Saturation properties of the refrigerant 143A

1,1,1-Trifluoroethane (CH₃---CF₃; R143a) is currently under consideration as a potential candidate as a component in refrigerant mixtures. Among other things, the accurate knowledge of saturation properties of the pure fluids is a pre-requisite for evaluation of mixture properties. There is a considerable amount of scatter in the available data for R143a. This article presents a conciliation of saturation property data for this refrigerant. Vapour pressures, saturated liquid and vapour densities have been correlated so that the ancilliary equations are related through a power β used for the temperature functions. The coefficients of the equations have been determined from a weighted least squares method using all the available data. The surface tension, viscosity and thermal conductivity in the saturated liquid phase have also been correlated.     

Human Perceptual Performance With Nonliteral Imagery: Region Recognition and Texture-Based Segmentation.

In this study the authors address the issue of how the perceptual usefulness of nonliteral imagery should be evaluated. Perceptual performance with nonliteral imagery of natural scenes obtained at night from infrared and image-intensified sensors and from multisensor fusion methods was assessed to relate performance on 2 basic perceptual tasks to fundamental characteristics of the imagery. Specifically, single-sensor imagery and fused multisensor imagery (both achromatic and false color) were used to test performance on a region recognition task and a texture segmentation task. Results indicate that the use of color rendering and type of scene content play specific roles in determining perceptual performance allowed by nonliteral imagery. The authors argue that the usefulness of various image-rendering methods should be evaluated with respect to multiple perceptual tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A complex two-unit system with random breakdown of repair facility

This paper deals with a two-unit warm standby system with a single repair facility. The lifetime of the functioning (online) unit has a general distribution, while the standby unit has a phase-type distribution. The repair facility is subjected to random breakdown and is restored after a random time. The statistical characteristics, such as reliability, availability and interval reliability, are provided for the model.     

Synthesis and characterization of polyamides containing arylene sulfide-sulfone groups

Polyamides containing arylene sulfide as well as arylene sulfide-sulfone linkages were prepared from bis(4-phenylthio)dibenzoyl chloride (BPCl), 4,4′-[sulfonylbis(4-phenylthio)]dibenzoyl chloride (SPCl) and aromatic diamines both by solution and interfacial polymerization techniques. In the solution polymerization the effect of two different acid acceptors, lithium chloride and triethylamine, on inherent viscosity of the polyamides was studied. The effect of aromatic sulfone ether diamines and conventional aromatic diamines on viscosity and thermal properties of polyamides was also investigated. The polyamides prepared were characterized by IR, ¹H NMR, elemental analysis, solution viscosity, thermogravi-metry, differential scanning calorimetry and X-ray diffraction. Thermal and physical properties of polyamides prepared from BPCl and SPCl were compared.     

Myiasis in filarial lymphoedema due to Chrysomyia bezziana

In patients with filarial lymphoedema of the limbs, infestation by maggots is extremely rare. We saw three patients with lymphoedema who harboured Chrysomyia bezziana in leg ulcers and in one of them 128 maggots were recovered. A course of local dressing, antibiotics and anti-inflammatory drugs resulted in healing of the wounds. Ulcers in patients with lymphoedema should be carefully tended with cleaning and dressing otherwise myiasis may supervene.     

Heuristics for operator allocation and sequencing in just-in-time flow line manufacturing cell

Group technology tries to exploit the similarity between parts and machines and forms machine groups and part families. Just-in-time production tries to manufacture the parts whenever required there by reducing the inventory and eliminating waste.

In order to apply JIT in a GT cell, the cell is divided into modules and parts move from one module to another in small transfer batches. This paper addresses the problem of operator allocation for the modules and sequencing the variety of parts with the objective of minimizing the makespan.

Six different methodologies have been presented and the results compared in terms of makespan and computational time.     

Transcranial Doppler in the evaluation of internal carotid artery dissection

BACKGROUND AND PURPOSE: A subject with dissection of the internal carotid artery (ICA) may present with a variety of symptoms, from headache to stroke. Thus far, it has not been possible to identify the subset of patients at risk for cerebral ischemia. Because the majority of these ischemic events are secondary to embolic phenomena, we used transcranial Doppler (TCD) evaluation with emboli monitoring to study 17 consecutive patients with ICA dissection treated at Harborview Medical Center, Seattle, Wash, during a 2-year period from 1992 until 1994. METHODS: Ten patients with ICA dissection secondary to trauma and seven with spontaneous ICA dissection were diagnosed by carotid angiography and studied by TCD from the time of diagnosis through initiation of therapy. Emboli monitoring was performed in the middle cerebral artery (MCA) ipsilateral to the dissection at the initial evaluation and intermittently thereafter to ensure that the emboli stopped with treatment. RESULTS: Emboli were detected in the MCA distal to the dissection in 10 of 17 patients (59%). Patients with microemboli detected by TCD presented with a stroke (70%) much more frequently than those without emboli (14%) (P=.0498). The presence of a pseudoaneurysm did not increase the risk of either microemboli or stroke. CONCLUSIONS: We have demonstrated a high incidence of intracranial microemboli in the MCA distal to carotid dissections and a significant correlation between the presence of emboli and stroke. TCD can therefore be used as an adjunctive tool to manage patients with suspected carotid dissection and may prove useful in evaluating the efficacy of treatment in reducing microemboli and subsequent stroke.     

155 W CW optical power from 1 cm monolithic AlGaAs/InGaAs laserdiode array

155 W continuous-wave output power from a 1 cm wide monolithic AlGaAs/InGaAs laser diode array with an emitting aperture of 4800 μm has been demonstrated at a cooling water temperature of 3°C. A continuous-wave output power of 72 W was achieved at room temperature with an emitting aperture of 1600 μm. High T₀ was observed for the laser structures