Spatial Envelope Research Articles

Digital generating method for cylindrical helical gear based on indexable disk milling cutter

To solve the problem of low efficiency in digital generating machining for producing small or medium batches of helical gears, a method to improve the machining efficiency with an indexable disk milling cutter is presented in this paper. First, the mathematical model of the tooth profile and the indexable disk milling cutter are established. Second, according to the spatial free-form envelope theory, the overall planning scheme of the tool path is given; the relative position and the relative transformation matrix of the tool and tooth profile during digital generating machining using the indexable disk milling cutter are solved, the simulation cutting and actual cutting experiments are conducted, and the cutting efficiency per unit time and cutting simulation time of the two tools under the same deformation conditions is obtained through a finite element analysis experiment. The results show that the cutting efficiency of the indexable disk milling tool was 2–3 times higher than that of the end mill cutter.

River Surface Analysis and Characterization Using FMCW Radar

Today’s warning systems for floods or droughts require sensor applications that provide a vast array of information. Current systems provide insight into either the water level or the river velocity. In order to obtain additional parameters for the characterization of the flow behavior in a noncontact manner, a frequency-modulated continuous-wave radar with chirp sequence is used. Since these sensors provide range and velocity information but also enable gathering of additional parameters. The presented measurements in this contribution were performed at four different rivers with a commercially available radar sensor. The results of the classical postprocessed 2-D fast Fourier transform are used as basis for an imagewise processing approach to obtain additional features for classifying the behavior of the river surface. For this purpose, the framewise enveloping velocities are depicted in a time sequence. Due to processing the detected reflection patterns in relation to time, a characteristic pattern for river flow profiles can be extracted. By reducing the information using time averaging, characteristic features for different flows can be extracted from the spatial envelope velocity distribution. In particular, the resulting insights lead to characteristic features for single flow distributions that enable novel monitoring systems with new possibilities to classify rivers using radar sensors.

Modeling of Resistive Forces and Buckling Behavior in Variable Recruitment Fluidic Artificial Muscle Bundles

Fluidic artificial muscles (FAMs), also known as McKibben actuators, are a class of fiber-reinforced soft actuators that can be pneumatically or hydraulically pressurized to produce muscle-like contraction and force generation. When multiple FAMs are bundled together in parallel and selectively pressurized, they can act as a multi-chambered actuator with bioinspired variable recruitment capability. The variable recruitment bundle consists of motor units (MUs)—groups of one of more FAMs—that are independently pressurized depending on the force demand, similar to how groups of muscle fibers are sequentially recruited in biological muscles. As the active FAMs contract, the inactive/low-pressure units are compressed, causing them to buckle outward, which increases the spatial envelope of the actuator. Additionally, a FAM compressed past its individual free strain applies a force that opposes the overall force output of active FAMs. In this paper, we propose a model to quantify this resistive force observed in inactive and low-pressure FAMs and study its implications on the performance of a variable recruitment bundle. The resistive force behavior is divided into post-buckling and post-collapse regions and a piecewise model is devised. An empirically-based correction method is proposed to improve the model to fit experimental data. Analysis of a bundle with resistive effects reveals a phenomenon, unique to variable recruitment bundles, defined as free strain gradient reversal.

Category systems for real-world scenes.

Categorization performance is a popular metric of scene recognition and understanding in behavioral and computational research. However, categorical constructs and their labels can be somewhat arbitrary. Derived from exhaustive vocabularies of place names (e.g., Deng et al., 2009), or the judgements of small groups of researchers (e.g., Fei-Fei, Iyer, Koch, & Perona, 2007), these categories may not correspond with human-preferred taxonomies. Here, we propose clustering by increasing the rand index via coordinate ascent (CIRCA): an unsupervised, data-driven clustering method for deriving ground-truth scene categories. In Experiment 1, human participants organized 80 stereoscopic images of outdoor scenes from the Southampton-York Natural Scenes (SYNS) dataset (Adams et al., 2016) into discrete categories. In separate tasks, images were grouped according to i) semantic content, ii) three-dimensional spatial structure, or iii) two-dimensional image appearance. Participants provided text labels for each group. Using the CIRCA method, we determined the most representative category structure and then derived category labels for each task/dimension. In Experiment 2, we found that these categories generalized well to a larger set of SYNS images, and new observers. In Experiment 3, we tested the relationship between our category systems and the spatial envelope model (Oliva & Torralba, 2001). Finally, in Experiment 4, we validated CIRCA on a larger, independent dataset of same-different category judgements. The derived category systems outperformed the SUN taxonomy (Xiao, Hays, Ehinger, Oliva, & Torralba, 2010) and an alternative clustering method (Greene, 2019). In summary, we believe this novel categorization method can be applied to a wide range of datasets to derive optimal categorical groupings and labels from psychophysical judgements of stimulus similarity.

Spatial Solution to Measure Regional Efficiency — Introducing Spatial Data Envelopment Analysis

When investigating healthcare efficiency at the regional level, the problem of interactions between neighbouring locations arises. The health of the population in a given region is related to the healthcare in other areas through a medical tourism, a limited number of highly specialised institutions, competition between institutions, etc. Ignoring these inter-regional links may result in a systematic bias in the efficiency analysis. Similar issues may hinder any regional studies. Hence, the main purpose of this paper is to introduce a new approach to measuring efficiency in regional studies through spatial data envelopment analysis (SDEA). The paper offers a proper mathematical formulation of the new methodology and highlights differences between classic data envelopment analysis (DEA) and the newly developed method. The motivation for seeking a new solution to the problem of spatially adequate assessment of regional efficiency is derived from the literature review and a discussion of the presented theoretical examples. The classic DEA allows for multidimensional analysis of the performance of homogenous independent decision-making units. However, in regional studies, an area where DEA has gained popularity, the assumption of the isolation of decision-making units seems to be unfounded. In the SDEA approach, the region-specific spatial context is incorporated into the analysis via the W matrix and spatial interactions are reflected in the model through spatially weighted inputs and outputs. Therefore, in our paper, we verify the hypothesis that spatial interactions are an indispensable factor of regional efficiency analysis. A study of healthcare efficiency in European regions is presented as an illustration of the utility of the new methodology. Furthermore, we compare the results of the classic DEA approach with those of the SDEA, which is augmented with the spatial equivalents of inputs and outputs. Our results suggest that classic DEA undervalues regional healthcare efficiency by underestimating the region-specific spatial context.2 Researchers may find the introduced SDEA method useful in all space related fields when investigated phenomenon exhibits spatial autocorrelation. In particular, the new approach may deepen the regional efficiency analysis of innovation, development, logistics, tourism, etc.

Design optimisation of a hybrid electric vehicle cooling system considering performance and packaging

Optimal system design at the conceptual functional level, i.e., before the embodiment of the functions is determined in detail, focuses primarily on performance. Embodiment determines the geometry and position of subsystems and components, which must be packaged usually within strict spatial envelopes to achieve compactness or other external requirements such as styling. Packaging objectives and constraints may therefore compete with performance ones, leading to redesign and costly delays if these conflicts are not addressed early in the design process. This paper presents a design optimisation framework for coupled performance and packaging problems. Using the cooling system for a heavy duty tracked series hybrid electric vehicle (SHEV) as an example, we demonstrate the framework combining commercial CAD software with optimisation tools and including pipe routing which is a basic requirement in many mechanical systems.

Design optimisation of a hybrid electric vehicle cooling system considering performance and packaging

Optimal system design at the conceptual functional level, i.e., before the embodiment of the functions is determined in detail, focuses primarily on performance. Embodiment determines the geometry and position of subsystems and components, which must be packaged usually within strict spatial envelopes to achieve compactness or other external requirements such as styling. Packaging objectives and constraints may therefore compete with performance ones, leading to redesign and costly delays if these conflicts are not addressed early in the design process. This paper presents a design optimisation framework for coupled performance and packaging problems. Using the cooling system for a heavy duty tracked series hybrid electric vehicle (SHEV) as an example, we demonstrate the framework combining commercial CAD software with optimisation tools and including pipe routing which is a basic requirement in many mechanical systems.

What is a parked bicycle? Vehicle fleet characteristics in Australia

Bicycle parking facilities are an important part of the transport system and their design can make bicycle transport more convenient. At a detailed level, the design of bicycle parking devices depends on how they relate to the bicycle's properties. This research seeks to provide a more detailed understanding of the characteristics and fleet of bicycles to inform better policy and practice. Set in Australia, an urbanised country aiming to increase a presently low bicycle mode share, the results are potentially useful to other low bicycle mode share cultures. Visual analysis reveals that although the relevant Australian standard describes a spatial envelope for bicycles, the envelope introduces a treatment of bicycle geometry at odds with vehicle characteristics; namely the contradiction that the spatial envelope in the standard significantly over states the volume of a bicycle, while at the same time the handlebars of the bicycle are inadequately accommodated. A random sample of 180 parked bicycles in Australian urban environments provides a detailed geometry database and shows that the Australian bicycle fleet is heterogeneous around clusters of geometry reflecting industry standards, but does not match with the spatial envelope provided in the standard. Photographic observations of these bicycles provide an insight into bicycle characteristics and parking behaviours, in particular revealing that 55% of the sample bicycles were not equipped with kick stands and thus depend on parking infrastructure for stability. Evidence from the field suggests that some bicycle users are willing to park bicycles more closely than suggested in the standard.

Relativistic electron-spin dynamics in a strong unipolar laser field

The behavior of an electron spin interacting with a linearly polarized laser field is analyzed. In contrast to previous considerations of the problem, the initial state of the electron represents a localized wave packet, and a spatial envelope is introduced for the laser pulse, which allows one to take into account the finite size of both objects. Special attention is paid to ultrashort pulses possessing a high degree of unipolarity. Within a classical treatment (both nonrelativistic and relativistic), proportionality between the change of the electron spin projections and the electric field area of the pulse is clearly demonstrated. We also perform calculations of the electron spin dynamics according to the Dirac equation. Evolving the electron wave function in time, we compute the mean values of the spin operator in various forms. It is shown that the classical relativistic predictions are accurately reproduced when using the Foldy-Wouthuysen operator. The same results are obtained when using the Lorentz transformation and the nonrelativistic (Pauli) spin operator in the particle's rest frame.

Modeling and experiment of grinding wheel axial profiles based on gear hobs

Hobbing is one of the crucial gear manufacturing processes with high precision and high efficiency. In order to improve the accuracy of hobbing and hob relief grinding, more precise grinding wheels are demanded for relief grinding in the production of gear hobs. In this paper, a new and accurate mathematical method for calculating the axial profile of grinding wheel based on the corresponding gear hob to be ground is proposed. Considering that most researches have been conducted to focus on the optimization of hob geometric feature and only can be applied to a specific type of hand of helix and rake angle of gear hobs. The method in this paper can be served as a general algorithm for generating axial profile of grinding wheels on the basis of the spatial envelope theory, the principle of coordinate system transformation, and studies on normal profile of single-tooth. The accuracy of grinding hobs is based on applying the approach in practical manufacturing. Taking two typical different kinds of pre-grinding gear hobs as examples for calculation and experiment, the results of tooth profile errors strengthen the position that the validity and feasibility of this method, it can be employed for gear hob design and grinding processing.

0437 Characterizing the Impact of EEG Referencing on Sleep Spindle and Slow Oscillation Analyses

Abstract Introduction The impact of EEG referencing on sleep oscillations, such as spindles and slow oscillations, is largely overlooked across studies. While it is recognized that a topographic head plot of EEG activity does not reflect the true location of the underlying cortical activity, spatial distributions, as well as spectral properties and morphology of EEG oscillations can change dramatically as a function of referencing scheme. It is therefore vital to understand the impact of referencing when drawing inferences about the nature of EEG sleep oscillations. In this study, we use MRI structural data to construct subject-specific forward models of EEG signals. Using these models, we can simulate cortical activity and observe its true representation on the scalp. In particular, we simulate spindles and slow wave oscillations and examine how referencing affects topography, spectral power, and phase of oscillations. Methods High-density EEG (Brain Vision, 64-channel) polysomnography was performed on 9 healthy young subjects. 3T structural MRI scans were acquired and forward models were built in MNE-Python using 3-shell Boundary Element Models (BEM) based on individual anatomical details processed with Freesurfer. Simulations of various sleep spindle and slow oscillation dynamics were projected to the sensor space. Different referencing schemes (common average, Laplacian, linked-mastoid) were then applied to the experimental and simulated data and analyzed for effects on time-frequency characteristics of sleep oscillations. Results Analyses of experimental data showed distinct reference-based differences in topographical distribution of spectral power and phase of oscillations. Simulated data revealed many scenarios in which the spatial distribution of activity the EEG sensor space poorly represented the true location of the underlying source activity. Moreover, there were alterations to the spatial spread and envelope form of sleep spindle events under different referencing schemes despite from identical source activities. Conclusion This study shows that spindle and slow oscillation activity is highly variable across referencing schemes and that EEG topographical plots on the scalp may poorly represent cortical activity locations. It is thus vital to consider the choice of referencing when quantifying characteristics of sleep EEG oscillations. Support This work was supported by R01 NS-096177.

The development and application of passive architecture in China

Passive buildings can achieve energy saving goals through their own spatial form, envelope, building materials and structural design. However, at present, there are many problems in the development of passive buildings in China, such as inadequate foundation, unreasonable passive design, which make the development of passive buildings have many obstacles, not conducive to the promotion of the construction industry. Therefore, this paper analyzes the obstacle factors of passive buildings and puts forward reasonable solutions for reference.

A semi-automated approach for quantitative mapping of woody cover from historical time series aerial photography and satellite imagery

Savanna landscapes are characterised by a canopy of discontinuous tree cover overlying an understorey of shrubs and continuous grass cover. The distribution of trees (woody cover) is variable both spatially and temporally. Analysis of woody cover dynamics can provide a spatial and temporal envelope encompassing variability is useful for informing mine closure criteria. With the impending closure of Ranger uranium mine, ecologically appropriate closure criteria for ecosystem restoration are being developed through a framework of rehabilitation standards. One such closure criteria is canopy cover and historical woody cover is being used to derive the range in woody cover that can be expected over time once the mine site has been revegetated. This study reports on the development and testing of a technique for extracted woody cover from remotely sensed data (in the form of historical aerial photography and satellite imagery) in the areas adjacent to Ranger uranium mine in the World Heritage listed Kakadu National Park, northern Australia. An object-based image analysis technique was applied to four data sets from four different dates: greyscale, true colour and colour infrared aerial photo mosaics (from 1964, 1976 and 1981 respectively) and a high spatial resolution satellite image (from 2010). Overall accuracies of woody cover from each of the data sets exceeded 94%. In addition, proportional cover derived from this method displays linear relationships to cover derived from visual estimates. Due to the success of the technique, it will be applied to more data sets from different dates over the study area to assess the variability of woody cover over time to inform ecosystem restoration criteria for the mine closure.

Controlling the spatio-temporal dose distribution during STEM imaging by subsampled acquisition: In-situ observations of kinetic processes in liquids

Subsampled image acquisition followed by image inpainting in a scanning transmission electron microscope is a novel approach to control dose and increase the image frame rate during experiments, thereby allowing independent control of the spatial and temporal dose envelope during image acquisition. Here, subsampled imaging is shown to permit precise in situ observations of the fundamental kinetic processes behind nucleation and growth of silver (Ag) nanoparticles from an aqueous solution. At high sampling-levels, nanoparticles can be observed with morphologies that are consistent with strong interface interactions, i.e., rafts and pillars, whereas at low sampling-levels, the particles exhibit regular spherical morphologies. The relative numbers of rafts/pillars and regular nanoparticles, their sizes, and their incubation times can be attributed to local changes in the molar concentration of the Ag ions in the aqueous solution; higher sampling-levels significantly increase the reactants in the vicinity of the window, leading to rapid supersaturation and the precipitation on the window surface. These precisely controlled kinetics highlight subsampled imaging as a method by which the driving force for nucleation and growth (i.e., the electron beam) can be disentangled from the spatial/temporal resolution of the observation in all in situ experiments, providing a pathway to identify and quantify the importance of individual kinetic factors behind nucleation and growth in a wide variety of complex materials systems and architectures.

New Parsimonious Multivariate Spatial Model: Spatial Envelope

Dimension reduction provides a useful tool for analyzing high dimensional data. The recently developed \textit{Envelope} method is a parsimonious version of the classical multivariate regression model through identifying a minimal reducing subspace of the responses. However, existing envelope methods assume an independent error structure in the model. While the assumption of independence is convenient, it does not address the additional complications associated with spatial or temporal correlations in the data. In this article, we introduce a \textit{Spatial Envelope} method for dimension reduction in the presence of dependencies across space. We study the asymptotic properties of the proposed estimators and show that the asymptotic variance of the estimated regression coefficients under the spatial envelope model is smaller than that from the traditional maximum likelihood estimation. Furthermore, we present a computationally efficient approach for inference. The efficacy of the new approach is investigated through simulation studies and an analysis of an Air Quality Standard (AQS) dataset from the Environmental Protection Agency (EPA).

الإسرائيليات في کتب التفسير الأسباب والآثار

ملخص بحث الإسرائيليات کتب التفسير الأسباب والآثار لا شک أن القرآن الکريم قد اعتمدت علاقته بالتوراة والإنجيل على التصديق تارة والهمينة تارة أخرى، ومعنى تصديقه أنه يقر بقايا الوحي الصحيح فيهما، لکنه الوقت ذاته ينکر تحريفاتهما، فهو تصديق في أصول العقائد التي اتفقت عليها الکتب السماوية، ودعت إليها الرسل ، وذلک مثل دعوة الناس إلى التوحيد وإقامة الدين والتحذير من الشرک وخطره. أما تفصيلات الشرائع والأحکام العملية فإن القرآن الکريم يتباين طرحه مع الکتب السماوية السابقة عليه، نظرا لاختلاف الظرف الزماني والمکاني. وأرى أن سر هذه الهيمنة يکمن تأسيس القرآن الکريم للمنهج التشريعي والأخلاقي الراقي الذي يحوي مضامين قيمية وأخلاقية لا تقصي الکتب السماوية السابقة ولا تلغيها، وإنما تقوم ما اعتراها من خلل، وتجبر ما أصابها من نقص، وأيضا تقرر کامل الحقوق والواجبات لأصحابها إطار الحق الذي تقره والباطل الذي ترفضه. وأحب التأکيد على أن الهيمنة القرآنية لا تظهر کشف عوار الکتب السابقة بعد تحريفها من الناحية العقدية فحسب؛ بل من الناحية التشريعية والأخلاقية والاجتماعية وغيرها، وفي الوقت ذاته تعلن التصديق لما فيها من حق. summary Israeli books explain causes and effects There is no doubt that Quran had adopted his connection to Torah and Gospel to ratify at Dominate at other times, meaning that correct revelation remains believable, but at same time denying their changes،It is believe in the origins of creeds agreed by heavenly books, called Apostles, such as inviting people to standardization and establishment of religion and warning against shirk and dangerous. Either details of divine judgments, Qur'an vary in scarves with heavenly books earlier, given different temporal and spatial envelope. I believe that mystery of this hegemony lies in establishing Qur'an legislative approach and high moral value and ethical content containing no truth divinely past cancel, but are marred by imbalance and lack of force, also decides entire rights and obligations of owners within By right and wrong which reject it. And I like to assert that Quranic domination does not appear in earlier books Awar revealed after distorted nodal hand; legislative and ethical and social and other, at same time Announces certification of its right.

Psychophysical evaluation of contrast sensitivity using Gabor patches in tobacco addiction

This study, an extension of Fernandes et al. (2017), provided consistent contrast sensitivity function (CSF) measurements in a large sample. CSF was assessed for luminance stimuli in different 48 chronic smokers and 50 healthy nonsmokers. Stimuli for the CSF were Gabor patches with spatial frequencies of .2, 2.5, 5.0, 10.0, and 20.0 cycles per degree (cpd). The use of Gabor patches minimizes uncertainty in spatial position and detection of frequencies. The Gabor patches consisted of vertical gratings that were multiplied by a two-dimensional spatial Gaussian envelope. All of the groups were matched for gender and level of education. All of the participants were free from any neurological disorder, cardiovascular disease, and identifiable ocular disease, and they had normal or corrected-to-normal visual acuity. No abnormalities were detected on the fundoscopic examination or optical coherence tomographic examination. The smoker group had a lower CSF compared with healthy nonsmokers at all spatial frequencies. These results indicate that cigarette smoking or chronic exposure to its constituent compounds affects early-stage visual discrimination, suggesting the existence of deficits in early visual spatial processing in smokers.

Performance of Hyperspectral Imaging with Drone Swarms

The ongoing proliferation and diversification of remote sensing platforms offer greater flexibility to select from a range of hyperspectral imagers as payloads. The emergence of low-cost unmanned aircraft systems (drones) and their launch flexibility present an opportunity to maximize spectral resolution while scaling both daily spatial coverage and spatial resolution simultaneously by operating synchronized swarms. This article presents a model to compare the performance of hyperspectral-imaging platforms in their spatial coverage and spatial resolution envelope. The authors develop a data acquisition framework and use the model to compare the achievable performance among existing airborne and spaceborne hyperspectral imaging vehicles and drone swarms. The results show that, subject to cost and operational limitations, a platform implemented with drone swarms has the potential to provide greater spatial resolution for the same daily ground coverage compared with existing airborne platforms.

Teager–Kaiser energy methods for signal and image analysis: A review

This paper provides a review of the Teager–Kaiser (TK) energy operator and its extensions for signals and images processing. This class of operators possesses simplicity and good time-resolution and is very efficient in instantaneously estimating AM–FM signals and images. We point out the importance of the concept of energy from the point of view of the generation of the signal. More precisely, we emphasize the importance of analyzing signals from the point of view of the energy of the system needed to produce them. We show how this class of TK energy operators can be used to estimate useful features for signals and images analysis in time, space and frequency domains such as instantaneous frequency, second-order moment frequency, coherence function or spatial envelope and phase. We also show the importance of the higher derivative order of TK energy operator in terms of demodulation for both mono and multi-dimensional signals. Most of the developed tools around TK energy operators deal with real and complex-valued signals and some of them extended to multi-dimensional case. Due to their low complexity and their instantaneous-adapting nature, the class of TK energy operators offers valuable processing tools for time (space), frequency and time–frequency analysis.

Limit on Excitation and Stabilization of Atoms in Intense Optical Laser Fields.

Atomic excitation in strong optical laser fields has been found to take place even at intensities exceeding saturation. The concomitant acceleration of the atom in the focused laser field has been considered a strong link to, if not proof of, the existence of the so-called Kramers-Henneberger (KH) atom, a bound atomic system in an intense laser field. Recent findings have moved the importance of the KH atom from being purely of theoretical interest toward real world applications; for instance, in the context of laser filamentation. Considering this increasing importance, we explore the limits of strong-field excitation in optical fields, which are basically imposed by ionization through the spatial field envelope and the field propagation.