scholarly journals Interpretation of Extragalactic Jets

1986 ◽  
Vol 89 ◽  
pp. 425-437
Author(s):  
Michael L. Norman
Keyword(s):  
High Resolution ◽  
Visual Inspection ◽  
Physical Parameters ◽  
Model Calculations ◽  
Radio Jets ◽  
Extragalactic Jets ◽  
Self Consistent ◽  
Interferometric Observation ◽  
The Subject

The subject of this paper is the interpretation of extragalactic radio jets. In this paper I will focus on what we have learned about the nature of extragalactic jets on the basis of model calculations. By model I mean any set of calculations, whether analytic, semi-analytic or numerical, which, when carried through from their respective assumptions to their internally self-consistent conclusions, help place constraints on the physical parameters and processes in the jets and their associated radio lobes. In this field, a visual inspection of a modern high-resolution radio interferometric observation (see review by PERLEY in these proceedings) often leads to statements like “that looks just like such and such in Landau and Lifschitz; I betcha that’s what’s going on!” This I call a speculation, or, at best, a hypothesis. I am addressing here the step beyond hypothesis, namely modeling, which is necessary to confront not only the object in question, but more importantly, the hypothesis itself. In the end, we will remember only the hypotheses.

scholarly journals Hubble Space Telescope Observations of Extragalactic Jets

1996 ◽  
Vol 175 ◽  
pp. 195-200 ◽  
Author(s):  
F. Duccio Macchetto
Keyword(s):  
Hubble Space Telescope ◽  
Space Telescope ◽  
Central Source ◽  
Radio Jets ◽  
Extended Radio ◽  
Extragalactic Jets ◽  
The Subject ◽  
Radio Band ◽  
Better Than

The study of the optical counterparts to the radio jets has been the subject of a number of observing programs with the Hubble Space Telescope (HST). We know that these jets play a fundamental role in transporting energy from the central source to the extended radio lobes. Observations at optical and ultraviolet wavelengths with the HST are essential to obtain spatial resolutions similar to, or better than, those achieved in the radio band and, thus, provide the possibility of directly comparing the sites and mechanisms responsible for the emission at these different wavelengths.

Twin stars as tracers of binary evolution in the Kepler era

2021 ◽  
Author(s):  
Sara Bulut ◽  
Baris Hoyman ◽  
Ahmet Dervisoglu ◽  
Orkun Özdarcan ◽  
Ömür Cakilrli
Keyword(s):  
High Resolution ◽  
Internal Structure ◽  
Spectroscopic Analysis ◽  
Independent Method ◽  
Eclipsing Binaries ◽  
Physical Parameters ◽  
Evolutionary Status ◽  
Mass Ratio ◽  
Orbital Parameters ◽  
Binary Evolution

Abstract We present results of the combined photometric and spectroscopic analysis of four systems, which are eclipsing binaries with a twin–component (mass ratio q ≃ 1). These are exceptional tools to provide information for probing the internal structure of stars. None of the systems were previously recognized as twin binaries. We used a number of high–resolution optical spectra to calculate the radial velocities and later combined them with photometry to derive orbital parameters. Temperatures and metallicities of systems were estimated from high-resolution spectra. For each binary, we obtained a full set of orbital and physical parameters, reaching precision below 3 per cent in masses and radii for whole pairs. By comparing our results with PARSEC and MIST isochrones, we assess the distance, age and evolutionary status of the researched objects. The primary and/or secondary stars of EPIC 216075815 and EPIC 202843107 are one of the cases where asteroseismic parameters of δ Sct and γ Dor pulsators were confirmed by an independent method and rare examples of the twin–eclipsing binaries, therefore the following analyses and results concern the pulsating nature of the components.

scholarly journals High-Resolution Pixel LED Headlamps: Functional Requirement Analysis and Research Progress

2021 ◽  
Vol 11 (8) ◽  
pp. 3368
Author(s):  
Liping Wang ◽  
Jianshe Ma ◽  
Ping Su ◽  
Jianwei Huang
Keyword(s):  
High Resolution ◽  
Functional Diversity ◽  
Traffic Safety ◽  
New Technologies ◽  
Light Distribution ◽  
Research Progress ◽  
Requirement Analysis ◽  
Functional Requirement ◽  
Traffic Conditions ◽  
The Subject

High-resolution pixel LED headlamps are lighting devices that can produce high-resolution light distribution to adapt to road and traffic conditions, intelligently illuminate traffic areas, and assist drivers. Due to the complexity of roads and traffic conditions, the functional diversity of high-resolution pixel LEDs headlamps and traffic safety has come into question and is the subject of in-depth research conducted by car manufacturers and regulators. We summarize the current possible functions of high-resolution pixel LED headlamps and analyze ways in which they could be improved. This paper also discusses the prospect of new technologies in the future.

scholarly journals Hydrodynamic Models of Solar and Stellar Flares

1989 ◽  
Vol 104 (1) ◽  
pp. 289-298
Author(s):  
Giovanni Peres
Keyword(s):  
High Resolution ◽  
Light Curve ◽  
Solar Flares ◽  
Impulsive Phase ◽  
Light Curves ◽  
Physical Parameters ◽  
The Sun ◽  
Hydrodynamic Models ◽  
X Ray ◽  
Stellar Flares

AbstractThis paper discusses the hydrodynamic modeling of flaring plasma confined in magnetic loops and its objectives within the broader scope of flare physics. In particular, the Palermo-Harvard model is discussed along with its applications to the detailed fitting of X-ray light curves of solar flares and to the simulation of high-resolution Caxix spectra in the impulsive phase. These two approaches provide complementary constraints on the relevant features of solar flares. The extension to the stellar case, with the fitting of the light curve of an X-ray flare which occurred on Proxima Centauri, demonstrates the feasibility of using this kind of model for stars too. Although the stellar observations do not provide the wealth of details available for the Sun, and, therefore, constrain the model more loosely, there are strong motivations to pursue this line of research: the wider range of physical parameters in stellar flares and the possibility of studying further the solar-stellar connection.

scholarly journals Application of Model-Based Tests for Analysing the Consequences of Mine Fires

2018 ◽  
Vol 1 (1) ◽  
pp. 767-774
Author(s):  
Magdalena Tutak
Keyword(s):  
Fire Hazard ◽  
Physical Parameters ◽  
Gas Mixture ◽  
New Approach ◽  
Model Based ◽  
Underground Coal Mines ◽  
Mine Fires ◽  
Underground Mine Workings ◽  
The Subject ◽  
Chemical Products

Abstract One of the most common and most dangerous hazards in underground coal mines is fire hazard. Mine fires can be exogenous or endogenous in nature. In the case of the former, a particular hazard is posed by methane fires that occur in dog headings and longwalls. Endogenous and exogenous fires are large hazard for working crew in mining headings and cause economics losses for mining plants. Mine fires result in emission of harmful chemical products and have a crucial impact on the physical parameters of the airflow. The subject of the article concerns the analysis of the consequences of methane fires in dog headings. These consequences were identified by means of model-based tests. For this purpose, a model was developed and boundary conditions were adopted to reflect the actual layout of the headings and the condition of the atmosphere in the area under analysis. The objective of the test was to determine the effects of methane fires on the chemical composition of the atmosphere and the physical parameters of the gas mixture generated in the process. The results obtained clearly indicate that fires have a significant impact on the above-mentioned values. The paper presents the distributions for the physical parameters of the resulting gas mixture and the concentration of fire gases. Moreover, it shows the distributions of temperature and oxygen concentration levels in the headings under analysis. The methodology developed for the application of model-based tests to analyse fire events in mine headings represents a new approach to the problem of investigating the consequences of such fires. It is also suitable for variant analyses of the processes related to the ventilation of underground mine workings as well as for analyses of emergency states. Model-based tests should support the assessment of the methane hazard levels and, subsequently, lead to an improvement of work safety in mines.

scholarly journals A METADATA-BASED APPROACH FOR USING CCTV TO FACILITATE EMERGENCY RESPONSE

2020 ◽  
Vol XLIV-3/W1-2020 ◽  
pp. 51-57
Author(s):  
J-H. Hong ◽  
Y-T. Shi
Keyword(s):  
Emergency Response ◽  
Crucial Role ◽  
Visual Inspection ◽  
September 11 ◽  
September 11 Attacks ◽  
The Subject ◽  
Long Term Monitoring ◽  
Term Monitoring ◽  
2D To 3D

Abstract. The installation of closed-circuit television monitors (CCTV) has been rapidly increasing ever since the September 11 attacks and has become one of the most widely used types of sensors for the tasks that require instantaneous and long-term monitoring. With the distinguished characteristics of direct visual inspection of the subject of interests, the availability of CCTVs offers the EOC commanders a quick way to validate and access the reported disaster incidents during emergency response. However, the heterogeneity of CCTV systems and the lack of appropriate descriptions precludes the optimized use of CCTV and causes immense difficulties in effectively coordinating or appraising the use of CCTV systems. By arguing standardized metadata plays the most crucial role in quickly and precisely finding the needed CCTV during emergency response, regardless of its specifications, suppliers, or locations, we propose an integrated operational framework based on the CCTV metadata specifically designed for emergency response in this paper. This framework standardizes the metadata to unify the descriptions for heterogeneous CCTV systems and fulfill the requirements for searching and selecting CCTV. Instead of the 2D point-based location or sector-based CCTV FOV coverage, we also propose to extend the FOV from 2D to 3D to precisely describe the area and even the features that can be monitored by the CCTV. This not only improves the precision and efficiency of selecting CCTV but also increase the commander’s ability to make quick and accurate responses to disasters. The advantages of integrating heterogeneous CCTV systems can tremendously improve the possibility of monitoring and updating the real-time status caused by hazards.

scholarly journals Condition Monitoring Technologies for Synthetic Fiber Ropes - a Review

2020 ◽  
Vol 8 (2) ◽  
Author(s):  
Espen Oland ◽  
Rune Schlanbusch ◽  
Shaun Falconer
Keyword(s):  
Condition Monitoring ◽  
State Of The Art ◽  
Degradation Process ◽  
Synthetic Fiber ◽  
Physical Parameters ◽  
The Subject ◽  
Condition Monitoring System ◽  
Future Direction ◽  
Monitoring Technologies ◽  
Insight Into

This paper presents a review of different condition monitoring technologies for fiber ropes. Specifically, it presents an overview of the articles and patents on the subject, ranging from the early 70’s up until today with the state of the art. Experimental results are also included and discussed in a conditionmonitoring context,where failuremechanisms and changes in physical parameters give improved insight into the degradation process of fiber ropes. From this review, it is found that automatic width measurement has received surprisingly little attention, and might be a future direction for the development of a continuous condition monitoring system for synthetic fiber ropes.

The spectrum of gaseous methane at 77 K in the 1.1 – 2.6 μm region: a benchmark for planetary astronomy

1989 ◽  
Vol 67 (11) ◽  
pp. 1027-1035 ◽  
Author(s):  
A. R. W. McKellar
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Low Temperature ◽  
Spectral Resolution ◽  
Fourier Transform Spectrometer ◽  
Absorption Cell ◽  
Model Calculations ◽  
Testing Model ◽  
Medium Resolution ◽  
Spectrometer Data

The spectrum of CH4 obtained in CH4 plus N2 mixtures at a temperature of 77 K has been recorded with a spectral resolution of 0.14 cm−1 in the region 3800 to 9100 cm−1. The experiments were performed with long paths (66 or 88 m) in a cooled absorption cell using a Fourier-transform spectrometer. Data are presented here at low and medium resolution, and examples of some spectral regions are also shown at high resolution. The complete results are available from the author in an Appendix. Comparisons are made with previous model calculations of CH4 absorption, and with the observed spectrum of Neptune's satellite, Triton. The results should be useful for the interpretation of the spectra of Triton, Titan, and Pluto. They will also be of value for testing model calculations of low-temperature CH4 absorption, which, thus verified, can be used with greater confidence to analyze observations of Jupiter, Saturn Uranus, and Neptune.

scholarly journals Small Galactic Nebulae

1987 ◽  
Vol 115 ◽  
pp. 191-192
Author(s):  
Yervant Terzian ◽  
Kenneth C. Turner
Keyword(s):  
High Resolution ◽  
Planetary Nebula ◽  
Physical Parameters ◽  
H Ii Regions ◽  
Radio Observations ◽  
Cluster Emission ◽  
Active Star ◽  
Star Forming ◽  
Cometary Nebula ◽  
Significant Flux

We have performed high resolution VLA radio observations for several small H II regions, including the cluster emission nebulae S258, S255, S257, and S256. The region (PP56) between S255 and S257 at λ2 cm reveals significant flux structure close to OH, H2O and infrared emitting sources as shown in Figure 1. The flux densities and positions are indicated in Table 1. Observations of the cometary nebula PP59 (S269) also reveal similar characteristics as shown in Figure 2. These regions are considered to be active star-forming clouds. The cometary nebula PP40 was also observed and we note that its physical parameters are very similar to those of a typical planetary nebula.

scholarly journals Combined Use of 3D Metric Survey and GPR for the Diagnosis of the Trapezophoros with Two Griffins Attacking a Doe of Ascoli Satriano (Foggia, Italy)

Geosciences ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 307
Author(s):  
Marilena Cozzolino ◽  
Andrea Di Meo ◽  
Vincenzo Gentile ◽  
Paolo Mauriello ◽  
Enza Zullo
Keyword(s):  
Cultural Heritage ◽  
Ground Penetrating Radar ◽  
Visual Inspection ◽  
Careful Analysis ◽  
Preventive Strategies ◽  
State Of Health ◽  
Noninvasive Techniques ◽  
Combined Use ◽  
The Subject ◽  
Ground Penetrating

Protection and conservation are not feasible without a deeper knowledge of the cultural heritage of the subject of intervention. A careful analysis of documentation, a detailed visual inspection of surfaces, and a systematic diagnosis of the inner properties are the basis for planning preventive strategies of restoration. Digital noninvasive techniques represent an advantageous tool with useful outputs to estimate the state of health of cultural heritage in order to minimize the progress of degradation. This paper deals with a 3D metric survey through photogrammetry and ground-penetrating radar (GPR) tests applied to the study of the trapezophoros with two griffins attacking a doe of Ascoli Satriano, a masterpiece of ancient art that needs to be protected. This work provided information on both visible and hidden defects, such as numerous cracks that affect the sculpture.

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