Zeitschriftenartikel zum Thema „Orthogonal grid plan“

Abstract: This paper uses the Gulliverian metaphor to examine the organization of a well-known Classical orthogonal planning in Magna Graecia, south Italy. After observing the relationship between the elements of the urban grid of Thourioi, we will propose the application of a modular unit formed by the sum of ten Attic feet by the geometer of its urban plan. According to our main argument here, this module orientated the land-measurement of Thourioi by co-measuring the width of ithe roadway network and width/length of blocks, lots, and “major rectangles”. Furthermore, certain alignments in its planning are physically established, as it will be demonstrated in the case of its major roads. Thourioi calls forth through its compositional structure of older formulas a wider horizon of orthogonal planning tradition, an ancient scansion rhythm reified in archaeological patterns of many Greek Western foundations since the VIII century BC.

Photovoltaic (PV) power generation is greatly affected by meteorological environmental factors, with obvious fluctuations and intermittencies. The large-scale PV power generation grid connection has an impact on the source-load stability of the large power grid. To scientifically and rationally formulate the power dispatching plan, it is necessary to realize the PV output prediction. The output prediction of single power plants is no longer applicable to large-scale power dispatching. Therefore, the demand for the PV output prediction of multiple power plants in an entire region is becoming increasingly important. In view of the drawbacks of the traditional regional PV output prediction methods, which divide a region into sub-regions based on geographical locations and determine representative power plants according to the correlation coefficient, this paper proposes a multilevel spatial upscaling regional PV output prediction algorithm. Firstly, the sub-region division is realized by an empirical orthogonal function (EOF) decomposition and hierarchical clustering. Secondly, a representative power plant selection model is established based on the minimum redundancy maximum relevance (mRMR) criterion. Finally, the PV output prediction for the entire region is achieved through the output prediction of representative power plants of the sub-regions by utilizing the Elman neural network. The results from a case study show that, compared with traditional methods, the proposed prediction method reduces the normalized mean absolute error (nMAE) by 4.68% and the normalized root mean square error (nRMSE) by 5.65%, thereby effectively improving the prediction accuracy.

AbstractIn recent years, an on-going project investigating the urban landscape of Naxos has surveyed and produced several new digital reconstructions of the settlement’s simple non-peripteral temples, most with highly decorative roofs. Three Archaic sacred buildings of Sicilian Naxos are used to demonstrate different approaches to recording the remains and reconstructing their architectural features. This work reflects changes in digital strategies over the past ten years. Tempietto H is a small shrine located outside the city’s boundaries and the site is currently inaccessible, so its reconstruction is based on excavation documentation and roof terracottas. The visible half of Tempietto C was documented using three-dimensional line-drawing with total stations and photogrammetry; the back-filled south-western part was surveyed with ground penetrating radar. Temple B is the largest sacred structure in Naxos. A geophysical survey gives new data on the eastern extent of the sanctuary. The area has been recorded with handheld and aerial photography to create a three-dimensional model of the sanctuary. A new orthogonal grid of the city was established circa 470 BCE and a rectangular base was placed in the south-east corner of every crossroad. These bases were the starting point for the plan, and their interpretation as altars converts the entire urban plan into a sacred landscape.

Purpose Almost design code is required for repairability of the buildings after a major earthquake. One such idea is “directed-damage design” (DDD), which means guiding the damage to some pre-decided parts of the structural system. To use the DDD idea for creation of repairable buildings, in this study, a structural system with seesaw motion with respect to a central massive support has been considered for steel buildings with square plan, and the bottom ends of the all circumferential columns at the lowest story have been equipped with double-ADAS (DADAS) dampers, which dissipate a great portion of the seismic input energy. The purpose of this paper is to investigate the hysteretic behavior of DADAS dampers by using finite element analysis. At first, a set of regular steel multistory buildings with five stories have been designed based on the conventional code provisions. Then, the structures of the designed buildings have been changed into the structure with seesaw motion by using, at the base level of the building, a massive central column, eliminating other middle columns, and equipping circumferential columns with DADAS dampers. Design/methodology/approach For repairability buildings in the last three mentioned studies a set of orthogonal strong girders, in the form of grid, has been used. In the present study, the number of bays in the considered building is four in both directions. A major modification has been made in the yielding-plate energy dissipating elements of the circumferential columns, which makes their manufacturing and installation much practical as illustrated in the following sections of the paper. Findings In the proposed rocking structural system for regular multistory steel buildings, creation of the possibility of rocking motion has been done by using a space truss resting on a huge central hinge support at base level with a series of circumferential energy dissipating columns at that level. Originality/value One such idea is DDD idea, which means guiding the damage to some pre-decided parts of the structural system.

An analytical method for the static analysis of double layer grids consisting of diagonals and top and bottom layers which are plane orthogonal grids is presented. It is assumed that the double layer grid is simply supported at all nodes located at the boundary of the top layer. By using the double U-transformation technique, exact solutions for the nodal displacements and axial forces of the bars in the double layer grid can be derived. The validity of the method is demonstrated with a simple example.

Biedl et al.1 presented an algorithm for unfolding orthostacks into one piece without overlap by using arbitrary cuts along the surface. They conjectured that orthostacks could be unfolded using cuts that lie in a plane orthogonal to a coordinate axis and containing a vertex of the orthostack. We prove the existence of a vertex unfolding using only such cuts.

The article reveals an analytical description of the formation of families of orthogonal flat curved lines in the implicit form based on the analysis of the parametric equation of a flat isometric grid constructed by separating the real and imaginary parts of the function of a complex variable. This problem is due to the fact that flat isometric grids, as two families of orthogonal coordinate lines with square cells, are used in conformal mappings, for example, when drawing images on curved surfaces with the least distortion. At the same time, families of flat parallel lines are widely used in geometric modeling of heat transfer, electric fields, fluid flow, etc. There is a connection between these geometric images, which is explained by specific examples. Analytical calculations of deriving the parametric equation of an isometric grid are quite time-consuming, so they are performed in the environment of symbolic algebra Maple. For this purpose, the corresponding software of the interactive model of derivation of parametric equations of isometric grids for any initial function of a complex variable with the subsequent separation of its real and imaginary parts was created. It was found that the values of the abscissa and ordinates of the parametric equation of a flat isometric grid can be represented as explicit surface equations. For integer values of the power of the exponential function of the complex variable, the values of the abscissa and the ordinate will be represented by algebraic surfaces in the explicit form. The projections of the cross sections of the abscissa and ordinate surfaces by horizontal cutting planes on the horizontal plane form two families of curved lines, the equations of which can be obtained only implicitly. By the example of the quadratic function of a complex variable, it is proved that these families of lines are mutually perpendicular. The practical application of building a family of lines for geometric modeling of fluid flow lines that flow around the barrier in the form of a semicircle is shown. Key words: isometric grids, functions of a complex variable, families of orthogonal lines, geometric flow modeling

In order to accord well with the requirements of sustainable development and green construction, a cross-laminated bamboo composed of an odd number of orthogonally oriented layers of bamboo scrimber is proposed in this paper. Adjacent bamboo layers are face-bonded by structural adhesives under pressure. The uniform mechanical and physical properties can be obtained through the orthogonal layup. Flexural performances of three groups of one-way CLB slabs and two groups of one-way CLB slabs strengthened with CFRP grids were investigated via four-point monotonic loading configuration until failure. Experimental parameters of thickness of the layer, number of layers, and manufacturing processes of CFRP grids were taken into consideration. Experimental observations showed that the failure of the CLB slab was brittle, and different failure modes were found in the CLB slab with CFRP grids via different manufacturing processes. Test results showed that the load-carrying capacity increased with the thickness of the layer, number of layers, and application of CFRP grids pressed in the bamboo layer, but the CFRP grids pressed in the interface of adjacent bamboo layers weakened the load-carrying capacity. The strain analysis demonstrated that the compression region was utilized with more efficiency via CFRP grids pressed in the bamboo layer, and the plane cross section assumption is suitable for both CLB slab and CLB slab strengthened with CFRP grids. A theoretical calculation method of flexural load-carrying capacity was proposed for the CLB slab, the accuracy of which was proved.

The out-of-plane free vibration behaviour of a rotating annular disc under the application of uniform transverse pressure is presented. The method of analysis is based on energy principles, and the governing equations are obtained by the application of variational principles. Both rotation and transverse pressures act as external loading on the disc, producing in-plane and out-of-plane displacements. The displacements are approximated through linear combinations of admissible orthogonal functions and unknown coefficients. The orthogonal functions are generated numerically and the entire analysis is performed on a numerically generated grid in the physical domain of interest. The results are validated successfully with the results available in the literature and also with the results generated by the commercial finite-element package ANSYS. The dynamic behaviour of the rotating disc is furnished in a non-dimensional plane for different combinations of rotational speed and uniform transverse pressure, up to the initiation of yielding.

This study investigates the possible ball burnishing and spherical polishing surface finish process of a freeform surface plastic injection mold on a machining center. The optimal plane polishing parameters were determined by utilizing the Taguchi’s orthogonal array method for plastic injection molding steel PDS5. Five polishing parameters, namely the speed of the polishing ball, abrasive material, feed, stepover distance and the depth of penetration were selected as the experimental factors of Taguchi’s Design of Experiment to determine the optimal plane polishing parameters, which have the dominant influence on surface roughness. The optimal plane polishing parameters have been determined after conducting the experiments of the Taguchi’s L18 orthogonal table. The optimal plane polishing parameters for the plastic injection mold steel PDS5 were the combination of the polishing speed 18,000 rpm, the abrasives of aluminum oxide (Al2O3) with grid no. 5000, the feed of 100 mm/min., stepover distance of 60μ m, and the depth of penetration of 240 μ m. The surface roughness Ra of the specimen can be improved from about 1.125μ m to 0.067μ m using the optimal ball burnishing parameters for plane burnishing. The surface roughness Ra of the burnished specimen can be further improved from about 0.067μ m to 0.023μ m using the optimal polishing parameters.

An experimental investigation concerning the most energetic turbulent features of the flow exiting from an axisymmetric converging nozzle at Mach 0.85 and ambient temperature is discussed using planar optical measurement techniques. The arrangement of the particle image velocimetry (PIV) system allows for all three components of the velocity field to be captured along the (r, θ)-plane of the jet at discrete streamwise locations between x/D=3.0 and 8.0 in 0.25 diameter increments. The ensemble-averaged (time-suppressed) two-point full Reynolds stress matrix is constructed from which the integral eigenvalue problem of the proper orthogonal decomposition (POD) is applied using both scalar and vector forms of the technique. A grid sensitivity study indicates that the POD eigenvalues converge safely to within 1% of their expected value when the discretization of the spatial grid is less than 30% of the integral length scale or 10% of the shear-layer width. The first POD eigenvalue from the scalar decomposition of the streamwise component is shown to agree with previous investigations for a range of Reynolds numbers and Mach numbers with a peak in azimuthal mode 5 at x/D=3.0, and a gradual shift to azimuthal mode 2 by x/D=8.0. The eigenvalues from the scalar POD of the radial and azimuthal components are shown to be much lower-dimensional with most of their energy residing in the first few azimuthal modes, that is modes 0, 1 and 2, with little change in the relative energies along the streamwise direction. From the vector decomposition, the azimuthal eigenspectra of the first two POD modes shift from a peak in azimuthal mode 5 at x/D=3.0, followed by a gradual decay to azimuthal mode 2 at x/D=8.0, the differences in the peak energies being very subtle. The conclusion from these findings is that when the Mach number is subsonic and the Reynolds number sufficiently large, the structure of the turbulent jet behaves independently of these factors.

The four-dimensional (4D) incompressible Navier–Stokes equations are solved numerically for the plane channel geometry. The fourth spatial coordinate is introduced formally to be homogeneous and mathematically orthogonal to the others, similar to the spanwise coordinate. Exponential growth of small 4D perturbations superimposed onto 3D turbulent solutions was observed in the Reynolds number range from Re = 4000 to Re = 10000. The growth rate of small 4D perturbations expressed in wall units was found to be λ+4D = 0.016 independent of Reynolds number. Nonlinear evolution of 4D perturbations leads either to attenuation of turbulence and relaminarization or to establishment of a self-sustained 4D turbulent solution (4D turbulent flow). Both results on flow evolution were obtained at the lowest Reynolds number, depending on the grid resolution, pointing to the proximity of Re = 4000 as the critical Reynolds number for 4D turbulence. Self-sustained 4D turbulence appeared to be less intense compared with 3D turbulence in terms of mean wall friction, which is about 55% of that predicted by the empirical Dean law for turbulent channel flow at all Reynolds numbers considered. Thus, the law of resistance of 4D turbulent channel flow can be expressed as Cf = 0.04Re−0.25.

Over-parameterization and over-correction are two of the major problems in the rational function model (RFM). A new approach of optimized RFM (ORFM) is proposed in this paper. By synthesizing stepwise selection, orthogonal distance regression, and residual systematic error correction model, the proposed ORFM can solve the ill-posed problem and over-correction problem caused by constant term. The least square, orthogonal distance, and the ORFM are evaluated with control and check grids generated from satellite observation Terre (SPOT-5) high-resolution satellite data. Experimental results show that the accuracy of the proposed ORFM, with 37 essential RFM parameters, is more accurate than the other two methods, which contain 78 parameters, in cross-track and along-track plane. Moreover, the over-parameterization and over-correction problems have been efficiently alleviated by the proposed ORFM, so the stability of the estimated RFM parameters and its accuracy have been significantly improved.

Over-parameterization and over-correction are two of the major problems in the rational function model (RFM). A new approach of optimized RFM (ORFM) is proposed in this paper. By synthesizing stepwise selection, orthogonal distance regression, and residual systematic error correction model, the proposed ORFM can solve the ill-posed problem and over-correction problem caused by constant term. The least square, orthogonal distance, and the ORFM are evaluated with control and check grids generated from satellite observation Terre (SPOT-5) high-resolution satellite data. Experimental results show that the accuracy of the proposed ORFM, with 37 essential RFM parameters, is more accurate than the other two methods, which contain 78 parameters, in cross-track and along-track plane. Moreover, the over-parameterization and over-correction problems have been efficiently alleviated by the proposed ORFM, so the stability of the estimated RFM parameters and its accuracy have been significantly improved.

AbstractA calculation of the electromagnetic response of a thin conductor in the presence of an exciting primary magnetic field has been attempted by various authors. Analytic solutions are obtainable when either the conductor is of infinite extent or when the problem possesses some symmetry. The loss of symmetry makes the problem difficult to solve except for the simplest shape – that of a circular conductor. A numerical method has been used for the rectangular conductor by other authors. In this paper we consider the response due to a thin plane conductor of arbitrary shape. The method involves the numerical generation of a set of body-fitted orthogonal curvilinear coordinates which maps the conductor onto a unit square. Good orthogonal grids can be generated for shapes that do not deviate too far from the rectangular. In terms of these curvilinear coordinates the vector potential for the area current density satisfies an integro-differential equation which is solved numerically.

The stability and turbulence characteristics of a vortex filament emanating from a single-bladed rotor in hover are investigated using proper orthogonal decomposition (POD). The rotor is operated at a tip chord Reynolds number and tip Mach number of 218 000 and 0.23, respectively, and with a blade loading of $C_{T}/{\it\sigma}=0.066$. In-plane components of the velocity field (normal to the axis of the vortex filament) are captured by way of two-dimensional particle image velocimetry with corrections for vortex wander being performed using the ${\it\Gamma}_{1}$ method. The first POD mode alone is found to encompass nearly 75 % of the energy for all vortex ages studied and is determined using a grid of sufficient resolution to avoid numerical integration errors in the decomposition. The findings reveal an equal balance between the axisymmetric and helical modes during vortex roll-up, which immediately transitions to helical mode dominance at all other vortex ages. This helical mode is one of the modes of the elliptic instability. The spatial eigenfunctions of the first few Fourier-azimuthal modes associated with the most energetic POD mode is shown to be sensitive to the choice of the wander correction technique used. Higher Fourier-azimuthal modes are observed in the outer portions of the vortex and appeared not to be affected by the choice of the wander correction technique used.

A numerical scheme for simulation of activated sludge sediment flow in a circular secondary clarifier is developed. The flow and settling processes are simulated, using the k–ε turbulence model on a two-dimensional axisymmetric and orthogonal grid. To incorporate the sedimentation of the activated sludge in the field of gravity, a convection–dispersion equation governing the mass transfer in the clarifier is extended. The computational domain includes the sludge blanket where the viscosity is affected by the rheological behavior of the sludge. The double-exponential equation is used to describe the dependence of the settling velocity on the solids concentration. The compression and consolidation process of the activated sludge is simulated by this equation. The experimental data provided by Weiss et al. show that the rheograms follow the Bingham law at low-shear rates. The modified Bingham model was introduced to overcome the blanket height overestimation problem with the results showing that the local sludge distribution in the clarifier has an excellent agreement with the concentration profile measurements by Weiss et al. (2007) and the sludge viscosity dominates the flow and sedimentation of activated sludge within the sludge blanket.

Elastic optical networks (EONs) have emerged to provide higher spectrum efficiency than traditional Dense Wavelength-Division-Multiplexing (DWDM) by utilizing enabling technologies such as flexible spectrum grid, Orthogonal Frequency Division Multiplexing (OFDM), and distance adaptive rate and modulation. The choice of the control-plane is an important consideration when deploying any new technology, especially in optical networks. This paper considers generic distributed and centralized spectrum assignment policies in conjunction with the accompanying connection set-up signaling protocols in EONs. A network simulator for Generalized Multiprotocol Label Switching (GMPLS) was developed with Forward Reservation Protocol and Backward Reservation Protocol signaling methods. These signaling techniques are used with the First Fit (FF) and Random Fit (RF) Routing and Spectrum Allocation (RSA) algorithms. The paper discusses control elements (central and distributed architectures) decisions under busy hour and normal network conditions and presents a comprehensive performance analysis of key performance metrics such as connection success rate, connection establishment time, and capacity requirement.

Purpose This paper aims to investigate the convergence and error properties of a finite volume-based heat conduction code that uses automatic differentiation to evaluate derivatives of solutions outputs with respect to arbitrary solution input(s). A problem involving conduction in a plane wall with convection at its surfaces is used as a test problem, as it has an analytical solution, and the error can be evaluated directly. Design/methodology/approach The finite volume method is used to discretize the transient heat diffusion equation with constant thermophysical properties. The discretized problem is then linearized, which results in two linear systems; one for the primary solution field and one for the secondary field, representing the derivative of the primary field with respect to the selected input(s). Derivatives required in the formation of the secondary linear system are obtained by automatic differentiation using an operator overloading and templating approach in C++. Findings The temporal and spatial discretization error for the derivative solution follows the same order of accuracy as the primary solution. Second-order accuracy of the spatial and temporal discretization schemes is confirmed for both primary and secondary problems using both orthogonal and non-orthogonal grids. However, it has been found that for non-orthogonal cases, there is a limit to the error reduction, which is concluded to be a result of errors in the Gauss-based gradient reconstruction method. Originality/value The convergence and error properties of derivative solutions obtained by forward mode automatic differentiation of finite volume-based codes have not been previously investigated.

Under polar projection (the natural projection for visual scenes) motion parallax is a powerful cue specifying relative depth. For small-field stimuli, it is ambiguous in the sense that a concave surface can be perceived as convex and deforming. By contrast, concavity/convexity of wide-field surfaces is unambiguously perceived. This led us to hypothesise a critical role of the 3-D rigidity constraint for large visual scenes in motion (Dijkstra et al, 1995 Vision Research35 453 – 462). To examine this hypothesis, we exposed subjects to planes inclined in space, and asked them to report the tilt (direction of inclination). Depth was specified either by motion parallax (MP, the surface oscillated around a frontoparallel axis) or by static perspective cues (SP, orthogonal square grids drawn on the plane). At ECVP95, we had reported a predominance of SP over MP when the tilts specified by these two cues ( tMP and tSP respectively) differed (1995 Perception24 Supplement, 137). Since these results were obtained for fast movements (oscillation frequency for MP: 3.6 Hz), we extended our investigation to a slower frequency (0.5 Hz) which is more likely to be involved during natural head-movements. We found that: (i) errors in tilt reports were larger for MP than for SP, and decreased with increasing field-size; (ii) in the case of conflict ( tMP= tSP±90°), the reported tilt was either tMP or tSP, rather than an average of these two values; (iii) in this case, tilt was most often reported according to SP, rather than to MP cues; this effect occurred even when the accuracies for the two individual cues were similar. Therefore, in a conflict situation between MP and SP, surface orientation is reported according to a winner-take-all rule, which is largely in favour of static grid-cues. Hence, even for wide-field movements, the image contrast distribution can lead the visual system to prefer an unrigid, rather than rigid, solution to the 3-D shape-from-motion problem.

The streamwise velocity component is studied in fully developed turbulent channel flow for two very rough surfaces and a smooth surface at comparable Reynolds numbers. One rough surface comprises sparse and isotropic grit with a highly non-Gaussian distribution. The other is a uniform mesh consisting of twisted rectangular elements which form a diamond pattern. The mean roughness heights (±) the standard deviation) are, respectively, about 76(±42) and 145(±150) wall units. The flow is shown to be two-dimensional and fully developed up to the fourth-order moment of velocity. The mean velocity profile over the grit surface exhibits self-similarity (in the form of a logarithmic law) within the limited range of 0.04≤y/h≤0.06, but the profile over the mesh surface does not, even though the mean velocity deficit and higher moments (up to the fourth order) all exhibit outer scaling over both surfaces. The distinction between self-similarity and outer similarity is clarified and the importance of the former is explained. The wake strength is shown to increase slightly over the grit surface but decrease over the mesh surface. The latter result is contrary to recent measurements in rough-wall boundary layers. Single- and two-point velocity correlations reveal the presence of large-scale streamwise structures with circulation in the plane orthogonal to the mean velocity. Spanwise correlation length scales are significantly larger than corresponding ones for both internal and external smooth-wall flows.

We present a fast algorithm for solving the eikonal equation in three dimensions, based on the fast marching method. The algorithm is of the order O(N log N), where N is the total number of grid points in the computational domain. The algorithm can be used in any orthogonal coordinate system and globally constructs the solution to the eikonal equation for each point in the coordinate domain. The method is unconditionally stable and constructs solutions consistent with the exact solution for arbitrarily large gradient jumps in velocity. In addition, the method resolves any overturning propagation wavefronts. We begin with the mathematical foundation for solving the eikonal equation using the fast marching method and follow with the numerical details. We then show examples of traveltime propagation through the SEG/EAGE salt model using point‐source and plane‐wave initial conditions and analyze the error in constant velocity media. The algorithm allows for any shape of the initial wavefront. While a point source is the most commonly used initial condition, initial plane waves can be used for controlled illumination or for downward continuation of the traveltime field from one depth to another or from a topographic depth surface to another. The algorithm presented here is designed for computing first‐arrival traveltimes. Nonetheless, since it exploits the fast marching method for solving the eikonal equation, we believe it is the fastest of all possible consistent schemes to compute first arrivals.

The article is devoted to the scientific approach with the help of computer-aided design tools for modeling the processes of interaction of tillage tools with soil. The article has an applied character, which is expressed in the fact that the method of computer-aided design in Mathcad using software CAD COMPASS 3D has been used. The analyses of expressions in the form of three-dimensional graphs are widely presented and their detailed review is given, which can be used to perform the improvement of the design of units that perform the main treatment of the soil with a turnover of a layer. As a result of the work done, there was obtained a combined plowshare with additional flat-cutting working bodies, there was made a matrix of experiment planning, there was obtained a graph of the dependence of the width grip of the flat-cutting razor on the speed of the arable unit. There were substantiated the factors of influence on performance as a result of using the planning of the two-factor experiment due to the orthogonal plan, there were determined the optimal settings of the operation modes of the plowshare.

Drying is a method of preservation widely used to prolong the post-harvest life of several agricultural products. In this work, experiments were accomplished involving drying of whole bananas, using hot air at temperature of 40.0ºC and constant velocity of 1.5 m s-1. The mass loss in regular time intervals was measured using the gravimetric method. In order to describe the process, the liquid diffusion model was used, assuming variable volume and effective mass diffusivity [. Thus, the diffusion equation was numerically solved through the finite volume method, with a fully implicit formulation. Due to the geometry of the product, the diffusion equation was written in generalized coordinates, and then discretized, assuming boundary condition of the third kind [. To take advantage of the symmetry, bananas were considered as revolution solids, obtained by the rotation of an area in the plane (x,y) about the axis y. The area was obtained directly of the photography of a banana, which served to create a non-orthogonal structured grid with 32 x 40 control volumes. The thermo-physical parameters were obtained through an optimization algorithm, based on the inverse method. Once the thermo-physical parameters were known, the drying kinetics as well as the water distribution within the bananas in stipulated times were presented and analyzed. The statistical indicators enable to conclude the methodology proposed to describe whole banana drying presents good results.

We performed three-dimensional analysis of the conjoint changes of digit forces during prehension (prehension synergies) and tested applicability of the principle of superposition to three-dimensional tasks. Subjects performed 25 trials at statically holding a handle instrumented with six-component force/moment sensors under seven external torque conditions; –0.70, –0.47, –0.23, 0.00, 0.23, 0.47, and 0.70 Nm about a horizontal axis in the plane passing through the centers of all five digit force sensors (the grasp plane). The total weight of the system was always 10.24 N. The trial-to-trial variability of the forces produced by the thumb and the virtual finger (an imagined finger producing the same mechanical effects as all 4 finger forces and moments combined) increased in all three dimensions with the external torque magnitude. The sets of force and moment variables associated with the moment production about the vertical axis in the grasp plane and the axis orthogonal to the grasp plane consisted of two noncorrelated subsets each; one subset of variables was related to the control of grasping forces ( grasp control) and the other sassociated with the control of the orientation of the hand-held object ( torque control). The variables associated with the moment production about the horizontal axis in the grasp plane did not include the grip force (the normal thumb and virtual finger forces) and showed more complex noncorrelated subsets. We conclude that the principle of superposition is valid for the prehension in three dimensions. The observed high correlations among forces and moments associated with the control of object orientation could be explained by chain effects, the sequences of cause-effect relations necessitated by mechanical constraints.

The energy barrier method, first proposed by Boothroyd and associates, can be used to determine the probabilities of the natural resting aspects of objects to be conveyed on and oriented by vibratory devices. However, for parts of uniform cross-section other than square or rectangular ones, the application of the method can be intractable. In such cases, Boothroyd and associates recommended circumscribing the part by a cylinder and using the energy barrier for the cylinder to approximate the probabilities of the natural resting aspects of the part. This approximation is understandably inexact although computationally expedient. This paper outlines the CAD (computer aided design) computation of the probabilities from the energy barriers for two objects: one, a triangular prism with equilateral sides (representing objects with adjacent faces that are not mutually perpendicular) and the second, an L-shaped prism with a virtual resting aspect. The significance of the centroid plane of the part in the determination of the probabilities is discussed. The CAD computations were carried out using the Graphical Interface Programming (GRIP) Language of McDonnell Douglas' UniGraphics II™ CAD system running on a DEC 9000 workstation.

The scaling laws for the reconnection of isolated pairs of quantised vortices are characterised by numerically integrating the three-dimensional Gross–Pitaevskii equations, the simplest mean-field equations for a quantum fluid. The primary result is the identification of distinctly different temporal power laws for the pre- and post-reconnection separation distances $\unicode[STIX]{x1D6FF}(t)$ for two configurations. For the initially anti-parallel case, the scaling laws before and after the reconnection time $t_{r}$ obey the dimensional $\unicode[STIX]{x1D6FF}\sim |t_{r}-t|^{1/2}$ prediction with temporal symmetry about $t_{r}$ and physical space symmetry about the mid-point between the vortices $x_{r}$. The extensions of the vortex lines close to reconnection form the edges of an equilateral pyramid. For all of the initially orthogonal cases, $\unicode[STIX]{x1D6FF}\sim |t_{r}-t|^{1/3}$ before reconnection and $\unicode[STIX]{x1D6FF}\sim |t-t_{r}|^{2/3}$ after reconnection are respectively slower and faster than the dimensional prediction. For both configurations, smooth scaling laws are generated due to two innovations. The first innovation is to use an initial low-energy vortex-core density profile that suppresses unwanted density fluctuations as the vortices evolve in time. The other innovation is the accurate identification of the position of the vortex cores from a pseudo-vorticity constructed on the three-dimensional grid from the gradients of the wave function. These trajectories allow us to calculate the Frenet–Serret frames and the curvature of the vortex lines, secondary results that might hold clues for the origin of the differences between the scaling laws of the two configurations. Reconnection takes place in a reconnection plane defined by the average tangents $\boldsymbol{T}_{av}$ and curvature normal $\boldsymbol{N}_{av}$ directions of the pseudo-vorticity curves at the points of closest approach, at time $t\approx t_{r}$. To characterise the structure further, lines are drawn that connect the four arms that extend from the reconnection plane, from which four angles $\unicode[STIX]{x1D703}_{i}$ between the lines are defined. Their sum is convex or hyperbolic, that is $\sum _{i=1,4}\unicode[STIX]{x1D703}_{i}>360^{\circ }$, for the orthogonal cases, as opposed to the acute angles of the pyramid found for the anti-parallel initial conditions.

Object Functional imaging is an established neurosurgical modality for studying the brain in health and disease. Identifying numerous activation loci on many functional images and reading their underlying cortical and subcortical anatomy, coordinates, and anatomical and functional values is a tedious, time-consuming, and error-prone task. In this study the authors propose a novel approach to this problem by using an electronic brain atlas in conjunction with a locus-driven mechanism. Methods The Brain Atlas for Functional Imaging containing an enhanced and extended electronic version of the Talairach–Tournoux brain atlas was used for analysis. It enables loading of anatomical and functional data, correlation of these data, identification of activation loci, and their labeling with Brodmann areas, gyri, and subcortical structures by means of the atlas. The Talairach proportional grid system transformation is used to register the anatomical and functional data with the atlas. The availability of numerous tools supports this process. A locus-driven mechanism for analysis of activation loci is implemented. Locus placement within the activation region is supported by thresholding, and its location can be further edited in three dimensions on any orthogonal plane. Once all loci are identified and edited, their labels, coordinates, and anatomical/functional values are read automatically and saved in an external file. This mechanism enables the analysis to be performed in an automated, rapid, explicit, three-dimensionally consistent, and user-friendly way. Conclusions The electronic brain atlas with locus-driven mechanism is a useful tool for localization analysis of functional images.

AbstractThe tree species composition can influence the dynamics of herbaceous species and enhance the spatial heterogeneity of the soil. But there is very little evidence on how both overstorey structure and soil properties affect the spatial variation of the herb layer. The aim of this study is to evaluate the factors of the soil and overstorey structure by which it is possible to explain the fine-scale variation of herbaceous layer communities in an Eastern European poplar-willow forest. The research was conducted in the “Dnipro-Orils’kiy” Nature Reserve (Ukraine). The research polygon (48°30′51″N, 34°49″02″E) was laid in an Eastern European poplar-willow forest in the floodplain of the River Protich, which is a left inflow of the River Dnipro. The site consists of 7 transects. Each transect was made up of 15 test points. The distance between rows in the site was 3 m. At the site, we established a plot of 45×21 m, with 105 subplots of 3×3 m organized in a regular grid. The adjacent subplots were in close proximity. Vascular plant species lists were recorded at each 3×3 m subplot along with visual estimates of species cover using the nine-degree Braun-Blanquet scale. Within the plot, all woody stems ≥ 1 cm in diameter at breast height were measured and mapped. Dixon’s segregation index was calculated for tree species to quantify their relative spatial mixing. Based on geobotanical descriptions, a phytoindicative assessment of environmental factors according to the Didukh scale was made. The redundancy analysis was used for the analysis of variance in the herbaceous layer species composition. The geographic coordinates of sampling locations were used to generate a set of orthogonal eigenvector-based spatial variables. Two measurements of the overstorey spatial structure were applied: the distances from the nearest tree of each species and the distance based on the evaluation of spatial density of point objects, which are separate trees. In both cases, the distance matrix of sampling locations was calculated, which provided the opportunity to generate eigenvector-based spatial variables. A kernel smoothed intensity function was used to compute the density of the trees’ spatial distribution from the point patterns’ data. Gaussian kernel functions with various bandwidths were used. The coordinates of sampling locations in the space obtained after the conversion of the trees’ spatial distribution densities were used to generate a set of orthogonal eigenvector-based spatial variables, each of them representing a pattern of particular scale within the extent of the bandwidth area structured according to distance and reciprocal placement of the trees. An overall test of random labelling reveals the total nonrandom distribution of the tree stems within the site. The unexplained variation consists of 43.8%. The variation explained solely by soil variables is equal to 15.5%, while the variation explained both by spatial and soil variables is 18.0%. The measure of the overstorey spatial structure, which is based on the evaluation of its density enables us to obtain different estimations depending on the bandwidth. The bandwidth affects the explanatory capacity of the tree stand. A considerable part of the plant community variation explained by soil factors was spatially structured. The orthogonal eigenvector-based spatial variables (dbMEMs) approach can be extended to quantifying the effect of forest structures on the herbaceous layer community. The measure of the overstorey spatial structure, which is based on the evaluation of its density, was very useful in explaining herbaceous layer community variation.

Abstract BACKGROUND The Hælo pediatric system, an investigational medical device intended to treat diffuse midline glioma (DMG), emits a magnetic field intended to disrupt the growth of DMG tumors. The Hælo headcoil is positioned on the back of the patient’s head; the field envelopes the patient’s head and the specific frequencies of the field penetrate the skull and brain tissue without any significant attenuation. METHODS The shape and intensity of the magnetic field emitted by the Hælo headcoil were measured using a triaxial magnetic sensor, which measures the flux density along three orthogonal axes. The headcoil is designed to conform to the back of the head and is not planar. To account for the slight difference in field shape due to the coil’s convex shape, the field was measured with the coil held in both a convex and concave position relative to the central plane. A custom-designed measurement system was used to position the sensor in a three-dimensional grid with 1 cm resolution (approximately 10,000 individual measurements for each coil position.) A test field with the same flux density produced by the Hælo pediatric system treatment field was used. The root mean square of the field along each axis was calculated and combined to yield the total flux density at each position. The datasets from each coil position were combined to create a complete three-dimensional map of the field generated by the headcoil. RESULTS The greatest flux density is proximal to the coil. The test field ranged from approximately 200 mGauss near the headcoil to 100 mG within the ellipsoid formed by the headcoil. CONCLUSION The field of the Hælo pediatric system encompasses the brain and portions of the brainstem, and thus delivers a targeted magnetic therapeutic to the common tumor locations for DMG.

Overhead high-voltage conductors are the chief components of power lines and their safety has a strong influence on social and daily life. In the recent decade, the airborne laser scanning (ALS) technique has been widely used to capture the three-dimensional (3D) information of power lines and surrounding objects. Most of the existing methods focused on extraction of single conductors or extracted all conductors as one object class by applying machine learning techniques. Nevertheless, power line corridors (PLCs) are built with multi-loop, multi-phase structures (bundle conductors) and exist in intricate environments (e.g., mountains and forests), and thus raise challenges to process ALS data for extraction of individual conductors. This paper proposes an automated method to extract individual subconductors in bundles from complex structure of PLCs using a combined image- and point-based approach. First, the input point cloud data are grouped into 3D voxel grid and PL points and separated from pylon and tree points using the fact that pylons and trees are vertical objects while power lines are non-vertical objects. These pylons are further separated from trees by employing a statistical analysis technique and used to extract span points between two consecutive pylons; then, by using the distribution properties of power lines in each individual span, the bundles located at different height levels are extracted using image-based processing; finally, subconductors in each bundle are detected and extracted by introducing a window that slides over the individual bundle. The orthogonal plane transformation and recursive clustering procedures are exploited in each window position and a point-based processing is conducted iteratively for extraction of complete individual subconductors in each bundle. The feasibility and validity of the proposed method are verified on two Australian sites having bundle conductors in high-voltage transmission lines. Our experiments show that the proposed method achieves a reliable result by extracting the real structure of bundle conductors in power lines with correctness of 100% and 90% in the two test sites, respectively.

Laplace equation is the basic differential equation that governs the steady flow of a fluid through an isotropic and homogeneous porous medium and also the steady flow of current in a conducting medium. Therefore, a steady-state groundwater flow problem can be formulated as an analogous electrical current flow problem. A flow net, set of grids formed by orthogonally intersecting equipotential lines and flow lines, is a graphical solution to the equations of steady groundwater flow. By definition, flownet for the original groundwater problem and the corresponding analogous electrical problem should be similar. This feature allows the possibility of introducing the concepts of flownets to students using the easily demonstrable electrical counterpart of the problem in a laboratory setting. This paper discusses the efforts of the authors to widen the scope of an experiment already included in the Fluid Mechanics laboratory course of a Civil Engineering curriculum and to better teach flownet principles using the electrical analogy of groundwater flow problems. Students used a simple experimental setup to obtain flownets for selected groundwater flow situations with different boundary conditions using the electrical analogy concept. Students also used a groundwater flow computer model to obtain flownets for the same flow situations and compared the results. The laboratory lesson plan consisted of five steps: (i) study and understand the selected physical groundwater problems, (ii) conceptualize the corresponding analogous electrical problems (iii) use the electrical analogy experimental setup to obtain flownets, (iv) study and understand the mathematical formulation of the problems, and (v) compare the analogous results with those obtained from a groundwater flow computer model. Sample results obtained by students are presented. The student feedback indicated that this approach resulted in an effective learning of the concepts involved.

Abstract An important but insufficiently addressed issue for machine learning in engineering applications is the task of model selection for new problems. Existing approaches to model selection generally focus on optimizing the learning algorithm and associated hyperparameters. However, in real-world engineering applications, the parameters that are external to the learning algorithm, such as feature engineering, can also have a significant impact on the performance of the model. These external parameters do not fit into most existing approaches for model selection and are therefore often studied ad hoc or not at all. In this article, we develop a statistical design of experiment (DOEs) approach to model selection based on the use of the Taguchi method. The key idea is that we use orthogonal arrays to plan a set of build-and-test experiments to study the external parameters in combination with the learning algorithm. The use of orthogonal arrays maximizes the information learned from each experiment and, therefore, enables the experimental space to be explored extremely efficiently in comparison with grid or random search methods. We demonstrated the application of the statistical DOE approach to a real-world model selection problem involving predicting service request escalation. Statistical DOE significantly reduced the number of experiments necessary to fully explore the external parameters for this problem and was able to successfully optimize the model with respect to the objective function of minimizing total cost in addition to the standard evaluation metrics such as accuracy, f-measure, and g-mean.

The digital era has brought about an impressive increase in the volume of published species occurrence data. Research infrastructures such as the Global Biodiversity Information Facility (GBIF), the digitization of legacy data, and the use of mobile applications have all played a role in this transition. More data implies, unavoidably, more heterogeneity at multiple levels as a result of the different methods and standards used to collect data. Data standardization and aggregation help to reduce this heterogeneity. Furthermore, intermediate data products that can be used for activities such as mapping, modeling and monitoring improve the repeatability and reproducibility of biodiversity research (Kissling et al. 2017). Occurrences can be defined as events in a three-dimensional space where the dimensions are taxonomic (what), temporal (when) and spatial (where). They are then aggregated into what we coined occurrence cube (Fig. 1). The taxonomic dimension is categorical. Research infrastructures like GBIF use a taxonomic backbone, thus making data aggregation at species level or higher rank relatively easy. The temporal dimension is a continuum and the temporal uncertainty is usually lower than the typical aggregation span, typically a year. Regarding the spatial dimension, occurrences are typically filtered to remove those with too large an uncertainty to fit the grid scheme being used. Meaning that the spatial uncertainty is largely unused. We developed a method to take into account this spatial uncertainty while aggregating data. In particular, we state that an occurrence is spatially representable as a closed plane figure such as a circle, hexagon or square, never as the geometric centre (centroid) of it. As for GBIF occurrence data, the coordinateUncertaintyInMeters is defined as the radius describing the smallest circle containing the whole of the location (see Darwin Core standard). So, spatially speaking, we refer to occurrences as circles, even if the method described below is general. After harvesting the occurrence data and providing a data quality assessment (e.g. removing occurrences without coordinates or with suspicious coordinates) we can assign occurrences to a reference grid such as the European reference grid of the European Environment Agency (EEA) at 1 km scale. In this spatial aggregation we randomly choose a point within the occurrence circle and assign it to the grid cell in which it is contained. We can aggregate further by time (e.g. by year) and taxonomy (e.g. by species), where aggregating means counting how many occurrences are in each specific taxonomic-spatial-temporal unit. The analogy with geometry goes further: the occurrence cube can, as any cube, be projected on an orthogonal plane by aggregating along one of the three dimensions. In particular, projecting the cube on the taxonomic and temporal dimensions can be done by adding up the number of occurrences, or counting the number of occupied cells, thus estimating the area of occupancy. The occurrence cube paradigm has been developed within the Tracking Invasive Alien Species (TrIAS) project (Vanderhoeven et al. 2017) following Open Science and FAIR principles. We created and published occurrence cubes at the species level for Belgium and Italy (Oldoni et al. 2020b) and the occurrence cubes for non-native taxa in Belgium and Europe (Oldoni et al. 2020a).

Fluid flow in fractured porous media has always been important in different engineering applications especially in hydrology and reservoir engineering. However, by the onset of the hydraulic fracturing revolution, massive fracturing jobs have been implemented in unconventional hydrocarbon resources such as tight gas and shale gas reservoirs that make understanding fluid flow in fractured media more significant. Considering ultralow permeability of these reservoirs, induced complex fracture networks play a significant role in economic production of these resources. Hence, having a robust and fast numerical technique to evaluate flow through complex fracture networks can play a crucial role in the progress of inversion methods to determine fracture geometries in the subsurface. Current methods for tight gas flow in fractured reservoirs, despite their advantages, still have several shortcomings that make their application for real field problems limited. For instance, the dual permeability theory assumes an ideal uniform orthogonal distribution of fractures, which is quite different from field observation; on the other hand, numerical methods like discrete fracture network (DFN) models can portray the irregular distribution of fractures, but requires massive mesh refinements to have the fractures aligned with the grid/element edges, which can greatly increase the computational cost and simulation time. This paper combines the extended finite element methods (XFEM) and the gas pseudo-pressure to simulate gas flow in fractured tight gas reservoirs by incorporating the strong-discontinuity enrichment scheme to capture the weak-discontinuity feature induced by highly permeable fractures. Utilizing pseudo-pressure formulations simplifies the governing equations and reduces the nonlinearity of the problem significantly. This technique can consider multiple fracture sets and their intersection to mimic real fracture networks on a plain structured mesh. Here, we utilize the unified Hagen–Poiseuille-type equation to compute the permeability of tight gas, and finally adopt Newton–Raphson iteration method to solve the highly nonlinear equations. Numerical results illustrate that XFEM is considerably effective in fast calculation of gas flow in fractured porous media.

Introduction Explorations of the multimedia game format within cultural studies have been broadly approached from two perspectives: one -- the impact of technologies on user interaction particularly with regard to social implications, and the other -- human computer interactions within the framework of cybercultures. Another approach to understanding or speaking about games within cultural studies is to focus on the game experience as cultural practice -- as an activity or an event. In this article I wish to initiate an exploration of the aesthetics of player space as a distinctive element of the gameplay experience. In doing so I propose that an understanding of aesthetic spatial issues as an element of player interactivity and engagement is important for understanding the cultural practice of adventure gameplay. In approaching these questions, I am focussing on the single-player exploration adventure game in particular Myst and The Crystal Key. In describing these games as adventures I am drawing on Chris Crawford's The Art of Computer Game Design, which although a little dated, focusses on game design as a distinct activity. He brings together a theoretical approach with extensive experience as a game designer himself (Excalibur, Legionnaire, Gossip). Whilst at Atari he also worked with Brenda Laurel, a key theorist in the area of computer design and dramatic structure. Adventure games such as Myst and The Crystal Key might form a sub-genre in Chris Crawford's taxonomy of computer game design. Although they use the main conventions of the adventure game -- essentially a puzzle to be solved with characters within a story context -- the main focus and source of pleasure for the player is exploration, particularly the exploration of worlds or cosmologies. The main gameplay of both games is to travel through worlds solving clues, picking up objects, and interacting with other characters. In Myst the player has to solve the riddle of the world they have entered -- as the CD-ROM insert states "Now you're here, wherever here is, with no option but to explore." The goal, as the player must work out, is to release the father Atrus from prison by bringing magic pages of a book to different locations in the worlds. Hints are offered by broken-up, disrupted video clips shown throughout the game. In The Crystal Key, the player as test pilot has to save a civilisation by finding clues, picking up objects, mending ships and defeating an opponent. The questions foregrounded by a focus on the aesthetics of navigation are: What types of representational context are being set up? What choices have designers made about representational context? How are the players positioned within these spaces? What are the implications for the player's sense of orientation and navigation? Architectural Fabrication For the ancient Greeks, painting was divided into two categories: magalography (the painting of great things) and rhyparography (the painting of small things). Magalography covered mythological and historical scenes, which emphasised architectural settings, the human figure and grand landscapes. Rhyparography referred to still lifes and objects. In adventure games, particularly those that attempt to construct a cosmology such as Myst and The Crystal Key, magalography and rhyparography collide in a mix of architectural monumentality and obsessive detailing of objects. For the ancient Greeks, painting was divided into two categories: magalography (the painting of great things) and rhyparography (the painting of small things). Magalography covered mythological and historical scenes, which emphasised architectural settings, the human figure and grand landscapes. Rhyparography referred to still lifes and objects. In adventure games, particularly those that attempt to construct a cosmology such as Myst and The Crystal Key, magalography and rhyparography collide in a mix of architectural monumentality and obsessive detailing of objects. The creation of a digital architecture in adventure games mimics the Pompeii wall paintings with their interplay of extruded and painted features. In visualising the space of a cosmology, the environment starts to be coded like the urban or built environment with underlying geometry and textured surface or dressing. In The Making of Myst (packaged with the CD-ROM) Chuck Carter, the artist on Myst, outlines the process of creating Myst Island through painting the terrain in grey scale then extruding the features and adding textural render -- a methodology that lends itself to a hybrid of architectural and painted geometry. Examples of external architecture and of internal room design can be viewed online. In the spatial organisation of the murals of Pompeii and later Rome, orthogonals converged towards several vertical axes showing multiple points of view simultaneously. During the high Renaissance, notions of perspective developed into a more formal system known as the construzione legittima or legitimate construction. This assumed a singular position of the on-looker standing in the same place as that occupied by the artist when the painting was constructed. In Myst there is an exaggeration of the underlying structuring technique of the construzione legittima with its emphasis on geometry and mathematics. The player looks down at a slight angle onto the screen from a fixed vantage point and is signified as being within the cosmological expanse, either in off-screen space or as the cursor. Within the cosmology, the island as built environment appears as though viewed through an enlarging lens, creating the precision and coldness of a Piero della Francesca painting. Myst mixes flat and three-dimensional forms of imagery on the same screen -- the flat, sketchy portrayal of the trees of Myst Island exists side-by-side with the monumental architectural buildings and landscape design structures created in Macromodel. This image shows the flat, almost expressionistic trees of Myst Island juxtaposed with a fountain rendered in high detail. This recalls the work of Giotto in the Arena chapel. In Joachim's Dream, objects and buildings have depth, but trees, plants and sky -- the space in-between objects -- is flat. Myst Island conjures up the realm of a magic, realist space with obsolete artefacts, classic architectural styles (the Albert Hall as the domed launch pad, the British Museum as the library, the vernacular cottage in the wood), mechanical wonders, miniature ships, fountains, wells, macabre torture instruments, ziggurat-like towers, symbols and odd numerological codes. Adam Mates describes it as "that beautiful piece of brain-deadening sticky-sweet eye-candy" but more than mere eye-candy or graphic verisimilitude, it is the mix of cultural ingredients and signs that makes Myst an intriguing place to play. The buildings in The Crystal Key, an exploratory adventure game in a similar genre to Myst, celebrate the machine aesthetic and modernism with Buckminster Fuller style geodesic structures, the bombe shape, exposed ducting, glass and steel, interiors with movable room partitions and abstract expressionist decorations. An image of one of these modernist structures is available online. The Crystal Key uses QuickTime VR panoramas to construct the exterior and interior spaces. Different from the sharp detail of Myst's structures, the focus changes from sharp in wide shot to soft focus in close up, with hot-spot objects rendered in trompe l'oeil detail. The Tactility of Objects "The aim of trompe l'oeil -- using the term in its widest sense and applying it to both painting and objects -- is primarily to puzzle and to mystify" (Battersby 19). In the 15th century, Brunelleschi invented a screen with central apparatus in order to obtain exact perspective -- the monocular vision of the camera obscura. During the 17th century, there was a renewed interest in optics by the Dutch artists of the Rembrandt school (inspired by instruments developed for Dutch seafaring ventures), in particular Vermeer, Hoogstraten, de Hooch and Dou. Gerard Dou's painting of a woman chopping onions shows this. These artists were experimenting with interior perspective and trompe l'oeil in order to depict the minutia of the middle-class, domestic interior. Within these luminous interiors, with their receding tiles and domestic furniture, is an elevation of the significance of rhyparography. In the Girl Chopping Onions of 1646 by Gerard Dou the small things are emphasised -- the group of onions, candlestick holder, dead fowl, metal pitcher, and bird cage. Trompe l'oeil as an illusionist strategy is taken up in the worlds of Myst, The Crystal Key and others in the adventure game genre. Traditionally, the fascination of trompe l'oeil rests upon the tension between the actual painting and the scam; the physical structures and the faux painted structures call for the viewer to step closer to wave at a fly or test if the glass had actually broken in the frame. Mirian Milman describes trompe l'oeil painting in the following manner: "the repertory of trompe-l'oeil painting is made up of obsessive elements, it represents a reality immobilised by nails, held in the grip of death, corroded by time, glimpsed through half-open doors or curtains, containing messages that are sometimes unreadable, allusions that are often misunderstood, and a disorder of seemingly familiar and yet remote objects" (105). Her description could be a scene from Myst with in its suggestion of theatricality, rich texture and illusionistic play of riddle or puzzle. In the trompe l'oeil painterly device known as cartellino, niches and recesses in the wall are represented with projecting elements and mock bas-relief. This architectural trickery is simulated in the digital imaging of extruded and painting elements to give depth to an interior or an object. Other techniques common to trompe l'oeil -- doors, shadowy depths and staircases, half opened cupboard, and paintings often with drapes and curtains to suggest a layering of planes -- are used throughout Myst as transition points. In the trompe l'oeil paintings, these transition points were often framed with curtains or drapes that appeared to be from the spectator space -- creating a painting of a painting effect. Myst is rich in this suggestion of worlds within worlds through the framing gesture afforded by windows, doors, picture frames, bookcases and fireplaces. Views from a window -- a distant landscape or a domestic view, a common device for trompe l'oeil -- are used in Myst to represent passageways and transitions onto different levels. Vertical space is critical for extending navigation beyond the horizontal through the terraced landscape -- the tower, antechamber, dungeon, cellars and lifts of the fictional world. Screen shots show the use of the curve, light diffusion and terracing to invite the player. In The Crystal Key vertical space is limited to the extent of the QTVR tilt making navigation more of a horizontal experience. Out-Stilling the Still Dutch and Flemish miniatures of the 17th century give the impression of being viewed from above and through a focussing lens. As Mastai notes: "trompe l'oeil, therefore is not merely a certain kind of still life painting, it should in fact 'out-still' the stillest of still lifes" (156). The intricate detailing of objects rendered in higher resolution than the background elements creates a type of hyper-reality that is used in Myst to emphasise the physicality and actuality of objects. This ultimately enlarges the sense of space between objects and codes them as elements of significance within the gameplay. The obsessive, almost fetishistic, detailed displays of material artefacts recall the curiosity cabinets of Fabritius and Hoogstraten. The mechanical world of Myst replicates the Dutch 17th century fascination with the optical devices of the telescope, the convex mirror and the prism, by coding them as key signifiers/icons in the frame. In his peepshow of 1660, Hoogstraten plays with an enigma and optical illusion of a Dutch domestic interior seen as though through the wrong end of a telescope. Using the anamorphic effect, the image only makes sense from one vantage point -- an effect which has a contemporary counterpart in the digital morphing widely used in adventure games. The use of crumbled or folded paper standing out from the plane surface of the canvas was a recurring motif of the Vanitas trompe l'oeil paintings. The highly detailed representation and organisation of objects in the Vanitas pictures contained the narrative or symbology of a religious or moral tale. (As in this example by Hoogstraten.) In the cosmology of Myst and The Crystal Key, paper contains the narrative of the back-story lovingly represented in scrolls, books and curled paper messages. The entry into Myst is through the pages of an open book, and throughout the game, books occupy a privileged position as holders of stories and secrets that are used to unlock the puzzles of the game. Myst can be read as a Dantesque, labyrinthine journey with its rich tapestry of images, its multi-level historical associations and battle of good and evil. Indeed the developers, brothers Robyn and Rand Miller, had a fertile background to draw on, from a childhood spent travelling to Bible churches with their nondenominational preacher father. The Diorama as System Event The diorama (story in the round) or mechanical exhibit invented by Daguerre in the 19th century created a mini-cosmology with player anticipation, action and narrative. It functioned as a mini-theatre (with the spectator forming the fourth wall), offering a peek into mini-episodes from foreign worlds of experience. The Musée Mechanique in San Francisco has dioramas of the Chinese opium den, party on the captain's boat, French execution scenes and ghostly graveyard episodes amongst its many offerings, including a still showing an upper class dancing party called A Message from the Sea. These function in tandem with other forbidden pleasures of the late 19th century -- public displays of the dead, waxwork museums and kinetescope flip cards with their voyeuristic "What the Butler Saw", and "What the Maid Did on Her Day Off" tropes. Myst, along with The 7th Guest, Doom and Tomb Raider show a similar taste for verisimilitude and the macabre. However, the pre-rendered scenes of Myst and The Crystal Key allow for more diorama like elaborate and embellished details compared to the emphasis on speed in the real-time-rendered graphics of the shoot-'em-ups. In the gameplay of adventure games, animated moments function as rewards or responsive system events: allowing the player to navigate through the seemingly solid wall; enabling curtains to be swung back, passageways to appear, doors to open, bookcases to disappear. These short sequences resemble the techniques used in mechanical dioramas where a coin placed in the slot enables a curtain or doorway to open revealing a miniature narrative or tableau -- the closure of the narrative resulting in the doorway shutting or the curtain being pulled over again. These repeating cycles of contemplation-action-closure offer the player one of the rewards of the puzzle solution. The sense of verisimilitude and immersion in these scenes is underscored by the addition of sound effects (doors slamming, lifts creaking, room atmosphere) and music. Geographic Locomotion Static imagery is the standard backdrop of the navigable space of the cosmology game landscape. Myst used a virtual camera around a virtual set to create a sequence of still camera shots for each point of view. The use of the still image lends itself to a sense of the tableauesque -- the moment frozen in time. These tableauesque moments tend towards the clean and anaesthetic, lacking any evidence of the player's visceral presence or of other human habitation. The player's navigation from one tableau screen to the next takes the form of a 'cyber-leap' or visual jump cut. These jumps -- forward, backwards, up, down, west, east -- follow on from the geographic orientation of the early text-based adventure games. In their graphic form, they reveal a new framing angle or point of view on the scene whilst ignoring the rules of classical continuity editing. Games such as The Crystal Key show the player's movement through space (from one QTVR node to another) by employing a disorientating fast zoom, as though from the perspective of a supercharged wheelchair. Rather than reconciling the player to the state of movement, this technique tends to draw attention to the technologies of the programming apparatus. The Crystal Key sets up a meticulous screen language similar to filmic dramatic conventions then breaks its own conventions by allowing the player to jump out of the crashed spaceship through the still intact window. The landscape in adventure games is always partial, cropped and fragmented. The player has to try and map the geographical relationship of the environment in order to understand where they are and how to proceed (or go back). Examples include selecting the number of marker switches on the island to receive Atrus's message and the orientation of Myst's tower in the library map to obtain key clues. A screenshot shows the arrival point in Myst from the dock. In comprehending the landscape, which has no centre, the player has to create a mental map of the environment by sorting significant connecting elements into chunks of spatial elements similar to a Guy Debord Situationist map. Playing the Flaneur The player in Myst can afford to saunter through the landscape, meandering at a more leisurely pace that would be possible in a competitive shoot-'em-up, behaving as a type of flaneur. The image of the flaneur as described by Baudelaire motions towards fin de siècle decadence, the image of the socially marginal, the dispossessed aristocrat wandering the urban landscape ready for adventure and unusual exploits. This develops into the idea of the artist as observer meandering through city spaces and using the power of memory in evoking what is observed for translation into paintings, writing or poetry. In Myst, the player as flaneur, rather than creating paintings or writing, is scanning the landscape for clues, witnessing objects, possible hints and pick-ups. The numbers in the keypad in the antechamber, the notes from Atrus, the handles on the island marker, the tower in the forest and the miniature ship in the fountain all form part of a mnemomic trompe l'oeil. A screenshot shows the path to the library with one of the island markers and the note from Atrus. In the world of Myst, the player has no avatar presence and wanders around a seemingly unpeopled landscape -- strolling as a tourist venturing into the unknown -- creating and storing a mental map of objects and places. In places these become items for collection -- cultural icons with an emphasised materiality. In The Crystal Key iconography they appear at the bottom of the screen pulsing with relevance when active. A screenshot shows a view to a distant forest with the "pick-ups" at the bottom of the screen. This process of accumulation and synthesis suggests a Surrealist version of Joseph Cornell's strolls around Manhattan -- collecting, shifting and organising objects into significance. In his 1982 taxonomy of game design, Chris Crawford argues that without competition these worlds are not really games at all. That was before the existence of the Myst adventure sub-genre where the pleasures of the flaneur are a particular aspect of the gameplay pleasures outside of the rules of win/loose, combat and dominance. By turning the landscape itself into a pathway of significance signs and symbols, Myst, The Crystal Key and other games in the sub-genre offer different types of pleasures from combat or sport -- the pleasures of the stroll -- the player as observer and cultural explorer. References Battersby, M. Trompe L'Oeil: The Eye Deceived. New York: St. Martin's, 1974. Crawford, C. The Art of Computer Game Design. Original publication 1982, book out of print. 15 Oct. 2000 <http://members.nbci.com/kalid/art/art.php>. Darley Andrew. Visual Digital Culture: Surface Play and Spectacle in New Media Genres. London: Routledge, 2000. Lunenfeld, P. Digital Dialectic: New Essays on New Media. Cambridge, Mass.: MIT P 1999. Mates, A. Effective Illusory Worlds: A Comparative Analysis of Interfaces in Contemporary Interactive Fiction. 1998. 15 Oct. 2000 <http://www.wwa.com/~mathes/stuff/writings>. Mastai, M. L. d'Orange. Illusion in Art, Trompe L'Oeil: A History of Pictorial Illusion. New York: Abaris, 1975. Miller, Robyn and Rand. "The Making of Myst." Myst. Cyan and Broderbund, 1993. Milman, M. Trompe-L'Oeil: The Illusion of Reality. New York: Skira Rizzoli, 1982. Murray, J. Hamlet on the Holodeck: The Future of Narrative in Cyberspace. New York: Simon and Schuster, 1997. Wertheim, M. The Pearly Gates of Cyberspace: A History of Cyberspace from Dante to the Internet. Sydney: Doubleday, 1999. Game References 7th Guest. Trilobyte, Inc., distributed by Virgin Games, 1993. Doom. Id Software, 1992. Excalibur. Chris Crawford, 1982. Myst. Cyan and Broderbund, 1993. Tomb Raider. Core Design and Eidos Interactive, 1996. The Crystal Key. Dreamcatcher Interactive, 1999. Citation reference for this article MLA style: Bernadette Flynn. "Towards an Aesthetics of Navigation -- Spatial Organisation in the Cosmology of the Adventure Game." M/C: A Journal of Media and Culture 3.5 (2000). [your date of access] <http://www.api-network.com/mc/0010/navigation.php>. Chicago style: Bernadette Flynn, "Towards an Aesthetics of Navigation -- Spatial Organisation in the Cosmology of the Adventure Game," M/C: A Journal of Media and Culture 3, no. 5 (2000), <http://www.api-network.com/mc/0010/navigation.php> ([your date of access]). APA style: Bernadette Flynn. (2000) Towards an aesthetics of navigation -- spatial organisation in the cosmology of the adventure game. M/C: A Journal of Media and Culture 3(5). <http://www.api-network.com/mc/0010/navigation.php> ([your date of access]).