Multi-vane expander performance: Breathing characteristics

The throttling of the working fluid flow at the inlet and exhaust port openings of multi-vane expanders leads to power losses. Therefore, a mathematical model has been developed to analyse their breathing characteristics. In particular two existing designs of multi-vane expanders, using refrigerant 113 as the working fluid, were considered. The results obtained indicate that multi-vane expanders exhibit easy-breathing behaviours. Improved breathing characteristics can be achieved by the wise selection of operating conditions for any existing design or by optimising the design parameters for a specific application.     

Dynamic fields generated by rapid crack growth

Stresses and strains near a rapidly propagating crack tip are affected by the mass density of the material. This paper starts with a brief summary of analytical results for near-tip dynamic fields as predicted by linear elastic fracture mechanics. Next, exact expressions are derived for dynamic crack-line strains, for mode-III crack propagation in a nonlinear elastic material and in an elastic perfectly-plastic material. These expressions are valid on the crack line from the moving crack tip to the moving boundary with the region of linearly elastic deformation. For steady-state crack growth, a critical strain criterion is used to compute the relation between external load and crack tip speed. The required external load increases with crack-tip speed.     

Guest Editors' Introduction: Application-Level QoS

Application-level quality of service (QoS) is the Achilles' heel of services offered overthe Internet. The articles in this special issue cover various aspects of this complex problem, while exposing the challenges we have yet to overcome.     

The importance of structural and gel fractions in determining shear sensitivity of sludge.

Shear sensitivity measurements with variation of ingredients in a synthetic sludge can be related to biosolids' structural properties and particulate amount. The shear sensitivity is primarily controlled by the gel fraction, with alginate and the associated cations increasing the gel-like behavior. However the effect of particulate fraction on shear sensitivity should also be taken into account. Shear sensitivity is thus a complex parameter including two types of response: the resistance to dispersed mass concentration into centrate, and the maintenance of desired strength while the solids concentration increases in the shear field.     

Nutritional composition, processing, and utilization of horse gram and moth bean

Horse gram and moth bean are the unexploited legumes of the tropics and subtropics grown mostly under dry-land agriculture. The chemical composition is comparable with commonly cultivated legumes. Like other legumes, these are deficient in methionine and tryptophan. Horse gram is an excellent source of iron and molybdenum. Comparatively, horse gram seeds have higher trypsin inhibitor and hemagglutinin activities and polyphenols than moth bean seeds. Dehusking, germination, cooking, and roasting have been shown to produce beneficial effects on nutritional quality of both the legumes. Both the legumes require prolonged cooking to obtain product of acceptable nature. A soak solution (1.5% NaHCO3 + 0.5% Na2CO3 + 0.75% citric acid) treatment has been shown to reduce cooking time and improve protein quality. Moth bean is mostly consumed as dhal or sprouts. The whole seeds of horse gram are generally utilized as cattle feed. However, it is consumed as a whole seed, sprouts, or whole meal by a large population in rural areas of southern India. Medical uses of these legumes have been discussed.     

Buffer Capacity of Cheese Wheys

Titration and buffer capacity curves of Mozzarella, Cheddar and Cottage cheese-type wheys were studied at concentrations of 6–24% solids. Buffer maxima due to lactate and phosphate occurred at pH 3.2 – 4.0 and 5.6 – 7.0, respectively, and were dependent on the type and concentration of whey. Titration curves of all whey varieties intersected at pH 3.7. An equation was developed to define whey pH as a function of pH at dipping, concentration and level of HCI or NaOH (r = 0.99, p < 0.01). The pH of Mozzarella and Cheddar cheese-type whey decreased during concentration but the pH of Cottage cheese whey increased. This difference is explained by calcium-phosphate equilibria in whey.     

Estimation of multipath channel response in frequency selectivechannels

A novel discrete-time method is proposed for estimating the impulse response of a frequency-selective digitally modulated communication channel. The received signal is first demodulated and sampled and then the fourth-order cumulants of the resulting discrete-time sequence are estimated. The method estimates the channel impulse response from the complex cepstrum of the aforementioned fourth-order cumulants (i.e. tricepstrum). The method depends only on the second- and fourth-order statistics of the transmitted sequence and is capable of reconstructing nonminimum-phase impulse responses. Monte Carlo simulation results demonstrate the effectiveness of the method, its low sensitivity to observation noise, and its improved performance in terms of probability of error or the reconstructed transmitted sequence     

Interfacial stress singularities in a bimaterial wedge

In this paper methods of computing stress singularity factors for strain-hardening materials are reviewed. The methods are applied to calculation of these factors for a bimaterial wedge comprising two power-law hardening materials of arbitrary external and internal angles.