Layout Geometry Research Articles

Interactions between extreme climate and urban morphology: Investigating the evolution of extreme wind speeds from mesoscale to microscale

This paper investigates the interactions between urban morphology indicators and extreme weather variables. In this regard, variations of wind speed and air temperature at the urban microscale are studied for three urban morphologies by means of numerical simulations. Each urban model contains ninety-nine calculation points at different locations and heights to assess the variations during two 24-h cycles of extreme low and high wind speeds by introducing a microscale indicator. According to the results, transforming from mesoscale to microscale can considerably dampen the magnitude of wind speed (up to 66%) and amplify the air temperature (up to 39%). Moreover, the urban morphology parameters (layout geometry, final height and urban density) can change the average magnitude of wind speed (up to 23%) and air temperature (up to 16%) at microscale. For extreme low wind speeds (0.16–1.14 m/s), strong correlations exist between the mesoscale and microscale magnitude of wind speed and air temperature, while there is no significant correlation for extreme high wind speeds (12.2–14 m/s). For extreme low wind speeds, stronger buoyancy effects are observed at the urban canopies. An easy-to-setup approach is proposed to count for microscale conditions during extreme low wind speeds in urban climate studies.

Research on the working mechanism of the PDC drill bit in compound drilling

A combined ground-driven and down-hole-driven motor significantly improves the penetration rate of polycrystalline diamond compact (PDC) drill bits but greatly reduces bit life. By studying the mechanical behavior of the drill string in compound drilling, a kinematics model of a PDC drill bit under compound drilling was established, and the effects of transmission ratio, cutter layout, and drill string geometry on the cutting trajectory formed by the cutters were analyzed. Furthermore, a numerical drilling simulation of the PDC drill bit was developed and enhanced to research the kinematics and cutting regularities of the PDC drill bit in compound drilling. In addition to high rotation rate, nonparallel scraping of the PDC cutters and the unbalanced contact state between the cutters and the rock are the prime reasons for improvement of the penetration rate of the PDC bit in compound drilling. An error analysis comparing simulation and experimental results was performed and the two agree to within <20%. Based on the working mechanism of the PDC drill bit in compound drilling, technical ideas and implementation methods for customized designs of PDC drill bits are discussed.

Young children’s representation of geometric relationships between locations in location coding

From an early age, children are able to use surface layout geometry and landmarks to search for a hidden toy when disoriented. Theoretical debate remains regarding whether children represent locations based on the global environment or on local cues. Exploring whether children construct and use the relationships between discrete locations of the global environment can provide direct evidence regarding this issue. We investigated young children’s representation of two geometric relationships: diagonal relationships (Experiment 1) and same-side relationships (Experiment 2). Children (4- and 5-year-olds) were tested in a square room with a distinctively colored wall. Children completed two tasks. In a two-location task, children watched two toys hidden in two corners that formed one of the two relationships. After disorientating children, the experimenter uncovered one toy and children searched for the other one (target). In a one-location task, only one toy was hidden. In both experiments, children’s performance was better in the two-location task than in the one-location task. Furthermore, accuracy in the two-location task of Experiment 1, in which the two corners formed a diagonal relationship, was higher than that of Experiment 2, in which the two corners formed a same-side relationship and a correct location required the combination of this relationship and landmark. These findings suggest that at least by 4 years of age, children can construct geometric relationships between individual corners in their spatial representation and support the global accounts of young children's location coding.

Effects of Road Infrastructure on Pedestrian Safety

Pedestrians represent more than 30% of all of Poland’s road traffic fatalities. This is much higher than the EU average (about 20%). Pedestrian accidents are usually the result of a complex situation and a number of contributing factors involving road users, the road and roadside and the vehicle. Pedestrian accidents are caused by road user error (drivers and pedestrians) and wrong planning and design. Poorly maintained road infrastructure is also a very frequent cause. The objective of the work was to identify risks for pedestrians that involve road infrastructure and roadside and to define how selected elements of geometry and traffic layout affect driver behaviour (speed on approaching pedestrian crossings). The results have helped to formulate recommendations on pedestrian crossing design. The research included an analysis of 2013-2017 statistics to identify the circumstances and causes of pedestrian accidents. Field work at about 2, 000 unsignalized pedestrian crossings was the basis for assessing the safety of these crossings. Assessment criteria were selected and a safety classification was made with specific recommendations made for possible treatments. More field work was designed to measure speeds near pedestrian crossings in three cases: no pedestrians in the crossing area, a pedestrian is approaching a crossing, a pedestrian is waiting to cross the road. The study was conducted in different areas (city, transit roads passing through small towns, non-built-up areas) for different cross-sections (one carriageway and two lanes – 1x2, two carriageways with two or three lanes each – 2x2, 2x3, one carriageway and four lanes – 1x4). The study also looked at speed limits – 50 and 70 km/h. The share of drivers giving way to pedestrians waiting to cross was also assessed. Pedestrians were surveyed and asked about how safe they feel crossing the road. The survey also asked drivers about driver behaviour and use of speed management measures. Statistical analyses show the circumstances and causes of pedestrian accidents. These include driving across a pedestrian crossing illegally, pedestrians stepping onto the road abruptly, night-time, excessive speed and others. Pedestrian crossings are the site of more than 30% pedestrian fatalities which shows the need for treatments. By assessing the hazards caused by road infrastructure near and at pedestrian crossings, the following hazards could be identified: limited sight-distance, poor illumination, excessive speed and no means of speed management, wrong geometry (length of crossing, number of traffic lanes), technical condition of the road and signage. Speed tests near pedestrian crossings show that some 40% of drivers do not observe the speed limits in built-up areas (especially on sections of transit roads passing through small towns and on dual carriageways in urban areas) and 30% do not observe the speed limits on rural roads.

ПОНЯТИЕ КОЭФФИЦИЕНТА ЭЛЛИПТИЧНОСТИ ТРАПЕЦИЕВИДНОГО КРЫЛА И МЕТОД ЕГО ОЦЕНКИ

When developing modifications of the transport category aircraft to increase their transport efficiency and economy in many cases, there is a need for profound changes in wing parameters. When such changes are implemented, the problem of the wing layout geometry, and the whole lift system “wing + tail unit assemblies”, inevitably arises. The most important step in the selection of parameters of lifting surfaces is to ensure, during their design, the law of change in circulation spanwise, the maximum approximate distribution of circulation in an elliptical wing, which leads to a minimum value of its inductive resistance for a given lift value.The ratio of the circulation values of the velocity of the elliptical (Ge) and tapered (Gt) wings, the values of which are usually estimated using the known coefficients of the wing shapes, was taken as the elliptic coefficient of the tapered wing:– Ktsh and Kesh – the factors of the tapered wing shape and elliptical wing in plan view, equivalent in lift force, as well as in the span and aspect ratio;– Ksh(hi) – the shape factor of the tapered wing, depending on its taper ratio (hi);– Kesh – the optimal value of the shape factor of a simple tapered wing if the taper ratio is h = 2.857 (according to Karafoli), and Сxi min.The analysis of such dependences showed that the increase in the elliptic coefficient Кe is realized by increasing the number of trapezoids (n), forming the plan of the composite wing, and the geometric twist of their local chords.When using such design solutions, it is possible to increase the value Ken, e, and the numerical evaluation models depend, among other things, on: n – the number of trapeziums that form the wing half-sizes; zn i- the coordinates of the wing kinks in its span; ηn – total narrowing of the wing, formed by n trapeziums. e - the relative angles of the geometric twist of the local chords of the trapezoids forming the plan of the modified wing.The developed models are the scientific basis for the re-assembly of not only an isolated wing, but also the entire lift system “wing + tail unit assemblies” that provide minimal inductive resistance, and should also be used as the basis for constructing longitudinal static stability limits and reducing the trim loss of the modification.

Variation aware design of controlled voltage swing ring oscillator

ABSTRACTAn inverter is designed using an innovative controlled voltage swing logic and having two different current sources. The logic levels are detected by sensing the voltage drop across a termination resistance. Logic 1 is defined when both the current sources are pumping current through termination resistance, whereas a logic 0 is determined when one of the sources is pumping current. This inverter is the newest class of inverter and used in designing a ring oscillator, capable of operating at various frequencies, fosc. Varying the external load capacitance (CL) from 1 to 10 fF, the values of fosc are tuned in between 0.8 and 1.0 GHz. Mathematical equations relating fosc as a function of CL and intrinsic capacitive components (Θ) are obtained and subsequently validated using gpdk 90 nm technology CMOS process. The proposed controlled voltage swing ring oscillator is observed to draw a current of 0.716 μA at fosc close to 1.0 GHz. The corresponding CL and the Θ happen to be 1.0 and 53.8 fF, respectively. The effect on fosc due to layout geometries and other process parameters keep on changing only by 16% compared to a 7% change in the intrinsic values between pre and post layout for the said ring oscillator. Lastly, a linear empirical relation is obtained to indicate fosc as a function of both CL and the power supply voltage (Vdd).

Clouds of Oriented Gradients for 3D Detection of Objects, Surfaces, and Indoor Scene Layouts.

We develop new representations and algorithms for three-dimensional (3D) object detection and spatial layout prediction in cluttered indoor scenes. We first propose a clouds of oriented gradient (COG) descriptor that links the 2D appearance and 3D pose of object categories, and thus accurately models how perspective projection affects perceived image gradients. To better represent the 3D visual styles of large objects and provide contextual cues to improve the detection of small objects, we introduce latent support surfaces. We then propose a "Manhattan voxel" representation which better captures the 3D room layout geometry of common indoor environments. Effective classification rules are learned via a latent structured prediction framework. Contextual relationships among categories and layout are captured via a cascade of classifiers, leading to holistic scene hypotheses that exceed the state-of-the-art on the SUN RGB-D database.

RADICALLY NEW FEATURES OF THE POSITIVE KEYBOARD

The article highlights a new alternative to traditional keyboards - a positive keyboard. The positive keyboard sharply reduces the complexity of the keyboard, namely the number of keys from 30 to 9 by increasing the length of a codeword from 1 to 2. This is made possible by graphical support, which is laid out in the geometry of the 9-key layout. One or two of these keys generate a signal, and the rest, as it turns out, can be quite close in their shape to the entered characters. That's why this keyboard is positive: all of its 9 keys are useful at any time, unlike traditional keyboards, which have a performance of 1/30 (approximately 3%). Therefore, a positive keyboard does not require marking, which is also a source of errors. Thanks to this, a positive keyboard frees up the creative abilities of a person.

Uniaxial Cyclic Tests on Reinforced Concrete Members with Lap Splices

This data paper presents the quasi-static uniaxial cyclic tests of 24 reinforced concrete members, of which 22 feature lap splices and 2 are reference units with continuous reinforcement. The objective of the experimental program is to investigate the influence of lap splice length ( ls), confining reinforcement, and loading history on the behavior of lap splices. Particular attention is placed on the measurement of local deformation quantities, such as lap splice strains and rebar-concrete slip. Details of the geometry and reinforcement layout of the specimens as well as the employed test setup, instrumentation, and loading protocols are provided. The global behavior of the test units, including the observed crack pattern and failure modes, are discussed. The organization of the experimental data, which are made available for public use under DOI: 10.5281/zenodo.1205887, is outlined in detail.

Identification of Determinants of the Speed-Reducing Effect of Pedestrian Refuges in Villages Located on a Chosen Regional Road

Traffic calming, as a traffic engineering discipline, is becoming an increasingly important aspect of the road engineering process. One of the traffic calming treatments are pedestrian refuges—raised islands located on or at the road centreline. This paper presents factors relevant to the performance of this kind of traffic calming devices retrofitted on the stretches of regional roads in village areas. To this end, speed surveys were carried out before and after the islands in each direction on purposefully chosen test sections. In order to identify the determinants, each test section was characterised by features including the symmetry of the road layout geometry, surrounding features and the existing traffic signs and, last but not least, visibility of the road ahead. The survey data were used by the authors to perform analyses in order to group the speeds at the pedestrian refuges and relate them to specific factors and, finally, identify the determinants of speed reduction. In this way, the authors arrived at a conclusion that the performance of pedestrian refuges depends on a number of factors rather than solely on their geometric parameters. The analyses showed that the pedestrian refuge geometric parameters, features located in its proximity that influence the driver’s perception and placement of appropriate marking, can, in combination, result in achieving the desired speed reduction and ensure safety of non-motorised users. These hypotheses were tested on a stretch of a regional road in village area at three points of the process: before upgrading, after installation of pedestrian refuges, and after retrofitting of enhancements.

Pressure-discharge and Hydraulic Gradient along the Lateral of the Drip Irrigation System for Okra

Micro irrigation system should ensure relatively same amount of water to each plant along the total length of lateral line. In general, the drip irrigation systems are low to medium operating pressure head systems with a pressure requirement in range of 0.5 kg/cm2 to 2.5 kg/cm2 depending on the area irrigated and field layout geometry. However, since these systems are pressure irrigation systems which require appropriate operating pressure heads to deliver the required rates of flow, the inevitable frictional head losses are to be compensated for maintaining uniformity in water application. Hence, the hydraulic gradient compensation needs to be achieved by some viable mechanism so that the inequality in pressure heads and discharges can be eliminated or minimized. The crop production will have its maximum yield and water use efficiency only one the water distribution uniformities at its the highest. Hydraulic gradient compensation assumes a vital role in compensating the operating pressure heads as well as the emitter discharges. The hydraulic gradient compensated drip lateral layout registered high order of water distribution uniformity in the range of 97.8% and irrigation usage efficiency in the range of 17.98 kg/ha/mm to 20.69 kg/ha/mm for 2 lph emitter arrangements.

Simulation Studies on the Effect of Material Characteristics and Runners Layout Geometry on the Filling Imbalance in Geometrically Balanced Injection Molds.

Simulation studies were performed on filling imbalance in geometrically balanced injection molds. A special simulation procedure was applied to simulate properly the phenomenon, including inertia effects and 3D tetrahedron meshing as well as meshing of the nozzle. The phenomenon was investigated by simulation using several different runner systems at various thermo-rheological material parameters and process operating conditions. It has been observed that the Cross-WLF parameters, index flow, critical shear stress (relaxation time), and zero viscosity, as well as thermal diffusivity and heat transfer coefficient strongly affect the filling imbalance. The effect is substantially dependent on the runners’ layout geometry, as well as on the operating conditions, flow rate, and shear rate. The standard layout geometry and the corrected layout with circled element induce positive imbalance which means that inner cavities fills out faster, and it is opposite for the corrected layouts with one/two overturn elements which cause negative imbalance. Generally, for the standard layout geometry and the corrected layout with circled element, an effect of the zero shear rate viscosity η0 is positive (imbalance increases with an increase of viscosity), and an effect of the power law index n and the relaxation time λ is negative (imbalance decreases with an increase of index n and relaxation time λ). An effect of the thermal diffusivity α and heat transfer coefficient h is negative while an effect of the shear rate is positive. For the corrected layouts with one/two overturn elements, the results of simulations indicate opposite relationships. A novel optimization approach solving the filling imbalance problem and a novel concept of global modeling of injection molding process are also discussed.

CFD simulation of dilute-phase pneumatic conveying of powders

A comprehensive validated numerical model simulating the pneumatic transport of fine particles through various geometries has been developed using Computational Fluid Dynamics (CFD). The prediction reliability of the model was tested over a range of operational conditions, geometry layouts and particle size distributions (PSD). Simulation results have shown a reasonable agreement with published experimental data. The achieved results indicate that this CFD model has an extensive applicability for different geometries when an alternative recently developed drag force correlation is used. Furthermore, the effect of PSD was introduced in the validated model to gain a better understanding of particle motions during conveying. The CFD model with PSD also provided reliable results in various geometries. Numerical results reveal completely different particle size distributions in horizontal and vertical pneumatic conveying. Moreover, the formation and disintegration of particle ropes are both found to be controlled mainly by the behavior of large particles during transportation in a horizontal-bend-vertical pipeline.

DC and high-frequency characteristics of trigate polycrystalline-silicon thin-film transistors with different layout geometries

In this paper, we present the dc and high-frequency characteristics of trigate polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) for RF applications. Trigate TFTs were fabricated using a 3D-IC process and designed with a multi-finger gate and multi-channel configuration. To obtain an optimal device design guideline, different source/drain (S/D) extension dimensions and channel layouts are investigated. We find that devices with a shorter or wider extension have higher cutoff frequencies (fT) and maximum oscillation frequencies (fmax) owing to their lower S/D resistances. In addition, the high-frequency performance can be further improved by adopting the tapered channel structure, where the channel width increases gradually from the source to the drain. For the optimal device designs, the values of fT and fmax are around 25 GHz and 30 GHz, respectively. The high fT and fmax as well as excellent gate controllability in our devices indicate the trigate poly-Si TFT could be a suitable candidate for low-cost RFIC applications.

Application of a New Geophone and Geometry in Tunnel Seismic Detection.

Seismic imaging is the most effective geophysical method and has been extensively implemented to detect potential geological hazards in tunnels during construction. The coupling of geophones and the design of geometry in tunnels are the two major challenges. To ensure successful coupling, a high-sensitivity semi-automatic coupling geophone with a broadband was designed. In practice, this geophone is attached with a wheel and two springs. Once inserted into the borehole, an automatic coupling action occurs. This semi-automatic coupling design within the geophone not only guarantees good coupling, but reduces the time and costs usually required to install a traditional geophone. In the use of geophones for tunnel seismic detection, we propose two new two-dimensional (2D) seismic geometries based on the two commonly used geometries. A test to assess the effectiveness of the qualities of imaging from four geometries was completed by comparing the results of the forward modeling of sandwich models. The conclusion is that the larger the horizontal offset of the layout geometry, the higher the resolution of the imaging; the larger the vertical offset, the weaker the mirror image. The vertical offset is limited due to the narrow tunnel condition. Therefore, the mirror effect cannot be entirely eliminated; however, it can be further suppressed by constructing 2D geometry. The two newly proposed 2D geometries caused the imaging arc of the inter-layer, but suppressed the mirror image. The mirror image added a significant number of errors to the data, which could misguide tunnel construction; therefore the new 2D geometries are more reasonable than the two most commonly used. We applied one of the two new 2D geometries that was more practical to an actual project, the Chongqing Jinyunshan Tunnel in China, and acquired high-quality seismic data using two semi-automatic coupling geophones. The detection results were essentially consistent with the excavation conclusions.

Flood inundation modeling in urbanized areas: A mesh-independent porosity approach with anisotropic friction

In the present work, a porosity-based numerical scheme for the Shallow Water Equations is presented. With the aim of accounting for the presence of storage areas, such as gardens, yards and dead zones, and for preferential flow pathways, both an isotropic storage porosity parameter and anisotropic friction are adopted. Particularly, the anisotropic effects due to the building alignments are evaluated defining conveyance porosities along principal directions and using them to express the friction losses in tensor form. The storage and conveyance porosities are evaluated from the geometry of the urban layout at a district scale and then assigned to computational cells rather than to cell sides, thus avoiding oversensitivity to the mesh design. The proposed formulation guarantees the C-property also in presence of wet-dry fronts. Model testing is performed analyzing schematic and idealized urban layouts, and against experimental data as well. The results obtained by the proposed anisotropic scheme are similar to a high-resolution model with resolved buildings, also in the presence of low-friction regimes, meanwhile with a remarkable reduction of the computational times.

Designs for Safer Signal-Controlled Intersections by Statistical Analysis of Accident Data at Accident Blacksites

This paper describes the collection and statistical analysis of accident counts and intersection layout geometries at a range of signal-controlled intersections, with the aim of improving safety at these sites. Negative binomial regression analysis is conducted to relate the accident count data as a dependent variable, with various independent variables to capture the intersection layout and lane-marking patterns. Statistically significant variables are identified, and their individual effects on accident counts are analyzed. Although the accident-prediction models for signalized intersections have been extensively investigated, this paper also considers the effects of shared lane markings, which is a new approach. The results of this paper show that the shared lane markings are indeed a statistically significant predictor of the number of accidents. It was found that the accident counts at signal-controlled intersections could be reduced by altering the lane-marking patterns using a combination of well-established lane-based design methods and new governing constraint sets to enhance the safety controls for turning traffic derived from our statistical analysis. These new lane-marking patterns also satisfy engineering performance requirements. The intersections in Hong Kong were investigated as illustrative case studies, and the numerical results show a substantial decrease in the predicted accident counts, with an acceptable tradeoff in the reduction of overall intersection capacity.

Wave-body interactions among energy absorbers in a wave farm

A semi-analytical method is developed to investigate surface-wave interactions among an array of wave-energy converters, each modeled as a truncated cylinder, and the interaction effects on power absorption from the array is studied. Each cylinder can have independent movements with six degrees of freedom. The method of matched eigen-function expansions is applied to solve the wave radiation problem. To achieve fast computation, effects of evanescent modes of local scattering waves from one cylinder is neglected in the near fields of neighboring cylinders, but the far-field radiated waves are retained. Wave-exciting forces and moments on an individual cylinder or a group of cylinders, situated among an array, are evaluated by a new, generalized form of the “Haskind relation” applicable to an array of arbitrary configuration, which only requires the solution to the radiation problem. Hydrodynamic properties and wave-exciting loads are presented for arrays of different configurations. This efficient computation facilitates investigating wave-interaction effects on the optimal power output of a cylinder array. Effects of the cylinder numbers, their spacing, and the layout geometry on power extraction are discussed. The interaction factor for a large wave farm consisting of multiple small arrays was evaluated by the current method combined with the point-absorber approximation.

Parametric instability behavior of tow steered laminated quadrilateral plates using isogeometric analysis

For the first time, the parametric instability regions of variable stiffness laminated composite quadrilateral plates subjected to uniform in-plane loadings are studied. The static as well as time-varying inplane loadings are assumed distributed throughout the whole geometry. The isogeometric analysis finite element formulation based on non-uniform rational B-splines is developed in order to address the dynamic instability of quadrilateral panels. The problem has been formulated by utilizing the principle of virtual work based on first order shear deformation plate theory. In terms of tow-steered reinforcements, the fiber orientations in every lamina is assumed to change linearly in the panel longitudinal direction. In order to demonstrate the capabilities of the developed formulation in predicting the structural parametric dynamic behavior, some representative results are obtained and compared with those available in the literature. The effects of geometry layout, loading frequency and amplitude, changes in curvilinear fiber orientations, and material orthogonality on the parametric instability regions are studied by applying Bolotin's first order approximation.

Process Optimization for Electron Down-Flow Electromigration Improvement in Copper Interconnects

Due to asymmetric structure of Copper (Cu) interconnects, Cu electromigration (EM) is related to the electron flow direction. In various technological nodes, Cu EM performance with electron down-flow direction is generally worse than that with electron up-flow direction due to the presence of voiding underneath the via. This study investigates Cu EM behavior with electron down-flow. The failure modes were verified and optimized processes were provided to improve EM performance. Additionally, layout geometry effect on electron down-flow EM was discussed.