•A ferro-nanofluid oscillating heat pipe (OHP) was used to generate voltage.•Marked improvement in OHP heat transfer occurred (∼70%) when using ferro-nanofluid.•A bias magnetic field is needed to ...locally magnetize suspended ferro-nanoparticles.•Energy harvesting via ferrofluidic induction can decrease OHP heat transfer.
A unique thermal-to-mechanical-to-electrical energy conversion process is demonstrated via thermally-excited, pulsating ferro-nanofluid within a solenoid-equipped oscillating heat pipe (i.e., ferrofluid-OHP or FF-OHP). The FF-OHP was charged with an aqueous cobalt ferrite ferro-nanofluid, comprised of custom-synthesized CoFe2O4 nanoparticles surface-modified with citric acid for increased suspensibility. Annular bias magnets were placed directly above and below the FF-OHP solenoid to temporarily magnetize the internal, oscillating ferrofluid. During FF-OHP operation, a measured peak-to-peak voltage of ∼2 mV was measured across the solenoid due to electromagnetic induction. When filled with ferro-nanofluid, the OHP heat transfer was enhanced (relative to pure water) by ∼58% with bias magnets and ∼71% without bias magnets. A maximum effective thermal conductivity of 12.9 kW/m·K was achieved in the FF-OHP at ∼470 W of heat input. With the bias magnets installed (i.e., harvesting configuration), the FF-OHP effective thermal conductivity was ∼11% lower than when the bias magnets were not present, and this is attributed to an increase in ferrofluid viscosity due to particle magnetization in the bias field. The FF-OHP/solenoid harvesting process is a novel means for accomplishing thermal-to-electrical energy conversion while maintaining high heat transfer capabilities and extreme temperature functionality.
Time-varying surface temperatures of two flat-plate oscillating heat pipes (OHPs), one with Tesla valves and one without, were analyzed in the time–frequency domain using the short-time Fourier and ...Hilbert–Huang transforms. Tesla valves were installed along the channel structure of the OHP for the purpose of rectifying the oscillatory internal flow field, thereby enhancing heat transfer. Spatial-averaged surface temperatures in the evaporator region of both OHPs were investigated in the time–frequency domain at three separate heat inputs in order to detect salient effects of the Tesla valves. In all cases, the temperature signals from both OHPs were found to contain intermittent, aperiodic oscillations with most energy concentrated at frequencies in the 0–200 mHz range. The energies of oscillations in both OHPs were found to decrease with increases in the heat input, suggesting more consistent inter-channel flow circulation at these heat inputs heat inputs. The non-valved OHP temperature signals contained oscillations of larger amplitude and over a broader frequency range than the valved OHP temperature signals, indicating that the Tesla valves reduced the occurrence of intermittent high-energy oscillations in the OHP evaporator surface temperature.
•The temperature signals for oscillating heat pipes (OHPs) are non-stationary.•OHP temperature oscillations occur predominantly at frequencies below 200 mHz.•‘Non-valved’ OHP temperature signals contain higher-energy oscillations.•Energy of OHP temperature oscillations decreases with increases in heat input.•‘Valved’ OHP temperature signals have less-deviant intrinsic mode functions.
•Thermocouples installed in oscillating heat pipe (OHP) for fluid temperature measurements.•Conduction along tube wall of OHP can be ∼10% of the overall heat transfer.•Tubular OHP measured to have ...internal Nusselt number between 4 and 6.•Internal OHP temperature oscillations have larger amplitudes than external.•Thermal conductivity of OHP is higher when considering internal fluid temperatures.
The current study examines the relationship between internal/fluidic and external/wall temperature measurements along the adiabatic section of an operating tubular oscillating heat pipe (T-OHP) for varying heat inputs. Temperature measurements were achieved using type-T thermocouples located either inside or along the OHP wall in the region between the evaporator and condenser. Measurements were utilized to elucidate the effects of wall thermal capacitance, external wall temperature gradient, and internal fluid advection. The internal, single-phase heat transfer coefficient was estimated, and the effective thermal conductivity of the OHP was determined. A 4-turn copper T-OHP (3.25mm ID) was charged with water (75% by volume) and tested in the bottom-heating condition. Heat input was varied in increments of 25W from 60W to 300W. Results indicate that the external thermocouples were unable to capture frequency components larger than ∼1Hz. Internal measurements indicate that average, evaporator-side fluid oscillation frequencies varied from ∼1.5Hz at 60W to ∼2.5Hz at 300W, whereas condenser-side frequencies remained fairly constant at ∼0.5Hz. The frequency transfer function corresponding to the thermal resistance network between the internal/external thermocouples was found to be constant across all tested power inputs. The low-frequency, large-amplitude changes in internal temperature associated with bulk fluid motion were not immediately measured at the external OHP tube surface. The effective thermal conductivity calculated using only external temperature measurements was found to be 4–12% lower than that calculated using internal measurements. The maximum, calculated effective thermal conductivity using internal or external temperature measurements was 15,300W/m·K and 14,000W/m·K, respectively. This difference arises from there being a smaller, length-wise temperature gradient along the fluid columns than along the tube wall due to the strong advection component of OHP heat transfer. Tube wall conduction was found to account for 2–10% of the overall heat transfer, with its significance decreasing as fluid advection increased at higher heat inputs. The heat transfer coefficient for single-phase fluid oscillation inside the OHP was estimated to be ∼1000W/m2K for power inputs larger than 100W; corresponding to Nusselt numbers between 4 and 6.
Neonatal sepsis caused by Streptococcus agalactiae group B streptococcus (GBS) is a life-threatening condition, which is preventable if colonized mothers are identified and given antibiotic ...prophylaxis during labour. Conventional culture is time consuming and unreliable, and many available non-culture diagnostics are too complex to implement routinely at point of care. Loop-mediated isothermal amplification (LAMP) is a method that, enables the rapid and specific detection of target nucleic acid sequences in clinical materials without the requirement for extensive sample preparation.
A prototype LAMP assay targeting GBS sip gene is described.
The assay was 100 % specific for GBS, with a limit of detection of 14 genome copies per reaction. The clinical utility of the LAMP assay for rapid direct molecular detection of GBS was determined by testing a total of 157 vaginal swabs with minimal sample processing using a rapid lysis solution. Compared to a reference quantitative real-time PCR assay, the direct LAMP protocol had a sensitivity and specificity of 95.4 and 100 %, respectively, with positive and negative predictive values of 100 and 98.3 %, respectively. Positive and negative likelihood ratios were infinity and 0.05, respectively. The direct LAMP method required a mean time of 45 min from the receipt of a swab to generation of a confirmed result, compared to 2 h 30 min for the reference quantitative real-time PCR test.
The direct LAMP protocol described is easy to perform, facilitating rapid and accurate detection of GBS in vaginal swabs. This test has a potential for use at point of care.
Important and controversial changes have recently taken place in industrial training in the United Kingdom. Training is a complex policy area – industrial, economic, educational and social objectives ...may be pursued through it. For the most part it has been policy formation which has been dominated by professionals and thus there has been a ‘closed system’ into which outsiders rarely intrude. But outside influences have become more powerful; consequently the professionals are careful about which issues they place on the agenda for discussion. However, the most striking impression made by the training system is its lack of coherence and this may undermine its effectiveness.
The establishment of the Scottish Parliament in 1999 Will pose questions about its relationship to local authorities, and about the local authorities' roles in education. The Parliament could become ...a force for further centralisation in Scottish education policy, or, as the Scottish Constitutional Convention proposed, it could initiate a radical programme of decentralisation. Both of these scenarios hold significant implications for education and local government.
Local government has recently been reformed in ways which make education much more central to the business of local councils. This gives the new councils an opportunity to shape the emerging debate, and establish for themselves a position as partners of the Parliament in the government of Scotland.
L'Écosse est aujourd'hui à la croisée des chemins : le maintien au sein du Royaume-Uni, dont les contours institutionnels ont été sensiblement remaniés depuis l'arrivée des néo-travaillistes au ...pouvoir en 1997, ou l'indépendance complète qui mettrait fin à un « partenariat » avec l'Angleterre qui dure depuis 1707. Comment expliquer cette volonté d'autonomie qui est devenue la nouvelle donne de la scène politique écossaise et britannique depuis un quart de siècle ? Quels sont les rapports exacts entre les revendications autonomistes qui dépassent, et de très loin, le vote nationaliste et l'effervescence culturelle qui caractérise l'Écosse depuis les années soixante-dix ? Quelles sont les nouvelles figures de l'identité écossaise qui émergent des débats actuels ? Quelle est la réalité économique et sociale de l'Écosse contemporaine, au delà des clichés médiatiques et des mythes ? Un ensemble de spécialistes, britanniques et français, apporte, dans cet ouvrage, des éléments de réponse à ces questions. En faisant le point sur le chemin parcouru depuis « l'éclatement de la Grande-Bretagne » dont les premiers signes furent repérés par l'historien Tom Nairn, il y a un quart de siècle. L'Autonomie écossaise propose une vision nouvelle et critique de celle nation de la « périphérie » britannique.
The training system in Scotland underwent a major change in the 1980s, as control of training programs devolved from the central government to Local Enterprise Companies (LECs) and Industry Training ...Organizations (ITOs). Fairley discusses the need for LEC-ITO coordination for the integration of the sectoral and local components of employment training.
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