Millimetre Range Research Articles

Sufficiency of near-surface water ice as a driver of dust activity on comets

Context. Nearly all contemporary theoretical research on cometary dust activity relies on models depicting heat transfer and sublimation products within the near-surface porous layer. Gas flow exerts a pressure drag to the crust agglomerates, counteracting weak gravity and the tensile strength of that layer. Our interpretation of data from the Rosetta mission, and our broader comprehension of cometary activity, hinges significantly on the study of this process. Aims. We investigate the role played by the structure of the near-surface porous layer and its associated resistance to gas flow, tensile strength, pressure distribution, and other characteristics in the scenario of the potential release of dust agglomerates and the resulting dust activity. Methods. We employ a thermophysical model that factors in the microstructure of this layer and radiative heat conductivity. We consider gas flow in both the Knudsen and transition regimes. To accomplish this, we use methods such as test-particles Monte Carlo, direct-simulation Monte Carlo, and transmission probability. Our study encompasses a broad spectrum of dust-particle sizes. Results. We evaluated the permeability of a dust layer composed of porous aggregates in the submillimetre and millimetre ranges. We carried out comparisons among various models that describe gas diffusion in a porous dust layer. For both the transition and Knudsen regimes, we obtained pressure profiles within a non-isothermal layer. We discuss how the gaps in our understanding of the structure and composition could impact tensile strength estimates. We demonstrate that for particles in the millimetre range, the lifting force of the sublimation products of water ice is adequate to remove the layer. This scenario remains feasible even for particles on the scale of hundreds of microns. This finding is crucial as the sublimation of water ice continues to be the most probable mechanism for dust removal. Conclusions. This study partially overturns the previously held, pessimistic view regarding the possibility of dust removal via water sublimation. We demonstrate that a more precise consideration of various physical processes allows elevation of the matter of dust activity to a practical plane, necessitating a fresh quantitative analysis.

Prompt gamma energy integration: a new method for online-range verification in proton therapy with pulsed-beams

Introduction: We propose a method for prompt-gamma verification of proton range during particle therapy, called Prompt-Gamma Energy Integration (PGEI).Method: This method is based on the measurement of the total energy deposited in a set of detectors located around a patient. It is particularly suited in the case of high-instantaneous beam intensities, like for pulsed beams extracted from a synchro-cyclotron. GATE simuations were used to evaluate the sensitivity, and dedicated scintillators were tested as a function of beam intensity.Results and discussion: Simulations show that millimetric range shifts can be measured at a beam-spot scale. The sensitivity is slightly degraded as compared to the Prompt-Gamma Peak Integration Method, for which Time-of-Flight can be employed to reduce the background in single-photon detection conditions at cyclotron accelerators. Experimentally, lead tungstate scintillators have shown to cope with the high instantaneous gamma count rates for PGEI at synchro-cyclotrons.

Density-based in-orbit collision risk model valid for any impact geometry

Neglecting small fragments in space debris evolutionary models can lead to a significant underestimation of the collision risk for operational satellites. However, when scaling down to the millimetre range, the debris population grows to over a hundred million objects, making deterministic approaches too computationally expensive. On the contrary, probabilistic models provide a more efficient alternative, which however typically works under some simplifying assumptions on the dynamics, limiting their field of applicability. This work proposes an extension of the density-based collision risk models to any orbital dynamics and impact geometry. The impact rate with a target satellite is derived from a multi-dimensional phase space density function in orbital elements, which discretely varies over both phase space and time. The assumption of a bin-wise constant cloud density allows for the analytical transformation of the six-dimensional distribution in orbital elements into the three-dimensional spatial density function, guaranteeing an efficient and accurate evaluation of the fragments flux. The proposed method is applied to the assessment of the collision risk posed by occurred fragmentation events in different orbital regions on a high-risk target object. The effect on the impact rate of the modelling improvements, compared to previous probabilistic formulations, is discussed.

Surface wave communication-based wave guide design concerns for flip chip package-based integrated circuits with bump pitch sizes of 1.2 mm and above

ABSTRACT The flip chip package (FCP) based integrated circuits supports millimetre wave frequency range (30 - 300 GHz), analysing the conditions for optimal signal transmission between the integrated circuits for FCP type being the primary essence of this article. The effective signal transmission occurs through a dielectric-coated conductor structure based on the surface wave communication phenomenon, known as a surface wave communication-based wave guide (SWW). The article focuses primarily on design considerations to build SWW for FCP applications at millimetre wave frequency ranges. The efficiency of the proposed waveguide was investigated in terms of power transmission capacity, voltage standing wave ratio (VSWR) and signal attenuation. The analysis comprises examining these parameters at the frequency range of 50 GHz to 150 GHz while taking into account varied degrees of waveguide dimensions and surface reactance. The measured results show that at the signal frequency of 100 GHz with dielectric and conductor thickness of 0.2 mm and surface reactance of 100 Ω, the suggested waveguide provides efficient signal transmission with approximately 0 dB signal attenuation, ideal high-power flow of 41,000 VA m 2 and VSWR of 1.2. Overall, this article provides insights on the design and performance of SWW for FCP applications at millimetre wave frequency band.

Optimizing Algorithm for Existing Fiber-Optic Displacement Sensor Performance.

This paper describes the optimal design of a miniature fiber-optic linear displacement sensor. It is characterized by its ability to measure displacements along a millimetric range with sub-micrometric resolution. The sensor consists of a triangular reflective grating and two fiber-optic probes. The measurement principle of the sensor is presented. The design of the sensor's triangular grating has been geometrically optimized by considering the step angle of the grating to enhance the sensor's resolution. The optimization method revealed a global optimum at which the highest resolution is obtained.

The electron beam freeform fabrication of NiTi shape memory alloys. Part II: Influence of the heat treatment on the superelastic behaviour

In a previous study (part I), the deposition of functional single-track and multi-layer Ni-rich NiTi using the electron beam freeform fabrication (EBF3) technique was demonstrated. The processed microstructure consists of columnar millimetre range grains that grow parallel to the build direction. Based on the same parameters of part I, this work successfully deposited a stable multi-track and multi-layer NiTi block. Different heat treatments were applied to modify the superelastic properties of the deposited material. Initially, the solution treatment reduces the chemical inhomogeneity and the thermal stresses that originated during the deposition and cooling. Subsequently, due to ageing, Ni4Ti3 particles precipitate at 350 °C and 450 °C for 1, 6 and 12 h, modified the superelastic behaviour of the deposited NiTi. The differential scanning calorimetry results did not reveal any difference in the martensitic starting temperature between as-built and solution-treated samples. However, a remarkable influence of the ageing temperature was detected: while ageing at 350 °C impacted R-phase starting temperatures, 450 °C altered the martensitic starting one. The superelastic behaviour was evaluated by cycling compression. As-built and solution heat-treated samples presented poor mechanical performance, with about 40% of strain recovered after 10 cycles. The ageing at 350 °C for 1 h led to a maximum measured strain recovery of 72.5% after 10 uniaxial compression cycles up to 860 MPa. This condition also resulted in 3.3% permanent deformation out of 11.3% of the total. This study addressed for the first time the fabrication by the EBF3 technique of a stable multi-track and multi-layer NiTi block besides the importance of heat treating it, demonstrating that this post-treatment improves the superelastic performance of EBF3 fabricated parts.

P‐12.9: Self‐powered Large Aperture Liquid Crystal Lens for Light Field Imaging Based on Fur Triboelectric Nanogenerators

Liquid crystal (LC) is an intermediate state compound between liquid and crystal, which has the anisotropy of crystal molecules while having the fluidity of liquid. It is a cutting‐edge technology in optoelectronics. LC lens is an electrically controlled focusable gradient refractive index lens. In light field displays, LC lenses with diameters in the millimetre range can cover more areas. Therefore, we propose a large aperture (LA) liquid crystal (LC) lens with an electrically controlled focal length of 4 mm in diameter. LC lenses with large apertures require large voltages and there are certain safety issues and equipment requirements. We have therefore utilised a triboelectric nanogenerator (TENG) that can harvest energy from the environment and convert it into usable electrical energy. TENG has the advantages of being small and portable and enables the use of renewable energy. In this paper, we propose a new type of feather TENG (F‐TENG) with a positive friction electrode of feathers and a negative electrode of polytetrafluoroethylene (PTFE) mixed with graphene, which enables the use of F‐TENG to power LC lens systems, thus providing a new application idea for the display field.

A high sensitivity Cherenkov detector for prompt gamma timing and time imaging

We recently proposed a new approach for the real-time monitoring of particle therapy treatments with the goal of achieving high sensitivities on the particle range measurement already at limited counting statistics. This method extends the Prompt Gamma (PG) timing technique to obtain the PG vertex distribution from the exclusive measurement of particle Time-Of-Flight (TOF). It was previously shown, through Monte Carlo simulation, that an original data reconstruction algorithm (Prompt Gamma Time Imaging) allows to combine the response of multiple detectors placed around the target. The sensitivity of this technique depends on both the system time resolution and the beam intensity. At reduced intensities (Single Proton Regime—SPR), a millimetric proton range sensitivity can be achieved, provided the overall PG plus proton TOF can be measured with a 235 ps (FWHM) time resolution. At nominal beam intensities, a sensitivity of a few mm can still be obtained by increasing the number of incident protons included in the monitoring procedure. In this work we focus on the experimental feasibility of PGTI in SPR through the development of a multi-channel, Cherenkov-based PG detector with a targeted time resolution of 235 ps (FWHM): the TOF Imaging ARrAy (TIARA). Since PG emission is a rare phenomenon, TIARA design is led by the concomitant optimisation of its detection efficiency and Signal to Noise Ratio (SNR). The PG module that we developed is composed of a small PbF_{2} crystal coupled to a silicon photoMultiplier to provide the time stamp of the PG. This module is currently read in time coincidence with a diamond-based beam monitor placed upstream the target/patient to measure the proton time of arrival. TIARA will be eventually composed of 30 identical modules uniformly arranged around the target. The absence of a collimation system and the use of Cherenkov radiators are both crucial to increase the detection efficiency and the SNR, respectively. A first prototype of the TIARA block detector was tested with 63 MeV protons delivered from a cyclotron: a time resolution of 276 ps (FWHM) was obtained, resulting in a proton range sensitivity of 4 mm at 2sigma with the acquisition of only 600 PGs. A second prototype was also evaluated with 148 MeV protons delivered from a synchro-cyclotron obtaining a time resolution below 167 ps (FWHM) for the gamma detector. Moreover, using two identical PG modules, it was shown that a uniform sensitivity on the PG profiles would be achievable by combining the response of gamma detectors uniformly distributed around the target. This work provides the experimental proof-of-concept for the development of a high sensitivity detector that can be used to monitor particle therapy treatments and potentially act in real-time if the irradiation does not comply to treatment plan.

HetNet security solution using femtocell network architecture and UMTS technology in the millimetre range

Heterogeneous network security is a prime concern in the era where billions of human beings and physical devices will get connected through next-generation technologies like millimetre-wave wireless, the internet of things, artificial intelligence and machine learning. Higher bandwidth in the millimetre range will help to achieve seamless connectivity and tens of gigabits per second data rate. In femtocells, handoff security will play a vital role to avoid call drops. This article focuses on how new handoff security algorithm deployed in the femtocells network by a method that uses Call Admission Control protocol and UMTS technology. Call admission control protocol gives variable quality of services by efficient utilisation of network resources and available bandwidth. The number of handoffs and probability of call drops is less when the user moves from femtocells to macro-cells. Dynamic threshold time reduces number of handoffs and improves handoff security.

Stability of Bragg reflectors under megahertz heat load at XFELs

Modern X-ray free-electron laser (XFEL) sources can deliver photon pulses with millijoule pulse energies and megahertz repetition rate. As shown by the simulations in this work, for particular cases the dynamical heat load effects for Bragg reflectors could cause problems at these facilities. These problems would be underestimated if only quasi-static thermoelastic simulations are considered. Nevertheless, for the sake of simplicity the quasi-static approach is a common choice for estimating heat load effects. To emphasize the relevance of dynamical thermoelastic effects, the response to the partial absorption of an X-ray pulse, as provided by a saturated X-ray free-electron laser oscillator (XFELO) in a single crystal diamond with a thickness of 100 µm and lateral dimensions in the millimetre range, is discussed in this work. The outcome of the dynamic thermoelastic simulations indicates a clear dominance regarding the strain value reached, which is present for consecutive X-ray matter interactions with megahertz repetition rate.

HetNet security solution using femtocell network architecture and UMTS technology in the millimetre range

HetNet security solution using femtocell network architecture and UMTS technology in the millimetre range

Low-cost photogrammetric reconstruction of a panel with palaeolithic engravings of Siega Verde (Salamanca, Spain): From the rocky outcrop to the details

The goal of this work is the photogrammetric reconstruction of a rocky outcrop with a panel decorated with palaeolithic engravings of the Siega Verde archaeological site (Salamanca, Spain) using photographs obtained with mobile phone cameras.The engravings present in this panel have been previously studied and published. The main objective of this work is the generation of 3D models by low-cost photogrammetry that allow the diffusion and study of the panel.The processing is approached at different quality levels with different photosets to provide the reconstruction of the complete rocky outcrop, the decorated wall, and the details of the engravings. The reconstruction of the rocky outcrop provides interactive 3D models useful to appreciate the morphology and the context of the engraved wall. The reconstruction of the decorated wall, after referencing, permits measurements with errors in the millimetre range and was used to obtain objective and subjective tracings of the engraved motifs. The highest quality level of photogrammetric processing makes it possible to determine the morphology, direction, and dimensions of the pecks and even depths and widths of the individual pecks.

TLS-Detectable Plane Changes for Deformation Monitoring.

TLS is nowadays often used for deformation monitoring. As it is not able to scan identical points in different time epochs, mathematical models of objects derived from point clouds have to be used. The most common geometric form to describe built objects is a plane, which can be described by four parameters. In this study, we aimed to find out how small changes in the parameters of the plane can be detected by TLS. We aimed to eliminate all possible factors that influence the scanning. Then, we shifted and tilted a finite physical representation of a plane in a controlled way. After each controlled change, the board was scanned several times and the parameters of the plane were calculated. We used two different types of scanning devices and compared their performance. The changes in the plane parameters were compared with the actual change values and statistically tested. The results show that TLS detects shifts in the millimetre range and tilts of 150″ (for a 1 m plane). A robotic total station can achieve twice the precision of TLS despite lower density and slower performance. For deformation monitoring, we strongly recommend repeating each scan several times (i) to check for gross errors and (ii) to obtain a realistic precision estimate.

Investigation for conductor loss calculation including effect of adhesive layer of titanium in microwave, millimetre and terahertz frequency range

This paper presents the investigation of calculations for conductor loss including effect of adhesive layer of Ttitanium from frequency range 1 GHz to 1000 GHz. Here we present comparison between experimental conductor loss of the Thin Film Microstrip line with loss calculation from suggested model for the structures of TFML. It is found that the loss estimation in Millimeter wave and Terahertz frequency range is much more with adhesive layer than without adhesive layer in comparison to Microwave range for Thin Film Microstrip Line.

An enhanced marker pattern that achieves improved accuracy in surgical tool tracking

ABSTRACT In computer assisted interventions (CAI), surgical tool tracking is crucial for applications such as surgical navigation, surgical skill assessment, visual servoing, and augmented reality. Tracking of cylindrical surgical tools can be achieved by printing and attaching a marker to their shaft. However, the tracking error of existing cylindrical markers is still in the millimetre range, which is too large for applications such as neurosurgery requiring sub-millimetre accuracy. To achieve tool tracking with sub-millimetre accuracy, we designed an enhanced marker pattern, which is captured on images from a monocular laparoscopic camera. The images are used as input for a tracking method which is described in this paper. Our tracking method was compared to the state-of-the-art, on simulation and ex vivo experiments. This comparison shows that our method outperforms the current state-of-the-art. Our marker achieves a mean absolute error of 0.28 [mm] and 0.45 [°] on ex vivo data, and 0.47 [mm] and 1.46 [°] on simulation. Our tracking method is real-time and runs at 55 frames per second for image resolution.

Single crystals of SnTe3O8 in the millimetre range grown by chemical vapor transport reactions.

Tin(IV) trioxidotellurate(IV), SnTe3O8, is a member of the isotypic M IVTeIV 3O8 (M = Ti, Zr, Hf, Sn) series crystallizing with eight formula units per unit cell in space group Ia . In comparison with the previous crystal structure model of SnTe3O8 based on powder X-ray diffraction data [Meunier & Galy (1971 ▸). Acta Cryst. B27, 602-608], the current model based on single-crystal X-ray data is improved in terms of precision and accuracy. Nearly regular [SnO6] octa-hedra (Sn site symmetry ..) are situated in the voids of an oxidotellurate(IV) framework built up by corner-sharing [TeO4] bis-phenoids (Te site symmetry 2..). A qu-anti-tative structural comparison revealed a very high degree of similarity for the structures with M = Ti, Zr, Sn in the M IVTe3O8 series.

Hygienic assessment of the impact of 5G/IMT-2020 communication networks on public health (literature review)

The program “Digital Economy of the Russian Federation” approved the Concept for the creation and development of 5G / IMT-2020 networks. The development of 5G communications will significantly impact the implementation of many innovative projects and initiatives: the Smart City project, Unmanned Transport, etc. Along with significant technical advantages compared to previous generations of communication (2G, 3G, 4G), 5G technology has completely different emitting characteristics: more emitting elements, signal modulation, three-dimensional beam, the ability to control the beam, SHF (ultra-high) and EHF (extremely high) radio frequency ranges and centimetre and millimetre wavelengths of electromagnetic radiation. Therefore, it is becoming an especially urgent problem to ensure exposure to the human body of non-ionizing electromagnetic fields of the radio frequency range (30 kHz-300 GHz). The authors searched the literature on the biological effects of 5G cellular communications and electromagnetic radiation in the centimetre and millimetre ranges using the appropriate keywords in PubMed search engines, Scopus, Web of Science, Medline, The Cochrane Library, EMBASE, Global Health, CyberLeninka, RSCI and others. There is currently tentative and conflicting evidence on the impact of 5G. The rapidly growing density of wireless devices and antennas (considering future 5G networks) increases the public health risk from exposure to RF EMFs as the penetration depth for 5G EHF radiation is only a few millimetres. At these wavelengths, resonance phenomena are possible at the cellular and molecular levels, particularly concerning stimulating SHF and EHF oxidative processes and damaging DNA. The influence of the millimetre range of RF-EMF is poorly understood; oncological and non-oncological (impact on the reproductive, immune systems, etc.) effects are possible. Using numerical simulation methods of EMF radiation resonances on insects, Thielens A et al., 2018, found a significant overall increase in the absorbed RF power at a frequency of 6 GHz and higher than a frequency below 6 GHz.

The influence of the low-intensity electromagnetic radiation of mm-range on the ulcerogenic damages, induced by chronic hypokinetic stress

The antiulcerogenic effectiveness of the low-intensity electromagnetic radiation of the millimetric range was studied in the model of chronic hypokinetic stress. It was found out that chronic hypokinetic stress causes the development of the ulcerogenesis, the intensity of which depends on the duration of the stress factor, which for animals is being in hypokinesia. Along with this, the maximum ulcerogenic damages are registered after 10 days of the mobility restriction; this is evident by the increase of the affected animals’ number, and by the growth of Pauls’ index by 586 % (p≤0.05) in comparison with the first day of the mobility restriction.The application of the low-intensity electromagnetic radiation of the millimetric (mm) range has the gastroprotective effect in the conditions of hypokinesia. The effect depends on the length of the impact, the maximum ulceroprotective effect was observed after the ten-fold mm-impact: the number of the affected animals decreases by 50 %, Pauls’ index decreases by 70 % (p≤0.05) in relation to the same in the group of animals, having undergone the hypokinesia, and the index of antiulcerogenic activity of mm-impact was 3.3, (>2), this indicates the occurrence of the antiulcerogenic activity of the mm-radiation.

Processing and Analysis of Long-Range Scans with an Atomic Force Microscope (AFM) in Combination with Nanopositioning and Nanomeasuring Technology for Defect Detection and Quality Control.

This paper deals with a planar nanopositioning and -measuring machine, the so-called nanofabrication machine (NFM-100), in combination with a mounted atomic force microscope (AFM). This planar machine has a circular moving range of 100 mm. Due to the possibility of detecting structures in the nanometre range with an atomic force microscope and the large range of motion of the NFM-100, structures can be analysed with high resolution and precision over large areas by combining the two systems, which was not possible before. On the basis of a grating sample, line scans over lengths in the millimetre range are demonstrated on the one hand; on the other hand, the accuracy as well as various evaluation methods are discussed and analysed.

Micro-notches as a novel connection system for timber-concrete composite slabs

Timber-concrete composite slabs are more and more in use: the combination of timber and concrete combines the advantages of both materials and offer a valid solution for the increasing demand for sustainable construction. The connection between timber and concrete is the crucial element, yet its potential regarding material and time expenses is not exploited. This paper presents the novel connection system micro-notches, an interlocking concept between timber and concrete with indentations in the millimetre range. Micro-notches provide a continuous shear transfer without additional steel fasteners such as screws or dowels. The paper presents the development of the micro-notch concept in an extensive experimental program supplemented with analytical and numerical models, a calculation model, and practice-relevant guidelines. The results of the investigations show that micro-notches feature an approximately rigid composite action between timber and concrete and a sufficient shear strength for the use in office and residential buildings.