S.D.), 3.85 ± 2.92, 3.62 ± 2.71, 2.47 ± 2.12, 3.45 ± 3.35, 3.56 ± 2.80, 3.65 ± 3.02, 4.27 ± 3.69, 4.63 ± 4.05, 3.79 ± 2.66 and 2.18 ± 1.47 μmol CO 2 m −2 s −1 from site 1F (forest) to 11B (bare), respectively, and 3.51 ± 0.71 μmol CO 2 m −2 s −1 across the 11 sites. Cumulative annual R s (March to December) varied from 692.1 to 1472.0 g C m −2 yr −1, with an average of 1114.6 g C m −2 yr −1 across all 11 sites. The spatial variations (between-site and within-site) of R s were significant, but there was no clear evidence for which factor mainly affected the spatial variation. Temporal variations of R s were dominantly controlled by T s during most days of the year. However, during early summer, when W s was limiting, R s decreased dramatically and W s exerted control over R s. At all sites, T s was the primary factor driving temporal variations in R s. The functional relationships of R s to T s could be described well by exponential and Lloyd and Taylor equations. The coefficients of determination R 2 of T s to R s in 11 sites varied from 0.55 to 0.84 for the exponential equation, and from 0.51 to 0.86 for the Lloyd and Taylor equation when the drought-affected data were excluded. The relationships of W s to R s could be described well by linear and power equations. The R 2 of W s to R s in 11 sites ranged from 0.27 to 0.73, which were smaller than those of T s to R s, when the R s was normalized using the fit of the Q 10 function with T s at 10 °C. Both the Q 10 and R 10 increased when dry-affected data were removed from the data sets. The Q 10 ranged from 2.37 to 5.53 in 11 sites, and the R 10 of the exponential equations varied from 1.27 to 2.90 μmol CO 2 m −2 s −1, slightly lower than those of Lloyd and Taylor equations ranging from 1.34 to 4.34 μmol CO 2 m −2 s −1. The calculated Q 10 and R 10 of each site at the seasonal time scale were negatively correlated with T s and positively correlated with W s. For all data sets, four two-variable equations including linear and non-linear ones could be used to model relationships of R s to both T s and W s together, with the R 2 ranging from a minimum of 0.58 to a maximum of 0.86 for individual site. Our research results can bear important implications for the study of CO 2 efflux in similar semiarid regions.

Evaluation of the tool life and fracture toughness of cutting tools boronized by the paste boriding process

The present study evaluates the tool life and the fracture toughness of AISI M2 steel cutting tools boronized by the paste boriding process. The treatment was done in selective form on the tool tips of the steels. The temperatures were set at 1173 and 1273 K with 4 h of exposure time and modifying the boron carbide paste thicknesses in 3 and 4 mm. Microindentation fracture toughness method was used on the borided tool at the temperature of 1273 K and a 4 mm paste thickness, with a 100 g load at different distances from the surface. Also, the borided cutting tools were worn by the turning process that implied the machining of AISI 1018 steel increasing the nominal cutting speed, of 55 m/min, in 10 and 25% and maintaining the feed and the depth cut constants. The tool life was evaluated by the Taylor's equation that shows the dependence of the experimental parameters of the boriding process.