General Trend Of Variation Research Articles

Frozen kinetics for the effects of a functional glazing on physical, chemical, and microbial properties of tilapia during storage

This work aimed to quantify the effects of a fresh-keeping glazing on the shelf life of frozen fish. In this work, glazing was prepared using modified chitosan as the backbone. Essential oils (EOs) extracted from two Zanthoxylum species were introduced as functional additive agents to improve the physical and chemical properties of chitosan. Kinetics models were established to predict the shelf life of the preserved fish. As the results, the shelf life increased up to 1.7–2.0 times when the temperature every dropped 4 K. Ice glazing further prolonged the shelf life. As the results, the shelf life of the samples with chitosan glazing were 1.1–1.5 times than that of the naked samples, while that of the samples with chitosan-EOs glazing were 1.3–1.9 times. The findings revealed a general trend of variations in storage quality of frozen fish, as well as the effects of an ice glazing. It is instructive to establish application models for a real distribution chain. Novelty impact statement This work modified chitosan glazing by the introduction of antioxidant and antimicrobial EOs to keep the storage qualities of frozen fish. Systematical work to quantize the effects of both frozen storage and modified glazing layers on shelf life of the preserved fish was present. The overall findings could be instructive for real distribution chain.

GRANITOID MAGMATISM IN THE NORTH OF THE URALS: U–Pb AGE, EVOLUTION, SOURCES

This work presents the summarization of U–Pb (SIMS, TIMS) zircon dates and petrogeochemical signatures of granitoids of the north of the Urals (Polar, Subpolar, and Northern Urals) obtained over the last decade. Granitе melts were formed from melting of different substrates, highly heterogeneous in composition and age, at all geodynamic stages distinguished in the studied area. Preuralides include island arc–accretionary (735–720 Ma, 670 Ma), collisional (650–520 Ma), and rift-related (520–480 Ma) granitoids. Uralides includes primitive island-arc granitoids (460–429 Ma), mature island-arc granitoids (412–368 Ma), early collisional (360–316 Ma) and late collisional (277–249 Ma) granitoids. As a result, the general trend of variations of oxygen (δ18OZrn, ‰), neodymium (εNd(t)wr), and hafnium (εHf(t)Zrn) isotope compositions identified in time. Mantle isotope compositions (δ18OZrn (+5.6), εNd(t)wr (+1.7), εHf(t)Zrn (+8.7...+10.6)), common for island arc granitoids (Preuralides) are changed by crustal–mantle ones (δ18OZrn (+7.2...+8.5), εNd(t)wr (–4.8...+1.8), εHf(t)Zrn (+2.1 to +13)), typical of collisional granites. According to this, the crustal matter played a significant role during the formation of the latter. The crustal-mantle isotope compositions are changed by the mantle ones, characteristic of rift-related (δ18OZrn (+4.7...+7), εNd(t)wr (+0.7...+5.6), εHf(t)Zrn (–2.04...+12.5)) and island-arc (Uralides; δ18OZrn (+4.2...+5.7), εNd(t)wr (+4.1...+7.4), εHf(t)Zrn (+12...+15.2)) granitoids.

Efficient and data-driven prediction of water breakthrough in subsurface systems using deep long short-term memory machine learning

Water coning is one of the common issues in subsurface systems in which water flows into the production well through perforated zones. This phenomenon can cause severe problems in wellbore and surface facilities. Thus, accurate prediction of water breakthrough can help to adapt to the production mode and avoid such issues. Conducting flow simulations, as a conventional approach, can be very time demanding if one deals with large subsurface systems. Furthermore, several types of data are often collected during the life of a subsurface system each of which can help to predict the breakthrough and water coning. As such, it is very important to produce similar results using the time sequence data gathered from various geo-sensing tools. In this paper, a deep long short-term memory (LSTM) model is developed to predict the water cut and water breakthrough time for multiple production wells in a water flooding case. The dataset is generated by the Egg model with a multi-input-multi-output system. We found that the proposed model can capture the general trend of variation for the water cut time sequence data for a complex subsurface system. To evaluate the performance of our data-driven method, the results are compared with vanilla recurrent neural network (RNN), deep gated recurrent unit (GRU), and artificial neural network (ANN). The conducted comparison indicates that the proposed deep LSTM model outperforms the other three approaches when the results are compared with the numerical data.

Study of shape, size and temperature-dependent elastic properties of nanomaterials

The impact of shape, size and temperature on elastic properties of nanomaterials is studied in this work. We have extended the melting temperature expression for nanostructures formulated by Guisbiers et al. and obtained the expression of elastic moduli and thermal expansivity for nanomaterials. An isobaric Tait equation of state is combined with Guisbiers model and the model so obtained is applied to analyze the shape, size and temperature effect on Young’s modulus and thermal expansivity in nanomaterials. The present computed results are compared with the simulated results and available experimental data. The Young’s modulus is observed to decrease as particle size is reduced while thermal expansivity increases with decrease in the size of nanomaterial. The Young’s modulus shows decrease with increase in temperature and decrement is observed maximum in spherical nanomaterials and minimum in nanofilms (NFs). Rate at which modulus is decreasing is found to increase as particle size is reduced. Good consistency of present predicted results with the available theoretical and experimental data is observed. The present calculated results are thus found consistent with the general trend of variation.

Bridging the gap between macroscopic electrochemical measurements and microscopic molecular dynamic simulations: Porous carbon supercapacitor with ionic liquids

We apply a combination of experimental measurements and molecular dynamic (MD) simulations to describe imidazolium ionic liquids with porous carbon electrode. On the experiment's side, electrochemical measurements are conducted on two types of porous carbon electrodes prepared from different pore size distributions. The general trend of variations for impedance are identified at various temperatures and electrode geometries in Nyquist plots. On the simulation's side, fundamental geometries including slit and cylindrical pores are modeled to determine the ions' behaviours during charging and discharging process. By examining the local charges variations, the electrode charging or polarization are correlated with ion dynamics or relaxation, particularly in the vicinity of electrode. In one-to-one correspondence to experiments, linear segment of impedance for individual pores gives rise to the constant phase element in fitting of porous electrode's equivalent circuit. Our MD simulations explored the path of implementing the techniques of cyclic voltammetry and electrochemical impedance spectroscopy.

Ionospheric variations over Chinese EIA region using foF2 and comparison with IRI-2016 model

In the present work, we have analyzed data of critical frequency of the F2 region (foF2) for the period, 2008–2013 over low latitude Chinese station Guangzhou (Geog. Lat. 23.10°N, Geog. Long. 113.40°E, dip, Lat. 13.49°N) and results thereof have been compared with IRI-2016 model. foF2 data set of the present study encompasses period of unusual and extended solar minimum, i.e., the years 2008–2009 and rising phase of solar cycle 24. IRI data have been obtained by choosing topside electron density profile IRI-NeQuick for two F peak models, CCIR and URSI. It is found that the general trend of variation in foF2 closely follows the trend of the solar flux during the period of study. A linear regression analysis gave a correlation coefficient of 0.98 which shows strong dependence of foF2 variation over solar flux variation. Semi-annual and annual oscillations are clearly brought out in the foF2 data using the Lomb-Scargle periodogram. A presence of semiannual and winter anomaly in observed as well as modeled foF2 at Guangzhou have found to be consistent throughout the period 2008–2013 irrespective of the phases of the solar activity. Our results also show the stronger presence of winter anomaly during the years of higher solar flux and it has been confirmed by normalizing the difference of winter to summer foF2 values for each year. Comparative results of ionosonde observation and IRI-2016 model show a significant discrepancy with regard to values of foF2 in different seasons and local time variations. IRI 2016 model underestimates the foF2 values in winter and equinoxes and overestimates foF2 values in summer. IRI modeled foF2 values using CCIR and URSI F peak models were found greater during forenoon hours and smaller during afternoon hours than the observed foF2 values throughout the period 2008–2013.

Craniofacial Shape of Arfak People Based on Geometric Morphometric Features

Face and cranial (craniofacial) shape is highly specific to the individual; therefore, craniofacial shape is often used to identify individuals and to analyze variability in the human population. Previous studies, consisting only of verbal descriptions, suggested that the cranial shape of the Papuan people was highly variable. Despite their usefulness, verbal descriptions cannot fully demonstrate common and local variation in cranial shape. They also cannot be used to extract the general trend of variation or to group face shapes based on their similarity . Here we attempt to apply geometric analysis, a method of shape analysis, to measure facial anatomical structural landmarks of Papuan people. The craniofacial shape of Papuan people was constructed from those of Arfak people based on 16 anatomic landmarks on the lateral side . Arfak is one of the traditional Papuan tribes in Manokwari, West Papua Province. O ur result showed great variation in craniofacial shapes among the Arfak. The nose, chin, and mandible differed significantly, whereas other parts of the face were relatively stable and showed small variations. These differences reflected variations in the facial growth rate. The high level of diversity thus indicates that some parts of the face have higher plasticity in their growth pattern than others.

Temporal evolution of photon energy emitted from two-component advective flows: origin of time lag

X-Ray time lag of black hole candidates contains important information regarding the emission geometry. Recently, study of time lags from observational data revealed very intriguing properties. To investigate the real cause of this lag behavior with energy and spectral states, we study photon paths inside a Two Component Advective Flow (TCAF) which appears to be a satisfactory model to explain the spectral and timing properties. We employ the Monte-Carlo simulation technique to carry out the Comptonization process. We use a relativistic thick disk in Schwarzschild geometry as the CENtrifugal pressure supported BOundary Layer (CENBOL) which is the Compton cloud. In TCAF, this is the post-shock region of the advective component. Keplerian disk on the equatorial plane which is truncated at the inner edge i.e., at the outer boundary of the CENBOL, acts as the soft photon source. Ray-tracing code is employed to track the photons to a distantly located observer. We compute the cumulative time taken by a photon during Comptonization, reflection and following the curved geometry on the way to the observer. Time lags between various hard and soft bands have been calculated. We study the variation of time lags with accretion rates, CENBOL size and inclination angle. Time lags for different energy channels are plotted for different inclination angles. The general trend of variation of time lag with QPO frequency and energy as observed in satellite data is reproduced.

Further evidence for GHB naturally occurring in common non-alcoholic beverages

GHB has been implicated in many cases of suspected surreptitious administration with the purpose of increasing victim vulnerability to sexual assault. Low amounts of endogenous (or naturally occurring) GHB, which do not reach pharmacologically active levels, have been detected in alcoholic and non-alcoholic beverages. Due to the continued requirement to obtain data on the presence of endogenous GHB in various beverage types, GHB concentrations were measured in a series of non-alcoholic beverages.Tonic water and lemon flavoured tonic water beverages were analysed at 0, 24 and 96h after the bottle opening using gas chromatography coupled to tandem mass spectrometry (GC–MS/MS) on an Agilent 6890/7000C Triple Quadrupole. GHB was detected in all beverages at very low amounts ranging from 89 to 145ng/mL (0.089–0.145mg/L) and did not demonstrate a general trend of variation for concentration along the tested time span (96h). The presented data provide additional evidence for the endogenous nature of GHB in non-alcoholic beverages at very low concentrations, which are many orders of magnitude lower than those described to produce any pharmacological effect on the subject. However, when considering a case of alleged drug-facilitated sexual assault, a low level of GHB detected in a drink may be related both to a surreptitiously GHB administration with subsequent dilution for concealment or to the presence of endogenous GHB. On this basis, a comprehensive analysis of all the available information, including circumstantial data demonstrating possible attempts to conceal GHB administration and an assessment of levels of endogenous GHB in the suspected beverage type, is of the utmost importance for a proper interpretation of the toxicological results.

Theoretical and comparative investigations of Yb 3+ ion in MWO 4 and M′MoO 4 scheelites crystals (M=Sr, Pb, Ca, Ba) and (M′=Sr, Pb, Ca, Cd)

The crystal-field model is applied to a series of scheelites crystals (CaWO 4, SrWO 4, PbWO 4, BaWO 4, CdMoO 4, CaMoO 4, SrMoO 4 and PbMoO 4) doped with the Yb 3+ ion. The calculated crystal-field parameters present a general trend of variation with M 2+ ionic radius of the host cation. The maximum splitting Δ E of the 2F 7/2 manifold of the Yb 3+ ion is then obtained as a function of N V crystal-field strength parameters. The agreement between experimental results and theoretical predictions for all investigated systems is very satisfactory. The crystal-field effects are very important for the prediction of emission energies of the Yb 3+ ion in different scheelites.

Empirical ocean color algorithms for estimating particulate organic carbon in the Southern Ocean

We have examined empirical algorithms for estimating surface concentration of particulate organic carbon (POC) from remotely sensed ocean color in the Southern Ocean using field data of POC, spectral remote‐sensing reflectance, Rrs(λ), and the inherent optical properties (IOPs) of seawater collected during a number of cruises. Several algorithm formulations have been considered, including direct relationships between POC and the blue‐to‐green band ratios of reflectance and a single‐wavelength two‐step algorithm that consists of relationships linking reflectance to the backscattering coefficient and POC to the particulate backscattering coefficient at 555 nm. The best error statistics among the algorithms tested were obtained for the power function fit POC (in mg m−3) = 189.29 [Rrs(443)/Rrs(555)]−0.87. This band ratio algorithm is based on 85 pairs of field data and shows a small mean bias of about 3%, the normalized root mean square error of 27%, and the determination coefficient of 0.93. These error statistics as well as the analysis of matchup comparisons of satellite‐derived POC and in situ POC determinations support the prospect for reasonably good performance of this algorithm in the Southern Ocean. The two‐step empirical algorithm operating at 555 nm shows inferior error statistics of the regression fits and matchup comparisons compared with the band ratio algorithm. The analysis of our data set also indicates that a general trend of variation in the blue‐to‐green reflectance band ratio over the examined range of POC values is driven primarily by the green‐to‐blue ratio of particulate absorption coefficient.

Isotopic fractionations associated with phosphoric acid digestion of carbonate minerals: Insights from first-principles theoretical modeling and clumped isotope measurements

Phosphoric acid digestion has been used for oxygen- and carbon-isotope analysis of carbonate minerals since 1950, and was recently established as a method for carbonate ‘clumped isotope’ analysis. The CO 2 recovered from this reaction has an oxygen isotope composition substantially different from reactant carbonate, by an amount that varies with temperature of reaction and carbonate chemistry. Here, we present a theoretical model of the kinetic isotope effects associated with phosphoric acid digestion of carbonates, based on structural arguments that the key step in the reaction is disproportionation of H 2CO 3 reaction intermediary. We test that model against previous experimental constraints on the magnitudes and temperature dependences of these oxygen isotope fractionations, and against new experimental determinations of the fractionation of 13C– 18O-containing isotopologues (‘clumped’ isotopic species). Our model predicts that the isotope fractionations associated with phosphoric acid digestion of carbonates at 25 °C are 10.72‰, 0.220‰, 0.137‰, 0.593‰ for, respectively, 18O/ 16O ratios (1000 ln α ∗) and three indices that measure proportions of multiply-substituted isotopologues ( Δ 47 ∗ , Δ 48 ∗ , Δ 49 ∗ ) . We also predict that oxygen isotope fractionations follow the mass dependence exponent, λ of 0.5281 (where α 17 O = α 18 O λ ). These predictions compare favorably to independent experimental constraints for phosphoric acid digestion of calcite, including our new data for fractionations of 13C– 18O bonds (the measured change in Δ 47 = 0.23‰) during phosphoric acid digestion of calcite at 25 °C. We have also attempted to evaluate the effect of carbonate cation compositions on phosphoric acid digestion fractionations using cluster models in which disproportionating H 2CO 3 interacts with adjacent cations. These models underestimate the magnitude of isotope fractionations and so must be regarded as unsucsessful, but do reproduce the general trend of variations and temperature dependences of oxygen isotope acid digestion fractionations among different carbonate minerals. We suggest these results present a useful starting point for future, more sophisticated models of the reacting carbonate/acid interface. Examinations of these theoretical predictions and available experimental data suggest cation radius is the most important factor governing the variations of isotope fractionation among different carbonate minerals. We predict a negative correlation between acid digestion fractionation of oxygen isotopes and of 13C– 18O doubly-substituted isotopologues, and use this relationship to estimate the acid digestion fractionation of Δ 47 ∗ for different carbonate minerals. Combined with previous theoretical evaluations of 13C– 18O clumping effects in carbonate minerals, this enables us to predict the temperature calibration relationship for different carbonate clumped isotope thermometers (witherite, calcite, aragonite, dolomite and magnesite), and to compare these predictions with available experimental determinations. The success of our models in capturing several of the features of isotope fractionation during acid digestion supports our hypothesis that phosphoric acid digestion of carbonate minerals involves disproportionation of transition state structures containing H 2CO 3.

Stationary Fluid Dynamic Behaviour of V-Shaped Diffuser/Nozzle Elements for Valveless Micropump

A novel type of V-shaped (isosceles triangle cross-section) diffuser/nozzle element is proposed for use for valveless micropump. Stationary fluid dynamic behaviour of V-shaped diffuser/nozzle elements in a valveless micropump is investigated by experiment and simulation. Both the results agree well with each other when the Reynolds number is higher than 100 and the pressure loss coefficient ratio of micropump nearly always keeps a constant. For a single V-shaped diffuser, the general trends of variation of pressure loss coefficient with opening angle and Reynolds number are opposite in small and large angles. Compared with conical and flat-wall diffusers, V-shaped diffuser shows the smallest pressure loss when the Reynolds number is 200.

Experimental Results From Controlled Blade Tip/Shroud Rubs at Engine Speed

Abstract Experimental results obtained for an Inconel® compressor blade rubbing a steel casing at engine speed are described. Load cell, strain gauge, and accelerometer measurements are discussed and then applied to analyze the metal-on-metal interaction resulting from sudden incursions of varying severity, defined by incursion depths ranging from 13μm to 762μm (0.0005in. to 0.030in.). The results presented describe the transient dynamics of rotor and casing vibro-impact response at engine operational speed similar to those experienced in flight. Force components at the blade tip in axial and circumferential directions for a rub of moderate incursion depth (140μm) are compared to those for a severe rub (406μm). Similar general trends of variation during the metal-to-metal contact are observed. However, in the nearly threefold higher incursion the maximum incurred circumferential load increases significantly, while the maximum incurred axial load increases much less, demonstrating the non-linear nature of the rub phenomena. Concurrently, the stress magnification on the rubbing blade at root mid-chord, at tip leading edge, and at tip trailing edge is discussed. The results point to the possibility of failure occurring first at the airfoil trailing edge. Such a failure was in fact observed in the most severe rub obtained to date in the laboratory, consistent with field observations. Computational models to analyze the non-linear dynamic response of a rotating beam with periodic pulse loading at the free-end are currently under development and are noted.

The Relationship between Polycyclic Aromatic Hydrocarbons and Heavy Metals

Background : Heavy metals and PAH s in flue gas have received considerable attention in recent years due to their mutagenic or carcinogenic properties. PAH s are products of incomplete combustion of carbonaceous compounds at high temperatures. Heavy metals are released into the ambient air from the same sources as those earlier mentioned for PAH s . The present study was carried out to investigate the influence of the quantity of heavy metals on PAH s formation in ambient air. Methods : In this study, air particulates were collected on glass fiber filters using a high- volume air sampler. Each filter was exactly cut into equal pieces. One piece was digested with HNO 3 as well as H 2 O 2 and used for determination of heavy metals. Another piece was extracted using Soxhlet method. The latter was used for the determination of PAH s . The concentrations of heavy metals (Cr, Cd, Cu, Pb, and Zn) were measured using Perkin- Elmer atomic absorption spectrometer. The concentration of PAH s was measured by a PU4400 gas chromatograph equipped with FID detector. The concentrations of PAH s and heavy metals were determined in different seasons. Results : The results showed that the concentration of PAH s was minimum in the weekend and holidays, but maximum in winter. The relationship between ambient air concentrations of PAH s and heavy metals was investigated and an excellent agreement was found. The general trend of variations in concentration of heavy metals were found very similar to PAH s , therefore it could be concluded that the source of pollution was the same for both of pollutants. Conclusion : The general trend of variations in concentration of heavy metals was found very similar to PAH s , therefore it could be concluded that the source of pollution was the same for both of pollutants.

Low Reynolds number flow through nozzle-diffuser elements in valveless micropumps

Flow characteristics of low Reynolds number laminar flow through gradually expanding conical and planar diffusers were investigated. Such diffusers are used in valveless micropumps to effect flow rectification and thus lead to pumping action in one preferential direction. Four different types of diffuser flows are considered: fully developed and thin inlet boundary layer flows through conical and planar diffusers. The results from the numerical analysis have been quantified in terms of pressure loss coefficient. The variation of pressure loss coefficient with diffuser angle is presented for Reynolds numbers of 200, 500 and 1000. The pressure loss coefficients have been used to calculate the diffuser efficiency for two different types of nozzle-diffuser elements. The general trend of variation of pressure loss coefficient with diffuser angle was found to be similar to that for high Reynolds number turbulent flow. However, unlike at high Reynolds numbers, pressure loss coefficients at low Reynolds numbers vary significantly with Reynolds number. It was also observed that trends of variation in the pressure loss coefficient with Reynolds number are different for small and large diffuser angles. Also, at low Reynolds numbers, the pressure loss coefficients for a thin inlet boundary layer are not always smaller than those for fully developed inlet boundary layer, in contrast to the behavior for high Reynolds number flows. Contrary to past claims, flow rectification is shown to be indeed possible for laminar flows. The two different types of nozzle-diffuser elements considered led to pumping action in opposite directions. Further, it was observed that flow rectification properties of both kinds of nozzle-diffuser elements improved with increasing Reynolds number.

Bio‐optical relationships and ocean color algorithms for the north polar region of the Atlantic

Up to now, relatively few bio‐optical measurements have been made in the high northern latitude waters, which allow sound relationships for ocean color remote sensing to be determined. We collected optical and chlorophyll a concentration, Chl, data in the north polar region of the Atlantic in summer season. The investigated region includes subarctic and arctic waters between 70°N and 80°N within the meridional zone between 1°E and 20°E. Our measurements show that the current NASA global algorithms, OC2, OC4, and chlor‐MODIS, generally overpredict Chl in the investigated waters by a factor of about 2 at low pigment concentrations (<0.2 mg m−3) and underpredict Chl at higher concentrations (20–50% at 2–3 mg m−3). For our data set, the best two‐band algorithm for Chl involves the ratio of remote‐sensing reflectance, Rrs(442)/Rrs(555), at 442‐nm and 555‐nm light wavebands. We found that the general trend of variation in the blue‐to‐green reflectance ratio, Rrs(442)/Rrs(555) or Rrs(490)/Rrs(555), with Chl was driven primarily by Chl‐dependent change in the green‐to‐blue ratio of absorption by pure seawater and particles. The effect of the blue‐to‐green backscattering ratio was of secondary importance. We observed a characteristic optical differentiation of waters within the investigated region. The majority of waters, which are here hypothesized to be dominated by diatoms, exhibited a relatively high blue‐to‐green reflectance ratio. The waters at several other stations, presumably dominated by dinoflagellates and/or prymnesiophytes, showed much lower reflectance ratio. Our data also show that the seemingly random variations in particulate absorption and backscattering coefficients at any given Chl are significant (more than a factor of 2) in the investigated waters.

Calculation of the Precursor Flux from Optical Emission Spectroscopy Data in Plasma Enhanced Chemical Vapour Deposition of Silane and its Correlation with the Deposition Rate

Variation of the optical emission due to SiH*, Ar* and Hα at 414.2 nm, 750.4 nm and 656 nm respectively with respect to rf power were studied during the deposition of amorphous (a-Si:H) and microcrystalline (µc-Si:H) silicon films by plasma enhanced chemical vapor deposition (PECVD) method from a mixture of silane and argon. We compared the SiH* emission intensity with the SiH* density calculated from the chemical kinetics of the dominant bimolecular reactions occurring within the plasma. Extending the calculation to estimate concentrations of SiH3 and SiH2 radicals (precursors) generated by parallel reaction processes we find that the general trend of variation of the deposition rate of the samples with rf power follows that of the calculated precursor densities. Formation of µc-Si:H has been found to be associated with a sharp increase of the ratio of the density of the excited Ar* species to that of SiH3 or SiH2 radicals.

Adsorption characteristics of 47 elements on a calcareous soil, a red earth and an alumina: a multitracer study

The distribution coefficients, K d of 47 elements from Na to Bi on a calcareous soil, a red earth and an alumina were, respectively, determined using a multitracer technique. The multitracer solution was prepared by irradiation of UO 2(NO 3) 2 with 40Ar ion beam. It was found that there is a common general trend of variation in K d for both soils and the alumina, i.e. all the shapes of plots of log K d versus electron binding energy ( I z ) are an ‘inverted V’, hence the important role of chemical interaction in the adsorption of trace inorganic cations, anions and neutral complexes on the soils and the oxides was demonstrated. For the alkali and alkaline earth elements, the common sequences of K d values on the three adsorbents were Na +<K +<Rb +<Cs + (except for Rb + on the alumina) and Mg 2+<Sr 2+<Ba 2+ and accord with the sequences of effective ionic radii or single ion hydration enthalpies.

Effect of cut-outs on underexpanded rectangular jets

AbstractThe flowfield characteristics of jets from plain and rectangular orifices with semi-circular cut-outs have been experimentally investigated for both sonic and underexpanded conditions. Detailed pitot pressure measurements revealed that the cut-outs had a strong influence on the emerging flowfield. The rectangular orifice with cut-outs at the minor axis ends showed more effective mixing with shorter core lengths and faster near field jet decay when compared with the plain rectangular and the rectangular orifice with cut-outs at the major axis ends. The general trend of variation of shock cell length with fully expanded Mach number was consistent with Tam's theory, but the shock cell length of orifice jets were less than that predicted by Tam.