Theoretical Resolution Research Articles

Enhancing the resolution of airborne gamma-ray data using horizontal gradients

The spatial resolution characteristics of airborne gamma-ray data are largely controlled by survey elevation and line separation. In the UK, although low nominal surveys altitudes may be permitted, regulatory zones with elevations in excess of 180m are required above conurbations. Since the data, typically in the form of grids, are evaluated alongside many other detailed geoscientific spatial datasets their absolute resolution limits, together with their spatial characteristics, become relevant. Here, using published software, we study the theoretical resolution characteristics of this form of survey data obtained with a line separation of 200m. Of particular interest is the airborne response behaviour when non-uniform distributions of radioactivity are encountered. Although ultimately a function of the radioelement-concentration contrast encountered, the calculations reveal that such zones are most difficult to identify when their scale length decreases below the scale of the line separation. This limited resolution then further decreases with elevation. In order to increase our ability to resolve the edges of non-uniform source regions we calculate the horizontal gradient magnitude (HGM) of the observed data. While the data used can be the estimated radioelement concentrations (potassium, thorium and uranium) or their ratios, we demonstrate that the total count is particularly suited to this type of analysis. The theoretical calculations are supported by an examination of survey data across a series of isolated bodies (offshore islands). This empirical study indicates the practical limits to resolution when using the horizontal gradient and these are governed by the survey line separation. The HGM response provides an enhanced mapping of the edges of zones associated with a contrast in flux behaviour. The edges are detected using the maxima in the response and these can be additionally examined using grid curvature analysis. The technique is assessed using recent survey data containing geological, soil and environmental influences. The results demonstrate the spatially pervasive nature of flux contrasts associated with soil and environmental contributions which potentially mask, or perturb, the underlying bedrock geological response.

A non-imaging optical system for characterisation of ball-shaped micro-indenters

To quantitatively determine the tip radius of spherical/conical and Rockwell micro-indenters, a practical tip radius measurement system is presented. Realization of the optical system has been detailed, including its theoretical and actual resolution and error sources. For the purpose of experimental investigation of the performance of the non-imaging radius measurement system, a sapphire sphere with a nominal radius of 200μm has been measured. Detailed data analysis indicates that higher-order form deviation of the object under test might be one of the key error sources within the calibration setup. Further experiments indicate that the prototype of the non-imaging system is able to measure real conical and Rockwell indenters with adequate resolution.

Analytical Modelling and Simulation of Single and Double Cone Pinholes for Real-Time In-Body Tracking of an HDR Brachytherapy Source

The choice of pinhole geometry is a critical factor in the performance of pinhole-collimator-based source tracking systems for brachytherapy QA. In this work, an analytical model describing the penetrative sensitivity of a single-cone pinhole collimator to photons emitted from a point source is derived. Using existing models for single-cone resolution and double-cone sensitivity and resolution, the theoretical sensitivity and resolution of the single-cone collimator are quantitatively compared with those of a double-cone collimator with an equivalent field of view. Monte Carlo simulations of the single and double-cone pinhole collimators using an accurate 3D model of a commercial high dose rate brachytherapy source are performed to evaluate the relative performance of each geometry for a novel real-time HDR brachytherapy QA system, H DR BrachyView. The theoretical penetrative sensitivity of the single-cone pinhole is shown to be higher than the double-cone pinhole, which is in agreement with the results from the Monte Carlo simulations. The wider pinhole response function of the single-cone collimator results in a larger total error between the projected center of the source and the estimated center of mass of the source projection for the single-cone collimator, with the greatest error (at the maximum FoV angle) being 0.54 mm for the double-cone pinhole and 1.37 mm for the single-cone at $\theta ={ 60^ \circ }$ . The double-cone pinhole geometry is determined to be the most appropriate choice for the pinhole collimator in the H DR BrachyView probe.

ORGANIZATIONAL ASPECTS OF PROJECT FINANCING AS THE MECHANISM OF REALIZATION OF INVESTMENT PROJECTS

The purpose of the study As the goal of this work defined a comprehensive study of the essence of project financing and finding opportunities for its implementation in the Russian context. The stated goal logically led to the formulation and solution of the following tasks: 1. the review and update of the conceptual project financing; 2. performing risk analysis and project financing; 3. search of approaches to minimize the risks for the method of project financing. Research methods General scientific methods of cognition (synthesis, induction, deduction, classification, system and factor analysis constituted the methodological basis of research. The results of the study In the framework of the conducted research the following results are obtained: 1. The essence and clarify the definitions used in project financing, determined by its place in modern investment processes. 2. The basic differences of project financing from long-term investment lending, which consists in the fact that the project financing mechanism provides an opportunity to implement more reliable and effective assessment of the creditworthiness of the borrowers, to analyze investment projects in terms of their viability, feasibility, financial security, risk, and minimize project risks. 3. The developed model of project financing of investment projects. 4. A classification of risks that are typical for project financing. 5. 4 proposed strategies for a method of project financing in order to minimise risks. Conclusion The method of project financing, which is worldwide considered as a major political and economic tools in Russia has not yet received due development. This led to the fact that the Russian participants of the investment activities are forced to use a less efficient mechanism for long-term investment or lending tools and analogies learned from foreign law. Since the traditional Russian approaches and under existing law because of their lack of competitiveness in project Finance transactions are not used, requires further adapt the mechanism of project financing in the Russian conditions. Scientific novelty Scientific novelty of research consists in statement, a theoretical substantiation and resolution of complex issues involved: • systematization of the existing approaches to understanding the project financing; • clarifying the conceptual framework of project financing. Refined interpretation allows us to consider project Finance as a system, including related parties of the investment process (banks; insurance companies; initiators of investment projects; logistics organisations; service providers, etc.). This system is formed in order to implement investment projects in which the sources of debt repayment and returning cash to become produced by the project cash flows; • with the development of a 3-step model of project financing of investment projects; • with the creation of the modern classification of risks of project financing, under which the allocation of legal risks, risks of lack of access to land, design risks, construction risks, economic risks, price risks, leasing risks; • approaches that minimize risks during implementation of investment projects with use of project financing mechanisms. The essence of these approaches is to introduce into the working scheme of project financing of the special tools (internal control procedures, transfer of risk to professional agents split cash flows, risk differentiation between the main contractors).

Vibrotactile Spatial Acuity and Intensity Discrimination on the Lower Back Using Coin Motors.

Tactile vision substitution devices are assistive devices for the blind that redirect visual information to the skin. The amount of visual information that can be presented on a tactile display is limited mainly by the spatial resolution of the skin and the ability to distinguish between various vibration intensities. In this study, we have determined the two-point discrimination (TPD) threshold and intensity-discrimination threshold (just-noticeable difference, or JND) on the lower back using coin motors. Given the importance of stimulus timing, we have determined TPD threshold and JND at different stimulus onset asynchronies (SOAs). The JND was determined between two coin motors with a distance equal to the TPD threshold. In this way, we could establish the contrast sensitivity at the maximal theoretical resolution. TPD thresholds tended to decrease at longer SOAs, from 52 mm edge-to-edge at an SOA of 0 ms, to 28 mm at 200 ms. The JND did not depend on SOA, and the average Weber fraction was 0.14. A median of 5 JNDs was available across the available dynamic range. Together, these data provide the predicted spatial resolution and contrast resolution achievable with a back-worn tactile display based on coin motors.

A dual detector Fourier transform electrostatic linear ion trap utilizing in-trap potential lift

Ion capture from an external nano-electrospray ionization source in an electrostatic linear ion trap has been effected by in-trap potential lift so as to avoid a time-dependent frequency drift of trapped ions. This phenomenon was observed when using mirror switching for capturing ions and compromised the mass resolution when using Fourier transform techniques for mass determination. A dual image charge detection approach was also implemented to compensate for losses in mass resolution associated with increasing the length of the electrostatic trap to accommodate the lift region. The potential lift approach for ion capture led to no detectable frequency shifts, thereby enabling the achievement of pressure-limited theoretical resolutions. For example, a resolution of roughly 11,000M/ΔM FWHM was observed for a carborane anion population of average m/z=520 at a transient length of 125ms. The use of the dual detector approach led to an increase (∼12%) in the ion frequencies used for mass analysis, which more than compensated for the effect of increasing the length of the electrostatic trap. Although the implementation of the potential lift approach and dual detectors were successful in their objectives, these changes resulted in a narrower m/z range for a single ion injection event relative to mirror switching. Furthermore, the dual detector approach resulted in a higher noise floor and a more complicated frequency spectrum due to asymmetries in the electric fields of the ion trap.

A theoretical and numerical resolution of an acoustic multiple scattering problem in three-dimensional case

This paper develops an analytical solution for sound, electromagnetic or any other wave propagation described by the Helmholtz equation in three-dimensional case. First, a theoretical investigation based on multipole expansion method and spherical wave functions was established, through which we show that the resolution of the problem is reduced to solving an infinite, complex and large linear system. Second, we explain how to suitably truncate the last infinite dimensional system to get an accurate stable and fast numerical solution of the problem. Then, we evaluate numerically the theoretical solution of scattering problem by multiple ideal rigid spheres. Finally, we made a numerical study to present the “Head related transfer function” with respect to different physical and geometrical parameters of the problem.

Evaluating spatial resolution for quality assurance of UAV images

With advantages of operational convenience, quick process and economic feasibility, the availability of UAV Photogrammetry is increasing significantly in many different fields of acquiring geospatial information recently. In particular, it is being applied even to a cadastral surveying, including production of orthophotos and large scale topographic maps that require highly precise positional information. However, a quality verification process of UAV images should be preceded, because they are quite inhomogeneous by acquiring under strong variable conditions such as a rapid change of flying heights and exposure stations. In this paper, as part of a quality assurance plan for UAV images to ensure high quality products by UAV-Photogrammetry, a simple analysis method for the spatial resolution of UAV images was presented. To do this, portable resolution test charts in a pattern of Siemens star and Tri-bar were installed in a test area before imaging, and then visual resolution and GSD (Ground Sample Distance) appeared on the photographed images were measured. UAV images were taken with both payloads of fixed and rotary wing. The flight heights were 130 m and 260 m for fixed wing, and just 130 m for rotary wing. The results showed that a GSD of UAV image from fixed wing installed with a camera (Canon IXUS 127 HS) is 4.08 cm at the flying height of 130 m, 7.94 cm at 260 m, and a GSD of UAV image from rotary wing installed with a camera (Sony NEX-5N) is 4.10 cm at the flying height of 130 m. These values are almost consistent with theoretical resolution. The method proposed in this study is considered as a very useful for the applying of spatial resolution analysis of UAV images.

The necessity and possibility of powerful ‘regional’ knowledge: curriculum change and renewal

ABSTRACTThe paper argues that powerful regional knowledge is necessary and possible and that there are historical precedents supporting these claims. Regional knowledge is being used in a double sense: the first Bernsteinian, the second in relation to knowledge generated outside the academy. Both are important if the debate is not to be confined solely to the global north and if the curriculum is to be responsive to geo-political realities. In order to think critically about access to higher education, we need to consider the sorts of knowledge, engagement, and opportunities that are open to newer actors. This includes recognising the contextual nature of professional practice and also that social movements beyond the academy can and do challenge academic knowledge. The paper concludes that many of issues addressed are not capable of theoretical resolution alone and that we need more empirical work to inform curriculum change and renewal.

High Resolution Compact Spectrometer Based on Resonance Domain Diffractive Lens

We experimentally demonstrate a compact optical spectrometer with a resolution of up to ~0.1 nm suitable for spectral line measurements of laser diodes. This spectrometer is based on a transmission, 4-mm in diameter, and 0.14-NA off-axis binary resonance domain diffractive lens with strong lateral and longitudinal chromatic dispersion. After calibration with a mercury-argon source and a helium-neon laser, we measured the spectrum of RGB laser diodes. The results confirm the theoretical resolution and are in good match to data from optical spectrum analyzer with 0.05-nm resolution.

Functional optical coherence tomography of rat olfactory bulb with periodic odor stimulation.

In rodent olfactory bulb (OB), optical intrinsic signal imaging (OISI) is commonly used to investigate functional maps to odorant stimulations. However, in such studies, the spatial resolution in depth direction (z-axis) is lost because of the integration of light from different depths. To solve this problem, we propose functional optical coherence tomography (fOCT) with periodic stimulation and continuous recording. In fOCT experiments of in vivo rat OB, propionic acid and m-cresol were used as odor stimulus presentations. Such a periodic stimulation enabled us to detect the specific odor-responses from highly scattering brain tissue. Swept source OCT operating at a wavelength of 1334 nm and a frequency of 20 kHz, was employed with theoretical depth and lateral resolutions of 6.7 μm and 15.4 μm, respectively. We succeeded in visualizing 2D cross sectional fOCT map across the neural layer structure of OCT in vivo. The detected fOCT signals corresponded to a few glomeruli of the medial and lateral parts of dorsal OB. We also obtained 3D fOCT maps, which upon integration across z-axis agreed well with OISI results. We expect such an approach to open a window for investigating and possibly addressing toward inter/intra-layer connections at high resolutions in the future.

Fabrication of MEMS xylophone magnetometer by anodic bonding technique using SOI wafer

This paper reports the design, fabrication and characterization of Lorentz force based MEMS magnetometer. The paper focuses on fabrication process of the device by anodic bonding technique using SOI and glass wafers. The fabrication is a three-mask process. The structure is a xylophone resonator fabricated using highly doped Si as the structural layer. The highly doped structural layer avoids the need of an extra metallized top electrode, which in turn reduces the fabrication step. The proposed fabrication technique for the xylophone bar magnetometer is reported for the first time. The ease in fabrication, low temperature (≤400 °C) process, repeatable, reliable, reduced lithography steps and the ability to precisely control the gap between the electrodes makes it better from the conventional fabrication methods. The device exploits the Lorentz force transduction mechanism and operates at its primary resonant mode at about 108.75 kHz. The current is applied at the resonant frequency and magnetic field of 118 Gauss is applied orthogonal to the current direction. The frequency and transient response characterization of the out-of-plane vibration is carried out at atmospheric pressure with a quality factor of 4.2. Also, vacuum packaging at die level is done and a quality factor of 180 is achieved. The power consumption and theoretical Brownian noise limited resolution of the sensor is 0.45 mW and 215 nT/$$\sqrt {Hz}$$Hz.

Radiometric Resolution Analysis and a Simulation Model

Total power radiometer has a simple configuration and the best theoretical resolution. Gain fluctuations and calibration errors, however, can induce severe errors in the solved scene brightness temperature. To estimate the overall radiometer performance we present a numerical simulation tool that can be used to determine the radiometric resolution. Our model considers three main components that degrade the radiometric resolution: thermal noise, 1/f noise and calibration errors. These error sources have long been known to exist, but comprehensive models able to account all these effects quantitatively and accurately in a practical manner have been missing. We have developed a radiometer simulation model that is able to produce radiometer signals that incorporate realistic radiometer effects that show up as noise and other errors in the radiometer video signal. Our simulation tool integrates the fundamental radiometer theories numerically and allows the investigation of different calibration schemes and receiver topologies. The model can be used as a guide for design and optimization as well as for verification of the radiometer performance. Moreover, it can be extended to a much larger and more complex radiometer systems allowing better system level performance estimation and optimization with minimal bread-board implementations. The model mimics real radiometer video data and thus the complete data analysis pipeline can be developed and verified before the real video data is available. In this paper, the model has been applied to a total power radiometer operating in the 52 GHz frequency range.

Development of Microwave Superconducting Microresonators for Neutrino Mass Measurement in the Holmes Framework

The European Research Council has recently funded HOLMES, a project with the aim of performing a calorimetric measurement of the electron neutrino mass measuring the energy released in the electron capture decay of 163Ho. The baseline for HOLMES are microcalorimeters coupled to Transition Edge Sensors (TESs) read out with rf-SQUIDs, for microwave multiplexing purposes. A promising alternative solution is based on superconducting microwave resonators, that have undergone rapid development in the last decade. These detectors, called Microwave Kinetic Inductance Detectors (MKIDs), are inherently multiplexed in the frequency domain and suitable for even larger-scale pixel arrays, with theoretical high energy resolution and fast response. The aim of our activity is to develop arrays of microresonator detectors for X-ray spectroscopy and suitable for the calorimetric measurement of the energy spectra of 163Ho. Superconductive multilayer films composed by a sequence of pure Titanium and stoichiometric TiN layers show many ideal properties for MKIDs, such as low loss, large sheet resistance, large kinetic inductance, and tunable critical temperature $T_c$. We developed Ti/TiN multilayer microresonators with $T_c$ within the range from 70 mK to 4.5 K and with good uniformity. In this contribution we present the design solutions adopted, the fabrication processes and the characterization results.

A measurement setup for the 3D validation of fingertip deformation models

Deformable models of the human fingertip are commonly validated by evaluating a finger's silhouette when charged with a line load. To validate models, it would be desirable to measure 3D data of the fingertip at a high frequency. This paper proposes the use of a stereo camera setup to measure the 3D surface of the fingertip's side. The setup offers a theoretical depth resolution of 0.17 mm at a frame rate above 100 Hz. A feature point matching algorithm incorporating scene knowledge is implemented to obtain 3D points to which a paraboloid surface is fitted. Precision is compared with reference to a LIDAR sensor and experiments applying normal and tangential force to the fingertip recorded with a 6-DOF force sensor setup. The results imply that state-of-the-art feature-based algorithms are insufficient or unsuited to match the fingertip surface reliably. Further approaches are proposed to improve robustness.

A super-resolution infrared microscopy based on a doughnut pump beam

An approach to breaking through the diffraction limitation in infrared microscopies is put forward in this paper. In this method, instead of Gaussian pump beam, an intensive vortex beam is first focused on the sample, leading to the saturation absorption of peripheral molecules in the point spread function (PSF). The vortex beam is followed by a Gaussian probe beam with the same wavelength. Because of the previous saturation absorption, the probe beam can only be absorbed by the molecules near the center, resulting in a shrunk PSF which means super-resolution. Furthermore, the PSF of a system based on this approach is numerically simulated. With a 100 nJ pulse energy vortex beam and a 0.1 nJ pulse energy probe beam, the theoretical resolution FWHM (full width at half maximum) is measured to be about 236 nm which is 14 times better than that of the traditional infrared microscopy.

Method based on chirp decomposition for dispersion mismatch compensation in precision absolute distance measurement using swept-wavelength interferometry.

We establish a theoretical model of dispersion mismatch in absolute distance measurements using swept-wavelength interferometry (SWI) and propose a novel dispersion mismatch compensation method called chirp decomposition. This method separates the dispersion coefficient and distance under test, which ensures dispersion mismatch compensation without introducing additional random errors. In the measurement of a target located at 3.9 m, a measurement resolution of 45.9 μm is obtained, which is close to the theoretical resolution, and a standard deviation of 0.74 μm is obtained, which is better than the traditional method. The measurement results are compared to a single-frequency laser interferometer. The target moves from 1 m to 3.7 m, and the measurement precision using the new method is less than 0.81 μm.

Note: A small roll angle measurement method with enhanced resolution based on a heterodyne interferometer.

Small roll angle is hard to be measured directly by commercial interferometer instruments due to their low sensitivities in axial direction. A method for its measurement based on a heterodyne interferometer is presented, which adopts accessories including a half wave plate, a multiple-reflector, and a phase meter to achieve test by detecting phase differences between the measurement and reference arms. Mathematical model reveals the resolution will be improved by increasing pass times through the half wave plate. The theoretical resolution is up to 0.19 in. when the pass times increase to three and the phase meter resolution is 0.01°. The proposed method is proved by the experiment.

Multiple Silicon Nanowires with Enzymatic Modification for Measuring Glucose Concentration

This study fabricated a multiple poly-Si nanowires sensor through a top-down method and immobilized glucose oxidase on the multiple nanowires for determining glucose concentration. The proposed sensor is 340 nm in width and uses five physically identical and parallel nanowires. The sensor contained nanowires of various lengths (3, 5, and 10 μm). Experimental results showed that sensor sensitivity is inversely proportional to nanowire length. The sensor with 3 μm in nanowire length exhibited a theoretical resolution of 0.003 mg/dL and the highest sensitivity of 0.03 μA/(mg/dL). Furthermore, the proposed sensor retains this performance when reused for up to 10 applications.

High resolution microwave microstrip resonator for sensing applications

A microwave planar resonator with a very high quality factor is presented for sensing applications. The proposed resonator uses an active feedback loop with a microwave amplifier to generate negative resistance to compensate the resonator's loss and increases the loaded quality factor of the system. This high quality resonator is based on a planar microstrip resonator with a primary quality factor of 200. The active loop technique increases the primary quality factor up to 15,480 with no other material in its surrounding environment when measured at 1.55GHz resonance frequency. The high quality factor of the designed resonator provides very high resolution for detection of permittivity variation in its ambient environment with a theoretical resolution of 0.1ppb (10−10). It is experimentally demonstrated that the small permittivity variations such as that of foam (with permittivity very close to air) can be detected. The circuit demonstrated a resolution of 26dB in amplitude for a 1MHz variation in the frequency domain.