Sequence Of Strokes Research Articles

Meteorological Aspects of Self‐Initiated Upward Lightning at the Säntis Tower (Switzerland)

AbstractInterest in exploring the meteorological conditions favoring upward lightning from tall man‐made structures has grown in recent years, largely due to the worldwide expansion of wind energy. To this end, instrumented towers existing around the world are the most suitable places to study upward lightning. In this context, an LMA network was deployed around the Säntis Mountain (northeast Switzerland) during the summer of 2017, in order to complement the long‐term measurements currently held at the Säntis telecommunications tower, a lightning hot spot in central Europe. This campaign allowed, for the first time, to gather a comprehensive set of observations of self‐initiated upward lightning emerging from the Tower. With the help of C‐band dual‐polarimetric radar data, the present work focuses on the meteorological conditions conductive to self‐initiated upward lightning from the Säntis. The analysis revealed that the upward propagating positively charged leaders spread mostly horizontal above the melting level, after an initial short vertical path from the tower tip. After this initial stage, the majority of upward leaders were followed by a sequence of negative return strokes. The inception upward lightning under a stratiform cloud shield would be favored by the low height of the charge structure. From the obtained results, it turns out that a key feature favoring self‐initiated upward lightning would be the proximity of the tower tip to the melting level.

Design and development of an EOG-based simplified Chinese eye-writing system

Eye movement information provides an alternative way for patients with muscular and neurological disorders to communicate with other people or devices. Electrooculography (EOG) is an effective eye movement recording method that has been widely applied to design human–computer interaction systems. In this paper, we propose a simplified Chinese eye-writing system based on EOG (EsCew) by identifying the basic strokes of Chinese characters. Specifically, we first use a bandpass digital filter to preprocess the raw EOG signals to suppress noise interference. Then, we determine the effective eye movement segments according to different strokes by detecting blink signals using the sliding window technique. On this basis, we establish basic stroke templates in terms of the handwriting characteristics of Chinese characters. To reduce the computational complexity, the DTW algorithm is adopted to classify the EOG segments. Finally, we match the stroke sequence with the encoded Chinese characters to obtain the final recognition results. In the lab environment, the recognition experiments are performed on 10 most representative Chinese characters, i.e., ▪. The average accuracies of the basic strokes and Chinese characters are 93.998% and 94.52%, respectively. The experimental results validate the feasibility of the proposed EsCew system. [Display omitted]

A sketch recognition method based on transfer deep learning with the fusion of multi-granular sketches

Most of existing sketch recognition methods focus on the contour/shape of whole sketches. They ignore different granularities of sketches during sketching. Stroke sequences of sketches often demonstrate the change of various granularities. In the progress of sketching, a coarser-grained contour gradually changes to a finer-grained object. Different granularities of sketch imply different levels of semantic information and play different roles in sketch recognition. In this paper, a transfer-deep-learning-based sketch recognition method--“sketch-transfer-net” is proposed. Sketch-transfer-net designs a novel fine-tuning strategy to use different granular sketches to fine-tune different layers of neural network. The extensive comparative experiments show that the proposed sketch-transfer-net can capture descriptive information of various granular sketches and therefore improve the performance of sketch recognition. In addition, the novel fine-turning strategy could weaken the negative effect in transfer learning and enable CNNs to be well trained on small sketch datasets.

The association between children’s common Chinese stroke errors and spelling ability

The present study adopted an error analysis approach to examine the stroke errors committed by 43 Hong Kong Chinese children of Grades 1 and 3 from a Chinese Character Copying Task. It aimed to determine the common stroke error patterns, developmental changes and the cognitive problems implied. The different types of stroke errors and total number of correct stroke sequence were further linked to Chinese word spelling ability and associated cognitive-linguistic skills. Results revealed that wrong stroke sequence and wrong character configuration were the common stroke errors in both grades and Grade 3 students made significantly fewer errors in these two categories. Both wrong stroke sequence and wrong character configuration were found to be associated with poor visual discrimination skills and visual sequential and spatial memory. Character configuration error was a significant predictor of Chinese word spelling ability whereas correct stroke sequence only contributed significantly to Chinese word spelling performance in Grade 3. These findings suggest the significance of character configuration knowledge in Chinese spelling and its importance in facilitating the orthographic developments of structural knowledge and radical knowledge. The findings have implications for the design of an enriched curriculum to teach Chinese character so as to foster a better foundation for orthographic development as well as Chinese word spelling ability.

Efficiency limits of the three-sphere swimmer

We consider a swimmer consisting of a collinear assembly of three spheres connected by two slender rods. This swimmer can propel itself forward by varying the lengths of the rods in a way that is not invariant under time reversal. Although any non-reciprocal strokes of the arms can lead to a net displacement, the energetic efficiency of the swimmer is strongly dependent on the details and sequences of these strokes, and also the sizes of the spheres. We define the efficiency of the swimmer using Lighthill's criterion, i.e., the power that is needed to pull the swimmer by an external force at a certain speed, divided by the power needed for active swimming with the same average speed. Here, we determine numerically the optimal stroke sequences and the optimal size ratio of the spheres, while limiting the maximum extension of the rods. Our calculation takes into account both far-field and near-field hydrodynamic interactions. We show that, surprisingly, the three-sphere swimmer with unequal spheres can be more efficient than the equally-sized case. We also show that the variations of efficiency with size ratio is not monotonic and there exists a specific size ratio at which the swimmer has the highest efficiency. We find that the swimming efficiency initially rises by increasing the maximum allowable extension of the rods, and then converges to a maximum value. We calculate this upper limit analytically and report the highest value of efficiency that the three-sphere swimmer can reach.

Accentuating Features of Description Logics in High-Level Interpretations of Hand-Drawn Sketches

We propose an ontology-based approach to interpret hand-drawn sketches, originating from empirical results of experiments with human participants. The approach combines qualitative features of the sequence of sketch strokes with a high-level knowledge, and accentuates the potential effectiveness of interpretation via description logics. The results of an implementation, along with explanations, are presented to show how to extract the semantics of hand-drawn sketches of four object categories.

Evolution of an Upward Negative Lightning Flash Triggered by a Distant +CG From a 257‐m‐Tall Tower, Including Initiation of Subsequent Strokes

AbstractUsing the high‐speed optical and electric field records, in conjunction with Earth Networks Total Lightning Network and radar data, we examined in detail the morphology and evolution of an upward negative flash containing six downward leader/upward return stroke sequences terminated on a 257‐m tower in Florida. The upward flash was induced (triggered) by a single‐stroke 50‐kA +CG that occurred about 45 km from the tower. The in‐cloud part of +CG was optically detected to extend toward the tower and appeared to stop at a height of about 3 km above the tower top. The six leader‐return‐stroke sequences were each initiated by a bidirectional leader utilizing the remnants of branches created during the initial stage. Electric field signatures of bidirectional leaders were similar to K‐changes. The upper end of the return‐stroke channel in all six cases exhibited branching and appeared to extend to higher altitudes or/and move closer to Lightning Observatory in Gainesville with increasing stroke order.

Three-dimensional detection of sequence of strokes using confocal microscope

BackgroundIn the present study, three-dimensional application of confocal microscope is explored. The aim is to determine the sequence of intersecting lines written on a questioned document as a non-destructive technique. The authors have tested the Nikon confocal A1 microscope on two major criteria. The criterion 1 focuses on the analysis of homogenous intersecting lines, whereas the criterion 2 focuses on the effect of pen pressure on the sequence of the strokes. Fifty-four and 42 samples from criterion 1 and criterion 2 respectively were examined. All the intersecting strokes were homogeneous and in either black- or blue-coloured ink. They were made from glycol-based (ballpoint pen) and liquid-based (fountain pen and gel pen) inks.ResultThe authors were able to determine the correct sequence of homogeneous intersecting lines in 81 and 83% of the average data of samples for criterion 1 (the analysis of homogenous intersecting lines) and criterion 2 (the effect of pen pressure on the sequence of the strokes) respectively.ConclusionThe confocal microscope proved to be a reliable and precise technique for analysing the homogeneous intersected lines made by any pen pressure beyond all the errors during interpretation.

Influence of Process Fluctuations on Residual Stress Evolution in Rotary Swaging of Steel Tubes.

Infeed rotary swaging is a cold forming production technique to reduce the diameter of axisymmetric components. The forming is achieved discontinuously by a series of radial strokes that are spread over the shell of the part. Due to tolerances within the rotary swaging machine, these strokes perform individually and the resulting stroke pattern is not homogeneous with regards to circumferential and longitudinal distribution. Nevertheless, in combination with the high number of performed strokes and the large contact area between the dies and the part, the external part properties, such as diameter, roundness and surface roughness, show even values along the finished part. In contrast, strength-defining internal part properties, like microstructure and residual stress components, are more sensitive to the actual pattern and temporal sequence of the individual strokes, which is investigated in this study. The impact of process fluctuations during the conventional process, which are induced by the tolerances of machine tool components, was verified by numerical simulations, physical tests and measurements of residual stress distributions at the surface and at depth. Furthermore, a method is introduced to maintain the stroke following angle ∆φ at zero by flat dies, and thus the actual pattern and temporal sequence of the strokes was homogenized. The results show that the residual stress fluctuations at the surface could be controlled and reduced. Furthermore, it is demonstrated that the depth profile of the residual stresses at a distance of 300 µm from the surface developed independently from the process fluctuations.

An Advanced Model of Lightning M‐Component

AbstractAn advanced nonlinear and nonuniform distributed circuit (RLCG) model of lightning M‐component has been developed. The model accounts for the variation of the series resistance R of M‐component channel due to its heating by the transient current and its subsequent cooling, longitudinal voltage drop along the channel due to the background continuing current, ohmic losses in the channel corona sheath (represented by shunt conductance G), and variation of series inductance L and shunt capacitance C of the channel with height above ground. The model was tested against the channel‐base current and corresponding close electric fields measured for seven M‐components in negative lightning triggered using the rocket‐and‐wire technique. Detailed sensitivity analysis was performed for one M‐component. The influences of height‐varying series inductance and shunt capacitance and the length of in‐cloud channel (representing the excitation source) on the computed current and field waveforms were found to be relatively insignificant, while the influences of ohmic losses in the channel corona sheath and voltage drop along the grounded channel were significant. The effects of background continuing current level and grounding resistance were significant for M‐field, but not for M‐current. Model‐predicted overall power and current profiles below the cloud base are consistent with the observed M‐component luminosity profiles and are drastically different from the observed downward leader/upward return stroke profiles. The characteristic feature of M‐components, the time shift between the current onset and close electric field peak (essentially absent for leader/return stroke sequences), was well reproduced by our model.

Synchronized Two‐Station Optical and Electric Field Observations of Multiple Upward Lightning Flashes Triggered by a 310‐kA +CG Flash

AbstractA positive cloud‐to‐ground (+CG) lightning flash containing a single stroke with a peak current of approximately +310 kA followed by a long continuing current triggered seven upward lightning flashes from tall structures. The flashes were observed on 4 June 2016 at the Tall Object Lightning Observatory in Guangzhou, Guangdong Province, China. The optical and electric field characteristics of these flashes were analyzed using synchronized two‐station data from two high‐speed video cameras, one total‐sky lightning channel imager, two lightning channel imagers, and two sets of slow and fast electric field measuring systems. Three upward flashes were initiated sequentially in the field of view of high‐speed video cameras. One of them was initiated approximately 0.35 ms after the return stroke of +CG flash from the Canton Tower, the tallest structure within a 12‐km radius of the +CG flash, while the other two upward flashes were initiated from two other, more distant tall objects, approximately 18 ms after the +CG flash stroke. The initiation of the latter two upward flashes could be caused by the combined effect of the return stroke of +CG flash, its associated continuing current, and K process in the cloud. Each of these three upward flashes contained multiple downward leader/upward return stroke sequences, with the first leader/return stroke sequence of the second and third flashes occurring only after the completion of the last leader/return stroke sequence of the preceding flash. The total number of strokes in the three upward flashes was 13, and they occurred over approximately 1.5 s.

New approach for the optimization of pass-schedules in open-die forging

Open-die forging is an incremental forming process, which is mainly used for the production of large parts with high requirements regarding the mechanical properties and reliability of the forged parts. Finite element analysis (FEA) is able to simulate open die forging sequences. It is therefore very suitable to confirm, whether a selected schedule will be successful in terms of reaching the desired geometry and internal product quality. However, it is comparably slow and therefore not suitable for early process design, when out of an almost infinite number of potential sequences of strokes, an appropriate pass schedule needs to be designed. This is today usually achieved by pass schedule planning software, which takes into account volume constancy, empirical spread behavior and average temperature evolution. However, they do not account for product quality characteristics like microstructure and voids closure. In this paper recently developed fast models, which are able to calculate the temperature, equivalent strain and microstructure evolution along the core fibre of a forged workpiece are coupled with an optimization algorithm to allow automatic pass schedule layout and optimization. Different cost functions are evaluated regarding their impact on the resulting properties of the workpiece. The results indicate that for an overall optimization of open-die forging processes different phenomena and influencing parameters need to be considered, since all of these parameters have a significant influence on the resulting properties such as equivalent strain, temperature and grain size of the ingot.

SketchSegNet+: An End-to-End Learning of RNN for Multi-Class Sketch Semantic Segmentation

We investigate the problem of stroke-level sketch segmentation, which is to automatically assign strokes of a given sketch with semantic labels. Solving the problem of sketch segmentation opens the door for fine-grained sketch interpretation, which can benefit many novel sketch-based applications, including sketch recognition and sketch-based image retrieval. In this paper, we propose an approach for multi-class sketch semantic segmentation by considering it as a sequence-to-sequence generation problem. Specifically, an end-to-end learned network SketchSegNet+, built on recurrent neural networks (RNN), is presented to translate a sequence of strokes into a sequence of semantic labels. In addition, a large-scale stroke-level sketch segmentation dataset is constructed for the first time, which is composed of 150K annotated free-hand human sketch selected from QuickDraw. The dataset will be released publicly. The experimental results of stroke-level sketch semantic segmentation on this novel dataset and the SPG dataset demonstrate the effectiveness of our approach.

Pictionary-Style Word Guessing on Hand-Drawn Object Sketches: Dataset, Analysis and Deep Network Models.

The ability of intelligent agents to play games in human-like fashion is popularly considered a benchmark of progress in Artificial Intelligence. In our work, we introduce the first computational model aimed at Pictionary, the popular word-guessing social game. We first introduce Sketch-QA, a guessing task. Styled after Pictionary, Sketch-QA uses incrementally accumulated sketch stroke sequences as visual data. Sketch-QA involves asking a fixed question ("What object is being drawn?") and gathering open-ended guess-words from human guessers. We analyze the resulting dataset and present many interesting findings therein. To mimic Pictionary-style guessing, we propose a deep neural model which generates guess-words in response to temporally evolving human-drawn object sketches. Our model even makes human-like mistakes while guessing, thus amplifying the human mimicry factor. We evaluate our model on the large-scale guess-word dataset generated via Sketch-QA task and compare with various baselines. We also conduct a Visual Turing Test to obtain human impressions of the guess-words generated by humans and our model. Experimental results demonstrate the promise of our approach for Pictionary and similarly themed games.

An online overlaid handwritten Japanese text recognition system for small tablet

The paper presents a recognition system of online overlaid handwritten Japanese text patterns on a smart phone or baby-face tablet. The proposed system oversegments a sequence of strokes into primitive segments at candidate off-strokes between strokes using a SVM model. One or more consecutive primitive segments form a candidate character pattern, which is recognized into a list of candidate categories. Then, a segmentation and recognition candidate lattice is constructed to represent all candidate character patterns and their corresponding character classes. Finally, the optimal path is effectively found by the Viterbi search in the lattice, combining the scores of character recognition, geometric features, linguistic context, as well as the segmentation scores by SVM classification. This system incorporates feature reduction and non-character pruning to decrease the time cost per character, and semi-incremental recognition to decrease waiting time. The recognition rates on generated and collected overlaid handwritten text are 92.16% and 93.04%, respectively. The average time cost per character is not more than 0.6 s, and the average waiting time is less than 0.875 s even on an Intel Atom 1.33 GHz CPU: a low power consumption CPU for small tablets and embedded devices. Therefore, we confirm that our system recognizes online overlaid handwritten text composed of thousands of Japanese character classes with the high recognition rate without excessive waiting time.

All play and no work: skits and models in teaching skeletal muscle physiology.

All play and no work: skits and models in teaching skeletal muscle physiology.

Game of Sketches: Deep Recurrent Models of Pictionary-Style Word Guessing

The ability of machine-based agents to play games in human-like fashion is considered a benchmark of progress in AI. In this paper, we introduce the first computational model aimed at Pictionary, the popular word-guessing social game. We first introduce Sketch-QA, an elementary version of Visual Question Answering task. Styled after Pictionary, Sketch-QA uses incrementally accumulated sketch stroke sequences as visual data. Notably, Sketch-QA involves asking a fixed question ("What object is being drawn?") and gathering open-ended guess-words from human guessers. To mimic Pictionary-style guessing, we propose a deep neural model which generates guess-words in response to temporally evolving human-drawn sketches. Our model even makes human-like mistakes while guessing, thus amplifying the human mimicry factor. We evaluate our model on the large-scale guess-word dataset generated via Sketch-QA task and compare with various baselines. We also conduct a Visual Turing Test to obtain human impressions of the guess-words generated by humans and our model. Experimental results demonstrate the promise of our approach for Pictionary and similarly themed games.

Fewer peripheral asymmetrical cortical veins is a predictor of favorable outcome in MCA infarctions with SWI-DWI mismatch.

Outcome prediction of asymmetrical prominent cortical veins (APCVs) on infarction is still debated and may help in selecting patients for reperfusion treatment. To explore the relationship between fewer peripheral APCVs and the outcome in the patients of acute/subacute middle cerebral artery (MCA) infarctions as well as the relationship between this sign and stenosis of ipsilateral MCA. Retrospective case-control study. We enrolled 41 patients with MCA acute/subacute infarction. Compared to the low sign of cortical veins of contralateral hemisphere on susceptibility-weighted imaging (SWI), these patients were divided into fewer (n = 28) and prominent APCVs (n = 13) groups. 3.0T conventional stroke sequences, including T1 -weighted imaging, T2 -weighted imaging, fluid-attenuated inversion recovery (FLAIR), diffusion-weighted imaging (DWI) (b = 0 and 1000 s/mm2 ), MR angiography (MRA), and SWI. We explored the relationships between fewer peripheral APCVs sign and clinical outcome, as well as the relationship between this sign and the degree of ipsilateral MCA stenosis. Fisher's exact analysis, logistical regression, as well as Cohen's kappa coefficient were used for statistical analysis. Fewer and prominent peripheral APCVs were detected in 28 (56.10%) and 13 (43.90%) patients. In 28 patients with fewer peripheral APCVs, 23 patients (82.14%) had a favorable outcome (modified Rankin Scale [mRS] ≤2), and five patients (17.76%) had an unfavorable outcome (mRS >2) (P = 0.010). In terms of MCA stenosis, the rate of normal and mild to moderate stenosis of MCA in the fewer APCVs group (82.14%) was higher than that in the prominent APCVs group (23.08%) (P < 0.001). More severe stenosis of ipsilateral MCA was found in patients with prominent APCVs group (76.92%) than that of fewer APCVs group (17.86%). The peripheral APCVs was positively correlated with the degree of MCA stenosis (r = 0.538, P < 0.001). Fewer peripheral APCVs may suggest a favorable outcome in unilateral MCA infarction. The patency of ipsilateral MCA may correlate to fewer APCVs and favorable outcome. 3 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018;48:964-970.

Determination of the Sequence of Strokes Made from the Same Color and Type of the Ink

Determination of the Sequence of Strokes Made from the Same Color and Type of the Ink

A Database of Radicals in Written Chinese with Reliable Logographeme Boundaries

A Database of Radicals in Written Chinese with Reliable Logographeme Boundaries