Reflector Shape Research Articles

Integrated Technique Provides Effective Water Diagnostics in Tight Sand

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper URTeC 3864145, “Evaluating the Hydraulic Fracture Through Acoustic Reflection Imaging and Production Logging for Water Diagnostic Beyond the Wellbore: A Case Study From Chang 8 Tight Sand in the Ordos Basin, China,” by Guangsheng Liu, Dajian Li, and Gang Zheng, PetroChina, et al. The paper has not been peer reviewed. _ The Triassic Chang 8 tight sand reservoir in the Xifeng block of the Ordos Basin features low permeability, which means that hydraulic fracturing and subsequent waterflooding were performed during its development phase. Water breakthrough was encountered after a short period of oil production. A solution of borehole acoustic reflection imaging combined with production logging was proposed in a horizontal well suffering from high water cut. The objective was to determine which stages contributed most to water production, understand the cause, and, ultimately, create a water shutoff plan. Introduction The Ordos Basin, with an area of approximately 2.5×105 km2, is in North China. The Upper Triassic Yanchang formation is subdivided into the Chang 1 to 10 members, from top to bottom. It contains significant oil reserves in siltstone and sandstone reservoirs, especially in Chang 6 through Chang 8, that have been the major oil-producing resources in recent years. In the Triassic Chang 8 tight sand reservoir, horizontal well drilling and multiple-stage hydraulic fracturing have become common practice. In the study block, the well of interest was hydraulically fractured by coiled tubing with sand-jet perforation and fracturing operations in one run with a retrievable packer in the bottomhole assembly of the coiled tubing. In the study block, when some producing wells encountered water breakthrough, traditional water diagnostics using production logging was not enough; a survey to detect hydraulic fractures beyond the wellbore was needed. Theory and Methods Borehole Acoustic Reflection Imaging. The processing workflow for acoustic reflected waves mainly consists of two parts. The first is a filtering process to suppress the borehole mode and noise in order to preserve the reflected wave. The second is to migrate the reflected wave to the true position of a reflector. The conventional migration method used for acoustic reflection imaging normally requests previous information relating to reflector dip and produces 2D images, which show the reflector shape but have hard-to-extract precise quantitative information. A trial reflector-migration method covered in the literature was introduced in 2016 that does not require input of structure dip and is of high resolution. A 3D slowness-time-coherence method was developed in 2018, also covered in the literature, that could determine the true dip, azimuth, and distance of a reflector.

Control system of the radio-reflective surface shape of a large-size space reflector using its current-conducting structural parts

A comprehensive approach to creating a control system for the shape of the radio-reflecting surface of a large-size space reflector is considered. Large-aperture space antennas are used for satellite communications and space exploration. The design of these structures is one of the most promising areas. Ensuring the specified characteristics of the reflector is directly related to maintaining the specified shape of the radio-reflective netting. Developing a control system for the shape of the active antenna surface is an urgent task. Optimizing this process makes it possible to accomplish the mission during the operational period effectively. The paper evaluates the effects of perturbations on a large-scale structure operating in outer space. A method for adjusting the geometry of the frontal network is proposed. This allows for improved communication between spacecraft and ground stations, which is very important for the safety of space flights. The conductive parts of the reflector are considered to transmit energy and control signals to the actuators. The application results of various control algorithms of the executive device making it possible to correct the netting considering the minimization of energy costs and oscillations of the structure are shown. According to the simulation results, the optimal algorithm of the target criteria hierarchy showed greater stability in terms of convergence in the presence of measurement noise and disturbances, which allows it to be applied in real time. This algorithm is supposed to be used in the future when creating a prototype of the system for controlling the shape of the radio-reflective surface of a large-size space reflector using its current-conducting structural parts.

Shape Sensing for Continuum Robotics Using Optoelectronic Sensors with Convex Reflectors

Three-dimensional shape sensing in soft and continuum robotics is a crucial aspect for stable actuation and control in fields such as minimally invasive surgery, engine repairs and search and rescue operations, as the estimation of complex curvatures while using continuum robotic tools is required to manipulate through fragile paths. This challenge has been addressed using a range of different sensing techniques, for example, Fibre Bragg grating (FBG) technology, inertial measurement unit (IMU) sensor networks, or stretch sensors. Previously, an optics-based method using optoelectronic sensors was explored, offering a simple and cost-effective solution for shape sensing in a flexible tendon-actuated manipulator in two orientations. This was based on proximity-modulated angle estimation and has been the basis for the shape sensing method addressed in this paper. The improved and miniaturised technique demonstrated in this paper is based on the use of a convex shaped reflector with optoelectronic sensors integrated into a tendon-actuated robotic manipulator. Upgraded sensing capability is achieved using optimisation of the convex reflector shape in terms of sensor range and resolution, and improved calibration is achieved through the integration of spherical bearings for friction-free motion. Shape estimation is achieved in two orientations upon calibration of sensors, with a maximum Root-Mean-Square Error (RMS) of 3.37°.

Systematic Radio Telescope Alignment Using Portable Fringe Projection Profilometry

In 2019, the Event Horizon Telescope (EHT) released the first-ever image of a black hole event horizon. Astronomers are now aiming for higher angular resolutions of distant targets, like black holes, to understand more about the fundamental laws of gravity that govern our universe. To achieve this higher resolution and increased sensitivity, larger radio telescopes are needed to operate at higher frequencies and in larger quantities. Projects like the next-generation Very Large Array (ngVLA) and the Square-Kilometer Array (SKA) require building hundreds of telescopes with diameters greater than 10 ms over the next decade. This has a twofold effect. Radio telescope surfaces need to be more accurate to operate at higher frequencies, and the logistics involved in maintaining a radio telescope need to be simplified to support them properly in large quantities. Both of these problems can be solved with improved methods for surface metrology that are faster and more accurate with a higher resolution. This leads to faster and more accurate panel alignment and, therefore, a more productive observatory. In this paper, we present the use of binocular fringe projection profilometry as a solution to this problem and demonstrate it by aligning two panels on a 3-m radio telescope dish. The measurement takes only 10 min and directly delivers feedback on the tip, tilt, and piston of each panel to create the ideal reflector shape.

HARMONY OF LIGHT AND SHADOW: KEY ASPECTS OF LIGHTING IN PORTRAIT PHOTOGRAPHY

The article analyzes the role of lighting in portrait photography, emphasizing how the harmony between light and shadow can affect the emotional depth and visual appeal of an image. Photography, presented as an art and science of light, requires not only professional skills, but also the talent and skill of the photographer. The skill of a photographer lies not only in technical execution, but also in the ability to convey life and emotions through the image, revealing the true character of a person. Thus, a portrait photographer should be able to capture the soul and inner world of the model, which is a sign of his or her true skill. The article pays special attention to lighting under artificial lighting. It further discusses such aspects as distance between the subject and the light source, directionality of light, the size of light source and the distance to the subject, as well as the importance of shape of reflector. The different types of lighting in portrait photography are also discussed: back, side, front, diffused, and hard light, each of which affects the final image. The study includes analysis of current trends and innovative lighting techniques in portrait photography. It emphasizes the importance of the photographer’s ability to use different light sources to create images that reflect uniqueness and personality of the model. This study aims to expand the theoretical knowledge and practical skills of photographers, striving to improve the quality and expressiveness of portrait images.

Research on the realization and application prospect of FAST active reflector shape adjustment technology

Research on the realization and application prospect of FAST active reflector shape adjustment technology

Characterization and Deviation Analysis of a High-Flux Solar Simulator With Metal-Halide Lamps

Abstract Utilizing highly concentrated solar power for thermochemical processing as one of the extraterrestrial in situ resource utilization (ISRU) applications has been highlighted as an essential technique to support deep-space exploration in the future. Multi-source high-flux solar simulators (HFSSs) are widely employed to provide stable irradiance for indoor solar thermal experiments. Meanwhile, numerical modeling that can characterize the radiation transport mechanisms within the solar thermal system has been developed for performance evaluation before field trials. However, significant differences between simulated and measured flux distributions were shown for existing models developed based on the Monte-Carlo ray-tracing (MCRT) method, which has been attributed to only one or two specific reasons. In this paper, we proposed a comprehensive analysis of the concentration characteristics of a 42 kW metal-halide lamp HFSS, developed at Swinburne University of Technology, considering the effect of five aspects. The flux distribution, uniformity, and vector distribution under different configurations were compared to quantify the influence of these factors on receiving irradiance. The suitable arc size, reflector shape, and reflector surface properties of the existing HFSS have also been numerically determined to improve the model and reduce the root mean square error (RMSE) for the lamp array from 38.2% to 8.3%. This research provides a potential pathway to numerically predict the radiation transfer performance of HFSSs and determine the suitable configuration for desired solar thermochemical applications.

INFORMATION SYSTEM FOR MULTI-VECTOR RAYTRACING IN ELLIPSOIDAL REFLECTORS

Due to two focuses, ellipsoidal reflectors are unique reflective optical elements that allow conjugate imaging in two focal planes within their inner cavity. Such reflectors are used in various devices, such as lens telescopes, to achieve high resolution. They have found applications in microscope optical systems to increase the depth of field. They are used in scientific instruments, such as laser systems, to ensure the laser beam's high accuracy and stability. Despite their advantages, the non-spherical shape of ellipsoidal reflectors also introduces drawbacks in the form of errors arising from raytracing on the side surface. It complicates aberration analysis and necessitates specialized software for multi-vector ray tracing. Considering the deviations in the coordinates of the intersections between rays and the second focal plane allows for optimizing the reflector design to achieve maximum efficiency. Therefore, this work aims to enhance the efficiency of the aberration analysis of ellipsoidal reflectors by developing principles and informational tools for multi-vector ray tracing.
 The article presents the results of developing an information system for multi-vector analysis in ellipsoidal reflectors. The developed multi-vector algorithm enables selecting tracing modes, tuning launch parameters, and setting the step size for launching rays. The specialized software features for single- and multi-vector raytracing in an ellipsoidal reflector are presented. The side surface of the ellipsoid is the object under study. The software provides the capability to realize different methods of multi-vector ray tracing, such as radius-based, diameter-based, and partial radius-based, for different types of tasks, thereby expanding the possibilities for visualizing the simulation results.
 Based on the multi-vector aberration analysis of the side surface of the ellipsoidal reflector, the center coordinates and root mean square deviations were obtained for different reflection acts when changing the zenith angle of tracing. The influence of zenith angles on coordinate variations was assessed, which can be realized in selecting parameters for ellipsoidal reflectors and designing the optical system of photometers for various purposes. It can also aid in developing additional means to compensate for aberrations or modify the reflector's side surface shape.

Integrated attitude and shape control for OrigamiSats with variable surface reflectivity

OrigamiSats, a new concept in solar sailing, are origami spacecraft with reflective panels that, when flat, operate as a conventional solar sail. Shape reconfiguration, i.e. “folding” of the origami design, allows the OrigamiSat to change operational modes, performing different functions as per mission requirements. For example, a flat OrigamiSat could be reconfigured into the shape of a parabolic reflector, before returning to the flat configuration when required to operate again as a solar sail, providing propellant-free propulsion. The attitude dynamics and shape reconfiguration of OrigamiSats are known to be highly coupled, thus presenting a challenge from a control perspective. This paper investigates the problem of integrating attitude and shape control of a Miura-fold pattern OrigamiSat through the use of variable reflectivity, allowing differences in solar radiation pressure to be used to enact shape reconfiguration and attitude manoeuvres. A closed-loop feedback controller is presented which combines and balances the attitude and shape control requirements, and gain-scheduling is implemented to address some specific features of the system dynamics. Numerical simulations of the multibody dynamics of the system are used to test the proposed controller and simulations of some example manoeuvres are performed which demonstrate the system’s performance.

Shaped Omnidirectional Reflector Fed by a Dielectric Lens Associated with a Coaxial Feed Horn

The paper explores an omnidirectional antenna configuration composed of a reflector fed by a shaped dielectric lens associated with a coaxial TEM horn. A simple formula describes the lens shape obtained by applying Fermat’s principle to control the rays’ caustic emerging from the dielectric interface. Based on geometrical optics (GO) principles, a synthesis technique defines the reflector shape to control the antenna radiation pattern in the vertical plane. Concatenated conic describes the reflector generatrix. The study employs a full-wave analysis to validate the designs and explores the proposed configuration to attend two distinct far-field specifications.

A secondary reflector geometry optimization of a Fresnel type solar concentrator

The present paper aims to develop a new shape of secondary reflector for Fresnel linear concentrator; it represents the continuation of a series of optimization carried out on a solar prototype with Fresnel type concentration, the new developed form represents a Double Parabolic Concentrator (DPC). This study was carried out through an optimization scheme in order to determine the parameters that influence on the prototype's performances. For this purpose, a numerical model is proposed. It aims at determining the different performance of the solar prototype. In this context, a parametric study and an optimization were carried out in order to determine the influence of certain parameters on the prototype's performances, namely: 1) the secondary reflector: Double Parabolic Concentrator (DPC), and 2) the different elements that characterize it such as the focal length, the aperture, the spacing, and the tube position. The modeling of the various parameters describing the solar field was carried out by the Monte Carlo ray-tracing (MCRT) method. The results are analyzed and presented in the form of tables and curves. In fact, they allowed the determination of the optimal configuration of the solar receiver. According to the optimization results, we can notice that the optimal DPC is not a double parabola. Moreover, the new form of DPC has a power gain of 10 to 13% compared to the existing form and also gives an optical efficiency of the receiver which reaches 100 %, that means that all the rays which cross the glass are absorbed by the tube. As a result, this configuration gives better theoretical and experimental performance. On the basis of this optimal configuration, several thermal power stations based on LFR technology have been produced and marketed.

Basic data visualization in vintage seismic profiles: Indications for the interpretation of the ViDEPI database (offshore Puglia, southern Italy)

The Visibility of Petroleum Exploration Data in Italy (ViDEPI) project represents a freely accessible valuable resource for the research community. However, seismic profiles available from this project present several limitations because information such as the basic shape of the seismic wavelets and the seismic polarity are not available. In this study, using subsurface (i.e., 2D seismic profiles) data related to the Marine Zones B, D and F (offshore Puglia) a review of the basic pulse shape and polarity of seismic wavelets, as well as the shape and polarity of principal reflectors has been addressed. Moreover, borehole data (i.e., lithology and sonic logs) have been used to identify abrupt average velocity changes linked to different lithostratigraphic successions recorded as dominant high-amplitude reflectors.

Development of technological equipment for autonomous testing of the shaping structure of the umbrella reflector

A shaping structure is element in most transformable reflectors to ensure the required accuracy of the reflective surface. An umbrella reflector shaping structure is a system of tensioned dimensionally stable cords in the open position. External factors influence the cords of the shaping structure, which lead to a change in the length of the cords throughout the entire life cycle of the product. It is advisable to assess the stability of the geometric dimensions of the cords, from the point of view of labor intensity, on a piece of the shaping structure – the arch system. To conduct this kind of research, there is a need to develop special technological equipment. The article considers the requirements for technological equipment and testing. The authors propose an original design of technological equipment, which allows fixing the cords of the arch system with boundary conditions similar to a real reflector. The paper describes a 3D model of the technological equipment, on the basis of which a prototype was made. The prototype ensured the assembly of a separate arch system corresponding to the standard design in terms of size, configuration and cord tension. Tests were carried out to assess the measurement error of the arch system in the manufactured experimental model. The test results confirmed the possibility of using the developed technological equipment for component tests of the shaping structure.

Influence of Optimal Adjustment of FAST Active Reflector on Receiving Efficiency

In this study, how to optimize and adjust the five hundred-meter aperture spherical radio telescope—FAST—active reflector and the impact on the receiving efficiency after optimization are discussed. The shape adjustment of the active reflector of FAST can be taken as the deformation of a continuous and ideal surface. The surface equation with parameter idealization is established. Meanwhile, the ideal surface equation is obtained and the corresponding evaluation function is given to evaluate the ideal parabolic equation. Furthermore, the ideal surface equation is discretized, and the discrete points are taken as the position to which the actual main cable node should be displaced by the down-tie cable. Finally, a receiving efficiency model is established to compare the actual receiving efficiency of the previous and after reflection panels. The accuracy similar to the ideal paraboloid of the reflector shape in the working area previous and after deformation is given. The results show that our optimization and adjustment model can improve the receiving efficiency of FAST reflective panel with small deformation.

Advances in acoustically-tensioned metastable detector neutron detection technology

Nuclear security, the prevention of special nuclear material (SNM) smuggling, at borders and ports has been described as one of the 21st century grand challenges. Currently, thermal neutron detectors (a majority of which are He-3 detectors), are used to monitor for neutrons emitted from special nuclear materials. He-3 neutron absorption cross-sections are ∼103 times higher for thermal vs fast neutrons; as such, moderated He-3 detectors must suffer from reduced efficiency (due to scattering and absorption in moderators) for detection of fast neutrons emitted from fission of SNMs. Development of a real-time high-efficiency gamma/beta blind, directionality-determining thermal and fast neutron monitoring system without need for bulky moderation is needed to allow for optimal SNM monitoring. The previously developed economical acoustically tensioned metastable fluid detector (E-ATMFD(Ver.0), offered all of these capabilities but exhibited low (∼0.01–0.05%) efficiencies than conventional neutron monitors. Design optimization guided via coupled multiphysics-neutron transport simulation tools, together with devising a figure of merit algorithm, experimental validation work with various reflector shapes, and a novel detection fluid “DFP”, the direct drive E-ATMFD(Ver.1) architecture was devised and demonstrated to offer ∼5 to 27x improvement in neutron detection efficiency. Using borated DFP mixture version E-ATMFD(Ver.1B), epithermal to fast neutron detection capabilities were demonstrated — effectively extending the sensitivity to all energies of neutrons and increasing the efficiency by another factor of up to ∼2.5. Further research included development of a novel frequency sweep-cum-rate drive mode to successfully operate multiple E-ATMFDs simultaneously from a single power source; resulting in a further 4x detection efficiency improvement from enhanced scattering and electromagnetic coupling — showing potential for enabling large array mode SNM interrogation.

Optical and structural optimization of a large aperture solar parabolic trough collector

Concentrating solar power is well established renewable energy technology. It involves the same heat engine cycle as the conventional power plants, and the heat produced can be stored effectively. However, expensive mirrors and structural support systems required to maintain high precision in the shape of reflectors for better optical and thermal efficiencies are the challenges involved in making it competitive with other solar power technologies. In the present work, a methodology is proposed based on the finite element method and Monte-Carlo ray tracing to design and optimize a parabolic trough collector. The effect of geometric and optical parameters such as rim angle, the width of the collector, tracking errors, and slope errors are analyzed. The effect of tracking errors in the East-West direction and slope errors are substantial compared to the other non-random errors. Loss of 25% and 7.1% in optical efficiency occurs for tracking errors of 20 mrad and slope error of 3.2 mrad, respectively. Based on the structural and optical study, an optimization method and optimum configurations are proposed. Using the proposed methodology, heat flux maps at the receiver can also be obtained for the structural health monitoring of the receiver tube.

Minimization of Cable-Net Reflector Shape Error by Target-Approaching and Procedural-Learning Method

Minimization of Cable-Net Reflector Shape Error by Target-Approaching and Procedural-Learning Method

A novel solution method for reflector shape of solar Compound Parabolic Concentrator and verification

In the existing studies, there are many methods to obtain the reflector shape equations of a CPC(Compound Parabolic Concentrator), but these methods are complicated and not unified. This paper aims to propose a novel method that is based on the edge-ray principle, the differential geometry theory, and the geometrical optical reflection law to get the reflector shape equations. Then, the reflector shape equations of an arc absorber CPC (A-CPC) which focuses light on the lower part of a circular absorber are calculated. The optical properties of such an A-CPC experimental model determined by these equations are studied via laser experiments. Afterward, the error between the calculated values obtained by MCRT(Monte Carlo Ray-Trace) method and experimental values are analyzed. The experimental results show that the optical properties of the A-CPC are in accordance with the theoretical expectations. They indicate also that the theoretical method is flexible and suitable for calculating a specific CPC reflector shape.

Form-Finding Analysis of Mesh Reflector of Large Parabolic Cylindrical Antenna

In this study, a hybrid iteration force density method (HIFDM) was proposed to ensure both tension uniformity and accuracy of an antenna mesh reflector. Based on a genetic algorithm (GA), the boundary cable tension of the antenna reflector net was optimized, which further improved the precision of the antenna mesh reflector. The static model of the large deployable structure was established using the finite element method (FEM), and thus, an iterative strategy for form-finding of the antenna reflector net was proposed, which considered the influence of the elastic deformation of the deployable structure. The results showed that the HIFDM was effective for the form-finding of the antenna mesh reflector, and the shape precision was improved by further optimization using the GA. Finally, it was noted that the elastic deformation of the deployable structure will reduce the uniformity of cable tension and affect the precision of antenna reflectors. Due to the large-scale and soft stiffness, the large deployable structure had a high sensitivity to cable pretension, and it is important to design a reasonable cable pretension to ensure the accurate shape of antenna mesh reflectors.

Optimal Topology Configuration Design of Contoured-Beam Mesh Reflectors

It is significant for the practical application of space-borne mesh-shaped reflectors to reduce the structural complexity under the condition of the far-field electromagnetic (EM) performance being satisfied. To address this problem, an optimal topology configuration design method is proposed for the mesh-shaped reflectors. First, a multifrequency optimization model is established to obtain the mesh-shaped reflector. The reflector nodal deviations in the x-, y-, and z-directions are simultaneously selected as design variables to design the shape of the mesh reflector and realize the required contoured beams within the whole frequency band. Then, based on the multifrequency optimization model, an iterative design technology is proposed to obtain the optimal topology configuration of the mesh-shaped reflector. Finally, a typical example of a mesh reflector with contoured beams covering the continental United States (CONUS) is investigated to demonstrate the feasibility of the method.