Background: Neuropathic symptoms and signs are common in the elderly and are often considered normal findings. However, symptomatic polyneuropathy may contribute to disability and falls in the elderly. The prevalence of peripheral neuropathy in the elderly in Malaysia has not been previously reported. The objective of this pilot study is to determine the frequency of symptomatic sensory polyneuropathy in a group of elderly subjects in the community and their possible associated factors. Methods: Cross sectional survey of subjects aged 65 years and above, carried out in an urban neighbourhood in Petaling Jaya. Using a standardised questionnaire, subjects were asked about sensory neuropathic symptoms, associated medical conditions and social habits. They were examined for the ankle reflex, vibration, joint position, and pinprick sensations. Possible symptomatic sensory polyneuropathy was defined as bilateral distal neuropathic symptoms, loss of pinprick sensation and proprioception sense. Results: Of the 100 subjects, 63% had neuropathic symptoms and signs and 20% had possible symptomatic sensory polyneuropathy. Subjects with polyneuropathy complained of more postural instability and giddiness and distal weakness. Diabetes mellitus was associated with the presence of neuropathic symptoms and signs but not with polyneuropathy. Age was significantly associated with polyneuropathy. Conclusion: The frequency of symptomatic sensory polyneuropathy in a group of elderly subjects in an urban Malaysian community was 20%. The frequency increased with advancing age.

Pool boiling experiments were conducted with three horizontal, flat, silicon surfaces, two of which were coated with vertically aligned multiwalled carbon nanotubes (MWCNTs). The two wafers were coated with MWCNT of two different thicknesses: 9 μm (Type-A) and 25 μm (Type-B). Experiments were conducted for the nucleate boiling and film boiling regimes for saturated and subcooled conditions with liquid subcooling of 0–30°C using a dielectric fluorocarbon liquid (PF-5060) as test fluid. The pool boiling heat flux data obtained from the bare silicon test surface were used as a base line for all heat transfer comparisons. Type-B MWCNT coatings enhanced the critical heat flux (CHF) in saturated nucleate boiling by 58%. The heat flux at the Leidenfrost point was enhanced by a maximum of ∼150% (i.e., 2.5 times) at 10°C subcooling. Type-A MWCNT enhanced the CHF in nucleate boiling by as much as 62%. Both Type-A MWCNT and bare silicon test surfaces showed similar heat transfer rates (within the bounds of experimental uncertainty) in film boiling. The Leidenfrost points on the boiling curve for Type-A MWCNT occurred at higher wall superheats. The percentage enhancements in the value of heat flux at the CHF condition decreased with an increase in liquid subcooling. However the enhancement in heat flux at the Leidenfrost points for the nanotube coated surfaces increased with liquid subcooling. Significantly higher bubble nucleation rates were observed for both nanotube coated surfaces.

Naphthalene sublimation experiments were conducted to study heat transfer for flow through blockages with holes in an internal cooling passage near the trailing edge of a gas turbine airfoil. The cooling passage was modeled as two rectangular channels whose heights decreased along the main flow direction. The air made a right-angled turn before passing through two blockages with staggered holes in each channel, and left the channel through an exit that was partially blocked by periodic lands with rounded leading edges. There were ten holes along each blockage and all of the holes had rounded edges. Local heat (mass) transfer was measured, and overall heat (mass) transfer results were obtained, on the exposed surfaces of one of the walls downstream of the two blockages, for Reynolds numbers (based on the hydraulic diameter of the channel at the upstream surface of the first blockage) between 5,000 and 36,000. The results showed that the blockages with the larger hole-to-channel cross-sectional area ratio in one of the two test sections enhanced the heat (mass) transfer downstream of the blockages more than the blockages with the smaller open area ratio in the second test section. For the geometric configurations and flow conditions studied, the average heat (mass) transfer was higher downstream of the second blockage than downstream of the first blockage. The configurations of the inlet channel and the exit slots considered in this study did not significantly affect the local heat (mass) transfer distributions or the average heat (mass) transfer downstream of the blockages.

Experiments were conducted to determine the average heat transfer coefficients on three wall segments between blockages with holes in a wide rectangular channel. Eight different configurations of the holes in the blockages-two diameters and four aspect ratios of the holes-were examined. The pressure drops across the blockages were also measured. The results showed that the elongated holes in the blockages in this study enhanced more heat transfer than the round holes, but they also caused larger pressure drops across the blockages.

The heat transfer characteristics of airflows in serpentine cooling channels in stator vanes of gas turbines were studied. The cooling channels were modeled as a two-pass trapezoidal channel with a 180deg turn. Naphthalene sublimation experiments were conducted and the heat and mass transfer analogy was applied to study the local heat (mass) transfer distributions on one of the two primary walls of the channel. Results were obtained for turbulent airflow through the channel with smooth walls, and with transverse ribs on one wall and on two opposite walls, over a range of Reynolds numbers between about 10,000 and 60,000. The results showed that there was a very large variation of the local heat (mass) transfer distribution in the turn and downstream of the turn. In all of the cases studied, the regional average heat (mass) transfer was higher on the downstream half of the turn than on the upstream half of the turn and was higher in the turn with the flow entering the channel through the smaller straight section than when the flow was reversed. The shape of the local heat (mass) transfer distribution at the turn was not significantly affected by varying the air mass flow rate. In the smooth wall case, the local heat (mass) transfer was high near the end wall and the downstream outer wall in the turn and was relatively low in two regions near the upstream outer wall and the downstream edge at the tip of the divider wall in the turn. With ribs on two opposite walls, the variation of the local heat (mass) transfer was larger, especially in the turn and downstream of the turn, than in the smooth wall case. The pressure drop across the turn was higher in the case of the flow entering the channel through the larger straight section than when the flow was reversed. As expected, the ribs increased the pressure drop across the turn.

Turbulent forced convective mass (heat) transfer downstream of blockages with round and elongated holes in a rectangular channel was studied. The blockages and the channel had the same 12:1 (width-to-height ratio) cross section, and a distance equal to twice the channel height separated consecutive blockages. The diameter of the holes was either 0.5 or 0.75 of the height of the channel. Naphthalene sublimation experiments were conducted with four hole aspect ratios (hole-width-to-height ratios) between 1.0 and 3.4, two hole-to-channel area ratios (ratios of total hole cross-sectional area to channel cross-sectional area) of 0.2 and 0.3, and Reynolds numbers (based on the channel hydraulic diameter) of 7000 and 17,000. The effects of the hole aspect ratio, for each hole-to-channel area ratio, on the average mass (heat) transfer and the local mass (heat) transfer distribution on the exposed primary channel wall between consecutive blockages were examined. The results of the study showed that the blockages with holes caused the average mass (heat) transfer to be as high as about eight times that for fully developed turbulent flow through a smooth channel at the same mass flow rate. The elongated holes caused higher overall mass (heat) transfer and larger spanwise variation of the local mass (heat) transfer on the channel wall than round holes.

The hygrothermal model has been developed to predict the temperature evolution, epoxy conversion ratio, the glass transition temperature increase and associated resin yield stress rise, and absorbed moisture vapor pressure in ISbF 6 -catalyzed DGEBA epoxy resin systems during e-beam-induced polymerization on the effects of four different initiator concentrations: 0.1,1,3, and 10 phr. This paper summarizes the modeling procedure of e-beam-induced cure kinetics, and the results of local temperature and degree of cure rise within the sample as a function of dose. Dynamic characteristics of Tg y Pv rise and their modeling procedures together with an attempt at optimizing e-beam cure process will be presented in a subsequent paper. These papers provide a methodology to generate the overall integrated model for the e-beam, fast cure process of composites and the consequences upon process control in terms of thermal control, moisture-induced void elimination, and minimization of inherent composite processing stresses that had not been previously addressed by composite process model studies. An autocatalytic model was chosen to describe the cure kinetics for this study and provided excellent agreement with experimental results. The numerical results showed that the cure reaction of ISbF 6 –DGEBA epoxy resin is diffusion controlled, but long lived reactive species allowed for measurable increase in conversion after e-beam irradiation (postcure effects). Higher initiator concentration results in higher degree of cure at a specific dose, causing higher temperature rise and larger temperature and conversion ratio gradients within the sample under given experimental conditions.

A hygrothermal thermoset resin-cure model has been developed, in conjunction with experimental data, for the e-beam processing of composites in terms of e-beam dose-time sequences in order to achieve full resin cure, minimum residual stresses and avoidance of moisture-induced cavitation within the resin system. This paper, as Part II of this study, summarizes dynamic characteristics of Tg y Pv rise and their modeling procedures together with an attempt at optimizing the e-beam-cure process. The modeling procedure of e-beam-induced cure kinetics, and the results of local temperature and degree of cure rise within the sample as a function of dose were presented in Part I.

Experiments have been conducted to study steady heat transfer between two blockages with holes and pressure drop across the blockages, for turbulent flow in a rectangular channel. Average heat transfer coefficient and local heat transfer distribution on one of the channel walls between two blockages, and overall pressure drop across the blockages were obtained, for nine different staggered arrays of holes in the blockages and Reynolds numbers of 10,000 and 30,000. For the hole configurations studied, the blockages enhanced heat transfer by 4.6 to 8.1 times, but significantly increased the pressure drop. Smaller holes in the blockages caused higher heat transfer enhancement, but larger increase of the pressure drop than larger holes. The heat transfer enhancement was lower in the higher Reynolds number cases. Because of the large pressure drop, the heat transfer per unit pumping power was lower with the blockages than without the blockages. The local heat transfer was lower nearer the upstream blockage, the highest near the downstream blockage, and also relatively high in regions of reattachment of the jets leaving the upstream holes. The local heat transfer distribution was strongly dependent on the configuration of the hole array in the blockages. A third upstream blockage lowered both the heat transfer and the pressure drop, and significantly changed the local heat transfer distribution.

Naphthalene sublimation experiments were conducted to study heat (mass) transfer enhancement by blockages with staggered round and square holes for turbulent air flows through a wide rectangular channel. The blockages and the channel had the same cross-section. The results showed that the blockages enhanced the average heat (mass) transfer on the channel walls by 4.7–6.3 times that for fully developed turbulent flow through a smooth channel. The blockages with round holes enhanced more heat (mass) transfer on the channel walls but caused larger pressure drops than the blockages with square holes, which had a 27% larger flow cross-sectional area.

Dimpled surfaces may be considered for heat transfer enhancement in internal cooling of gas turbine airfoils. In this study, convective heat transfer and pressure drop for turbulent airflow in a square channel with a dimpled wall were examined. Experiments were conducted to determine the average heat transfer coefficient on the dimpled wall and the overall pressure drop across the channel, for nine concave and cylindrical dimples with various diameters and depths, and for Reynolds numbers (based on the channel hydraulic diameter) between 10,000 and 65,000. For the concave and cylindrical dimple configurations studied, the dimples were found to enhance the heat transfer coefficient by 70% (1.7 times) to over three times the value for fully developed turbulent flow through a smooth tube, with increase of the overall pressure drop of over four times. For both the concave and cylindrical dimples, heat transfer was enhanced more when the dimples covered a larger portion of the surface of the wall. The cylindrical dimples caused higher overall heat transfer coefficient (based on the projected area) and lower pressure drop than the concave dimples with the same diameters and depths. Thus, cylindrical dimple configuration may be a better alternative than concave dimples in enhancing heat transfer, for the experimental conditions and dimple configurations investigated. Further experiments are recommended to determine if cylindrical dimples of other dimensions also give higher thermal performances than concave dimples of the same dimensions, subjected to other flow and thermal boundary conditions, such as irregular channels with or without rotation.

This experimental research examines, for turbulent parallel and counter flows of air through an annular channel, the effects of varying the geometries of the channel and the array of holes along the inner tube on the heat transfer distribution on the inner surface of the outer tube. Each hole array has 5 or 6 inline or staggered circular holes around the circumference of the inner tube at 10 axial stations along the inner tube. Heat transfer experiments are performed for three inner tube diameters, two hole diameters, and Reynolds numbers of 5,000, 12,250 and 30,000, to determine the distribution of the regional average Nusselt numbers along the outer tube, as a result of the jets impinging on its inner surface. Pressure measurements give the overall pressure drops, and the pressure distributions along the inner tube and the annular channel between the inner and outer tubes. The pressure data is needed to determine the mass flow rates of the impinging jets along the inner tube. The jets along the inner tube enhance the regional heat transfer on the inner surface of the outer tube by up to eight times when compared with the heat transfer for fully developed turbulent flow through an annular channel. Heat transfer enhancement is higher for a smaller inner tube and a lower Reynolds number. In the parallel flow case, the heat transfer coefficient on the outer wall of the annular channel is higher near the downstream end of the annular channel, while in the counter flow case, the heat transfer coefficient is higher near the upstream end of the annular channel. For both parallel and counter flows, the heat transfer coefficient is higher in a channel with a larger inner tube. With smaller holes along the inner tube, the heat transfer coefficient along the outer tube is higher and more uniform. Smaller holes, however, cause a higher overall pressure drop across the annular channel, resulting in a lower thermal performance. Increasing the total number of holes lowers the heat transfer, and causes a lower overall pressure drop. The hole mass flow rate increases along the main flow direction in the annular channel for parallel flow, and decreases for counter flow. The variation of the hole mass transfer is smaller for a larger inner tube diameter.

Experiments have been conducted to study heat transfer between two blockages with holes and pressure drop across the blockages, for turbulent flow in a rectangular channel. Average heat transfer coefficient and local heat transfer distribution on one of the channel walls between two blockages, and overall pressure drop across the blockages were obtained, for nine different staggered arrays of holes in the blockages and Reynolds numbers of 10,000 and 30,000. For the hole configurations studied, the blockages enhanced heat transfer by 4.6 to 8.1 times, but significantly increased the pressure drop. Smaller holes in the blockages caused higher heat transfer enhancement, but larger increase of the pressure drop than larger holes. The heat transfer enhancement was lower in the higher Reynolds number cases. Because of the large pressure drop, the heat transfer per unit pumping power was lower with the blockages than without the blockages. The local heat transfer was lower nearer the upstream blockage, the highest near the downstream blockage, and also relatively high in regions of reattachment of the jets leaving the upstream holes. The local heat transfer distribution was strongly dependent on the configuration of the hole array in the blockages. A third upstream blockage lowered both the heat transfer and the pressure drop, and significantly changed the local heat transfer distribution.

Dimpled surfaces may be considered for heat transfer enhancement in internal cooling of gas turbine airfoils. In this experimental and numerical study, the heat transfer and flow characteristics of dimpled surfaces, for turbulent airflow in a square channel with concave or cylindrical dimples on one of the walls, were studied. Experiments were conducted to determine the average heat transfer coefficient on the dimpled wall and the overall pressure drop across the channel, for four concave and cylindrical dimples with a fixed diameter and two different depths, and for Reynolds numbers (based on the channel hydraulic diameter) between 10,000 and 65,000. Numerical results that included flow and temperature fields were obtained for turbulent airflow through a square dimpled channel with dimple geometries and boundary conditions that were the same as those for the experiments. For the concave and cylindrical dimple configurations studied, the dimples were found to enhance the heat transfer coefficient by 73% to 126% over the value for fully developed turbulent flow through a smooth tube, with increase of the overall pressure drop of up to 2.6 times. The cylindrical dimples caused higher heat transfer than the concave dimples. The numerical results showed the highly complex and unique flow patterns near the surfaces with the concave and cylindrical dimples and inside the cavities of these dimples. The numerical results also showed that cylindrical dimple configuration might be a better alternative than concave dimples in enhancing heat transfer.

Naphthalene sublimation experiments have been conducted to examine the effects of channel orientation, rotational Coriolis force, ad a sharp turn, on the local heat (mass) transfer distributions in a two-pass square channel with rib-roughened walls, rotating about a perpendicular axis. The test channel was oriented so that the direction of rotation was perpendicular or at a 45 deg angle to the leading and trailing walls. In the two straight passes of the test channel, there were parallel 90 or 60 deg ribs on the leading and trailing walls. The test channel modeled serpentine cooling passages in modern gas turbine blades. The results showed that the heat (mass) transfer was very low on the leading wall of the first pass when the channel was oriented with the rotating direction normal to the leading and trailing walls. There were regions of very low heat (mass) transfer on both the leading and trailing walls in the turn, especially on the trailing wall in the turn when the channel with transverse ribs was oriented diagonally. For the given diagonal channel orientation, rotational Coriolis forces caused the leading and trailing wall heat (mass) transfer to be high near the outer edges of the walls in the channel with transverse ribs; rotation-induced secondary flows dominated near wall rib-induced secondary flows in the channel with angled ribs, since the heat (mass) transfer was generally higher near the outer edges of the walls than near the inner edges in the first and second straight passes.

Experiments have been conducted to study the local heat (mass) transfer distributions in a two-pass test model of internal turbine blade cooling passages, with 60 ribs on the leading and trailing walls. For radial outward flow in the first pass, rotation did not significantly increase the local nor the overall heat (mass) transfer between consecutive ribs on the trailing wall. Rotation-induced Coriolis force lowered the relative overall heat (mass) transfer on the leading wall less in the rib-roughened channel than in a smooth channel. When the rotation number was high, there were twin peaks in the local heat (mass) transfer distribution between ribs on the leading wall. For radial inward flow in the second pass, the sharp turn reduced the difference between the heat (mass) transfer.on the leading wall and that on the trailing wall.

The objective of this experimental investigation was to examine the effects of rotation, flow ejection, channel orientation, and transverse ribs on the local heat (mass) transfer distribution for radial outward flow in a square channel, rotating about a perpendicular axis. The test channel was oriented so that the direction of rotation was perpendicular or at a 45 deg angle to the leading and trailing walls. There were eight ejection holes along the leading or trailing wall of the test channel. The diameter of each ejection hole was equal to one-fifth of the channel hydraulic diameter. The wall with the ejection holes was either smooth or roughened with seven transverse ribs. The ribs were located midway between two ejection holes. The height of the ribs was equal to one-tenth of the channel hydraulic diameter, and the spacing between two ribs was equal to 10 times the rib height. The Reynolds number was 5.5 X 10 3 and the rotation number range was between O.Q and 0.24. In a smooth normally oriented channel, rotation in the direction of the ejection flow significantly reduced the local heat/mass transfer on the leading wall, except in the vicinity of the ejection holes. Rotation in a direction opposite to that of the ejection flow widened the high heat/mass transfer regions near the ejection holes on the trailing wall, and reduced the heat/ mass transfer in the regions between the ejection holes. In a smooth diagonally oriented channel, the trend of higher heat/mass transfer near the leading side of the leading wall rather than near the trailing side was the opposite of the expected trend for the radial outward flow through a smooth diagonally oriented channel with no ejection holes. Flow reattachment downstream of transverse ribs and flow acceleration toward ejection holes together caused very high heat/mass transfer in bell-shaped regions around the ejection holes. Rotation changed the shape of the local heat/mass transfer distribution more on the leading wall than on the trailing wall of a rib-roughened diagonally oriented channel.

In this experimental investigation, the variations of the local heat transfer coefficient in rib-roughened turbine blade internal cooling passages are examined. Using liquid crystal thermometry, the detailed local heat transfer distributions are determined for turbulent flows through a long, straight, square test channel model with ribs of various configurations, including perforated ribs, on two opposite walls. Angled and V-shaped solid ribs enhance more heat transfer than transverse solid ribs. Angled solid ribs cause very large spanwise variations of the local heat transfer distribution. With the highest overall heat transfer and relatively small spanwise heat transfer variation, V-shaped ribs are recommended for internal cooling of gas turbine blades. Perforated ribs enhance less heat transfer than solid ribs, because the jet streams leaving the holes interrupt and weaken flow reattachment on the wall downstream of a rib. Increasing the size or the number of holes, or the total hole area, lowers the overall heat transfer. The lower pressure drop caused by perforated ribs reduces the required pumping power, but does not improve the thermal performance.

Naphthalene sublimation experiments have been conducted to study the effects of channel orientation, rotational Coriolis force, and a sharp turn, on the local heat (mass) transfer distributions in a two-pass square channel with a sharp turn and smooth walls, rotating about a perpendicular axis. The test channel was oriented so that the direction of rotation was perpendicular to or at a 45 deg angle to the leading and trailing walls. The Reynolds number was kept at 5,500 and the rotation number ranged up to 0.24. For the radial outward flow in the first straight pass of the diagonally oriented channel, rotation-induced Coriolis force caused large monotonic spanwise variations of the local mass transfer on both the leading and trailing walls, with the largest mass transfer along the outer edges of both walls. Rotation did not lower the spanwise average mass transfer on the leading wall and did not increase that on the trailing wall in the diagonally oriented channel as much as in the normally oriented channel. The combined effect of the channel orientation, rotation, and the sharp turn caused large variations of the local mass transfer distributions on the walls at the sharp turn and immediately downstream of the sharp turn. The velocity fields that were obtained with a finite difference control-volume-based computer program helped explain how rotation and channel orientation affected the local mass transfer distributions in the rotating two-pass channel.