Statistical analysis of astrometric errors for the most productive asteroid surveys

Re: Hoffer et al.: Update on intraocular lens power calculation study protocols: the better way to design and report clinical trials (Ophthalmology. 2020; Jul 9 [Epub ahead of print

In mechanical assemblies, the performance, quality, cost and assemblability of the product are significantly affected by the geometric errors of the parts. This paper develops the statistical error analysis approach for dimensional control in automotive body multi-station assembly process. In this method, the homogeneous transformation matrices are used to describe the location and orientation of part and assembly features and the small homogeneous transformation matrices are used to model the errors. In this approach, the effective errors in automotive body assembly process are classified in three categories: manufacturing errors (dimensional and geometric tolerances), locating errors (fixture errors) and process errors (joining errors). In a mechanical assembly, small variations due the errors propagate according to a complex mechanism that in this approach it formulated in error analysis procedure. The propagation chain of geometric errors is described based on CAD models. The estimation of the error accumulation and the percent contributions of individual errors are based on the statistical model (root-sum-square method). The application of the proposed method is illustrated through presenting an example problem.

Digital implementations of neural nets must consider finite wordlength effects. For large sized nets, it is particularly important to investigate the roundoff errors in order to realize low-cost hardware implementations while satisfying precision constraints. This paper presents output error expressions for a large feedforward neural net, which are based on statistical error analysis. Weight quantization errors as well as arithmetic errors due to rounding of multiplier output and sigmoid output are modeled. The results indicate that for equal wordlengths, multiplier roundoff errors exceed weight quantization errors by about an order of magnitude.

Uncertainty calculation for spacecraft thermal models using a generalized SEA method

PII: S0965-2299(02)00111-5

A statistical analysis of errors is performed by consideration of fringe number and geometrical errors. The results of the analysis are applied to an optimized interferometer for the fringe-counting method, and simple relations for the calculation of the condition number and standard deviation are discussed, taking into account overdetermined equation systems.

The apparent velocities of near-Earth asteroids (NEAs) are usually high when they pass by Earth. Observing these fast-moving objects with long exposure times would cause their images to streak and significantly decrease the precision of astronomical measurements. The rotating-drift-scan (RDS) charge-coupled device technique is a promising approach to observe fast-moving NEAs during their close approaches to Earth. By rotating the camera of a telescope, an NEA can be observed in the time delay integration mode. This allows the asteroid to be imaged as a point source, even with a long exposure time. Here, we thoroughly present the RDS follow-up observation and orbit determination of a newly discovered NEA 2023 BJ7. This technique makes an impactful contribution to improving the NEA's orbit accuracy by extending the observation arc. A detailed statistical analysis of the astrometric error was conducted, revealing that RDS observations can achieve a competitive accuracy with an rms error of 0.″24 in right ascension and 0.″32 in declination. The instability of the telescope is thought to be the main reason affecting the internal precision. Furthermore, the RDS technique excels at observing fast-moving NEAs, as well as newly discovered NEAs without accurate ephemerides. For NEAs with rates of motion exceeding 10 deg day−1, the rms of RDS observation residuals is 0.″35 in the along-track direction and 0.″23 in the cross-track. With this technique, a network of small-aperture telescopes would substantially benefit our global NEAs monitoring system to ensure Earth’s safety from any asteroid impacts.

The authors present the results of analysis of quantization effects on a wideband FFT (fast Fourier transform) beamformer using two different approaches: a simulation of the quantization errors and a statistical analysis of the quantization errors. First, a brief description of the FFT beamformer is presented. Next, the statistical analysis of the quantization error effects is presented. Finally, analysis of the FFT beamformer performance by simulation is compared with the beamformer performance predicted by the statistical analysis technique. The theoretical results, which were derived as worst-case analysis, were shown to be consistent with the simulation results. A design based on the results of these analyses demonstrated that satisfactory performance was achieved with a 12 bit wordlength with 6 bits to the right of the radix for the scenario presented. >

<p indent="0mm">Karayaylak Glacier (38°35′6″N–38°44′48″N, 75°7′47″E–75°22′29″E) is located in the northern slope of Jiubie Peak of Kongur Mountains, eastern Pamir, China. Its surge in May 2015 brought property losses to local residents. To enhance the monitoring and analysis of the surged glacier has important practical significance for exploring the glacier surge mechanism and for establishing a disaster early-warning mechanism. This study obtained the surface velocities of Karayaylak Glacier from April 13, 2015 to July 11, 2015 from Landsat images by using feature-tracking method. With a spatial resolution of <sc>240 m,</sc> these data were stored in GeoTiff format in 32-bit floating point. A statistical analysis indicates that the results have an overall accuracy of less than ± <sc>0.42 m d^-1.</sc> The elevation change between 2013 and 2015 was also obtained from ASTER-derived DEM. With a spatial resolution of <sc>240 m,</sc> the data were stored in GeoTiff format in 32-bit floating point. A statistical analysis of the residual error in non-glacial areas indicates that the results have an overall accuracy of about ± <sc>0.7 m.</sc> The dataset can serve as the basis for investigating surged glaciers in this region, or as input data for building glacier dynamic models. It provides statistical support for glacier surge research. In addition, the monitoring data not only support further research in risk assessment and the early warning of glacier disasters, but also ensure the economic and social development of China–Pakistan Economic Corridor.

The rapid integration of renewable energy sources (RES), particularly wind, together with fluctuating demand, has introduced significant uncertainty into power system operation, challenging traditional approaches for estimating Transmission Reliability Margin (TRM) and Available Transfer Capability (ATC). This paper proposes a fully adaptive TRM estimation framework that leverages rolling-window statistical analysis of net-load forecast errors to capture real-time uncertainty fluctuations. By continuously updating both the confidence factor and window length based on evolving forecast-error statistics, the method adapts to changing grid conditions. The framework is validated on the IEEE 30-bus system with 80 MW wind (42.3% penetration) and assessed for scalability on the IEEE 118-bus system (40.1% wind penetration). Comparative analysis against static TRM, fixed-confidence rolling-window, and Monte Carlo Simulation (MCS)-based methods shows that the proposed approach achieves 88.0% reliability coverage (vs. 81.8% for static TRM) while providing enhanced transfer capability for 31.5% of the operational day (7.5 h). Relative to MCS, it yields a 20.1% lower mean TRM and a 2.5% higher mean ATC, with an adaptation ratio of 18.8:1. Scalability assessment confirms preserved adaptation (12.4:1) with sub-linear computational scaling (1.82 ms to 3.61 ms for a 3.93× network size increase), enabling 1 min updates interval.

The uncertainties in the determination of the stratigraphic profile of natural soils is one of the main problems in geotechnics, in particular for landslide characterization and modeling. The study deals with a new approach in geotechnical modeling which relays on a stochastic generation of different soil layers distributions, following a boolean logic – the method has been thus called BoSG (Boolean Stochastic Generation). In this way, it is possible to randomize the presence of a specific material interdigitated in a uniform matrix. In the building of a geotechnical model it is generally common to discard some stratigraphic data in order to simplify the model itself, assuming that the significance of the results of the modeling procedure would not be affected. With the proposed technique it is possible to quantify the error associated with this simplification. Moreover, it could be used to determine the most significant zones where eventual further investigations and surveys would be more effective to build the geotechnical model of the slope. The commercial software FLAC was used for the 2D and 3D geotechnical model. The distribution of the materials was randomized through a specifically coded MatLab program that automatically generates text files, each of them representing a specific soil configuration. Besides, a routine was designed to automate the computation of FLAC with the different data files in order to maximize the sample number. The methodology is applied with reference to a simplified slope in 2D, a simplified slope in 3D and an actual landslide, namely the Mortisa mudslide (Cortina d’Ampezzo, BL, Italy). However, it could be extended to numerous different cases, especially for hydrogeological analysis and landslide stability assessment, in different geological and geomorphological contexts.

This quasi-experimental study, limitedly, explores the level of English grammar awareness as a potential partial indicator of “underpreparedness” in a population of first-year students doing an English for Academic Purposes (EAP) module in a South African university. This is done by comparing the mean test scores and linguistic errors in two slightly different but equivalent parts-of-speech grammar test components in the assignment and supplementary examination scripts of two naturally-occurring subpopulations of the EAP population. Members of the EAP population were in the tests required to correct authentic text parts that had been morphologically and syntactically corrupted for correction. The statistical and linguistic error analyses returned a higher mean test score and a bigger correct-incorrect response ratio for the assignment script sample (the A-Sample) than for the supplementary examination script sample (the SE-Sample). These results suggested, firstly, that extraneous variables were responsible for the variation in the sample test performances, and, secondly, that the grammar instruction, testing and error correction treatments had probably had negligible to no effect at all. The error analysis points to the inadvisability of the inclusion of peripheral grammatical categories such as adverbs in textual modifications for editing as they may not offer optimal opportunities for the exploitation for instructional purposes of the meaning potential of syntactic structures. The grammar instruction observation data showed that a majority of the SE-Sample participated with apparent interest and enthusiasm, thereby suggesting that they viewed the grammar instruction as useful. The observation data also contained a case of resistance to grammar instruction by an older student with a different background to the majority EAP population.

Relationships among statistical quantities used in the analysis of refractive error are derived from geometrical optics principles. The accuracy of these results are verified using the data of Sorsby et al. As an application of these results, it is shown that there is difficulty in accounting for leptokurtosis of refractive error in terms of correlation among the optical parameters of the eye. Also, it is shown that the distribution of the optical parameters of the eye cannot be a joint-normal distribution.

This paper describes the conceptions of first‐year University students, about ‘measuring’. A teaching sequence has been provided, involving a theoretical lecture course on the analysis of measurement errors, followed by laboratory work in optics and in electricity. Data have been gathered during the laboratory work. Their analysis shows that the students establish a hierarchy in the series of measurements and do not really understand the need to make several measurements. Few of them have critical insight into the notion of confidence interval. Random and systematic errors are not distinguished. The general view is that, the more measurements one makes, the ‘better’ the result is, without understanding the nature of this ‘better’.

In order to assess the uncertainties in the experimental measurements, the use of statistical error analysis is essential for a reliable technical diagnosis on structural safety in reinforced concrete of bridges. Two non-destructive techniques (ultrasound and rebound hammer) were performed, resulting in conflicting technical diagnostics when analyzed without the study of the variability of experimental errors. It was evident that physically the only use of arithmetic average means nothing. The obtained results also demonstrated the lack of correlations between those ones driven by the ultrasound and the impact hammer on the four tested bridges. &nbsp; Key words: Rebound hammer, ultrasound, compressive strength, nondestructive tests, statistical error analysis.