High-speed Pattern Research Articles

An Analysis of Air Conditioning System Operation Patterns on Droplet Particle Distribution in a Classroom-A CFD Approach

In the classroom context, the transmission of pathogens among students is a significant concern. Therefore, it is important to determine appropriate airflow patterns, the placement of supply and exhaust ventilation, and the optimization of classroom design to reduce the risk of pathogen transmission. This research aims to determine the performance of two air conditioning (AC) operating patterns—low speed and high speed—in six scenarios involving window and door configurations and identify the most effective strategies for minimizing virus exposure to occupants in classrooms. The method used in this research is numerical simulation with the 3D unsteady k-ε RNG model to simulate air flow and the Eulerian-Lagrange approach to capture the movement of SARS-CoV-2 aerosol droplets. The results of this research show that of the six scenarios determined by the researchers, the low-speed AC operating pattern with an incoming air speed of 3.5 m/s occurs in scenario 5, that is, all windows open and doors closed. This is based on the lowest number of students exposed to the virus, which is 22.22%. Meanwhile, the high-speed AC operating pattern with an incoming air speed of 6 m/s occurs in scenario 2, that is, all windows closed and doors open. This is based on the lowest number of students exposed to the virus, which is 22.22%, so it can be concluded that increasing the air flow speed originating from the AC will speed up the droplets to leave the room through the outlet. Meanwhile, increasing the outlet capacity will shorten the particle path, thereby shortening the time when the droplets are in the classroom.

P4Rex: Accelerating regular expression matching with programmable switches

Regular expression matching is pivotal in numerous network applications. With the ever-increasing scale of data center traffic, deploying regular expression matching modules on traditional servers struggles to meet throughput demands. Emerging programmable switches have brought new prospects for high-speed pattern matching. However, deploying regular expression matching onto programmable switches presents the challenge of space explosion incurred by compiling regular expressions into a Deterministic Finite Automata (DFA). In this paper, we introduce P4Rex, a regular expression matching system designed for programmable switches. P4Rex synergistically leverages two following techniques: an efficient regular expression grouping algorithm that partitions regular expressions into different groups to reduce memory consumption, and DFA compression technology to achieve transition sharing. Experimental results demonstrate that P4Rex exhibits an average improvement of 17% and maximum improvement of 30% on memory consumption compared to prior regular expression grouping schemes and saves more than 10x memory consumption compared to deploying DFA directly on programmable switch.

Assessing the Impact of 20 mph Speed Limits on Vehicle Speeds in Rural Areas: The Case of the Scottish Borders

This paper aims at delivering new empirical evidence as to the effectiveness of 20 mph speed limits in rural areas. For this purpose, speed and traffic data were drawn from the area of the Scottish Borders, UK, where the local Council led the rollout of a 20 mph speed limit trial in 97 villages and towns from October 2020. This intervention is considered as one of the first of its kind in the UK and overseas, as it was carried out on a large scale, in predominantly rural areas. To evaluate the impact of the 20 mph speed limit on vehicle speeds, we conducted a “before–after” quantitative analysis using traffic and speed data collected in different waves before and after the intervention. The descriptive analysis showed that both mean and 85th percentile speeds reduced directly after the introduction of the 20 mph speed limit (by 3.1 mph and 3.2 mph, respectively), and that such speed reductions were largely maintained even up to eight months after the onset of the intervention. The largest speed reductions were observed in locations with high-speed patterns before the intervention, and especially in those having mean speeds greater than 25 mph before the intervention. Both non-parametric and parametric statistical tests, which were conducted using approximately five million speed observations, showed that the observed speed changes were statistically significant for the vast majority of cases. Linear regression models were also estimated confirming the significant impact of the 20 mph limit on vehicle speeds, while controlling for the influence of traffic volume. Overall, the findings of this study will likely assist in filling an evidence gap regarding the effectiveness of 20 mph speed limits in rural settlements. They can also provide encouragement to those local authorities in the UK and abroad that are currently actively examining the possibility of setting the 20 mph as the default limit in built-up areas.

All-Optical Multiplexed Meta-Differentiator for Tri-Mode Surface Morphology Observation.

Current optical differentiators are generally limited to realizing a single differential function once fabricated. Herein, a minimalist strategy in designing multiplexed differentiators (1st - and 2nd -order differentiations), implemented with a Malus metasurface consisting of single-sized nanostructures is proposed, thus improving the functionality of optical computing devices without the cost of complex design and nanofabrication. It is found that the proposed meta-differentiator exhibits excellent differential-computation performance and can be used for simultaneous outline detection and edge positioning of objects, corresponding to the functions of the 1st - and 2nd -order differentiations respectively. Experiments with biological specimens showcase that boundaries of biological tissues can not only be identified, but also the edge information for realizing high-precision edge positioning is highlighted. The study provides a paradigm in designing all-optical multiplexed computing meta-devices, and initiates tri-mode surface morphology observation by combining meta-differentiator with optical microscopes, which can find their applications in advanced biological imaging, large-scale defect detection, and high-speed pattern recognition, etc.

Experimental demonstration of 84 Gbps QPSK signal’s 4-symbol all-optical pattern recognition

In the F5G era, a promising all-optical processing technology named all-optical pattern recognition has attracted more and more attention. Its applications include not only all-optical header recognition or address recognition in OCDMA but also optoelectronic firewalls. The higher the recognition rate of pattern recognition, the higher the processing rate of both applications can reach. To meet the development features of eFFB in F5G, high-speed all-optical pattern recognition should be achieved. In this paper, a QPSK all-optical pattern recognition system with a data rate of up to 84Gbps is proposed, analyzed, and experimentally demonstrated by employing commercial independent optical components. The system first converts the I branch of the input QPSK signal to a positive and a negative IM signal by adding the coherent carrier from the orthogonal polarization. Then the converted IM signals are coupled into time delay lines and optical AND logic gates implemented by HNLFs to achieve the optical correlation operation. In the end, a high-level optical pulse indicating the pattern recognized result is output. Numerical simulation results reveal that the proposed system can recognize the target sequence from the I branch of the input sequence and the position of the output high-level pulse in the time window of the I branch of the input sequence is the position of the last symbol of the target sequence. The results of the experiment demonstrate that the proposed system can recognize a 4-symbol target sequence from the I branch of an 8-symbol 84Gbps QPSK input sequence, which proves the all-optical pattern recognition of QPSK signals.

The behavior of standing waves near the end of an open pipe with low mean flow

The acoustic standing wave near the end of an open pipe is investigated using spectrally analyzed high-speed transmission electronic speckle pattern interferometry. It is shown that the standing wave extends beyond the open end of the pipe and the amplitude decays exponentially with distance from the end. Additionally, a pressure node is observed near the end of the pipe in a position that is not spatially periodic with the other nodes in the standing wave. A sinusoidal fit to the amplitude of the standing wave inside the pipe indicates that the end correction is well predicted by current theory.

End behavior of the acoustic standing wave in a flue organ pipe

The acoustic standing wave in a transparent flue organ pipe has been imaged using high-speed transmission electronic speckle pattern interferometry. Spectral filtering of the interferograms at the acoustic resonance frequency of the gas inside the pipe results in an image showing the sinusoidal pressure dependence inside the pipe as well as the expected extension of the standing wave beyond the pipe end. However, the image also reveals anomalous and unexplained behavior as the standing wave transitions from inside to outside the pipe.

Strategic Thinking and Countermeasures of Anhui's Urban Economic Development under the High-Speed Rail Economy

At present, the total mileage of Anhui's high-speed rail ranks first in China. The high-speed rail has brought a new development path to Anhui's economy, but it is also accompanied by challenges. Hefei City, located in the center of Anhui, has the largest high-speed rail station in Anhui - Hefei South Railway Station. In the future, it will also form a super "clock-shaped" high-speed rail radiation network pattern in 13 directions. Based on the data of Anhui's urban economic development, this project adopts the methods of comparative analysis and literature research, and uses dynamic comparison, content analysis, and bibliometric methods to obtain the process and law of economic development in Hefei, Anhui under the influence of high-speed rail economy, and the impact on Hefei's economic development. The current situation and direction are analyzed and summarized, and on this basis, the path and countermeasures for further reasonable development of Hefei in the era of high-speed rail economy are proposed.

Deep learning enabled single-shot absolute phase recovery in high-speed composite fringe pattern profilometry of separated objects

Deep learning enabled single-shot absolute phase recovery in high-speed composite fringe pattern profilometry of separated objects

Imaging acoustic standing waves in the presence of flowing gas.

A method for imaging an acoustic standing wave in the presence of flowing gas is described. The optical power at the acoustic frequency in each pixel of a series of high-speed transmission electronic speckle pattern interferograms is used to map the steady-state pressure variations of an acoustic standing wave. The utility of the process is demonstrated by imaging the standing wave inside a transparent organ pipe.

Ultrahigh frame rate digital light projector using chip-scale LED-on-CMOS technology

Digital light projector systems are crucial components in applications, including computational imaging, fluorescence microscopy, and highly parallel data communications. Current technology based on digital micromirror displays are limited to absolute frame rates in the few tens of kiloframes per second and require the use of external light sources and coupling optics. Furthermore, to realize gray-scale pixel values using duty cycle control, frame rates are reduced proportionally to the number of gray levels required. Here we present a self-emissive chip-scale projector system based on micro-LED pixels directly bonded to a smart pixel CMOS drive chip. The 128 × 128 pixel array can project binary patterns at up to 0.5 Mfps and toggle between two stored frames at megahertz rates. The projector has a 5-bit gray-scale resolution that can be updated at up to 83 kfps, and can be held in memory as a constant bias for the binary pattern projection. Additionally, the projector can be operated in a pulsed mode, with individual pixels emitting pulses down to a few nanoseconds in duration. Again, this mode can be used in conjunction with the high-speed spatial pattern projection. As a demonstration of the data throughput achievable with this system, we present an optical camera communications application, exhibiting data rates of > 5 Gb / s .

Industrialization, energy consumption, and environmental pollution: evidence from South Asia.

This study has been carried out to analyze the contribution of industrialization and energy consumption by keeping the role of urbanization on environmental pollution for South Asia. The study used Augmented Mean Group (AMG), Common Correlated Effects Mean Group (CCEMG) analysis, Westerlund co-integration test, and Dumitrescu-Hurlin causality test for the panel of South Asia covering the period 1984-2016. To measure the status of environmental pollution, CO2 is taken as a proxy indicator, and industrialization is measured by the industrial value-added. The results of AMG demonstrate that industrialization and energy consumption are significant indicators of environmental pollution and these empirical findings are also confirmed by the CCEMG model. The long-run co-integration between industrialization, energy use, urbanization, capital, and environmental pollution is also confirmed by the Westerlund co-integration test. The findings of the Dumitrescu-Hurlin causality test also confirmed the bidirectional causality between industrialization and pollution. A unidirectional causality is observed from energy consumption to pollution. The study suggests formulating policies for energy-efficient technologies in the industrial sector and the high-speed pattern of urbanization.

A new fast technique for pattern matching in biological sequences

At numerous phases of the computational process, pattern matching is essential. It enables users to search for specific DNA subsequences or DNA sequences in a database. In addition, some of these rapidly expanding biological databases are updated on a regular basis. Pattern searches can be improved by using high-speed pattern matching algorithms. Researchers are striving to improve solutions in numerous areas of computational bioinformatics as biological data grows exponentially. Faster algorithms with a low error rate are needed in real-world applications. As a result, this study offers two pattern matching algorithms that were created to help speed up DNA sequence pattern searches. The strategies recommended improve performance by utilizing word-level processing rather than character-level processing, which has been used in previous research studies. In terms of time cost, the proposed algorithms (EFLPM and EPAPM) increased performance by leveraging word-level processing with large pattern size. The experimental results show that the proposed methods are faster than other algorithms for short and long patterns. As a result, the EFLPM algorithm is 54% faster than the FLPM method, while the EPAPM algorithm is 39% faster than the PAPM method.

Identification of Small, Regularly Shaped Cerebral Aneurysms Prone to Rupture.

Many small, regularly shaped cerebral aneurysms rupture; however, they usually receive a low score based on current risk-assessment methods. Our goal was to identify patient and aneurysm characteristics associated with rupture of small, regularly shaped aneurysms and to develop and validate predictive models of rupture in this aneurysm subpopulation. Cross-sectional data from 1079 aneurysms smaller than 7 mm with regular shapes (without blebs) were used to train predictive models for aneurysm rupture using machine learning methods. These models were based on the patient population, aneurysm location, and hemodynamic and geometric characteristics derived from image-based computational fluid dynamics models. An independent data set with 102 small, regularly shaped aneurysms was used for validation. Adverse hemodynamic environments characterized by strong, concentrated inflow jets, high speed, complex and unstable flow patterns, and concentrated, oscillatory, and heterogeneous wall shear stress patterns were associated with rupture in small, regularly shaped aneurysms. Additionally, ruptured aneurysms were larger and more elongated than unruptured aneurysms in this subset. A total of 5 hemodynamic and 6 geometric parameters along with aneurysm location, multiplicity, and morphology, were used as predictive variables. The best machine learning rupture prediction-model achieved a good performance with an area under the curve of 0.84 on the external validation data set. This study demonstrated the potential of using predictive machine learning models based on aneurysm-specific hemodynamic, geometric, and anatomic characteristics for identifying small, regularly shaped aneurysms prone to rupture.

Impact of Temperature on the Spray Characteristics of Jatropha Curcas Biodiesel and Diesel Fuel Blends

Abstract There is an increasing demand of energy because of an increase in the number of vehicles with internal combustion engines, because of which industrial and automotive fields are concerned about fossil fuel depletion, environmental issues, and energy conservation. These challenges force the world to explore other alternative sources of energy. The extensive use of biodiesel as compression ignition engine fuel has further compelled the researchers to regulate the emission and improve the engine performance. Fuel spray behavior affects mixture formation, and this affects engine combustion and performance. This research work involves the evaluation of the relationship between spray parameters of used Jatropha curcas biodiesel fuel, including spray penetration, cone angle, and preheating temperature, compared with diesel fuel, conducted at ambient condition. In addition to this, the high-speed spray pattern photography is undertaken by using single-hole and multi-hole injectors. The spray behavior is analyzed through spray parameters such as spray cone angle and spray penetration for all test fuels. The fuel temperature has a strong relationship with spray behavior at high temperatures; as the fuel temperature increases, the spray tip penetration decreases due to the evaporation of the fuel having a low boiling point and good fuel atomization, which leads to smaller droplets and an increase in spray cone angle with the increase in temperature.

Prediction of bleb formation in intracranial aneurysms using machine learning models based on aneurysm hemodynamics, geometry, location, and patient population

BackgroundBleb presence in intracranial aneurysms (IAs) is a known indication of instability and vulnerability.ObjectiveTo develop and evaluate predictive models of bleb development in IAs based on hemodynamics, geometry, anatomical location,...

The effect of resonator shape on air flow in flue organ pipes

The effect of changing the shape of the resonator of a flue organ pipe was studied in a replica of an organ pipe that was printed using transparent media. The pipe was designed so that the rectangular resonator could be replaced by a cylindrical one of the same cross sectional area, and the airflow in the pipe was imaged using high-speed transmission electronic speckle pattern interferometry. The resulting images reveal that there is a fundamental difference in the flow when the resonator shape is altered. Differences in the airflow and sound attributable to the shape of the resonator will be discussed.

Hemodynamic conditions that favor bleb formation in cerebral aneurysms

BackgroundAlthough it is generally believed that blebs represent weaker spots in the walls of intracranial aneurysms (IAs), it is largely unknown which aneurysm characteristics favor their development.ObjectiveTo investigate possible associations...

Electron backscattered diffraction using a new monolithic direct detector: High resolution and fast acquisition

A monolithic active pixel sensor based direct detector that is optimized for the primary beam energies in scanning electron microscopes is implemented for electron back-scattered diffraction (EBSD) applications. The high detection efficiency of the detector and its large array of pixels allow sensitive and accurate detection of Kikuchi bands arising from primary electron beam excitation energies of 4 keV to 28 keV, with the optimal contrast occurring in the range of 8–16 keV. The diffraction pattern acquisition speed is substantially improved via a sparse sampling mode, resulting from the acquisition of a reduced number of pixels on the detector. Standard inpainting algorithms are implemented to effectively estimate the information in the skipped regions in the acquired diffraction pattern. For EBSD mapping, an acquisition speed as high as 5988 scan points per second is demonstrated, with a tolerable fraction of indexed points and accuracy. The collective capabilities spanning from high angular resolution EBSD patterns to high speed pattern acquisition are achieved on the same detector, facilitating simultaneous detection modalities that enable a multitude of advanced EBSD applications, including lattice strain mapping, structural refinement, low-dose characterization, 3D-EBSD and dynamic in situ EBSD.

Polysilicon Grating Switches for LiDAR

Novel polysilicon grating switches are demonstrated, consisting of an optical grating suspended on a moving platform above a waveguide. Electrostatic attraction pulls the grating into close proximity to the waveguide, ejecting light out of the waveguide plane. The switches move only 0.9 to 1.4 $\mu \text{m}$ , and have MHz mechanical resonant frequencies, making them robust to mechanical vibration and shock. These switches enable a new mode of LiDAR imaging; by creating a focal plane array of switches, and coupling it with a standard camera lens, the LiDAR beam can be scanned across the scene with high speed and arbitrary pattern. Both time of flight and coherent ranging techniques are compatible with this approach. We have demonstrated a $10\times 10$ pixel array of these switches in a LiDAR system, collecting 3D raging data at up to 15 meters away and 5 frames per second, over a 1 degree field of view with 0.1 degree resolution. Additionally, we have shown the switches to be robust, efficient, and reliable, actuating at 15 Volts, with speeds faster than $4~\mu \text{s}$ , for over 9 billion cycles without degradation or failure. [2020-0132]