Blank Area Research Articles

Research on Gas Explosion Pressure and Flame Propagation Characteristics in Turning Pipelines.

In order to investigate the overpressure and flame propagation characteristics of gas explosions in turning pipelines, this study designed a transparent organic glass pipeline test system with different turning angles (30°, 60°, 90°, 120°, and 150°) and conducted a series of experimental studies to analyze the explosion shock wave overpressure and flame propagation behavior. The experimental results show that with the increase of the turning angle of the pipeline, the overpressure of the explosion shock wave significantly increases. In terms of flame propagation characteristics, when the turning angle is small, the flame can adhere to the outer wall of the pipeline corner and gradually fill the entire pipeline section. When the turning angle increases, the flame forms a blank area near the outer wall of the corner, and the blank area expands with the increase in the corner. In addition, the increase in the turning angle promotes the increase in the velocity of the explosion flame front. The research results of this review are of great significance for a deeper understanding of the mechanism of gas explosions in turning pipelines and evaluating their potential hazards.

Optimalisasi Penentuan Posisi Access Point Pada Ruang Tertutup Menggunakan Algoritma Genetika

WiFi is a term used for wireless network devices (WLAN) based on IEEE 802.11 standard. Access Point is a WLAN device that is used as a transmitter or receiver. One of the parameters that can determine the performance of a WiFi is the coverage area of an access point. Placement it is not appropriate with environmental conditions will cause some of an area that is not covered or a blankspot area. In this research, the position of the access point was optimized using a genetic algorithm based on position and coverage area. Total coverage area is obtained by determining the union coverage area of all access points which appropriate with the range that is determined using indoor propagation model. From the research results, the most optimal number of access points is 5 access points. The existing condition with 5 access points has a coverage area of 75,27%, while optimization using 5 access points has a coverage area of 96,64%. The optimization can increase the coverage area by 21,38% and reduce the blank spot area to 3,36%.

Experimental study on the creep acoustic emission of fractured sandstone reinforced by anchor rods

To investigate the reinforcement and crack-stopping effect of anchor rods on fractured rock masses, Triassic sandstone from the Xiaolangdi Reservoir area was selected and fabricated into double-fractured specimens. Subsequently, 1 and 2 horizontal anchor rods were used to reinforce the double-fractured sandstone specimens sequentially. Using the RLJW-2000 rock rheological servo tester and the PCI-II type acoustic emission (AE) tester, indoor uniaxial compression creep and AE tests were conducted under the same experimental conditions for the unanchored, singly-anchored, and doubly-anchored sandstone specimens. Based on the experimental results, the creep mechanical characteristics and the three-dimensional spatial evolution of the AE events of the specimens with different numbers of anchor rods were analysed. This study focuses on the reinforcement and crack-stopping effect of anchor rods on fractured rock masses. The experimental results indicate the following: (1) Compared with those of the unanchored specimens, the creep failure strengths of the singly- and doubly-anchored specimens increase by 7.79 % and 22.14 %, respectively. (2) At a stress level of 60 MPa, the axial strains of the single-anchor and double-anchor specimens decreased by 8.41 % and 32.97 %, respectively, compared to the corresponding strain of the unanchored specimen, and the radial strains decreased by 9.21 % and 28.13 %, respectively. (3) Anchor rods have a good reinforcement effect on fractured sandstone, enhancing specimen strength and reducing deformation. (4) With an increase in the number of anchor rods, the reinforcement effect of anchor rods on fractured rock masses strengthened, and the reinforcement effect of double anchors was superior to that of single anchors. (5) Compared with those of the unanchored specimens, under relatively low stress levels, when the AE events extended to the area where the anchor rods were located, the number of AE events for both types of specimens decreased significantly, forming a blank area in the AE events, and the blank area of the double-anchored specimens was larger than that of the single-anchored specimens. (6) With increasing stress, many AE events originated, expanded, and passed through the anchor rod area, indicating that the specimen was about to undergo creep instability failure. (7) The evolution characteristics of the AE events are in good agreement with those of the macroscopic cracks on the specimen surface. The AE characteristics indicate that anchor rods have a significant crack-stopping effect on fractured rock masses, suppressing the initiation, expansion, connection, and penetration of internal microcracks in the specimens. Moreover, the crack-stopping effect of double anchors is superior to that of single anchors.

Exploration of the Path of Labor Dispute Resolution

According to the traditional view, the main ways to handle labor disputes include: workers and employers resolve disputes through consultation, apply for mediation to the Labor Dispute Mediation Committee, submit to the Labor Dispute Arbitration Committee to apply for arbitration in accordance with the law, and file labor lawsuits with the court. Each of these ways has its own advantages and disadvantages, but they are also closely related and interconnected. In practice, the parties may not know which route is more conducive to resolving a dispute, nor are they clear about the specific functions of the various institutional themes and the differences in the advantages and disadvantages of resolving specific issues. And in the legislative system, the functions of the various institutional subjects also have cross and blank areas. This article will focus on the labor security supervision system and the labor dispute arbitration system, as well as the relationship and interface between the labor dispute arbitration system and the labor litigation system to do a brief analysis and put forward proposals.

Emerging Themes and Future Directions in Neurodesign and Human-Computer Interaction: A Systematic Review

While considerable research has been conducted, the field of neurodesign and human-computer interaction (N-HCI) has yet to be methodically delineated in light of contemporary studies. In this context, this paper undertakes a systematic review with dual objectives: (a) to uncover emerging research themes within N-HCI, and (b) to provide future directions for research on N-HCI. Employing robust systematic review methodologies, this paper scrutinized 122 pertinent documents, revealing four principal emerging research themes and constructing a conceptual framework that synthesized key concepts in N-HCI. The results underscored the relative underdevelopment in research that leverages neural evidence to enhance general human-computer interface design, and the notable absence of research at the intersections of the “user” and “environment” aspects of neurodesign with HCI. Accordingly, this paper identifies underdeveloped areas in existing research that require more depth and blank areas in the conceptual framework that call for exploration as future directions.

Strategi Humas Dinas Komunikasi dan Informatika Kabupaten Maluku Tenggara dalam Pengelolaan Informasi Publik

The Department of Communication and Informatics (Diskominfo) of Southeast Maluku Regency plays a crucial role in supporting local governance and development. They focus on ensuring easy access to information for the public, especially in areas with limited internet coverage or low literacy rates. Diskominfo employs various strategies, including social media, digital platforms, as well as subscription-based radio and television stations. They are also responsible for providing public information services through various online platforms and seven public service applications. The information management process involves stages of collection, clarification, documentation, and distribution with principles of accurate news writing. Despite efforts to improve information access and public services, Diskominfo still faces several challenges such as telecommunication network blank spots, limited infrastructure, and the public's lack of knowledge about government information. To address these challenges, strategic issues such as expanding networks in blank spot areas, enhancing monitoring and evaluation, implementing electronic-based public service systems, and improving human resource capacity must be considered. Diskominfo of Southeast Maluku Regency continues to strive to ensure relevant and accurate information is available to the public, with the hope of supporting the development and empowerment of all layers of society in the region. Keywords: Strategies, Information Management System, Online, Diskominfo.

Reconstruction of Hourly FY-4A AGRI Land Surface Temperature under Cloud-Covered Conditions Using a Hybrid Method Combining Spatial and Temporal Information

Land Surface Temperature (LST) products obtained by thermal infrared (TIR) remote sensing contain considerable blank areas due to the frequent occurrence of cloud coverage. The studies on the all-time reconstruction of the cloud-covered LST of geostationary meteorological satellite LST products are relatively few. To accurately fill the blank area, a hybrid method for reconstructing hourly FY-4A AGRI LST under cloud-covered conditions was proposed using a random forest (RF) regression algorithm and Savitzky-Golay (S-G) filtering. The ERA5-Land surface cumulative net radiation flux (SNR) reanalysis data was first introduced to represent the change in surface energy arising from cloud coverage. The RF regression method was used to estimate the LST correlation model based on clear-sky LST and the corresponding predictor variables, including the normalized difference vegetation index (NDVI), the normalized difference water index (NDWI), surface elevation and slope. The fitted model was then applied to reconstruct the cloud-covered LST. The S–G filtering method was used to smooth the outliers of reconstructed LST in the temporal dimension. The accuracy evaluation was performed using the measured LST of the representative meteorological stations after scale correction. The coefficients of determination derived with the reference LST were all above 0.73 on the three examined days, with a bias of −1.13–0.39 K, mean absolute errors (MAE) of 1.46–2.4 K, and root mean square errors (RMSE) of 1.77–3.2 K. These results indicate that the proposed method has strong potential for accurately restoring the spatial and temporal continuity of LST and can provide a solution for the production and research of gap-free LST products with high temporal resolution.

Quantifying Coloring Skills Among Preschoolers.

Coloring is popular with preschool children and reveals their developmental state. However, interpreting coloring performances is challenging because descriptive and subjective evaluations are commonly used with large variations. To develop a scoring method to objectively quantify children's coloring skills. Colored blank train templates were analyzed using four indicators (entropy, complexity, coloring outside the lines, and unexpected blank areas) to form a summed score. Kindergarten in a urban city (Tainan, Taiwan). Two hundred thirty-nine typically developing children ages 3 to 6 yr. A newly developed method to assess coloring skill on the basis of a colored picture of a train. The summed score exhibited good internal consistency (Cronbach's α = .80), discriminative validity (p = .04), convergent validity (rs = .66 and .59 with age and visual-motor integration), and acceptable factorial validity (comparative fit index = .99, standardized root-mean-square residual = .04, and root-mean-square error of approximation = .13). Moreover, three coloring patterns (mature, transitional, and immature) were identified. The new method provides objective, reliable, and valid scores representing coloring skills in typically developing children. In addition, the coloring patterns can be recognized. This method can be used to facilitate comparisons of children's coloring skills with peers and provide valuable insight into children's development. Plain-Language Summary: This study proposes a new method to objectively quantify children's coloring skills with sound reliability and validity in typically developing children. The method can be used to evaluate children's coloring skills and patterns to shed light on their developmental stages.

Magnetic printing characteristics of burst signals by using double magnet master media

In this study, the magnetic printing characteristics of burst signals with double magnet master (DMM) media, which consists of hard and soft magnet patterns corresponding to the burst signals, onto energy-assisted magnetic recording (EAMR) media was investigated by the micromagnetic simulation. For comparison, the magnetic printing characteristics with the conventional master media, which includes only soft magnet patterns, was also calculated. The magnetic film patterns of each master media transfer automatic-gain-control (AGC) and burst parts to the recording medium. The burst signals was amplitude AB-burst patterns, which consists of the repeated pattern region and blank area without burst patterns. Two possible master media structures of DMM media were considered, which are herein called positive- and negative- DMM media. By utilizing the positive-DMM, which spatially divides soft magnets, the AGC and the burst signals can be clearly printed, comparing with the conventional master media. While the negative-DMM is insufficient to print burst signals because the blank area without burst patterns has some non-recorded clusters. Thus, the positive-DMM are feasible for the magnetic printing of burst signals. The clear printing onto EAMR media is expected to be obtained by the optimum non-magnetic separator thickness and the optimum printing field. Therefore, the magnetic printing with positive DMM master is promising onto EAMR media.

Machine learning-based field geological mapping: A new exploration of geological survey data acquisition strategy

Geological mapping, as the fundamental core of geological research and investigation, provides indispensable basic understanding and exploration data for mineral prospecting, disaster prevention and control, and other related fields. The emergence of big data algorithms and models, such as machine learning and deep learning, has brought new assistance to the task of geological mapping. By utilizing these advanced technologies, long-term accumulated exploratory data has been deeply mined and analyzed, significantly enriching the information obtained through conventional mapping methods and laying a solid foundation for subsequent research. However, challenges faced by machine learning in the field of geological mapping are gradually being recognized: the vast demand for data volume, interference from irrelevant information, the “black box” problem, limitations in computing power, algorithm applicability, and data security, among others. To address these challenges, this study takes the Duolong mineral district, Tibet, China, a region with a high degree of exploration, as an example, assuming it to be a blank area without mapping, and attempts to integrate the light gradient boosting machine (LightGBM) algorithm into the field geological mapping process. Firstly, based on remote sensing data, the distribution of alteration was identified to design the initial mapping route. Subsequently, geological units along the route were labeled, and the model was trained using geochemical sampling point data and remote sensing data as feature inputs. During the model prediction stage, the probability distribution obtained through the Softmax function was utilized to guide the subsequent design and planning of field mapping routes. After five iterations, based on field mapping that covers 20% of the entire area, 90% of the lithological units were successfully predicted. This study explores an effective combination of machine learning algorithms with field geological mapping that establishes a new method for field geological mapping based on machine learning. It not only improves the efficiency and accuracy of mapping but also provides a new strategy for balancing geological work with structured data acquisition.

Dissipation and residues of 18% imidacloprid + buprofezin SC in citrus and soil

ABSTRACT Eighteen per cent imidacloprid + buprofezin suspension concentrate (SC) has been registered for the control of scale insect on citrus trees, but the dissipation of this pesticide mixture on citrus is still a research blank area. In order to fill the gaps and ensure the safe application of mixture formulation, field trials were conducted in Guangdong, Guangxi and Hunan Provinces of China for 2 consecutive years to evaluate the final residue and dissipation dynamic of imidacloprid and buprofezin in citrus and soil. Both pesticides were extracted by the modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method, while imidacloprid was determined by high-performance liquid chromatography (HPLC) and buprofezin was determined by gas chromatography (GC). The established method achieved a good linearity relationship (r = 0.9999) and high sensitivity, the LODs (limit of detection) of imidacloprid and buprofezin were 0.002–0.013 mg/kg, which can fully meet the need for pesticide residue detection. Average recoveries (AR) of imidacloprid and buprofezin in citrus and soil were 77.64–105.95% and 85.89–102.28%, with relative standard deviations (RSD) of 3.06–7.91% and 3.29–7.25%, respectively. Results of field trials showed that the half-lives of imidacloprid in citrus and soil were 1.90–3.97 and 2.52–16.98 days, and that of buprofezin were 1.69–9.14 and 1.21–8.56 days. On the 21st day after the last application, final residues of imidacloprid and buprofezin in all samples were below their maximum residue limits (MRL) stipulated by China, indicating that it is safe to apply 18% imidacloprid + buprofezin SC on citrus trees. In conclusion, 18% imidacloprid and buprofezin SC was recommended to be spared twice at the intervals of 7 days with dosages of 180 or 270 mg/L, and the citrus fruit can be harvested safely 21 days after the last application. These results help ensure the safe application of imidacloprid and buprofezin in citrus orchards.

Tunable Far‐Infrared Polarization Imaging Based on VO2 Metasurfaces

AbstractPolarization imaging enables the capture of material properties and surface characteristics of objects, finding applications in remote sensing and defense. However, most existing polarization imaging systems rely on polarization filtering elements, resulting in energy loss exceeding 50% and compromising intensity imaging performance. Conventionally, a rotary device equipped with different polarizers and a blank area is used to acquire both polarization and intensity images, which is cumbersome for integration and miniaturization purposes. In this study, a miniaturized and easily integrated active metasurface based on VO2 grating structure for switchable detection of intensity and polarization in the far‐infrared band (8–14 µm) is proposed. With VO2 in the dielectric state, the device exhibits high transmittance for both TE‐ and TM‐polarized light (Experimental transmittance of up to 65%). Upon phase transition to the metallic state, the device demonstrates low transmittance for TE‐polarized light while maintaining high transmittance for TM‐polarized light (linear polarization extinction ratio up to 10 dB). Finally, the tunable thermal intensity and polarization imaging capabilities of the custom‐made setup are characterized. The metasurface showcases comparable performance to standard commercial polarizers in terms of polarization imaging. The developed tunable far‐infrared polarization imaging system holds promise for next‐generation multidimensional information perception.

Comparative GIS Analysis of Public Transport Accessibility in Metropolitan Areas

With urban areas facing rapid population growth, public transport plays a key role to provide efficient and economic accessibility to the residents. It reduces the use of personal vehicles leading to reduced traffic congestion on roads and reduced pollution. To assess the performance of these transport systems, prior studies have taken into consideration the blank spot areas, population density, and stop access density; however, very little research has been performed to compare the accessibility between cities using a GIS-based approach. This paper compares the access and performance of public transport across Melbourne and Sydney, two cities with a similar size, population, and economy. The methodology uses spatial PostGIS queries to focus on accessibility-based approach for each residential mesh block and aggregates the blank spots, and the number of services offered by time of day and the frequency of services at the local government area (LGA) level. The results of the study reveal an interesting trend: that with increase in distance of LGA from city centre, the blank spot percentage increases while the frequency of services and stops offering weekend/night services declines. The results conclude that while Sydney exhibits a lower percentage of blank spots and has better coverage, performance in terms of accessibility by service time and frequency is better for Melbourne’s LGAs, even as the distance increases from the city centre.

Effectiveness Of Electronically Integrated Business Perizances Through Online Single Submission (OSS) In Bogor District

The government was trying to create an optimal service system to meet the needs of the community in managing permits, namely by implementing OSS. This system was built by implementing electronically integrated business licensing and enhanced by the implementation of the OSS Risk Based Approach (RBA) in 2021. The purpose of this study was to determine and analyze the effectiveness of electronically integrated business licensing through Online Single Submission ( OSS ) in Bogor Regency. This research used sociological juridical research methods, with data collection techniques through literature research and field research by conducting interviews. To measure the effectiveness of law enforcement using an approach according to Soerjono Soekanto which is determined by 5 ( five ) factors, namely: the legal factor itself; law enforcement factors; facilities factors; societal factors, and cultural factors. The results of the study found that OSS in Bogor Regency has been implemented since 2018. Such is the case with the RBA OSS which can be implemented in August 2021. The regulations needed in the implementation of OSS in Bogor Regency were quite available, the Human Resources were competent, the facilities were adequate, the community was open to electronic services, and the community's digital literacy culture was quite good. Based on the evaluation of 5 (five ) factors that affect law enforcement, it can be concluded that OSS can be implemented effectively in Bogor Regency. Responding to the development of civilization globally and towards a golden Indonesia in 2045, OSS was a bridge process in realizing it all. The researcher suggested that the weaknesses and shortcomings in the RBA OSS should be immediately responded to by the Ministry of Investment / BKPM. The local government immediately prepares an internet network so that there are no blank spot areas, socialization is further intensified, and the required bylaws and regulations are immediately issued.

Review on the Recent Development of Vehicle Seat Patent

Background: Seat is an important product in work and life, the rationality of its design directly affects people's work efficiency and physical and mental health. Especially in modern vehicles, it has become an inevitable trend to use ergonomics to design the seat of modern vehicles. This paper describes the recent research and development of seat patents based on ergonomics and tries to put forward improvement schemes for the disadvantages of existing vehicle seats. Objective: We summarized the technical contributions made by the existing vehicle seat patent achievements and summarize the existing problems or blank areas not reported. Through the comparison and discussion, the future research direction of the vehicle seat is predicted. Methods: Through tracing the patent varieties of different types of representative seats, the analysis and comparison are carried out from various angles. Results: According to the analysis of recent seat patents, the design of modern seats has gradually formed a scientific, systematic, and standardized system. Conclusion: The structural parameters and materials of seats have been closely combined with the safety and comfort of seats. With the development of science and technology and the innovation of theory, the seats of modern vehicles will develop in the direction of functionality and personalization.

Evaluation of DVB-T2 Digital TV Propagation Performance in the Bali Broadcast Area

The development of terrestrial television broadcasting technology in the world today is switching from analog broadcasting systems to digital broadcasting systems. Analog Switch Off (ASO) is the period when analog broadcasts are stopped and replaced with digital broadcasts. Through the jargon "Clean Picture, Clear Sound, Advanced Technology" people will feel better quality than analog TV. In the era of digital broadcasting, TV viewers not only watch broadcast programs but can also get additional facilities such as EPG (Electronic Program Guide) to find out the programs that have been and will be aired later. With digital broadcasting, there is the ability to provide interactive services where viewers can directly rate the sound of broadcast programs in addition to the presence of features that can be utilized, such as features related to disaster information. In this study, an evaluation of the performance of DVB-T2 Digital TV propaganda will be carried out in the Bali service area. The quality of digital TV broadcasts in the Bali broadcast area is influenced by signal propagation which is parameterized by parameters C / N (or S / N), Modulation Error Rate (MER), Bit Error Rate (BER) by measuring at the test point or location of the test point/test measurement which is the outermost limit of the service area under the Minister of Communication and Information no 23 / PER / M.KOMINFO / 11/2011. So this research can be produced a map of the quality of broadcasting services in Bali which can be used as an indicator to avoid Bali from blank spot areas that can be recommended for Digital TV operators in Bali for repeater installation planning.

Effect of Process Variables on Interface Friction Characteristics in Strip Drawing of AA 5182 Alloy and Its Formability in Warm Deep Drawing

Warm forming is widely used to enhance the formability of aluminum alloy sheets. In warm deep drawing, the process variables significantly affect frictional characteristics at the tool–blank interface. It has been a conventional approach to use a constant value of friction coefficients in the finite element (FE) simulations. However, this can occasionally result in suboptimal accuracy of the predictions. In the present work, strip drawing tests were carried out on AA5182 aluminum alloy sheets to investigate the effect of important process variables, namely, temperature, contact pressure, and drawing speed, on the friction coefficient in the warm forming temperature range (100–250 °C) under lubricated condition. The results obtained from the strip drawing tests were used for defining the friction conditions in the simulation of warm deep drawing of cylindrical cups incorporating the variation of the friction coefficient with contact pressure and speed at different temperatures. The Barlat89 yield criterion was used to define the effect of anisotropy in the material. The Voce hardening law and Cowper–Symonds model were used to incorporate the effect of strain hardening and strain rate, respectively, in the simulation. Drawability and peak force were compared with the predictions when a constant friction coefficient was assumed. Warm deep drawing experiments were conducted to validate the predicted drawability and load–displacement curves. It is clearly observed that the accuracy of prediction of the limiting drawing ratio and peak load through simulations is improved by incorporating the effect of pressure and speed on friction coefficient as it captures the local variations of friction during warm deep drawing precisely, rather than assuming a constant average friction coefficient at all the tool–blank contact areas.

B-198 Web-based Application of an Automated Quality Assurance Monitoring System for a Pain Management Panel by Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Abstract Background With its advantages in analytical sensitivity and specificity, quantitative drug analysis by LC-MS/MS platform allows the clinical laboratories to provide results that would meet various clinical needs, especially for those to assess patient compliance on pain medications. However, the complexity of the technology and data it generated, poses challenges and burdens to the quality assurance process. In our toxicology laboratory at the University of Kentucky, we offer a pain management panel to physicians for monitoring patients compliance purpose. This is a LC-MS/MS based assay that can simultaneously qualitative up to 52 drugs and their metabolites. Quality monitor of data from this multicomponent drug assays is laborious and inefficient. Our objective here is to develop and implement an effective automated quality assurance mechanism, and eventually improve the laboratory efficiency, reduce lab errors and enhance quality of patient care. Methods Using the Sciex Multiquant software, the daily processed txt file is generated and uploaded to shared drive to be analyzed using a Java based program. The processing of a file is split into three subparts: (1) saving original data, (2) calculating/ verifying the quality assurance metrics with the predefined limits, and (3) producing a report. The original data uses to the database to retrieve specific information without having to reload the file multiple times. When completed, all the data included in the initial report are read along with limit variables. The metrics for quality assurance with predefined criteria includes: System suitability test sample (Retention time, Peak area), Internal standard (IS) peak area, Blank sample peak area, Calibrator accuracy and calibration curve accuracy, Quality control, Ion ratio, Relative retention time to IS. Once these calculations are finished, a report is generated in a format that allows it to be easily read on the website. Results We are able to generated a daily QA report that is web-based application. Discrepancies within any of the statistics are color coded and given a button allows a user to “check” the measurement and provide a reason why this measurement was out-of-scope. All users are allowed to provide reasoning for an out-of-scope measurement and each of these users’ comments is tracked to provide an audit trail. Once all measurements have been reviewed, a report is ready form review. The process can only be completed by a privileged user. Once the process has been completed, the report cannot be modified. With this application, we are not only able to monitor the quality of the run on the day-to-day basis, the QC and instrument behavior can also be evaluated and reviewed longitudinally. Conclusion An effective and efficient web-based quality assurance monitoring system was successfully developed and implemented for this multicomponent drug analysis by LC/MS-MS. The application of this program will facilitate the mass spec platform use in clinical laboratories.

Optimalisasi Penentuan Posisi Access Point Pada Ruang Tertutup Menggunakan Algoritma Genetika

WiFi is a term used for wireless network devices (WLAN) based on IEEE 802.11 standard. Access Point is a WLAN device that is used as a transmitter or receiver. One of the parameters that can determine the performance of a WiFi is the coverage area of an access point. Placement it is not appropriate with environmental conditions will cause some of an area that is not covered or a blankspot area. In this research, the position of the access point was optimized using a genetic algorithm based on position and coverage area. Total coverage area is obtained by determining the union coverage area of all access points which appropriate with the range that is determined using indoor propagation model. From the research results, the most optimal number of access points is 5 access points. The existing condition with 5 access points has a coverage area of 75.27%, while optimization using 5 access points has a coverage area of 96.64%. The optimization can increase the coverage area by 21.38% and reduce the blank spot area to 3.36%.
 

Study on failure mechanism of tight sandstone based on moment tensor inversion

Understanding deep rocks' mechanical properties and failure evolution is crucial for efficient resource development. This study investigates the mechanical properties of tight sandstone and analyzes its acoustic emission (AE) characteristics using a combined discrete element model and moment tensor inversion. The AE activity during loading is categorized into three stages: crack initiation, stable crack propagation, and unstable crack propagation. Confining pressure loading suppresses AE activity during the crack initiation stage due to damage healing phenomenon. Moment tensor inversion reveals that tensile failure is the primary AE failure source, despite samples exhibiting splitting and shear failure modes. The proportion of AE failure types varies with stress levels and depends on the mechanical environment. Microcracks initiate at the ends of the sample and propagate inward along the loading direction, resulting in a blank area of AE events in the middle. This blank area can be utilized to predict specimen failure mode. The b value, representing the ratio of small to large magnitude events, decreases with increase of the confining pressure, indicating higher energy release during specimen failure under high confining pressure. The research results can provide a reference for predicting the failure of tight sandstone.