Comparison of 3D Landmark and 3D Dense Cloud Approaches to Hominin Mandible Morphometrics Using Structure‐From‐Motion

The objective of this study is to compare landmark‐based assessment of hominin mandible morphological variation with that from a high‐density point cloud, using 3D models constructed from structure‐from‐motion (SfM) surface capture techniques. Surface models of nine hominin mandible casts were created using SfM photogrammetry. The morphology of these models was described using traditional geometric morphometrics based on identification of landmarks. This was compared to the morphological variation described by the differences between high‐density point clouds, which do not rely on anatomical landmarks, using an iterative closest point algorithm. The landmark‐based approach grouped the anatomically modern human and Neanderthal mandibles with reasonable success. The high‐density point cloud approach also grouped these successfully, but was able to incorporate information from a specimen that was insufficiently preserved to be included in the landmark data set. This improved the accuracy of the grouping. The use of high‐density point clouds from surface capture to analyse hominin mandible morphology allows for greater amounts of information to be included and offers a potential method to identify shape affinity that is as successful as landmark‐based geometric morphometrics.     

Real-time Seismic Damage Detection of Concrete Shear Walls Using Artificial Neural Networks

Concrete shear walls are widely employed in buildings as a main resistance system against lateral loads. Early identification of seismic damage to concrete shear walls is vital for deciding post-earthquake occupancy in these structures. In this article, a method based on artificial neural networks for real-time identification of seismic damage to concrete shear walls was proposed. Inter-story drifts and plastic hinge rotation of concrete walls were used as the inputs and outputs of a MLP neural network. Modal Pushover Analysis was employed to prepare well-distributed data sets for training the neural network. The proposed method was applied to a five-story concrete shear wall building. The results from the network were compared with those obtained from Nonlinear Time History Analysis. It was observed that the trained neural network successfully detected damage to concrete shear walls and accurately estimated the severity of seismic-induced damage.     

The effect of atmospheric screening on the visible border of noctilucent clouds

The noctiiucent cloud display of 10/11th July 1979 was observed from two sites in Scotland: Clinterty near Aberdeen, using a low light level TV camera, and Milngavie near Glasgow, using a photographic camera. Coincident observations of the display were made from 23.55 UT until 00.50 UT.By projecting the image of the noctilucent cloud structure as seen by one camera into the field of view of the other camera, the height of the clouds was found to be 82 ± 1 km. Using this result, the effect of atmospheric screening on the visible border of the noctilucent clouds was determined. Taking account of the refraction on the solar grazing rays illuminating the clouds at the visible border and the finite angular diameter of the sun's disc, the altitude of the screening layer was determined to be 7 ± 1 km. Thus, on this occasion, the screening effect of the atmosphere was confined to the troposphere and was probably caused by atmospheric haze and/or tropospheric cloud.This result contrasts markedly with the high values of screening height, ~ 30 km, deduced from measurements made earlier this century, also using the visible boundary of the clouds. The analysis presented herein indicates that these large values were probably in error, due to the poor dynamic range of the photographic films employed.     

A quasi-DC model of electric fields in the ionosphere-ground region due to electrified clouds

The penetration of the quasi-DC electric fields, E due to electrified clouds, into the middle- and high-latitude ionosphere is theoretically studied during the initial stage of cloud charge separation. The electrification process is characterized by a source function S(t), whose variations are on the time scale of the relaxation process in the cloud. A first-order approximation solution for the time variation of E is obtained as an explicit function of the electric field in the steady-state case. Some features of the time variations of E at different altitudes (in the ionosphere and also in the atmosphere) are investigated, depending on the source function and the relaxation time constants. This result can also be applied for slowly electrifying clouds which do not produce lightning.     

Rapid On‐site Topographic Mapping with a Handheld Laser Range Finder for a Geoarchaeological Survey in Syria

A digital elevation model and a topographic map of an archaeological site in Syria were created from a field topographic survey with a handheld laser range finder and data post‐processing using a notebook personal computer with Geographical Information System software. The method enabled rapid on‐site topographical mapping even under technical and political restrictions in the country. In an area of about 1 km², coordinates of random points on the land surface were measured, and a DEM with a 10 m interval grid was generated from the point cloud using Kriging interpolation. The DEM enables various topographic representations to be constructed, such as contour lines, cross sections and slope distribution maps. The DEM‐derived contour lines with a 1 m interval were combined with vector data showing roads and buildings to provide a topographic map. Topographic cross sections created from the DEM generally agree with sections surveyed with a hand level and a measurement tape. The obtained DEM and map are useful for preliminary field research.     

SANET: A Toolbox for Spatial Analysis on a Network

This article shows a geographical information systems (GIS)-based toolbox for analyzing spatial phenomena that occur on a network (e.g., traffic accidents) or almost along a network (e.g., fast-food stores in a downtown). The toolbox contains 13 tools: random point generation on a network, the Voronoi diagram, the K -function and cross K -function methods, the unconditional and conditional nearest-neighbor distance methods, the Hull model, and preprocessing tools. The article also shows a few actual analyses carried out with these tools.     

The analysis of hydroxyl rotational temperatures to characterize moving thermal structures near the mesopause

Hydroxyl (OH) rotational temperatures near 85 km altitude have been monitored at Calgary, Alberta, Canada (51°N, 114°W) since 1981 with the objective of determining velocities, wavelengths and periods associated with moving temperature structures. A technique is described whereby the velocity of moving patterns in two dimensional data sets can be accurately determined and used as a parameter for a global smoothing algorithm. Velocities of the structures in the meridional direction were found to be directed poleward. Corresponding Doppler bulk wind velocities measured near the 95 km height region were directed equatorward indicating the presence of filtering of internal gravity waves by the background wind. Two coherent wave structures were often observed simultaneously during a night. The smaller of the two structures had true wavelengths less than 15–30 km and may be related to billow clouds often reported in noctilucent cloud observations. The second wave has a period on the order of an hour and meridional wavelengths ranging from 100 to 2000 km.     

Inca builders at Machu Picchu National Archaeological Park

Knowledge about the Inca measurement system is based on information from the colonial chronicles and modern studies of the 16th-century Quechua dictionaries. Based on those texts, we can presume that the Incas used an anthropometric system of measurement adopted from the proportions of the human body. Using cosine quantogram analysis and statistical verification, it is possible to verify the existence of the measurement system used by the Inca architects. For this purpose, a measurement series of architectural and water infrastructure elements were collected from 3D point cloud of the Chachabamba and Machu Picchu settlements in Machupicchu National Archaeological Park.     

Cloudiness decreases associated with Forbush-decreases of galactic cosmic rays

Variations of the amount of cloud following Forbush-decreases of the galactic cosmic ray flux have been investigated in different latitudinal belts. It has been found that decreases of the total cloud cover are most distinctly seen in the latitudinal belt ϕ ∼ 60–64°, and disappear at lower latitudes. In the auroral zone:, the apparent effects are weaker than in the subauroral zone. The cloudiness variations associated with the Forbush-decreases are shown to correlate mainly with the presence of cirrus clouds, at heights reached by protons with energy ∼ 1000 MeV.     

Analysis of a Distribution of Point Events Using the Network‐Based Quadrat Method

This study proposes a new quadrat method that can be applied to the study of point distributions in a network space. While the conventional planar quadrat method remains one of the most fundamental spatial analytical methods on a two‐dimensional plane, its quadrats are usually identified by regular, square grids. However, assuming that they are observed along a network, points in a single quadrat are not necessarily close to each other in terms of their network distance. Using planar quadrats in such cases may distort the representation of the distribution pattern of points on a network. The network‐based units used in this article, on the other hand, consist of subsets of the actual network, providing more accurate aggregation of the data points along the network. The performance of the network‐based quadrat method is compared with that of the conventional quadrat method through a case study on a point distribution on a network. The χ² statistic and Moran's I statistic of the two quadrat types indicate that (1) the conventional planar quadrat method tends to overestimate the overall degree of dispersion and (2) the network‐based quadrat method derives a more accurate estimate on the local similarity. The article also performs sensitivity analysis on network and planar quadrats across different scales and with different spatial arrangements, in which the abovementioned statistical tendencies are also confirmed.     

Measurement of the eddy diffusion coefficient of the middle atmosphere from a balloon at low latitude

A great deal of uncertainty exists concerning the distribution of the vertical eddy diffusion coefficient of the middle atmosphere. A new technique has been developed in this laboratory in which chemical clouds are released in the middle atmosphere from a balloon platform. The expansion of the cloud is monitored by ground photography, from which the value of the eddy diffusion coefficient is calculated. The experiment was successfully tested on 9 March 1985 at Hyderabad (17.5°N, 78.6°E), India. The value of the coefficient was found to be of the order of 10⁴ cm² s⁻¹ in the altitude range 10–20 km.     

Applicability of the two-layer model for simulation of non-linear evolution of a large scale plasma cloud in the ionospheric F-region

The adequacy of the two-layer model of Lloyd and Haerendel for describing the behaviour of an ionospheric irregularity is verified by numerical simulation of large plasma cloud dynamics. The background ionosphere is approximated by a set of conductive layers with ion mobilities and concentrations corresponding to the real ionospheric conditions. Polarization electric field produces positive and negative image clouds, i.e. plasma density enhancements and depletions in each layer. Their intensity, form and orientation turn out to change with height depending on the local conditions. However, the drift and deformation of the released cloud slightly differ from the case when the ionosphere is characterized by constant, height averaged parameters, at least if altitude dependent neutral wind and photochemical processes are ignored.     

A secular change in noctilucent cloud occurrence

Evidence is given for a secular change now taking place in the frequency of occurrence of noctilucent clouds. Separate lines of argument lead to the strong supposition that this change occurs as the result of a small, systematic cooling of the upper mésosphère in summertime. The change is likely to have amounted to 7 K over the last 20–30 years. While changes in water vapour concentration will affect the frequency of occurrence, it is just as likely that the changes may be taking place in the mean mesopause temperature. These changes in mean temperature increase the probability of occurrence of a low (threshold) temperature which allows cloud formation.     

Extraction of Hierarchical Surface Networks from Bilinear Surface Patches

Surface networks capture the topological relations between passes of a continuous surface, the paths of steepest descent and ascent starting at the passes, and the pits and peaks where the steepest paths end. Surface networks represent the topology of surfaces in a compressed form and allow fast investigation of the surfaces' convex and concave shapes. They are applied, for instance, for enhancing algorithms for surface analysis, for surface model simplification, and for surfaces visualization. Furthermore, they are themselves subjects of analysis as they are closely coupled to the intrinsic geometrical concepts and rules of continuous surfaces.
This article extends the topology of surface networks in four ways: (i) objects at the edge of the surface model are introduced; (ii) intersections between valley and ridge lines are found to be possible, and such intersections are incorporated into the topology; (iii) horizontal areas may represent passes, pits, or peaks, and therefore must be detected and explicitly incorporated; and (iv) valley and ridge line hierarchies are recognized as inherent components of the surface network. They are extracted and explicitly represented.
To ensure consistency and completeness of the surface network, a zero-order continuous surface is specified from the raster data prior to the extraction. This article presents a method to represent and derive valley and ridge line hierarchies. The results are illustrated with two examples. The extracted networks are found to be consistent and complete. However, the extraction method tends to produce spurious pits, peaks, and passes, which form a drawback if the surface data are affected by noise.     

The Evolution of Innovation Networks and Spin-off Entrepreneurship: The Case of RAD

Abstract

We conducted an in-depth analysis of an Israeli startup, RAD Bynet, founded in 1981, that has intentionally, through the vision of its founder, given rise to 129 other startups employing some 15,000 workers, and created a unique “cloud”. Through a survey of the existing firms, we sought to explore the nature of this ecosystem and to quantify the relationships that exist between the mother company and the enterprises that emerge from it. Our main findings were: (a) social and technological proximity encourages the tendency of the companies to maintain business relationships that probably contribute to knowledge exchange, while technological diversity drives innovation and startup formation; and (b) firms will choose to cooperate on the basis of a shared past and personal proximity relations, as well as technological proximity at a certain level; “viral clouds” of startups like the one we studied can thus intentionally be designed and developed.     

Estimates of gravity wave momentum fluxes in the winter and summer high mesosphere over northern Scandinavia

As part of the MAP/WINE campaign (winter 1983–1984) and the MAC/SINE campaign (summer 1987) high resolution wind profiles were obtained in the upper mesosphere using the foil cloud technique. Vertical winds were derived from the fall rate of the foil clouds and are used for estimating the momentum fluxes associated with vertical wavelengths shorter than about 10 km. From the ensemble average of 15 observations over an altitude range of 74–89 km we calculate a zonal net momentum flux of +12.6 ± 4.5 m²s⁻² in summer. The average of 14 measurements in winter between 73 and 85 km indicates a zonal net momentum flux of −3.7 ± 2.4 m²2 s⁻².     

基于海量点云数据的大雁塔三维重建

古建筑三维重建已成为历史遗迹保护与修复的重要内容。为了探讨三维激光扫描数据的获取流程、数据处理方法,以三维激光扫描获取的大雁塔海量点云数据为例,研究了古建筑三维重建中点云数据获取与处理的详细过程。联合Cyclone、AutoCAD和3D-Max软件的优点构建了大雁塔真实的横面、剖面、立面模型,其中重点研究了海量点云数据在Cyclone软件中分块建模的方法。结果表明:将拼接好的大雁塔海量点云数据分块建模,不仅加快了数据处理的速度,而且符合精度要求。在点云数据拼接时采用标靶拼接和同名点拼接相结合及测站间两两拼接之后再整体拟合平差的方法,减少了拼接中的误差,使每站拼接误差都不超过3cm。在建模过程中的墙体拟合是上万个点云经过平差计算得到,精度高达2mm。最后在3D-Max软件中组合、渲染和贴图,真实地构建了大雁塔三维立体模型。为古建筑数字化存档和后期的修缮工作提供了重要的依据。     

A neural network approach to the classification of electron and proton whistlers

Fractional whistlers, whistlers, and proton whistlers are automatically identified and characterized by means of a neural network. A feed-forward neural network with Time Delay Neural Network (TDNN) architecture is used. It has the ability to represent structures in frequency time diagrams; a set of 50 spectrogram elements (5 Fourier components × 10 time intervals) serves as input to the network. Applications to date have used ELF data recorded on board the low-altitude AUREOL-3 satellite. A first neural network was designed to identify and characterize fractional whistlers and whistlers. A set of 997 vector data is used for the training phase and 1088 other vector data are used for evaluating performance. It is observed that fractional whistlers and whistlers can be distinguished from noise with an accuracy of 90%. A second neural network, with the same architecture, was used for studying proton whistlers. Although the training database contains less examples, the accuracy of the classification is 89%. Neural networks of this type could be used in satellites for real-time classification and characterization of electron and proton whistlers.     

Location Modeling Utilizing Maximum Service Distance Criteria

The location set-covering problem (LSCP) and the maximal covering location problem (MCLP) have been the subject of considerable interest. As originally defined, both problems allowed facility placement only at nodes. This paper deals with both problems for the case when facility placement is allowed anywhere on the network. Two theorems are presented that show that when facility placement is unrestricted, for either the LSCP or MCLP at least one optimal solution exists that is composed entirely of points belonging to a finite set of points called the network intersect point set (NIPS). Optimal solution approaches to the unrestricted site LSCP and MCLP problems that utilize the NIPS and previously developed solution methodologies are presented. Example solutions show that considerable improvement in the amount of coverage or the number of facilities needed to insure total coverage can be achieved by allowing facility placement along arcs of the network. In addition, extensions to the arc-covering model and the ambulance-hospital model of ReVelle, Toregas, and Falkson are developed and solved.