Critical-Behavior Of The Diameters Of Liquid-Liquid Coexistence Curves

We have analyzed the diameters of the liquid–liquid coexistence curves of several binary liquid mixtures in search of the critical anomaly predicted by current theories. We find that while the data are consistent with the predicted functional form, the evidence for such an anomaly is not compelling.

Critical remarks on "On the compensation effect"

A critical assessment of a published paper (by Agrawal) is presented. The procedure proposed and used by Agrawal to distinguish a false compensation effect from a true one is shown not to be correct.

An E-Convergence Method For The Evaluation Of Critical Parameters

A simple cconversence technique is applied to obtain accurate estimates of critical temperatures and critical it\ponmts of a few two- and threpdiniensional king models. When applied to the virial series for hard spheres and hard discs, this method predicts a divergence of the equation-of-state at the density of closest packing.

Expansivity of liquid (cyclohexane + acetic anhydride) near its critical solution point

A simple volume dilatometer is described for the precise measurements of volume changes as a function of temperature in liquid mixtures. The expansivity of (cyclohexane + acetic anhydride) in the critical region was measured. The critical solution temperature Tc was approached to within 9 mK. For T > (Tc + 0.3 K), the results results follow both a logarithmic and a power-law behaviour with an exponent ≈ 1/8. But for T < (Tc + 0.3 K), the results seem to be affected possibly by gravity or temperature gradients. In this region, the expected expansivity anomaly is rounded off to a cusp. The expansivity shows a reduced anomaly for off-critical compositions. A discussion of the local extremum and a correlation between negative expansivity and the resistivity anomaly are also given.

Identification of dynamical systems with fractional derivative damping models using inverse sensitivity analysis

The problem of identifying parameters of time invariant linear dynamical systems with fractional derivative damping models, based on a spatially incomplete set of measured frequency response functions and experimentally determined eigensolutions, is considered. Methods based on inverse sensitivity analysis of damped eigensolutions and frequency response functions are developed. It is shown that the eigensensitivity method requires the development of derivatives of solutions of an asymmetric generalized eigenvalue problem. Both the first and second order inverse sensitivity analyses are considered. The study demonstrates the successful performance of the identification algorithms developed based on synthetic data on one, two and a 33 degrees of freedom vibrating systems with fractional dampers. Limited studies have also been conducted by combining finite element modeling with experimental data on accelerances measured in laboratory conditions on a system consisting of two steel beams rigidly joined together by a rubber hose. The method based on sensitivity of frequency response functions is shown to be more efficient than the eigensensitivity based method in identifying system parameters, especially for large scale systems.

Bile Acid Derived PET-Based Cation Sensors: Molecular Structure Dependence of their Sensitivity

A number of bile acid derived photoinduced electron transfer (PET) based sensors for metal ions are prepared. A general strategy for designing the sensor with a modular nature allows for making different molecules capable of sensing different metal ions by a change in the fluorophore and receptor unit. Keeping the basic molecular structure the same, different bile acid base fluoroionophores were prepared inorder to achieve the highest sensitivity toward the metal ions. Thesensors showed similar binding constants for the same metal ion, but the degree Of fluorescence enhancement upon addition of the metal salts were different. The sensitivities of the sensors towards a certain metal were determined from the observed fluorescence enhancement upon addition of the metal salt.

Comment: Eigenvalue sensitivity method for optimal stabilisation of linear systems

In a letter RauA proposed a new method for designing statefeedback controllers using eigenvalue sensitivity matrices. However, there appears to be a conceptual mistake in the procedure, or else it is unduly restricted in its applicability. In particular the equation — BR~lBTK = A/.I, in which K is a positive-definite symmetric matrix.

Nonstationary Random Critical Seismic Excitations

A method is presented to find nonstationary random seismic excitations with a constraint on mean square value such that the response variance of a given linear system is maximized. It is also possible to incorporate the dominant input frequency into the analysis. The excitation is taken to be the product of a deterministic enveloping function and a zero mean Gaussian stationary random process. The power spectral density function of this process is determined such that the response variance is maximized. Numerical results are presented for a single-degree system and an earth embankment modeled as shear beam.

Low-frequency dielectric constant measurements in the critical polar + non-polar binary liquid system: Methanol + n-heptane

The low-frequency (5–100 kHz) dielectric constant ε has been measured in the temperature range 7 × 10−5 < T = (T − Tc)/Tc < 8 × 10−2. Near Tc an exponent ≈0.11 characterizes the power law behaviour of dε/dt consistent with the theoretically predicted t−α singularity. However, over the full range of t an exponent ≈0.35 is obtained.

Critical Evaluation of Determining Swelling Pressure by Swell-Load Method and Constant Volume Method

For any construction activity in expansive soils, determination of swelling pressure/heave is an essential step. Though many attempts have been made to develop laboratory procedures by using the laboratory one-dimensional oedometer to determine swelling pressure of expansive soils, they are reported to yield varying results. The main reason for these variations could be heterogeneous moisture distribution of the sample over its thickness. To overcome this variation the experimental procedure should be such that the soil gets fully saturated. Attempts were made to introduce vertical sand drains in addition to the top and bottom drains. In this study five and nine vertical sand drains were introduced to experimentally find out the variations in the swell and swelling pressure. The variations in the moisture content at middle, top, and bottom of the sample in the oedometer test are also reported. It is found that swell-load method is better as compared to zero-swell method. Further, five number of vertical sand drains are found to be sufficient to obtain uniform moisture content distribution.

Resolution and sensitivity of the eyes of the Asian honeybees Apis florea, Apis cerana and Apis dorsata

Bees of the genus Apis are important foragers of nectar and pollen resources. Although the European honeybee, Apis mellifera, has been well studied with respect to its sensory abilities, learning behaviour and role as pollinators, much less is known about the other Apis species. We studied the anatomical spatial resolution and absolute sensitivity of the eyes of three sympatric species of Asian honeybees, Apis cerana, Apis florea and Apis dorsata and compared them with the eyes of A. mellifera. Of these four species, the giant honeybee A. dorsata (which forages during moonlit nights) has the lowest spatial resolution and the most sensitive eyes, followed by A. mellifera, A. cerana and the dwarf honeybee, A. florea (which has the smallest acceptance angles and the least sensitive eyes). Moreover, unlike the strictly diurnal A. cerana and A. florea, A. dorsata possess large ocelli, a feature that it shares with all dim-light bees. However, the eyes of the facultatively nocturnal A. dorsata are much less sensitive than those of known obligately nocturnal bees such as Megalopta genalis in Panama and Xylocopa tranquebarica in India. The differences in sensitivity between the eyes of A. dorsata and other strictly diurnal Apis species cannot alone explain why the former is able to fly, orient and forage at half-moon light levels. We assume that additional neuronal adaptations, as has been proposed for A. mellifera, M. genalis and X. tranquebarica, might exist in A. dorsata.

Critical-point Properties of Liquids and the Born-Green Theory

Recent work of Jones et al. giving the long-range behaviour of the pair correlation function is used to confirm that the critical ratio Pc/nckBTc = 1/2 in the Born-Green theory. This deviates from experimental results on simple insulating liquids by more than the predictions of the van der Waals equation of state. A brief discussion of conditions for thermodynamic consistency, which the Born-Green theory violates, is then given. Finally, the approach of the Ornstein-Zernike correlation function to its critical point behaviour is discussed within the Born-Green theory.

Low-frequency dielectric constant measurements in the critical polar + non-polar binary liquid system: Methanol + n-heptane

The low-frequency (5–100 kHz) dielectric constant epsilon (Porson) has been measured in the temperature range 7 × 10−5 < t = (T − Tc)/Tc < 8 × 10−2. Near Tc an exponent ≈0.11 characterizes the power law behaviour of Image consistent with the theoretically predicted t−α singularity. However, over the full range of t an exponent ≈0.35 is obtained.