Apparatus Configurations Research Articles

Improving Output Power of a Torsional-Flutter Harvester in Stochastic Thunderstorms by Duffing - Van Der Pol Restoring Torque

Abstract Wind energy harvesters are usually designed to operate in the low wind speed range. They rely on smaller swept areas, as a complement to larger horizontal-axis wind turbines. A torsional-flutter-based apparatus is investigated herein to extract wind energy. A nonlinear hybrid restoring toque mechanism, installed at equally spaced supports, is used to produce energy through limit-cycle vibration. Energy conversion and storage from the wind flow are enabled by eddy currents. The apparatus is used during thunderstorm outflows to explore the efficiency in non-ideal wind conditions. The thunderstorm flow model accounts for both non-stationary turbulence and slowly varying mean speed, replicating thunderstorm's intensification and decay stages. This paper evolves from a recent study to examine stochastic stability. More Specifically, the output power is a random process that is derived numerically. Various thunderstorm features and variable apparatus configurations are evaluated. Numerical investigations confirm the detrimental effect of non-ideal, thunderstorms on harvester performance with, on average, an adverse increment of operational speed (about +30\%). Besides nonlinear damping, the benign flutter-prone effect is controlled by the square of the flapping angle. Since flapping amplitudes are moderate at sustained flutter, activation of the apparatus is delayed and exacerbated by the non-stationary outflow and aeroelastic load features. Finally, efficiency is carefully investigated by quantification of output power and “quality factor”.

Fluorescence and Raman Micro-Spectroscopy of LiF Films Containing Radiation-Induced Defects for X-ray Detection

Lithium fluoride (LiF) film detectors for extreme ultraviolet radiation, soft and hard X-rays, based on the photoluminescence of radiation-induced electronic defects, have been proposed and are currently under further development and investigation. LiF film detectors are versatile and can be integrated in different experimental apparatus and imaging configurations. LiF can be grown in the form of polycrystalline thin films and it is compatible with several substrates. The radiation-induced color center (CCs) photoluminescence (PL) response can be enhanced through the appropriate choice of substrates and multilayer designs, and by tailoring the micro-structural properties of polycrystalline LiF films through the control of the growth conditions. In this work, we present the characterization, through fluorescence and Raman micro-spectroscopy, of LiF films, thermally evaporated on different substrates with thicknesses of up to 1 μm, irradiated with soft X-rays produced by a laser plasma source. The combination of these micro-spectroscopy techniques could represent an advanced method to investigate the role of the polycrystalline film structures in CC formation efficiency at the microscopic level, a fundamental aspect of the development of LiF film radiation-imaging detectors.

Oscillatory thermal response test using heating cables: A novel method for in situ thermal property analysis

In situ subsurface thermal conductivity (λ) and thermal diffusivity (α) are critical parameters to design ground-coupled heat pump systems (GCHP). λ is conventionally determined from thermal response tests (TRT), whereas α is commonly selected from literature data or with laboratory analyses. Alternatively, both thermal properties can be assessed independently with an oscillatory thermal response test (O-TRT), which consists of heating the subsurface at an oscillatory rate and monitoring the resulting thermal perturbation. Due to their flexibility and relatively small radius, heating cables can be used to carry out tests in shallow unconsolidated deposits in the scope of horizontal GCHP design. The duration of the tests is short compared to vertical ground heat exchangers (fractions of a day) since the thermal resistance between the heating cable and the soil is negligible. The objective of this work was to develop an apparatus and an analytical approach to assess λ and α from an O-TRT carried out in shallow unconsolidated deposits. Nine different O-TRTs were performed in the lab for a dry standard material and five O-TRTs were performed in situ in a natural sandy deposit. After validation via numerical modelling, results show that the analytical approach using correction factors allowed the estimation of λ and α with an accuracy of < 2%. The study demonstrates that O-TRTs are a useful method to estimate both λ and α. Further testing in other reference materials and with different apparatus configurations is needed to enhance the experimental setup and extend O-TRTs towards new applications.

Predictive Drug Release Modeling Across Dissolution Apparatuses I and II using Computational Fluid Dynamics

A modeling process is developed and validated with which active pharmaceutical ingredient (API) release is predicted across the United States Pharmacopeia (USP) dissolution apparatuses I and II based on limited experimental dissolution data (at minimum two dissolution profiles at different apparatus settings). The process accounts for formulation-specific drug release behavior and hydrodynamics in the apparatuses over the range of typical agitation rates and medium volumes. This modeling process involves measurement of experimental mass transfer coefficients via a conventional mass balance and the relationship of said mass transfer coefficients to hydrodynamics and apparatus setting via computational fluid dynamics (CFD). A novel 1-D model is hence established, which provided calibration data for a particular formulation, can model mass transfer coefficients and their corresponding drug release at apparatus configurations of interest. Based on validation against experimental data produced from five erosion-based formulations over a range of apparatus configurations, accuracy within 8 %LA (labelled amount of API) and an average root mean square deviation of 3 %LA is achieved. With this predictive capability, minimizing the number of dissolution experiments and the amount of chemical materials needed during method development appears feasible.

Study of flow of Buongiorno nanofluid in a conical gap between a cone and a disk

The cone–disk apparatus consists of a cone that touches the disk at its apex and is used in medical evices, viscosimeters, conical diffusers, etc. Theoretically, a three-dimensional flow of a nanofluid in a conical gap of a cone–disk apparatus is studied for four different physical configurations. Buongiorno nanofluid model, consisting of thermophoresis and Brownian diffusion mechanisms, is used to describe the convective heat transport of the nanofluid. The continuity equation, the Navier–Stokes momentum equation, the heat equation, and the conservation of nanoparticle volume fraction equation constitute the governing system for the flow of nanofluids. The Lie group approach is used to obtain self-similar equations. Solutions are computed for an appropriate rotational Reynolds number and four different gap angles to examine flow, mass, and heat transport features. The skin friction coefficients and torque are computed and analyzed. Multivariate nonlinear regression analysis is also performed. A co-rotating disk and cone configuration has been shown to produce less torque due to the increased centrifugal force. Of the four cone–disk apparatus configurations, the maximum heat/mass transport occurs for a rotating disk with a static cone for all selected gap angles, and the least drag in the radial direction is attained for a rotating cone with a static disk. In addition, there is a minimal drag along the tangential direction for the counter-rotating disk and cone configuration. Brownian diffusion and thermophoresis of the nanoparticles lead to a higher fluid temperature and, thus, lower Nusselt numbers are obtained.

Simulation and Optimization of Film Thickness Uniformity in Physical Vapor Deposition

Optimization of thin film uniformity is an important aspect for large-area coatings, particularly for optical coatings where error tolerances can be of the order of nanometers. Physical vapor deposition is a widely used technique for producing thin films. Applications include anti-reflection coatings, photovoltaics etc. This paper reviews the methods and simulations used for improving thin film uniformity in physical vapor deposition (both evaporation and sputtering), covering characteristic aspects of emission from material sources, projection/mask effects on film thickness distribution, as well as geometric and rotational influences from apparatus configurations. Following the review, a new program for modelling and simulating thin film uniformity for physical vapor deposition was developed using MathCAD. Results from the program were then compared with both known theoretical analytical equations of thickness distribution and experimental data, and found to be in good agreement. A mask for optimizing thin film thickness distribution designed using the program was shown to improve thickness uniformity from ±4% to ±0.56%.

Poly(dimethylsiloxane)/TiO2 Photocatalytic Membranes Obtained by Different Electrospinning Systems.

Porous membranes based on polydimethylsiloxane fibers with titanium dioxide nanoparticles were developed to be used as photocatalysts. PDMS was chosen as a support for the titania because of its high thermal and chemical resistance to the photodegradative effect of the TiO2. Porous membranes are produced via electrospinning using three different apparatus configurations. The photocatalytic activity analysis shows that the best results are obtained dispersing the titanium oxide on the surface of the polymer using an electrospinning configuration which involves the use of two needles. The membranes produced in this way show a good catalytic activity, even though lower than the one observed for the pure TiO2 nanoparticles. This is caused by the low wettability of the membranes and by the surface area of the oxide being hidden from the polymer.

A cryogenic tensile testing apparatus for micro-samples cooled by miniature pulse tube cryocooler

This paper introduces a cryogenic tensile testing apparatus for micro-samples cooled by a miniature pulse tube cryocooler. At present, tensile tests are widely applied to measure the mechanical properties of materials; most of the cryogenic tensile testing apparatus are designed for samples with standard sizes, while for non-standard size samples, especially for microsamples, the tensile testing cannot be conducted. The general approach to cool down the specimens for tensile testing is by using of liquid nitrogen or liquid helium, which is not convenient: it is difficult to keep the temperature of the specimens at an arbitrary set point precisely, besides, in some occasions, liquid nitrogen, especially liquid helium, is not easily available. To overcome these limitations, a cryogenic tensile testing apparatus cooled by a high frequency pulse tube cryocooler has been designed, built and tested. The operating temperatures of the developed tensile testing apparatus cover from 20 K to room temperature with a controlling precision of ±10 mK. The apparatus configurations, the methods of operation and some cooling performance will be described in this paper.

The utilisation of operant delayed matching and non-matching to position for probing cognitive flexibility and working memory in mouse models of Huntington's disease

BackgroundOperant behavioural testing provides a highly sensitive and automated method of exploring the behavioural deficits seen in rodent models of neurodegenerative diseases, including Huntington's disease (HD). The delayed matching to position (DMTP) and delayed non-matching to position (DNMTP) tasks probe spatial learning and working memory and when applied serially they can be used to measure reversal learning, which has been shown to be an early symptom of executive dysfunction in HD. New methodThe DMTP and DNMTP tasks were conducted in two configurations of operant apparatus; the conventional 9-hole operant apparatus, and a Skinner-like operant apparatus, to compare, contrast and optimise the DMTP and DNMTP operant protocols for use in mice. The optimised tasks were then tested in the HdhQ111 mouse model of HD. ResultsOptimisation of the operant apparatus demonstrated that the mice learned the DMTP and DNMTP tasks more rapidly and effectively in the Skinner-like apparatus configuration in comparison to the conventional 9-hole apparatus configuration. When tested in the HdhQ111 mouse model of HD, the DMTP and DNMTP tasks revealed significant deficits in reversal learning. Comparison with existing methodWe found that mice were capable of performing the DMTP and DNMTP tasks in both apparatus configurations, but in comparison to the 9-hole configuration, the Skinner-like configuration produced more efficient, robust and reliable results. ConclusionsThe results presented here suggest that DMTP and DNMTP tasks, incorporating a reversal learning manipulation, are valid and robust methods for probing selected cognitive deficits in mouse models of neurodegenerative diseases.

On the investigation of the effect of apparatus configurations on the nucleation mechanisms in a cooling crystallization of sodium chlorate

Continuous crystallization plays a key role in the drive to deliver consistent crystal properties while minimizing solvent waste and undesired crystals. Plug flow crystallizers such as the continuous oscillatory baffled crystallizer (COBC) have been investigated. Kinetics studies are often carried out in batch OBCs where two types of setup can be utilized: the moving baffle system and the pulsing fluid configuration. The former involves moving a set of orifice baffles up and down the column containing supersaturated solution, while the latter is associated with pulsing the solution at the base of the column with the presence of stationary baffles. Uniform mixing is achieved by the generation and cessation of eddies, and similar degrees of mixing can be controlled and achieved in both devices. In a temperature assisted crystallization of sodium chlorate however, we found that the latter gave more nucleation of the seed‐dissimilar enantiomorph than the former. By constructing and testing a number of hypotheses, we have demonstrated that the effects of external and internal fluid renewal were responsible for such differences in nucleation mechanisms.

Cue configuration effects in acquisition and extinction of a cocaine-induced place preference.

A pervasive finding in animal models of substance abuse is that associations form quickly between contexts and drugs of abuse, such as cocaine. Studies of conditioned place preference (CPP) demonstrate that animals approach cues previously paired with cocaine. This is a commonly used preparation, but the configuration of the CPP apparatus differs across laboratories. Two common apparatus configurations for CPP are one compartment (in which the animal has access to the entire apparatus and spatial cues are irrelevant) or two compartments (in which access is restricted to one half of the apparatus and spatial cues are relevant). We compared the effects of acquisition and extinction of cocaine-induced CPP as a function of configuration. During CPP acquisition, C57BL/6J mice received cocaine paired with one tactile floor (conditioned stimulus; CS+) and saline paired with the other (CS-). CS+ and CS- trials occurred on alternate days in one of three configurations: one-compartment (exposure to the entire apparatus during CS+ or CS-), two-compartment consistent position (exposure to CS+ or CS- in adjacent, spatially distinct compartments), or two-compartment alternating position (exposure to CS+ or CS- in adjacent compartments that alternated spatial locations across days). A stronger preference for the CS+ floor occurred in two- versus one-compartment groups, with the strongest preference observed when cocaine was paired with alternating chamber positions. In contrast, greater loss of preference occurred after extinction in a one-compartment procedure, regardless of one- or two-compartment acquisition history. These findings suggest that a two-compartment configuration facilitated acquisition but attenuated extinction of a cocaine-induced CPP. The use of different CPP configurations may distinguish the underlying substrates and relevant cues for acquisition and extinction processes in cocaine abuse.

A Compact, Pulsed Infrared Laser-Excited Photothermal Deflection Spectrometer

A prototype small photothermal deflection apparatus was constructed on a laboratory bench. Not including excitation laser, data collection computer, and gas pumps, the apparatus fits on a bench space with a footprint of about 10 cm × 10 cm. The apparatus lends itself to miniaturization in future assemblies. The apparatus was tested relative to the conventional laboratory-scale photothermal apparatus. Digital filtering procedures developed in this laboratory were used to collect and analyze the data. Numerical simulation of photothermal signal is performed to accurately predict the heat flow process as sample volumes are scaled down. The results show that increased sensitivity is possible with small apparatus configurations. The prototype apparatus also exhibits high linear response with pulsed irradiance for linear absorbers. Future improvements could include miniaturization with robust configuration that will allow for portable use in trace analysis monitoring of atmospheric pollutants.

Learning the morphine conditioned cue preference: Cue configuration determines effects of lesions

The morphine conditioned cue preference was investigated using two different apparatus configurations. In one configuration, with a clear Plexiglas partition separating the drug-paired and unpaired compartments, rats could see the cues in both compartments while in either one. In the other configuration, with an opaque wood partition separating the two compartments, rats could see the cues in only one compartment at a time. The experiment had three phases: a session of pre-exposure to the entire apparatus; four 2-day training trials during each of which rats received pairings of 5 mg/Kg morphine sulphate with one compartment and saline with the other (compartments and order counterbalanced), and a test session in which the undrugged rats moved freely between the compartments while the time spent in each was measured. Four groups of rats were trained using the opaque partition in all three phases. Normal rats and rats with amygdala or nucleus accumbens lesions exhibited preferences for their morphine-paired compartments; rats with fimbria-fornix lesions had no preferences. Four additional groups were trained using the clear partition during pre-exposure, the opaque partition during training and the clear partition during testing. Normal rats and rats with fimbria-fornix lesions exhibited preferences, rats with amygdala or nucleus accumbens lesions had no preferences. This interaction between lesioned structures and the apparatus configuration is accounted for by the idea that different types of learning produced the preference for morphine-paired cues in the two apparatus configurations. Each type was learned in a different memory system and so was impaired by different lesions. These findings contribute to understanding the nature of the learning processes that produce the morphine CCP.

Drag levels and energy requirements on a SCUBA diver

The popularity of sport diving has increased rapidly since its inception in the 1950s. Over this period, the trend has been to increase the amount of equipment carried by the diver. There are many undoubted safety advantages associated with the additional kit, but under some conditions, it can impose an additional burden in the form of increased drag. The purpose of this paper is to identify the drag penalties for a number of simple self-contained underwater breathing apparatus (SCUBA) configurations. This is achieved through scale model experiments conducted in a wind tunnel. Some comments on the associated energy requirements are made, and from these, the effect on a diver's bottom time is briefly addressed. The configurations tested include a study of the effect of the equipment configuration and the effect of small changes to the diver incidence. The tests show that the addition of a pony cylinder gives a 10% increase in drag compared with a conventional octopus set-up. When a dive knife, large torch and a surface marker bouy (SMB) are also added this increases to 29%. Over the range tested, the average effect of swimming at a head up incidence to the flow is to increase the drag coefficient by 0.013 per degree. This amounts to 16% at 5∘ and 49% at 15∘. Estimates of the effect of the drag changes on bottom time show that the drag increases result in approximately similar percentage reductions in bottom time. Some simple suggestions for drag reduction are proposed.

Protonium annihilation intoπ0π0at rest in a liquid hydrogen target

The annihilation frequency of the reaction p¯ p!p0p0 at rest in liquid hydrogen has been measured by the Obelix experiment by using different apparatus configurations and trigger conditions. The value obtained is f (p0p0, LH)5(2.860.1stat60.4syst)31024. With the same data samples, the p0h annihilation frequency has been determined to be f (p0h, LH)5(0.960.2stat60.1syst)31024. The results are discussed within the frame of the present experimental situation

Economic analysis of immunoadsorption systems

Immunoadsorption possesses an attractive combination of selectivity and yield, and in some cases may replace many conventional purification steps with a single step. The economic performance of immunoadsorption is dependent on apparatus configuration (e.g. Sepharose ® bed, perfusive bed and membrane), operating conditions (e.g. bed depth, flow rate and concentration of adsorbate in the effluent at breakthrough) and antibody binding kinetics. The solution space for the lowest operating cost is potentially very large and is prohibitive to exhaustively investigate in the laboratory. A mathematical model of a generic immunoadsorption process is useful in identifying the most promising configurations, operating conditions and antibodies, without having to resort to experiments that explore every possibility. The model system was chosen to represent the purification of a valuable biochemical product (1000 mg) from mammalian cell culture media or milk where the protein is present at low concentration (2 mg l −1). The antigen–antibody kinetic rate constants for a bovine serum albumin–monoclonal antibody system are available in the literature and were representative for this study. A modified chromatographic model was developed to predict the dimensionless operating cost of the generic immunoadsorption system subject to different apparatus configurations, operating conditions and antibody kinetics. Optimal operating conditions for each of the three configurations were identified. Under these conditions, the operating costs for a perfusive bed and a membrane were comparable and 28% lower than for a packed bed. The antibody binding kinetics significantly affected the dimensionless operating cost of the system and, therefore, the model can help select the most suitable antibody from a panel of prospective antibodies.

Friction-induced oscillations of a pin-on-disk slider: analytical and experimental studies

The paper presents coordinated experimental and numerical studies of friction-induced oscillations of a Pin-On-Disk (POD) slider. The primary objective is to verify and expand the understanding of friction-induced vibrations, and to confirm validity of the analytical predictive technology. A special experimental apparatus was built, which possesses desirable qualities of mechanical simplicity and controllable dynamic characteristics. For this apparatus, an analytical model is devised, taking into consideration both the dynamics of the mechanical system and the strongly nonlinear constitutive properties of the contact interface. These properties are determined through asperity-based homogenization approach. By variation of selected details of the apparatus, both stable and unstable configurations of the system were set up and tested. The experimental observations correlate very well with analytical predictions of dynamic instability and of limit cycle oscillations.

Eigenvalue analysis of the surface forces apparatus interferometer

The resonant wavelengths, transmission, and eigenpolarizations have been obtained for a symmetric three-layer multiple-beam interferometer comprising arbitrarily oriented mica sheets with high-reflectance coatings on the outer surfaces confining an optically anisotropic medium. The interferometer configuration is one that is commonly used in the surface forces apparatus. Numerical results for typical surface forces apparatus configurations are presented. The analysis is applicable to lossy media as well as to asymmetric configurations and to media with additional layers.

Shuttlebox performance in BALB/cByJ, C57BL/6ByJ, and CXB recombinant inbred mice: Environmental and genetic determinants and constraints

Male mice from nine strains (the CXB recombinant inbred set and their progenitors, BALB/cByJ and C57BL/6ByJ) were tested in a shuttlebox for two-way avoidance acquisition in an effort to resolve discrepancies between earlier studies. Mice were tested at one of three times of day (TOD) using one of three apparatus configurations. Analysis of variance revealed complex interactions between strain, apparatus configuration, and TOD. Subsequent analyses and tests of simple effects indicated very strong influences of apparatus configuration and/or TOD upon rate of acquisition in some strains, but not in others. C57BL/6 mice were relatively little affected by either variable; BALB/c mice were responsive to apparatus configuration but not to TOD. The recombinant inbred strains performed variously at levels that were either intermediate to, comparable with, or higher than those of the progenitors, depending upon the context of the testing situation. Genetic determination of behavior is, in part, a function of the particular context in which the behavior occurs. Both TOD and apparatus configuration are significant environmental factors.

X-ray fluorescence for heavy metal dust alarms in the industrial workplace

A new X-ray fluorescence (XRF) device for the analysis of dense particle-bearing aerosols at the worksite has been developed. It provides values of the mass concentration M of each element Z > 22 held in aerosols typical of “smokestack” or acute occupational exposures (mg/m 3−g/m 3) on-site and in-time for corrective action before extensive harm to workers or the environment occurs. In operation the monitor irradiates the dispersed aerosol directly with the output of an interchangeable anode X-ray tube. The energy and number of returning XRF photons are used to identify the respective energies and abundances of the heavier elements contained within the aerosol. To date several specific apparatus configurations have been evaluated, mainly by comparing their relative sensitivities and minimum measurable mass concentrations as derived from data acquired with simulated target aerosols. These results are discussed along with the general principles behind the device, the target simulation, and the measurements themselves.