Grid Distance Research Articles

Graph-enabled spatio-temporal transformer for ionospheric prediction

The ionosphere, crucial for satellite navigation and radio communication, is highly sensitive to solar and geomagnetic activities. Traditional ionospheric prediction models often struggle to capture its complexities. This paper introduces a Graph-Enabled Spatio-temporal transformer (GEST) model, designed to predict the Total electron content (TEC) in the ionosphere with higher accuracy. The GEST model innovatively integrates six dynamic space weather parameters, including the Kp index, and refines grid distances and weights in the Global ionospheric maps (GIM). Leveraging the efficiency of the Transformer architecture in processing spatio-temporal data, the GEST model adapts to varying ionospheric conditions and provides superior precision. Our evaluations, based on data from the Center for orbit determination in Europe (CODE), demonstrate that the GEST model significantly outperforms traditional methods and other intelligent algorithms such as conv-LSTM. It shows marked improvements in Mean absolute error (MAE), Root mean square error (RMSE), Pearson correlation coefficient (CC), and Mean absolute percentage error (MAPE), particularly during periods of intense solar and geomagnetic activity. These advancements highlight the GEST model’s substantial contributions to the field of ionospheric prediction technology, offering a robust tool for enhancing the reliability of satellite-based systems.

Indoor unknown radio transmitter localization using improved RSSD and grey correlation degree

Abstract Accurate location of unknown radio transmitter (URT) is the key to secure wireless communication. Since the fingerprint positioning methods based on received signal strength difference (RSSD) can adapt to the diversity of transmitting power and frequency, RSSD has become a popular scheme for locating the unknown radio transmitter. However, the RSSD is obtained by subtracting the RSS from two different access points (APs), so the interference of noise on the RSS is inherited and amplified by the RSSD. Besides, the need for more APs to ensure positioning accuracy leads to an increase in hardware costs. In this paper, a RSSD-based fuzzy weight grey correlation degree positioning algorithm, called FUZZY-GREY, is proposed to reduce the interference of noise, save AP hardware cost and improve the positioning accuracy. Firstly, online RSSD vector is improved by using fuzzy weight to reduce the noise interference. Secondly, the RSSD-based grey correlation coefficient is designed to calculate the correlation degree of the corresponding RSSD and ensure data integrity. Finally, a RSSD-based grey correlation degree scheme combining with fuzzy weight is proposed to select optimal reference points (RPs). Simulation and experimental results show that the proposed algorithm has better positioning performance than weighted k-nearest neighbor (WKNN), maximum correlation coefficient estimation (MCORE), Naive Bayes and support vector machine (SVM) in the case of different selected K numbers, grid distances, noise levels and AP numbers.

Particulate and gaseous air pollutants exceed WHO guideline values and have the potential to damage human health in Faisalabad, Metropolitan, Pakistan

First-ever measurements of particulate matter (PM2.5, PM10, and TSP) along with gaseous pollutants (CO, NO2, and SO2) were performed from June 2019 to April 2020 in Faisalabad, Metropolitan, Pakistan, to assess their seasonal variations; Summer 2019, Autumn 2019, Winter 2019–2020, and Spring 2020. Pollutant measurements were carried out at 30 locations with a 3-km grid distance from the Sitara Chemical Industry in District Faisalabad to Bhianwala, Sargodha Road, Tehsil Lalian, District Chiniot. ArcGIS 10.8 was used to interpolate pollutant concentrations using the inverse distance weightage method. PM2.5, PM10, and TSP concentrations were highest in summer, and lowest in autumn or winter. CO, NO2, and SO2 concentrations were highest in summer or spring and lowest in winter. Seasonal average NO2 and SO2 concentrations exceeded WHO annual air quality guide values. For all 4 seasons, some sites had better air quality than others. Even in these cleaner sites air quality index (AQI) was unhealthy for sensitive groups and the less good sites showed Very critical AQI (> 500). Dust-bound carbon and sulfur contents were higher in spring (64 mg g−1) and summer (1.17 mg g−1) and lower in autumn (55 mg g−1) and winter (1.08 mg g−1). Venous blood analysis of 20 individuals showed cadmium and lead concentrations higher than WHO permissible limits. Those individuals exposed to direct roadside pollution for longer periods because of their occupation tended to show higher Pb and Cd blood concentrations. It is concluded that air quality along the roadside is extremely poor and potentially damaging to the health of exposed workers.Graphical abstract

Method for Delineating the Formula Limit of the Continental Shelf under the Maximum Area Principle Constraint

In current practices of determining continental shelf area, the measured sediment thickness data do not effectively reflect the distribution of sediments across the area due to its dispersed nature. This issue raises potential limitations in unknown optimal survey line layout strategies for maximizing the posterior determination area. This paper adopts the binary search algorithm, relies on existing sediment thickness grid data, and uses geodetic formulas to build an ellipsoidal surface grid distance calculation model. This model quickly screens potential areas for the 1% sediment thickness line candidate points set. By constraining the azimuth parameter values during the construction process of the ellipsoidal point feature buffer zones, efficiently select the candidate points set for the 1% sediment thickness line. Furthermore, by elucidating the essential meanings of points on the formula limit and combining the candidate points set of the foot of the continental slope (FOS)+60 n mile line, the polygon minimal convex hull construction technique and a baseline points optimization algorithm with a length threshold are used to efficiently select points on formula limit. Experimental results demonstrate that this method can effectively assist coastal states in optimizing the determination of continental shelf area to the fullest extent under the length threshold requirements of the United Nations Convention on the Law of the Sea. Experiments have proven that compared to the traditional intersection method, the method presented in this paper can help coastal countries delineate a larger continental shelf area. In typical application scenarios, the gain in area can reach 77,278,427 m2 accounting for 0.51% of the total area.

Contrasting the requirements on MMC control for grid code compliance and distance protection

Contrasting the requirements on MMC control for grid code compliance and distance protection

Acute Intermittent Hypoxia Therapy alters Cognitive Behavioral Parameters in Wistar Albino Rats

Cognitive disorders, including dementia and Alzheimer’s disease, pose substantial global health challenges, demanding effective prevention and treatment strategies. Intermittent hypoxia therapy (IHT), involving brief exposures to reduced oxygen levels, is a novel approach with potential cognitive benefits. This study investigates the effects of IHT on cognitive behavior in wistar albino rats through comprehensive behavioral experiments, including the open field test (OFT) and Morris water maze (MWM). The results reveal that IHT promotes locomotor activity, reduces anxiety-related behaviors, and positively impacts cognitive flexibility. In the OFT, the IH group exhibited increased grid crossings and distance traveled, indicating heightened locomotion, which may be associated with cognitive improvement. Furthermore, IH significantly reduced thigmotaxis behavior and the number of fecal boli, indicating reduced anxiety levels compared to the control group. While IHT did not significantly enhance spatial memory acquisition in the MWM, it improved platform recognition during the probe test. The IH group spent more time in the target quadrant, suggesting enhanced memory retrieval and recognition. Additionally, in the reverse MWM, IH demonstrated moderate improvements in cognitive flexibility, with faster latency on trial 1. These findings suggest that IHT holds promise as a non-invasive intervention for cognitive enhancement, particularly in terms of locomotor activity, anxiety reduction, and certain aspects of memory and cognitive flexibility. Further research is warranted to elucidate the underlying mechanisms and explore the potential therapeutic applications of IHT in cognitive disorders. In summary, this study highlights the cognitive benefits of IHT in rats, paving the way for future investigations and potential clinical applications in the realm of cognitive disorders.

Sample of Groups: A New Strategy to Find a Representative Point for Each Undisclosed Cluster

Some problems involving the selection of samples from undisclosed groups are relevant in various areas such as health, statistics, economics, and computer science. For instance, when selecting a sample from a population, well-known strategies include simple random and stratified random selection. Another related problem is selecting the initial points corresponding to samples for the K-means clustering algorithm. In this regard, many studies propose different strategies for choosing these samples. However, there is no consensus on the best or most effective approaches, even when considering specific datasets or domains. In this work, we present a new strategy called the Sample of Groups (SOG) Algorithm, which combines concepts from grid, density, and maximum distance clustering algorithms to identify representative points or samples located near the center of the cluster mass. To achieve this, we create boxes with the right size to partition the data and select the representatives of the most relevant boxes. Thus, the main goal of this work is to find quality samples or seeds of data that represent different clusters. To compare our approach with other algorithms, we not only utilize indirect measures related to K-means but also employ two direct measures that facilitate a fairer comparison among these strategies. The results indicate that our proposal outperforms the most commonly used algorithms.

The full coverage approach to the detection of Extensive Air Showers

A shower array exploiting the full coverage approach with a high segmentation of the readout allow to image the front of atmospheric showers with unprecedented resolution and detail. The grid distance determines the energy threshold (small energy showers are lost in the gap between detectors) and the quality of the shower sampling. Therefore, this experimental solution is needed to detect showers with a threshold in the 100 GeV range. The full coverage approach has been exploited in the ARGO-YBJ experiment. In this contribution we will summarise the advantages of this technique and discuss possible applications in new wide field of view detectors.

Feasibility and sensitivity analysis of a self-sustainable hybrid system: A case study of a mountainous region in Bangladesh

The hilly territories in Bangladesh lack adequate electricity supplies due to their remote placement, which restrains the prosperity of the locality. This study presents a self-sustainable solution for Bilchari, a mountainous area of Bangladesh that shares the same electricity supply deficiency. The region lacks supplies but boasts a wealth of renewable energy resources, like biomass, wind, hydro, and solar. All of these sources are utilized to develop a hybrid system. The system load assessment is done for the winter and summer seasons according to the site's requirements. The overall simulation is performed using the hybrid optimization of multiple energy resources (HOMER) tool to find an optimum solution. Four competing solutions with different source combinations have been found by the simulation. Another four single-sourced systems are also investigated and compared to determine the superiority of hybrid systems over single-sourced systems. The results of thorough research using various optimization and sensitivity analysis exhibit that the Solar/Biomass/Battery/Wind/Hydrokinetic system is the optimum option for the location. The energy cost per kWh is only $0.128 in this configuration. And net present cost (NPC) is $303306, where operating cost is only 12,413 $/year. Moreover, the proposed system emits much lower CO2 (17.6 kg/year) with negligible other emissions making it eco-friendly. The decent outcomes from breakeven grid distance and payback period analysis make the hybrid more feasible. Therefore, the proposed hybrid system could be a viable solution for the community of the site and places with similar meteorological features worldwide, both economically and ecologically.

Spatial and temporal characteristics of extreme rainfall: Added benefits with sub‐kilometre‐resolution climate model simulations?

AbstractLocal, short‐duration extreme precipitation events can cause floodings and have massive economic consequences. The climate change impact on such events is of great interest, but due to the small spatio‐temporal scales involved, these are challenging to properly represent in climate models. This study analyses a new sub‐kilometre (750 m) HARMONIE‐Climate model simulation driven by ERA5 reanalysis data. Three convection‐permitting models at 750 m, 3 and 5 km grid distance are analysed and compared with driving reanalyses, intermediate model simulations and a dense rain gauge network. The representation of convective events is analysed by a range of metrics categorised as spatial, temporal and event‐focused. Precipitation events are analysed at both hourly and sub‐hourly scales and a clear difference between model performance on these scales is found. Overall, we find a better performance for HCLIM750m for most metrics, yet the added benefits of the computationally intensive sub‐kilometre scale simulation seems limited compared to the convection‐permitting models at 3 and 5 km.

An Indoor Unknown Radio Emitter Positioning Approach Using Improved RSSD Location Fingerprinting

The accurate location of an unknown radio emitter (URE) is a critical task in wireless communication security. The URE localization method based on the received signal strength difference (RSSD) has become popular due to the identification of unknown transmitting power and frequency. However, high computational complexity and low positioning accuracy have been caused by the RSSD fingerprint data’s redundancy and cross-correlation. In this article, an indoor RSSD-based positioning algorithm combining principal component analysis (PCA) and Pearson correlation coefficient (PCC), called RSSD-PCA-PCC, is proposed to realize efficient feature extraction and reduce false fingerprint matching. Firstly, to achieve reduction and decorrelation, the principal components of the RSSD fingerprint database are extracted by the singular value decomposition (SVD) method. Secondly, the PCC is applied to measure the relative distance between the principal component features. In particular, the PCC is used for selecting the reference points (RPs) in order to match the position accurately. The results show that the proposed algorithm can obtain a more superior performance compared with the conventional RSSD-based weighted k-nearest neighbor algorithm (RSSD-WKNN) and COS matching algorithm (RSSD-PCA-COS) in the case of different selected RP numbers, AP numbers, and grid distances.

Research on Distributed Software of College Online Education Based on Information Gain Optimization Algorithm

The paper analyzes the shortcomings of the information gain method, applies frequency, concentration and dispersion to the information gain method, and proposes a feature optimization selection method based on information gain. By introducing the service resource framework WSRF technical specification, a new grid distance education system model GEM based on the open grid service structure OGSA. According to the existing problems of modern distance education, a distributed distance education system based on object Web computing is studied by using CORBA/Java. On this basis, a new dynamic distributed system structure technology and idea based on object-oriented technology is applied to develop and realize the distance education question bank system.

Grid to Ground Solutions in Construction Projects

Nowadays, Global Navigation Satellite System (GNSS) techniques are considered the cornerstones in the field of surveying and civil engineering industry. At present, a plethora of companies is employing GNSS in their daily activities. The engineering construction projects are designed based on ground distances although rapid static works on grid coordinate system, where the distances between points vary from the ground. The established control points should be compatible with the design by converting distances to ground. This study investigates the effect of the scale factor (SF) to reduce the linear distortion when grid is converted to ground. For this purpose, eight different distances from 64.858 m to 887.974 m were taken with rapid static method. The results reveal that whereas the distances are increased, the difference between the grid and ground is proportional, and for the smallest distance, the difference was 54 mm and for the largest was 398 mm. Besides, the grid distances were converted to ground distances using the combined SFs that works as a divider; the average difference was decreased from 175 mm to 45 mm, and the maximum difference was decreased from 398 mm to 85 mm.

Validation of a fast and traceable radiographic scale calibration of dimensional computed tomography

A fast and highly precise method of determining the geometrical scale factor of computed tomography (CT) measurements has been validated successfully by Bundesanstalt für Materialforschung und -prüfung (BAM), the Federal Institute of Metrology (METAS) and Physikalisch-Technische Bundesanstalt (PTB) within the scope of AdvanCT (Advanced Computed Tomography for dimensional and surface measurements in industry), a project funded in the European Metrology Programme for Innovation and Research (EMPIR). The method has been developed by PTB and requires only two radiographic images of a calibrated thin 2D standard (hole grid standard) from two opposite directions. The mean grid distance is determined from both radiographs. From this and with the help of the calibration result, the radiographic scale and therefore the voxel size is determined. The procedure takes only a few minutes and avoids a time-consuming CT scan. To validate the method, the voxel sizes determined via this method were compared with voxel sizes determined from CT scans of calibrated objects. Relative deviations between the voxel sizes in the range of 10−5 were achieved with minimal effort using cone-beam CT systems at moderate magnifications.

Spatial Grid-Based Position Calculation Method for Satellite-Ground Communication Links

With the rapid development of global satellite constellation clusters and the popularity of ground-based intelligent terminals, the interconnection between large-scale low Earth orbit satellites and ground base stations has become more frequent. The calculation of satellite position requires a large number of floating point square calculations and coordinate system conversions, with high computational complexity and long computation time. Based on the grid encoding method of GeoSOT, we propose a GeoSOT-based grid calculation for a satellite-ground position (GCSGP) model. We use binary bit operations instead of complex topological operations and floating point calculations, and use grid distance calculations instead of existing angle calculations. Thus, the relative positions of satellites to the ground can be quickly calculated and thus connected to more suitable satellites quickly. The results of the grid calculation were verified by simulation experiments. The calculation speed was improved by about 82% compared with the traditional method. The test accuracy error of the 10-level grid at a terminal 45° inclination was less than 1% at all heights, and the maximum error of the 10-level grid within a 10–45° inclination was 7.2% at 10,000 km altitude, which provides theoretical support for the subsequent grid space calculation.

Method to Determine the Centroid of Non-Homogeneous Polygons Based on Suspension Theory

The centroid is most often used to describe the average position of an object’s mass and has very important applications in computational geometry, applied physics, and spatial information fields, amongst others. Based on the suspension theory of physics, this paper proposes a new method to determine the centroid of a non-homogeneous polygon by the intersection of the two balance lines. By considering the inside point value and distance to the balance line, the proposed method overcomes the traditional method’s limitation of only considering the geometric coordinates of the boundary points of the polygon. The results show that the consideration of grid distance and grid value is logical and consistent with the calculation of the centroid of a non-homogeneous polygon. While using this method, a suitable value for relative parameters needs to be established according to specific application instances. The proposed method can be applied to aid in solving specific problems such as location assessment, allocation of resources, spatial optimization, and other relative uses.

An integrated waste-to-energy approach: A resilient energy system design for sustainable communities

The idea of sustainable cities and communities is a collective goal that runs across intergovernmental programs, like the United Nations Sustainable Development Goals and the African Agenda 2063 strategic framework. However, with several communities in sub-Saharan Africa and some parts of Asia having no access to electricity, this objective is still a “mirage”. Developing a resilient energy system for an unelectrified community should involve a thorough assessment and integration of the local energy resources in a decentralized generation and distribution system. For example, technologies that convert the waste generated in the community into biogas should be a part of microgrid systems. This paper thus proposes a microgrid solution for small communities where a combination of waste-to-energy, battery storage, and solar photovoltaic technologies can provide enough energy needed for the sustainable development of local communities. An unelectrified village in Nigeria has been selected as a case study. The energy demand for the village was carefully analyzed as 574 kWh/day. Techno-economic analysis of the hybrid solar PV/biogas/diesel system fit to serve this load was carried out using hybrid optimization of multiple energy resources software. The optimum hybrid system configuration was found to have a net present cost of $436,943 for 25 years with carbon dioxide emission amounting to 4,070 kg/year, compared to the traditional solar/diesel/battery microgrid which will require net present cost of $655,521 and emit 22,648 kg of carbon dioxide annually. Also, the cost of energy from this system is $0.151/kWh which is similar to the average grid tariff in the region. From the breakeven grid distance analysis, it was noted that the proposed solution is much more economical than grid extension for communities above a distance of 2.78 km to the grid.

A Numerical Simulation of the “1907” Kaiyuan Tornado Weather Process in Liaoning, Northeast China

From 17:00 to 18:00 local standard time (LST) on 3 July 2019, a rare strong tornado occurred in Kaiyuan, Liaoning Province, northeast China. NCEP/NCAR 0.25° × 0.25° reanalysis data and WRF4.0 numerical prediction models were used to carry out the numerical simulation. Double nesting was adopted, and the horizontal grid distance was 9 km by 3 km. Based on the observation data of China meteorological observation stations, surface and upper charts, Doppler radar data, Himawari(HMW)-8 satellite images and numerical simulation results, the mesoscale structure and mechanism of the tornado were studied. The results show that: (1) At the northwest edge of the subtropical high, and the northeast cold vortex located in Northeast China, when the transverse trough moves southward, cold air is supplied continuously. Under the joint influence of the surface northeast cyclone, these are the main synoptic features of the tornado; (2) The northeast cold vortex cloud system was located at the junction of Heilongjiang and Jilin Provinces, and a squall line cloud system is formed. The tornado occurred at the tail of the squall line, and the strongest echo reached 65 dBZ. A mesocyclone, a 20 km northwest–southeast convergence belt, V-shaped gap, echo overhang structure and tornado vortex feature (TVS) were detected by the Doppler radar; (3) Before the tornado occurred, dry and cold air intruded from the northwest of the cold vortex, and a water vapor convergence zone appeared south of the squall line. The water vapor saturation zone with 80% relative humidity in northeast China was concentrated at 700 hPa, and the 20% dry column dropped down to 500 hPa between 115 and 124° E from the west. On the 850 hPa physical fields, there was a −20 × 10−5 s−1 convergence zone, and a 16 × 10−5 s−1 divergence belt appeared south and north of the squall line. A negative vorticity belt and a positive vorticity belt appeared south and north of the squall line, respectively. Kaiyuan is located at the smallest vertical shear, which is the junction place of three large vertical shear belts; (4) After 10:00 LST, the westerly wind 20 (10) m·s−1 dropped to 400 (800) hPa between 126 and 127° E. The northerly gale at 300 hPa north of 45° N moved southward. The rising center of the low level at 17:00 LST at approximately 45° N moved southward, and a sinking center appeared above it; (5) Several pairs of positive and negative vorticity columns formed between the lower troposphere and the place where the tornado occurred. There was convective instability at the lower level. CAPE increased, 0–3 km vertical wind shear increased, and LCL decreased remarkably during the afternoon.

Multiobjective Particle Swarm Optimization Based on Ideal Distance

Recently, multiobjective particle swarm optimization (MOPSO) has been widely used in science and engineering, however how to effectively improve the convergence and distribution of the algorithm has always been a hot research topic on multiobjective optimization problems (MOPs). To solve this problem, we propose a multiobjective particle swarm optimization based on the ideal distance (IDMOPSO). In IDMOPSO, the adaptive grid and ideal distance are used to optimize and improve the selection method of global learning samples and the size control strategy of the external archive, and the fine‐tuning parameters are introduced to adjust particle flight in the swarm dynamically. Additionally, to prevent the algorithm from falling into a local optimum, the cosine factor is introduced to mutate the position of the particles during the exploitation and exploration process. Finally, IDMOPSO, several other popular MOPSOs and MOEAs were simulated on the benchmarks functions to test the performance of the proposed algorithm using IGD and HV indicators. The experimental results show that IDMOPSO has the better convergence, diversity, and excellent solution ability compared to the other algorithms.

Elucidating the Effects of a Cryptomeria fortunei Forest Environment on Overall Health Based on Open Field Testing of Mice

In order to elucidate the impact of fortunei forest environment on overall health, the effect of the Cryptomeria fortunei forest environment on mice was examined. Using an OFT (Open Field Test), the behavior of mice in fortunei forest and in an indoor environment (used as a control) was analyzed, while minor changes in climate, oxygen, and suspended particulate matter were observed and recorded simultaneously. The results indicated that the two environments were significantly different in regard to relative humidity, wind speed, and the oxygen content of air, while there were no significant differences in temperature. Importantly, spontaneous activity behavioral indicators in mice were significantly different. Mice in the Cryptomeria fortunei environment (LS group) spent less time in the corners and near walls in comparison to mice in the indoor environment (CK group). Compared with indoor control mice, for the mice exposed to forest environments total distance traveled, central grid distance, frequency of movement through the central grid, frequency of standing, and body mass significantly increased; The number of fecal grains significantly decreased. The spontaneous activity behavioral indicators changed over time stages. In the early stages there were no differences, but after accumulation of environmental effects in the late stages, significant differences were evident. The above results showed that the Cryptomeria fortunei forest environment increased excitability and cognitive ability of mice, was able to effectively alleviate anxiety, and was able to emotionally relax and improve the appetite of the mice.