Millimetre Range Research Articles

Fifth Generation Cellular Networks

In this article the emerging requirements that are driving the fifth generation of mobile cellular networks are discussed and the technologies that will most likely be used to satisfy those requirements are identified. Proposals for 5G are at an early stage, but there is an expectation that the early 2020s will see the first deployments.The requirements for 5G are increased download speeds, the need to deal with increased cell density, increased bandwidth efficiency and availability of new bandwidth. It is likely that 5G will play a role in the emerging Internet of Things, potentially resulting in enormous increase in the number of attached devices.To meet the expected requirements 5G is likely to make use of spectrum in the millimetre range, beam-forming antenna arrays, massive Multi-Input Multi-Output, and fundamental changes to base station design. In this paper the key drivers for 5G are discussed including the very large numbers of devices in cells, the need to make available new spectrum, energy efficient ways of implementing base station capabilities, standards developments so far and 5G related issues for Australia.

Fifth Generation Cellular Networks

In this article the emerging requirements that are driving the fifth generation of mobile cellular networks are discussed and the technologies that will most likely be used to satisfy those requirements are identified. Proposals for 5G are at an early stage, but there is an expectation that the early 2020s will see the first deployments.The requirements for 5G are increased download speeds, the need to deal with increased cell density, increased bandwidth efficiency and availability of new bandwidth. It is likely that 5G will play a role in the emerging Internet of Things, potentially resulting in enormous increase in the number of attached devices.To meet the expected requirements 5G is likely to make use of spectrum in the millimetre range, beam-forming antenna arrays, massive Multi-Input Multi-Output, and fundamental changes to base station design. In this paper the key drivers for 5G are discussed including the very large numbers of devices in cells, the need to make available new spectrum, energy efficient ways of implementing base station capabilities, standards developments so far and 5G related issues for Australia.

Specific Adaptations of Mechanical Machining Processes for Laser Target Manufacturing

To produce the laser targets needed for laser plasma experiments, the CEA target department uses different mechanical machining techniques and develops methods that are consistent with the target requirements in terms of quality, timing, and cost.Combining these aims involves several challenges. First, laser experiments need a wide range of target geometries with common points: reduced dimensions (millimetric range) and thin walls (micrometric range), as well as very strict dimensional and geometric specifications. According to these requirements, the target specifications demand the machining of different kinds of materials from metals (aluminum, copper, and gold) to polymers and low-density foams.In this context, the versatility of the machining processes is the key issue. These challenges necessitate the development and upgrading of machining techniques and methods as well as optimizing the engineering design to use the full potential of these techniques. In this presentation, three main machining processes are developed and illustrated: adaptations of machine tools for planar targets (by the flycutting method) and for machining complex shapes (combined milling and turning), the development of the original process to produce a baffle hohlraum, and the parametric optimizations of machining tantalum aerogel.

Aseptic hydroponics to assess rhamnolipid-Cd and rhamnolipid-Zn bioavailability for sunflower (Helianthus annuus): a phytoextraction mechanism study.

The availability of cadmium (Cd) and zinc (Zn) to sunflower (Helianthus annuus) was investigated in rhamnolipid- and ethylenediaminetetraacetic acid (EDTA)-buffered solutions in order to evaluate the influence of aqueous speciation of the metals on their uptake by the plant, in relation to predictions of uptake by the free ion activity model (FIAM). Free metal ion activity was estimated using the chemical equilibrium program MINTEQ or measured by Donnan dialysis. The uptake of Cd followed the FIAM for the EDTA-buffered solution at EDTA concentrations below 0.4μM; for the rhamnolipid-buffered solution, the uptake of both metals in roots was not markedly affected by increasing rhamnolipid concentrations in solution. This suggests rhamnolipid enhanced metal accumulation in plant roots (per unit free metal in solution) possibly through formation and uptake of lipophilic complexes. The addition of normal Ca concentrations (low millimetre range) to the rhamnolipid uptake solutions reduced Cd accumulation in shoots by inhibiting Cd translocation, whereas it significantly increased Zn accumulation in shoots. This study confirms that although rhamnolipid could enhance accumulation of Cd in plants roots at low Ca supply, it is not suitable for Cd phytoextraction in contaminated soil environments where Ca concentrations in soil solution are orders of magnitude greater than those of Cd.

Effects of environment on accuracy of ultrasonic sensor operates in millimetre range

Summary The growing use of ultrasonic sensor now demands millimetre range of operation with high accuracy. Ultrasonic sensor uses sound waves for its ranging and the speed of sound is influenced by a number of environmental parameters. The objective of this paper is to discuss on the list of environmental parameters which have the major influence on the accuracy of the ultrasonic sensor and also to formulate a simplified mathematical equation to calculate instantaneous speed of sound by taking these influencing parameters into consideration. Comparison result shows the derived simplified equation for calculating instantaneous speed of sound gives maximum percentage error of 0.33 for the temperature range of 0–50 °С. Here we also focus on the steps to calibrate ultrasonic sensor for millimetres range of operation.

Diabetic peripheral angiopathy treatment using a multi-laser therapy device

Diabetic peripheral angiopathy treatment using a multi-laser therapy device

Longitudinal spin Seebeck effect contribution in transverse spin Seebeck effect experiments in Pt/YIG and Pt/NFO.

The spin Seebeck effect, the generation of a spin current by a temperature gradient, has attracted great attention, but the interplay over a millimetre range along a thin ferromagnetic film as well as unintended side effects which hinder an unambiguous detection have evoked controversial discussions. Here, we investigate the inverse spin Hall voltage of a 10 nm thin Pt strip deposited on the magnetic insulators Y3Fe5O12 and NiFe2O4 with a temperature gradient in the film plane. We show characteristics typical of the spin Seebeck effect, although we do not observe the most striking features of the transverse spin Seebeck effect. Instead, we attribute the observed voltages to the longitudinal spin Seebeck effect generated by a contact tip induced parasitic out-of-plane temperature gradient, which depends on material, diameter and temperature of the tip.

Using VNIR and SWIR field imaging spectroscopy for drought stress monitoring of beech seedlings

Drought stress is expected to become a recurrent problem for central European forests due to regional climate change. In order to study the effects on one of the most common tree species in Germany, the European beech (Fagus sylvatica), young potted beech trees were exposed to drought stress in a controlled experiment and their reaction was observed using visible/near-infrared (VNIR) and shortwave infrared (SWIR) field imaging spectroscopy cameras mounted on a platform. Equivalent water thickness (EWT) and leaf chlorophyll content (LCC) were measured and partial least squares (PLS) regression models were trained using these reference measurements and reflectance spectra of the trees. The models were applied to create maps of these properties with a spatial resolution in the millimetre range. These maps can be used to study the spatial distribution of EWT and LCC for single leaves or even for intra-leaf variability. Both properties can be estimated using only the VNIR sensor, but EWT estimation improves considerably by also incorporating SWIR data. LCC estimations with SWIR data alone do not work satisfactorily.

Lower Cambrian helcionelloid macromolluscs from South Australia

Early Cambrian univalve molluscs are predominantly represented by microscopic forms (body length of 1–3mm), preserved mainly as phosphatised internal moulds with limited definable features. Macromolluscs (≥5mm) are generally rare, occur in low abundance and are poorly preserved, often lacking apical features and ornament which hinders taxonomic assessment. New and previously undescribed material from lower Cambrian Hawker Group carbonates of the Flinders Ranges in South Australia includes four new taxa, Minastirithella silivreni gen. et sp. nov., Galeacalvus coronarius gen. et sp. nov., Helcionella histosia sp. nov., and Ilsanella enallaxa sp. nov. Three-dimensional silicified shell material preserved with intact apices offers new insight into protoconch morphology, growth habit (isometric vs. allometric) and developmental mode. This material supports previous suggestions that some micromollusc taxa may in fact be early ontogenetic stages (juveniles) of larger macroscopic taxa; such that the millimetric size range of helcionelloids conforms to the dimensions of earliest apical portion in some macromolluscs documented herein. However, taphonomic limitations associated with phosphatisation show that the morphology (especially height vs. width) of the apex can greatly influence the probability of steinkern formation and preservation potential for both micro- and macro-scale helcionelloids. Artificial inflation in the appearance of millimetric helcionelloids with an optimal morphology for phosphatisation is thus directly linked to taphonomic biases in the fossil record.

Millimetre wave attenuation of prototype diagnostic components for the ITER bolometers

Bolometers in current and future fusion devices, in particular those in ITER, are vulnerable to stray radiation from electron cyclotron resonance heating (ECRH) which results in measurement errors for plasma radiation detection. To protect the detectors from this stray radiation in the millimetre wavelength range, dedicated diagnostic components have been designed and tested. One option is to place a top plate which contains a microwave-reflecting grid onto the collimators. Another option investigated is the coating of the collimator channels using a microwave absorbing ceramic. Measurements of the mm-wave attenuation of the collimator in front of the bolometer detectors with and without top plate or coated collimator channels have been performed in the frequency range of 125–420GHz. The attenuation factor of the collimator channels at 170GHz (the ECRH frequency for ITER) with neither microwave grid nor coating is typically 10dB. The coating enhances this to 40dB and including the microwave grid yields at least an attenuation factor of 70dB, which is sufficient to reduce the residual ECRH induced signal significantly below the one due to plasma radiation. Placing a bolometer camera (collimator connected to detector housing) inside the isotropic microwave field of the test facility MISTRAL, the attenuation factor of the full diagnostic set-up using a top plate was determined to be in the order of 45dB. This degraded attenuation implies that particular attention has to be paid to design and quality control of the joints of diagnostic components to prevent microwave leakage.

Molecular phonons and their absorption/emission spectra from the far-IR to microwaves

Together with their fingerprint modes, molecules carry coherent vibrations of all their atoms (phonons). Phonon spectra extend from $\sim$20 to more than $10^{4}\,\mu$m, depending on molecular size. These spectra are discrete but large assemblies of molecules of the same family, differing only by minor structural details, will produce continua. As such assemblies are expected to exist in regions where dust accumulates, they are bound to contribute to the observed continua underlying the Unidentified Infrared Bands and the 21-mum band of planetary nebulae as well as to the diffuse galactic emission surveyed by the Planck astronomical satellite and other means. The purpose of this work is to determine, for carbon-rich molecules, the intensity of such continua and their extent into the millimetric range, and to evaluate their detectability in this range. The rules governing the spectral distributions of phonons are derived and shown to differ from those which obtain in the solid state. Their application allow the extinction cross-section per H atom, and its maximum wavelength, to be determined as a function of molecular size and dimensionality. Chemical modeling of more than 15 large molecules illustrate these results. It is found that the maximum phonon wavelength of a 2D structure increases roughly as the square of its larger dimension. Spectral energy distributions were computed as far as 4000 mum, for molecules up to 50 A{\deg} in length.

Multibeam Headlights in the Mercedes-Benz CLS-Class

Maximum illumination for the driver with minimal dazzling of oncoming traffi c are important criteria in the automotive illumination engineering and was even an important topic as early as the 1950s, when traffi c and congestion started to rise for the fi rst time. Computer pioneer Konrad Zuse then had the idea [1] of using multiple headlamps, each of which illuminated one area of the road and switched off via photo cells as soon as other vehicles were detected. This function is known as partial high beam. Due to the size of the bulbs used at the time, this technology was not able to be realised as the headlamp assembly would have been extremely large. When the blue LED was developed, however, it suddenly became possible to miniaturise the light sources to the extent that many white light LEDs with luminous surfaces in the millimetre range could be mounted behind a lens. It is exactly this technology that is employed in the Multibeam LED headlamps of the new Mercedes-Benz CLS-Class, FIGURE 1.

Multi-Scale Mechanical Property Characterisation of Quasi-Brittle Filter Graphite

In this paper PG25 filter graphite is characterised using mechanical tests conducted over a range of specimen length-scales from the centimetre (three-point bending and Brazilian disc compression) to the micrometre (micro-scale cantilever bending in a FEI Helios dualbeam work station). However, high resolution 3D tomography has revealed that apart from the known millimetre range of pores, the matrix contains a large population of micro-scale porosity. This leads to two discrete distributions of pore sizes in this material, so that a reduction in mechanical test specimen size results in sampling different proportions of the milli-and micro-scale pores. As a consequence, the measured mechanical properties such as elastic modulus, tensile strength and flexural strength change as a function of specimen size. This paper explores the potential benefits, difficulties and value of small-scale mechanical tests for this particular application.

Modelling bubble rise and interaction with a glass surface

A theoretical model has been developed to analyse bubble rise in water and subsequent impact and bounce against a horizontal glass plate. The multiscale nature of the problem, where the bubble size is on the millimetre range and the film drainage process happens on the micrometre to nanometre scale requires the combined use of different modelling techniques. On the macro scale we solve the full Navier–Stokes equations in cylindrical coordinates to model bubble rise whereas modelling film drainage on the micro scale is based on lubrication theory because the film Reynolds number becomes much smaller than unity. Quantitative predictions of this model are compared with experimental data obtained using synchronised high-speed cameras. Video recording of bubble rise and bounce trajectories are combined with interferometry data to deduce the position and time-dependent thickness of the thin water film trapped between the deformed bubble and the glass plate. Bubble rise velocity indicated that the boundary condition at the bubble surface was tangentially immobile. Quantitative comparisons are presented for bubbles of different size to quantify similarities and differences.

Crystal growth experiments in the systems Ni2MSbO6 (M = Sc, In) using chemical vapour transport reactions: Ni2InSbO6 and NiSb2O6 crystals in the millimetre range

Endothermic chemical vapour transport (CVT) reactions of Ni2MSbO6 (M = Sc, In), using a temperature gradient of 1313 → 1233 K and HgCl2, HgBr2, PtCl2 or TeCl4 as transport agents, led to growth of Ni2InSbO6 single crystals in the millimetre range, whereas in the case of Ni2ScSbO6 an incongruent dissolution of the solid in the source region was observed, leading to the formation of single crystals of the ternary phase NiSb2O6 in the sink region. The crystal structures of the obtained crystals were refined from single crystal X‐ray data with high precision [Ni2InSbO6: R3, Z = 3, a = 5.21640(10) Å, c = 14.0142(3) Å, 1279 structure factors, 33 parameters, R[F2 > 2σ(F2)] = 0.0189; NiSb2O6: P42/mnm, Z = 2, a = 4.63910(10) Å, c = 9.2182(2) Å, 500 structure factors, 19 parameters, R[F2 > 2σ(F2)] = 0.0145]. Ni2InSbO6 crystallizes in a corundum‐related structure, NiSb2O6 in the trirutile structure type. Spontaneous polarization and the ferroelectric transition temperature were estimated from the atomic arrangement and cation displacement along the polar axis in Ni2InSbO6. Magnetic measurements on Ni2InSbO6 evidence an antiferromagnetic transition near TN = 74 K, with significant magnetic frustration.

Alkali-bonded ceramics with hierarchical tailored porosity

Alkali-bonded ceramics and foams with tailored porosity have very interesting applications as thermal insulators, catalysts, filters, etc. Alkali-bonded ceramics were prepared starting from metakaolin and potassium silicate, selecting the process conditions, to change the intrinsic nano-micro-porosity of the geopolymer, and studying their influence on the degree of geopolymerization. Optimum geopolymerization conditions were chosen to develop porous 3D networks by inducing interconnected ultramacroporosity (up to the millimetre range) in the material, exploiting the ability of silicon powder to generate H2 in the reaction environment. The in situ foaming was strongly dependent on the water content of the geopolymeric precursors and the subsequent process of water elimination. The H2 formation is, in fact, a water-consuming process, just as consolidation is, thus increasing the viscosity. The geopolymeric inorganic matrices and the related foams were fully characterized in terms of microstructure, intrinsic and induced pore size distribution, specific surface area, geopolymerization degree, and surface accessibility of prepared materials. The thermal behaviour of the materials was also studied. The experimental findings highlighted the versatility of the foams that may be appropriately designed based on the possible application.

Plastic deformation of submicron-sized crystals studied by in-situ Kikuchi diffraction and dislocation imaging

Abstract The plastic deformation of submicron-size copper single crystals in the form of pillars has been characterized during in-situ compression in the transmission electron microscope up to strains of 28–33% using a state-of-the-art holder (PI-95 PicoIndenter). The dimensions of the crystals used were approx. 500 × 250 × 200 nm3 with the compression axis oriented 1.6° from [110]. Local crystallographic orientations have been determined with high accuracy using a Kikuchi diffraction method and glide of dislocations over a pillar has also been observed directly by dark field imaging. The variation in the local orientation during deformation has been followed by in-situ convergent beam electron Kikuchi diffraction. The in-situ observations have been followed up by post-deformation measurements with the samples still mounted in the electron microscope. Crystal breakup following localized deformation was observed in two of three crystals examined, and for all crystals the direction of rotation during deformation is in agreement with slip taking place on a subset of the four slip systems, with the highest Schmid factors on the (111) and (− 1–11) slip planes. A diffraction-based Burgers vector analysis confirms that the active dislocations are from slip systems with the highest Schmid factors. These results from testing of micropillars are in good agreement with the deformation behaviour previously reported for both single- and poly-crystal samples with dimensions in the millimetre range.

Effects of irradiation by the low-intensity electromagnetic field of the millimetric range on the Daphnia magna culture at various developmental stages

The influence of low-intensity electromagnetic irradiation and exposure to cadmium on survival and reproduction rates of daphnia in the process of their ontogenesis is investigated. The effects of the irradiation are clearly manifested in the toxicological experiments at coactions of the irradiation and cadmium and are weakly exhibited at action of the irradiation itself. At all stages of development, the irradiation does not influence the survival rate of daphnia. However, the irradiation increases their sensitivity to cadmium effects.

Computerised system for measurement of muscle thickness based on ultrasonography

In this paper, a computerised system for measuring muscle thicknesses of the transverse abdominus (TrA), internal oblique and external oblique muscles based on ultrasonography is presented. The system is designed to allow for quantitative analysis of changes in muscle recruitment and activity, which facilitates the study of such changes and its relationship with low back pain. The abdominal muscle area was localised and imaged under different standing conditions using B-mode ultrasonography. To account for issues such as misalignments due to probe and subject motion as well as speckle noise inherent to ultrasonography, automatic ensemble registration is performed on the acquired images using a sequential quadratic programming approach based on a novel log-Rayleigh likelihood function. Regions of interest are then automatically identified based on the medial border of the TrA for the purpose of quantitative muscle thickness measurements. Experimental results show that the proposed system achieves registration errors of under 0.4 mm when compared with ground-truth measurements, as well as allow for the measurement of muscle thickness changes in the millimetre range. The proposed system is currently in operational use as an analysis tool for studying the relationship between abdominal muscle thickness changes and postural changes.

Numerical analysis of guiding a microwave radiation using a set of plasma filaments: dielectric waveguide concept

A proposed model for a circular bunch of plasma filaments used as a virtual waveguide for microwave radiation is presented. The virtual circular guiding system is shown to support guided modes of electromagnetic radiation in the millimetre and sub-millimetre wavelength range. Transmission is due to total internal reflection of the wave on the less dense plasma cladding. The energy loss of microwave radiation propagating in such a virtual waveguide is calculated. Optimum spatial configurations of circular plasma filament waveguides are proposed. Plasma filament waveguides are shown to enhance microwave transmission relative to free space propagation of microwave radiation over limited distances.