Miracle-dz/UniFAR-FTUs huggingface dataset:
On the local minima in phase reconstruction algorithms

Signal reconstruction from phaseless data occurs in electromagnetics both in the diagnostics of large reflector antennas and in the near-field testing of microwave and millimeter wave antennas. The main difficulty in solving such problems arises from its inherent nonlinearity. Because of the latter, in fact, the solution procedure can converge to a function which has nothing to deal with the actual solution. In this paper we review and summarize the properties of a recently proposed approach to phase retrieval problems which allows to understand and possibly avoid the false solution problem. To this end, ill-posedness of the problem is briefly recalled, and a convenient generalized solution is introduced as the global minimum of a proper functional whose local minima are indeed the false solutions of the problem. Then the geometrical meaning of such a functional is considered, and properties of the solution are discussed according to the formulation of the problem as a quadratic inverse one. In particular, the relevance of using nonredundant representations for the unknown of the problem and as many independent data as possible are discussed in full detail from both a theoretical and a numerical point of view. Finally, it is shown how the proposed solution procedure, descending from the adopted formulation based on a weaker nonlinearity with respect to the other ones, has indeed a better behavior as far as local minima problem is concerned.
Event-triggered output tracking control for wireless networked control systems with communication delays and data dropouts

This study addresses the event-triggered output tracking control under wireless network environments. First, an improved event-triggered communication scheme and a sampled-state-error dependent tracking model for wireless networked control systems is presented. In this scheme and model, (a) the sensor takes samples in a periodic manner; (b) an improved event-triggering condition is applied in the communications to determine whether the sampled data is transmitted to the controller or not; and (c) the closed-loop tracking system with a networked state-dependent controller is modelled as an augmented time-delay system. Second, by constructing a novel Lyapunov–Krasovskii functional, two theorems are derived with guaranteed H∞ tracking performance subject to imperfect wireless communications. The tracking performance is based on two permissible limits on the signal transmission. That is, the maximum allowable communication delay bound and maximum allowable number of successive data dropouts. Finally, a satellite tracking example is given to show the effectiveness of the proposed method.
X-Ray Tomography Reconstruction Accelerated on FPGA Through High-Level Synthesis Tools

Model-Based Iterative Reconstruction (MBIR) algorithms iteratively use expensive computational operators of forward and backward projections. The irregular memory access pattern of these operators makes them a memory-bound application. Their computation time must be reduced to meet clinical routine constraints. This article proposes a hardware accelerator architecture based on Field Programmable Gate Arrays (FPGAs) through high-level language, as an alternative to GPU architecture. This acceleration is based on an offline memory access analysis to address the main bottleneck of the algorithm and maximize the data reuse rate. The offline analysis allows for the tuning of the architecture parameters so that they converge to an optimal solution. Then, the Berkeley Roofline model guides our optimization steps by iteratively analyzing the design performance. Our design flow significantly improved the algorithm's computational intensity and overcame the memory bottleneck. Thus, our architecture takes advantage of the FPGA local memory to achieve significant memory bandwidth and efficiently harness the pipeline without stalling the computation. Furthermore, we present the scaling-up strategy from mid-range FPGA to high-end FPGA and any concerns of portability. We used two Intel FPGA devices to implement the algorithm, and then we compared the results with our GPU implementation in terms of speedup and energy efficiency. Our experimental results show that our design has achieved better computational throughput than the works on FPGA architectures reported in the literature.
Metrological evaluation of a 3D electrical capacitance tomography measurement system for two-phase flow fraction determination

The industrial diagnostic and monitoring systems still require new methods offering new possibilities of non-invasive observation and analysis of the two-phase gas–liquid mixture flows. This paper demonstrates a new measurement system dedicated for non-invasive void fraction calculation and flow structure identification in vertical and horizontal pipelines. The study of the metrological validation of the designed three-dimensional capacitance tomography measurement system is discussed here. This research includes the 3D ECT sensor structure optimization process, the metrological evaluation of the image reconstruction accuracy and the developed liquid void fraction calculation method efficiency, in comparison with other common techniques. As a result of the performed analysis the advantages of the designed 3D ECT measurement system for non-invasive real-time dynamic flow process identification were discussed.
Sustainable green financial system perspective of environmental protection investment and the government’s environmental policy or public participation: evidence from Chinese A-share listed companies

Corporate environmental protection investment (EPI) is one of the ways to accelerate green development. This paper develops a theoretical model of EPI focusing on three factors: the government, the public, and the enterprises. It uses data from A-share listed Chinese companies from 2008 to 2014 to analyse the effects of the government environmental policy and public participation on the corporate EPI. Results of this research show that both the environmental regulations issued by the government and the demands put forward by public opinion encourage enterprises to increase investment in environmental protection. Moreover, the government ’ s green policy efforts and public participation result in synergy in governance. Relevant regulations issued by the government improve the efficiency of actual public participation. However, redundant government intervention is not conducive to increasing corporate investment in environmental protection. According to this research, market-oriented reforms can boost the positive impact of government and public efforts on corporate EPI. In order to improve environmental governance and achieve green development, it is necessary to deepen market-oriented reforms and build a coordinated, complementary, and incentive-compatible governance system that deals with issues, demands, rights, and responsibilities of the government, the public, and enterprises.
Bipolar Molecular Outflows in Massive Star Formation Regions

Bipolar molecular outflows are a basic component of the star formation process. This is true for stars of all masses, although it has not yet been well established how outflows associated with massive stars differ from those associated with low-mass stars. We present results from a project to identify bipolar outflows from massive young stellar objects (YSOs) and determine how they compare with low-mass YSO systems. Ten massive star formation regions with high-velocity 12CO(J = 1 − 0) line wings were mapped with the Kitt Peak 12 m telescope using the On-the-Fly (OTF) mapping technique. Five of the regions have bipolar outflows. We determine accurate mass estimates of the molecular gas in the red-and blueshifted lobes by taking into account variations in the optical depth as a function of velocity in the flow. We find that the molecular outflows have masses between ∼16 and 72 M☉ and kinetic energies between ∼1045 and 1046 ergs. The outflows have significantly more mass and kinetic energy than those from low-mass YSOs. Of the remaining five regions, two have a clumpy distribution in 12CO with multiple velocity components within the cloud complex, and three sources did not have sufficient signal-to-noise ratio (S/N) to map the high-velocity line wings. We combine our data with 18 additional outflow sources with stellar luminosities that range from 0.6 L☉ to 2.1 × 105 L☉ to predict the luminosity of the star responsible for the outflow. We find that the stellar luminosities of the sources in our sample range from ∼102 to 104 L☉, which correspond to mid- to early-B type stars; the precursors of Herbig Be stars. One source, G173.58, has an IRAS source on the flow axis with the appropriate luminosity to drive the observed outflow. For the remaining four sources, there is no detectable ultracompact (UC) H ii region or isolated IRAS source with the appropriate luminosity to produce the observed molecular outflow. The outflows mapped in this work begin to fill in a region of outflow parameter space in which relatively few sources have been studied, and they help to bridge the gap between low-luminosity outflow sources and the few isolated outflows from massive O stars. Our data are consistent with the ideas that (1) Ṁ in a molecular outflow increases continuously with Lbol of the driving source over a range from ∼1 L☉ to ∼106 L☉ (2) one can predict the central source luminosity from the measured mass flux in the flow, (3) there is a clear Mflow versus age (td) relationship for stars of all luminosities, and (4) the larger Ṁ for higher luminosity sources implies that these objects produce massive outflows on short timescales relative to low-mass stars.
Face authentification or recognition by profile extraction from range images

Work related to the authentification or recognition of human faces from their range images is described. The approach consists of comparing a part of the profile or the surface of two faces. For this purpose, the profile plane of each face is considered as a quasi-symmetry plane and is extracted by an iterative process which involves the similarity of the Gaussian curvature values of the face surface. Then an optimal matching of the two profiles is done, which allows the calculation of similarity indices of profiles or surfaces. Tests for robustness and the authentification or recognition results show the efficiency of the whole procedure. <<ETX>>
Analysis of UAV Thermal Soaring via Hawk-Inspired Swarm Interaction

A swarm of unmanned aerial vehicles (UAVs) can be used for many applications, including disaster relief, search and rescue, and establishing communication networks, due to its mobility, scalability, and robustness to failure. However, a UAV swarm’s performance is typically limited by each agent’s stored energy. Recent works have considered the usage of thermals, or vertical updrafts of warm air, to address this issue. One challenge lies in a swarm of UAVs detecting and taking advantage of these thermals. Inspired by hawks, a swarm could take advantage of thermals better than individuals due to the swarm’s distributed sensing abilities. To determine which emergent behaviors increase survival time, simulation software was created to test the behavioral models of UAV gliders around thermals. For simplicity and robustness, agents operate with limited information about other agents. The UAVs’ motion was implemented as a Boids model, replicating the behavior of flocking birds through cohesion, separation, and alignment forces. Agents equipped with a modified behavioral model exhibit dynamic flocking behavior, including relative ascension-based cohesion and relative height-based separation and alignment. The simulation results show the agents flocking to thermals and improving swarm survival. These findings present a promising method to extend the flight time of autonomous UAV swarms.
Target identification in terrestrial laser scanning

Abstract Target identification is an important process in terrestrial laser scanner (TLS) measurements; however, due to strong competition between manufacturers, the design of laser scanners is kept secret and is usually strengthened by accompanying proprietary software. Moreover, the target identification algorithms (i.e. definitions of the target centre) are not specified. This makes it difficult for users to objectively compare scanners from different manufacturers and to judge the reliability of the captured scan data by a brand scanner and accompanying software. This paper presents a unified general method to complete the process of target identification. The proposed method consists of four major steps: first, determination of the target plane; second, classification of the reflection intensity values and extraction of the border between white and black; third, detection and elimination of erroneous points from step two; and fourth, fitting of the intersection lines and calculation of the centre of the two lines. Because TLS is a reflectorless surveying model that can receive hundreds of signals, its measurements require more stringent objective conditions than traditional measurement by total stations (TS). Therefore, robust estimation methods are used to reduce the influence of random errors; moreover, the model of error-in-value (EIV) is also introduced to deal with captured data. Finally, the target’s centre can be obtained from an iteration process. For the experiments, a Leica HDS 7000 terrestrial laser scanner, with its accompanying software, Cyclone, and a Leica Laser Tracker AT901were employed. The performance of the proposed method is compared with Cyclone and some early methods from published studies at different resolutions and distances. The paper concludes that the proposed method can obtain reliable results at the same level of accuracy level as those obtained using accompanying software; thus, it provides an objective means to compare the quality of different scanners. The advantage is that our method only makes use of information provided by all scanners and does not require additional proprietary information that cannot be accessed.
Galactic dust and extinction

The ratio R between visual extinction and colour excess, is slightly larger than 3 and does not vary much throughout our part of the Galaxy. The distribution of dust in the galactic plane shows, on the large scale, a gradient with higher colour excesses towards 1=50 than towards 1=230 . On the smaller scale, much of the dust responsible for extinction is si­ tuated in clouds which tend to group together. The correlation between positions of interstellar dust clouds and positions of spiral tracers seems rather poor in our Galaxy. However, concentrated dark clouds as well as extended regions of dust show an inclined distribution similar to the Gould belt of bright stars.
Convergence Acceleration for Lucas-Kanade Algorithm via Discarding Strongly Concave/Convex Areas

Image alignment is a useful technique in many important research fields of computer vision. Among all the image alignment algorithms, Lucas-Kanade algorithm is one of the most widely used algorithms. During the past 30 years, a wide variety of extensions have been made to the original formulation and an unabridged Lucas-Kanade algorithm series has been formed. In this paper, we propose a novel method which can accelerate the convergence of Lucas-Kanade algorithm series. Based on the theory of strongly concave/convex function, we define the Strongly Concave/Convex Areas (SC/CA) of images. Through discarding the SC/CA, the iteration number of Lucas-Kanade algorithm series can be reduced without decreasing the precision. Finally, we present various experimental results that validate our method. These results also show that the proposed method is robust with the parameter used in detecting the SC/CA.
Raman-scattering and structure investigations on porous SiC layers

Raman scattering spectroscopy, scanning electron microscopy, and scanning acoustic microscopy were studied on porous SiC layers prepared by different technological routes and subjected to reactive ion treatment. The Raman spectra revealed a number of features specific for nanocrystallite materials, which can be used for characterization and diagnostics of porous SiC layers for technological applications.
On the use of wavelet analysis for the fitting of a dynamical theory to observations

We present methods to t planetary ephemerides to observational data. More precisely, we will consider an application of wavelet analysis to dynamical residuals of Jupiter. The eciency of this new technique is assessed by tests with extrapolations using observational samples not used in the t. The results are very encouraging. Since the work of Gaillot in 1913 (Gaillot 1913), the analytical solutions of the Bureau des longitudes have not been t to actual observations. The VSOPxx (Bretagnon 1982; Bretagnon & Francou 1988) analytical theories of the motion of the 8 planets of the solar system are presently the modern solutions of the IMC-Bureau des longitudes; however, until this work, VSOPxx were t only to the JPL numerical integrations, Dexxx (Standish 1995, 1998). This paper deals with some elements of the rst adjustment of the modern VSOP analytical theories of motion of the planets to optical and radar observations.
Small Satellite LEO Maneuvers with Low-Power Electric Propulsion

Chemical propulsion currently provides the means for near-Earth satellite orbit maneuvers. As electric propulsion (EP) devices become more accepted and flight qualified, EP may enable increases in satellite payload mass while decreasing satellite propellant mass. The Air Force Operationally-Responsive Space (ORS) program proposes the use of commercially available and readily configurable satellite buses with masses of approximately 500 kg for near-Earth missions. This paper discusses three orbital maneuvers considered important in the characterization of EP use for satellites in near-Earth orbits. The first maneuver changes an orbit from low-Earth orbit (LEO) at 800 km to mediumEarth orbit (MEO) at 20,000 km. The second maneuver changes the inclination of an orbit at LEO by 90°, while the third maneuver rephases a satellite in LEO orbit by 180°. Each maneuver considers thruster specific impulse, Isp, from 1,000 to 3,000 s and thruster power from 100 W to 1.5 kW for a 500 kg satellite to obtain propellant mass and transfer time. In general, as Isp increases the transfer time increases and the propellant mass decreases. These transfer times range from hours to years, but mission constraints will define appropriate levels of Isp and power. Analysis of these maneuvers finds that EP is beneficial to near-Earth satellites for altitude and phase changes. EP is not currently beneficial to missions requiring large inclination changes, but identifies a key interest in future low-power EP devices.
Development of Smart Irrigation Equipment for Soilless Crops Based on the Current Most Representative Water-Demand Sensors

Due to the edaphoclimatic conditions in southeast Spain, which are expected to worsen due to climate change, more efficient ways of using water must be found to maintain sustainable agriculture. Due to the current high price of irrigation control systems in southern Europe, 60–80% of soilless crops are still irrigated, based on the experience of the grower or advisor. The hypothesis of this work is that the development of a low-cost, high-performance control system will allow small farmers to improve the efficiency of water use by obtaining better control of soilless crops. The objective of the present study was to design and develop a cost-effective control system for the optimization of soilless crop irrigation after evaluating the three most commonly used irrigation control systems to determine the most efficient. Based on the agronomic results comparing these methods, a prototype of a commercial smart gravimetric tray was developed. The device records the irrigation and drainage volumes and drainage pH and EC. It also offers the possibility of determining the temperature, EC, and humidity of the substrate. This new design is scalable thanks to the use of an implemented data acquisition system called SDB and the development of software in the Codesys programming environment based on function blocks and variable structures. The reduced wiring achieved by the Modbus-RTU communication protocols means the system is cost-effective even with multiple control zones. It is also compatible with any type of fertigation controller through external activation. Its design and features solve the problems in similar systems available on the market at an affordable cost. The idea is to allow farmers to increase their productivity without having to make a large outlay. The impact of this work will make it possible for small-scale farmers to have access to affordable, state-of-the-art technology for soilless irrigation management leading to a considerable improvement in productivity.
Polarity particles in English and Romanian

This paper contrasts the distribution and interpretation of ‘polarity particles’ in English and Romanian. Polarity particles ( yes, no in English, da, nu, ba in Romanian) occur at the left edge of utterances that react to assertions, polar questions and imperatives but cannot be used in ‘out of the blue’ contexts. The paper makes sense of this distribution as well as of the contrasts between the two languages against the background of a context structure proposed in earlier work, which allows us to understand in what sense assertions, polar questions and imperatives form a natural class. Of particular interest here are cases where both yes and no can be used in otherwise identical responses in English as well as the distribution of these particles in reactions to imperatives.
Continuous-wave distributed-feedback quantum-cascade lasers on a Peltier cooler

Continuous-wave operation of λ∼9 μm distributed-feedback quantum-cascade lasers is reported up to a temperature of 260 K. Single-frequency emission with a side mode suppression ratio of ⩾27 dB and with a tuning range of 5 cm−1 between 200 and 245 K (a tunability of −0.078 cm−1/K and −0.764 cm−1/W) is obtained for the junction-down mounted buried heterostructure devices. Uncoated lasers display an output power of up to 18 mW at 180 K and still 1 mW at 250 K. Lasers with high-reflection coated facets could be operated up to 260 K.
Towards Exoscope Automation in Neurosurgery: A Markerless Visual-Servoing Approach

Exoscopes are a promising tool for neurosurgeons, offering improved visualisation and ergonomics compared with traditional surgical microscopes. They consist of an external scope that projects the surgical field onto a 2D or 3D monitor, providing a wider field of view and better access to the surgical site. Despite the advantages, exoscopes present some limitations, such as the need for manual or foot joystick repositioning, which can disrupt the flow of the procedure and increase the risk of user error. In this study, a markerless visual-servoing approach for autonomous exoscope control is proposed to address these limitations and enhance the ergonomics and reduce the physical and cognitive load compared with traditional joystick control. The system uses visual information from the operating field to control the exoscope, eliminating the need for markers or additional tracking devices. The proposed approach was validated using a 7-DOF robotic manipulator with a stereo camera in an eye-in-hand configuration. Results showed that the system achieved 89% accuracy in detecting the target and tracking its movement with a tracking error ranging from 0.50± 0.17 cm for low-speed movements to 1.38± 0.73 cm for high-speed movements. The proposed system also demonstrated improved efficiency, with a shorter execution time of 72.07± 19.36 s compared with 106.52± 18.50 s for the foot-joystick control. Additionally, the time out of the FoV was significantly higher in the joystick control mode and the frequency of appearance of the instrument in the centre of the image was higher when using the proposed system. The NASA TLX results indicated lower physical and cognitive load compared with the joystick control-based modality.