Point Placement Research Articles

Design and operation of a whole-body MRI scanner without RF shielding.

To investigate how a clinical MRI system can be operated without an RF cabin. Receive interference cancellation via signal processing and active transmit emission suppression are evaluated for mitigating image artifacts and achieving electromagnetic compatibility. A clinical whole-body MR scanner with B0 = 0.55 T was placed in an environment without RF shielding. The signals of 16 additional auxiliary receive antenna elements outside the scanner bore were used to remove interference from the wanted MR signal via a dedicated sidelobe cancellation algorithm. In vivo measurements with different MR sequences were performed in the presence of ambient RF noise and additional artificial interferers, covering brain and abdominal applications. To investigate the transmit electromagnetic compatibility, simulations with different auxiliary transmit antenna arrangements and body coil loading conditions were performed, and their emission suppression performance in the far field was evaluated. The MR sidelobe cancellation algorithm successfully removed interference artifacts up to more than 3 times of the wanted MR image energy; difference images carried little to no visibly removed wanted signal. According to the simulations, electromagnetic compliance can be achieved with 32 or more auxiliary transmit antennas. The number and placement of sensor points are essential. A whole-body 0.55T MR scanner can be operated without RF shielding. Image artifacts from external interference can be removed, requiring only a modest number of auxiliary antennas. Electromagnetic compliance appears to be achievable using active transmit cancellation, but the required hardware efforts may not be practical.

High-impedance fault location method using guessed fault resistance

Electromagnetic time reversal fault location method requires the placement of observation points at a single location and is effective for searching fault location. Among the various existing metrics, the transfer function correlation metric emerged as the most robust. However, its application to high-impedance faults also presents challenges. This difficulty can be attributed to the unknown real fault resistance in the direct-time process, where the guessed fault resistance is typically set to 0 during the reversed-time process of the electromagnetic time reversal fault location method. Consequently, this practice yields comparable direct-time and reversed-time transfer functions for low-impedance faults. Conversely, high-impedance faults exhibit significant discrepancies between direct-time and reversed-time transfer functions, leading to errors in fault location. To overcome this challenge, this paper proposes a location method based on specific guessed fault resistance preset during the reversed-time process. First, the direct-time voltage and reversed-time current transfer functions under high-impedance faults were derived in the frequency domain. Subsequently, by comparing transfer function differences when fault resistances in the direct-time and reversed-time processes did not align, a principle for selecting the guessed fault resistance was established. Additionally, the similarity of the two transfer functions under specific guessed fault resistances was investigated. Furthermore, the symmetry of the fault current was leveraged to reflect the correlation between the two transfer functions, and the differential fault current symmetry coefficient metric was introduced. A fault location time-domain algorithm based on guessed fault resistance was proposed, and its effectiveness was demonstrated through both reduced-scale and simulation experiments. The results indicate that the proposed method is not only applicable to complex lines but also offers a straightforward calculation approach, facilitating fault location under high-impedance faults.

Planning Public Space Climate Comfortability: A GIS-Based Algorithm for the Compact Cities of the Far North

The issue of forming a comfortable environment in cities with complex climatic conditions has always been an urgent and difficult issue for urban planners. Cities located in the territories of the Far North are characterized by extremely harsh climatic characteristics that affect the planning solutions for the public spaces of the city. Low temperatures and strong winds reduce the time of comfortable stay in the open air, which leads to a decrease in the mobility of the population in the city and stimulates the use of personal cars. The research question is the rational placement of points of interest on the street network to ensure a comfortable travel time between objects. The research methodology of public space planning taking into account the climatic comfortability of Far North cities is proposed in this article. Also, an automated GIS-based algorithm for determining intermediate points on linear objects to increase POIs’ connectivity for the development of the public space of Far North cities under the condition of organizing climatic comfort is proposed. Development of safe and comfortable public space on the basis of network accessibility, taking into account the difficult climatic conditions of these cities, will increase the social activity of the population and tourists, as well as promote economic growth and business development in the city.

A multi‐layer approach for additive manufacturing of continuous fiber composites

AbstractAdditive manufacturing (AM) of continuous fiber reinforced polymer composites (cFRPCs) requires innovative tool‐pathing strategies that account for the anisotropic properties of the continuous fibers and ensure their continuous deposition as reinforcement along the designed structure, reducing fibers bending and cutting. Existing 3D printing slicing software, designed for isotropic materials like neat polymers, has been adapted for 3D printing of continuous fiber composites, resulting in a layer‐by‐layer approach that necessitates filament cutting after each layer deposition. This method introduces discontinuities, weakening the material and underutilizing continuous fibers strength. In this research, we propose a novel tool‐pathing strategy designed to address these challenges through (1) Ensuring fiber continuity across layers by allowing overlapping filaments and (2) Strategically positioning fiber cut points based on stress distribution, modeled using finite element analysis. A Multi‐Layer Continuous Fiber Path (ML‐CFP) approach was introduced and validated on a simple bracket structure featuring two load‐application inserts. 3D printed brackets using different tool paths were tested to failure under tension and compression after compression molding to improve interlayer adhesion. Mechanical investigations confirmed that the ML‐CFP approach enhances fiber utilization, improving tensile strength and work to fracture by up to 46% and 100% through promoting failure in fibers rather than at cut points.Highlights Introduced the multi‐layer continuous fiber path method (ML‐CFP) in AM of cFRPCs. Introduced the strategic cut point placement (SCPP) based on stress distribution. Maintaining fiber continuity and reduce fiber bending by allowing filament overlap. Mechanical testing to compare the ML‐CFP with conventional slicing methods. Enhanced tensile strength by up to 46% and work to fracture by 100%.

The Validity of a Smartphone-Based Method for Acquiring 3D Images of the Face.

Objectives. To evaluate the accuracy and reproducibility of measurements obtained using the Bellus3D Face Application on a mobile smartphone by comparing them to direct measurements on pre-marked and blank face scans. Materials and Methods. Twenty-five healthy young adults (six males and nineteen females; age range 20-30 years) were included in this prospective cross-sectional study, with the only exclusion criterion being the presence of significant facial hair interfering with the placement and visualization of landmarks. Image acquisitions were performed using an iPhone XR with the Bellus3D FaceApp face scanning application, an iOS application for smartphones. Ten single midfacial and five paired bilateral landmarks were defined and marked. Two face scans were performed on each patient, both on blank and marked faces, and distances were measured directly with calipers and digitally. Results. The random error values were 1.0 mm and 0.4 mm for the manual point placement and measurements and virtual point placement on blank faces, respectively. The two methods used (the direct method and acquisition on faces with landmarks) demonstrate relatively similar reliability (ICC > 0.8); however, a paired t-test showed that the differences between several measurements were statistically significant (p < 0.05). Regardless of the method used, there was a systematic error for various values that included the nose and mouth (p < 0.05). The measurements demonstrating the most significant differences between the methods were those that included the tip of the nose, with the mean differences being -4.4-3.3 mm. The measurements of the distances that estimate face "depth" showed the greatest consistency irrespective of the tested method (p > 0.05 and ICC > 0.8). Conclusions. The use of the Bellus3D FaceApp is precise and reproducible for certain areas of the face, but digital reconstruction errors prohibit, for the time being, the use of this technology in everyday clinical practice. The noted discrepancies were consistent and more prevalent for specific areas such as the tip of the nose. Further investigations are required to determine other sources of error and for other smartphone-based applications released for 3D face image acquisitions.

Energy-efficient trajectory optimization algorithm based on K-medoids clustering and gradient-based optimizer for multi-UAV-assisted mobile edge computing systems

The mobile edge computing system supported by multiple unmanned aerial vehicles (UAVs) has gained significant interest over the last few decades due to its flexibility and ability to enhance communication coverage. In this system, the UAVs function as edge servers to offer computing services to Internet of Things devices (IoTDs), and if they are located distant from those devices, a significant amount of energy is consumed while data is transmitted. Therefore, optimizing UAVs’ trajectories is an indispensable process to minimize overall energy consumption in this system. This problem is difficult to solve because it requires multiple considerations, including the number and placement of stop points (SPs), their order, and the association between SPs and UAVs. A few studies in the literature have been presented to address all of these aspects; nevertheless, the majority of them suffer from slow convergence speed, stagnation in local optima, and expensive computational costs. Therefore, this study presents a new trajectory optimization algorithm, namely ITPA-GBOKM, based on a newly proposed transfer-based encoding mechanism, gradient-based optimizer, and K-Medoids Clustering algorithm to tackle this problem more accurately. The K-medoid clustering algorithm is used to achieve better association between UAVs and SPs since it is less sensitive to outliers than the K-means clustering algorithm; the transfer function-based encoding mechanism is used to efficiently define this problem’s solutions and manage the number of SPs; and GBO is utilized to search for the best SPs that could minimize overall energy consumption, including that consumed by UAVs and IoTDs. The proposed ITPA-GBOKM is evaluated using 13 instances with several IoTDs ranging from 60 to 700 to show its effectiveness in dealing with the trajectory optimization problem at small, medium, and large scales. Furthermore, it is compared to several rival optimizers using a variety of performance metrics, including average fitness, multiple comparison test, Wilcoxon rank sum test, standard deviation, Friedman mean rank, and convergence speed, to show its superiority. The experimental results indicates that this algorithm is capable of producing significantly different and superior results compared to the rival algorithms.

Thinking beyond the closure assumption: Designing surveys for estimating biological truth with occupancy models

Abstract Occupancy models estimate distributions of imperfectly detected species, but violations of the closure assumption can bias results. However, researchers working with mobile animals may find it impossible to eliminate such violations. Here, we tested the hypothesis that occupancy models fit to realistic sampling data can generate unbiased occupancy estimates for an itinerant Wood Thrush (Hylocichla mustelina) population. In 2013 and 2014, we tracked movements of 41 breeding Wood Thrush males. We modelled territory shift probabilities using logistic exposure models and within‐territory movements using continuous‐time stochastic process models. We then constructed an individual‐based model, simulated (1000 iterations) spatiotemporal locations for individuals and simulated sampling these populations using 162 different point count protocols with variable spatial (sampling radius and point placement method), and temporal (survey length, between‐survey intervals and number of surveys) characteristics. We compared occupancy estimates with true values of instantaneous, daily and seasonal occupancy from the simulations. We parameterized continuous time stochastic process models based on movements within 34 unique territories and estimated a daily territory shift probability of 0.0099 (95% CI: 0.0060, 0.0152). Simulated data indicated that estimates of occupancy ranged from 0.18 (0.06, 1.00) to 0.80 (0.71, 0.89) depending on protocol characteristics. Occupancy estimates increased with increasing survey radius, survey length and between‐survey interval. Protocols using shorter surveys and between‐survey intervals were good estimators for instantaneous occupancy (low bias and mean‐squared error) but poor estimators for daily and seasonal occupancy; longer surveys and intervals generated unbiased estimators of daily occupancy but underestimated seasonal occupancy. Logistic regression models that ignored imperfect detection outperformed occupancy models for estimating instantaneous occupancy but not daily or seasonal occupancy. For mobile animals, occupancy of sampling sites changes in space and time. Consequently, the spatial and temporal aspects of a sampling protocol have strong, but predictable, effects on occupancy model parameter estimates. Our results demonstrate that how these factors interact is critical for designing surveys that produce occupancy estimates representative of the biological process of interest to a researcher.

Investigation on load - transfer characteristics of spherical hinge structure of swivel bridge based on scale distortion model

The mechanical properties of the swivel spherical hinge, a critical component in swivel bridge structures, remain inadequately understood. This study precisely examines the load-transfer characteristics of the swivel spherical hinge using a combination of finite element simulation and scaled model loading tests. An optimized hinge model, accounting for distortion effects and strategic placement of measurement points, was constructed and tested in the laboratory. Results indicate that the scaled model exhibited consistent elastic deformation, ensuring structural integrity and stability. The results indicate that under a 122 kN load, the average discrepancy between the experimental data and numerical predictions was only 1.53 %, highlighting the numerical model's accuracy and reliability. Additionally, the center of the slider experienced a compressive stress of approximately 2.7 MPa, while the edge endured 5.3 MPa, reflecting a non-uniform load distribution. Stress concentrations at the slider's projection were 2–5 times greater than at other measurement points on the steel-concrete interface of the hinges. The lower spherical hinge surface displayed a complex stress pattern combining tensile and compressive stresses, resulting from slider compression and hinge surface expansion. This research provides valuable insights into the load-transfer mechanisms of swivel spherical hinges, offering guidance for the design and construction of swivel bridges.

Analytical and geometric interpretation of the flat arrangement of points by means of metric geometry in the study of metric spaces

Abstract When studying metric spaces, students of higher education often have difficulties with understanding the basic concepts and properties of these spaces. This, to a large extent, is a consequence of the significant level of formalization of such concepts on the one hand, and the preservation of the corresponding formulations and names familiar to students from a school mathematics course. To overcome these difficulties, it is advisable to use methods of geometric interpretation and visualization of these properties. At the same time, it is appropriate to use elements of metric geometry. Its methods make it possible to interpret the geometric features of the mutual placement of points of metric space in Cartesian (rectangular) coordinate systems, which are familiar to students of higher education. Moreover, it becomes possible to visualize these features with the help of graphic editors, since they, as a rule, use numerical values of the coordinates of points to visualize them. Based on the definition of an angle as an ordered trio of points of an arbitrary metric space, and the angular characteristic of this angle, the fact of the flat placement of four points of a non-Euclidean metric space is established, and examples of digital visualization of this arrangement using the dynamic geometric environment GeoGebra 3D are given.

ISAC‐oriented access point placement in cell‐free mMIMO systems

AbstractIn mobile communication networks for integrated sensing and communication, site planning of access points fundamentally determines both communication quality and sensing performance. This paper aims to tackle the AP placement problem under the setting of cell‐free massive multiple‐input multiple‐output, which represents a promising direction for network architecture evolution. Seeking a balance between the sum‐throughput of communication and the Cramér–Rao lower bound of target sensing, the access points are first pre‐placed by solving a convex optimization and further adjusted with optimal angular geometry. The final step involves employing nearest neighbour projection to refine access point positions in the cell‐free massive multiple‐input multiple‐output system, ensuring alignment with integrated sensing and communication requirements. The numerical results show that the proposed algorithm achieves 90% of the optimal communication sum‐rate and 95% of the optimal target localization accuracy.

A game-theoretic approach to managing the composition and structure of a bearing-only measurement system in conditions of a priori uncertainty

The problem of managing the composition and structure of a bearing-only measurements system (BOMS) in a game-theoretic formulation is considered. An approach of cooperative search for the placement of BOMS points and a method for estimating the work-time indicator of the system are proposed. The search for the placement of BOMS points uses the toolkit of multi-agent potential games. The criteria for selecting the placement of points and the type of potential function are determined. The management of the composition and structure of the BOMS is based on the results of the cluster-variation method. A structural and functional description of the simulation model is presented. The above results of simulation modeling confirm the practical effectiveness of the proposed approaches.

Correction: Zhu et al. Energy Efficient Access Point Placement for Distributed Massive MIMO. Network 2022, 2, 288–310

Following publication, concerns were raised regarding the peer-review process related to the publication of this article [...]

Selection of placement position of support points for early and mid-term mechanical repair of femoral head necrosis

To investigate the clinical efficacy of the placement of the main mechanical support points in the early and middle stages of mechanical repair of femoral head necrosis in preventing collapse of the femoral head. A retrospective analysis was performed for 17 cases 22 hips of non-traumatic femoral head necrosis in the early and middle stages from June 2018 to June 2019, including 14 males 18 hips and 3 females 4 hips, aged 34 to 47 years old. Among them, 6 cases were hormonal, 8 were alcoholic and 3 were idiopathic. According to China-Japan Friendship Hospital(CJFH) classification, 9 hip were type L1, 8 were L2, 5 were L3. All cases were given dead bone scraping, autologous iliac granules pressed bone grafting, and allogeneic fibula column support treatment. After surgery, Sanqi Jiegu Pill() was administered orally for 3 months. X-rays of both hips were performed after surgery and follow-up, and the clinical efficacy was evaluated by hip Harris score before and after surgery. All cases were followed up for 24 to 38 months. The Harris score of 22 hips increased from 58 to 77 preoperative to 68 to 94 at the final follow-up. At the final follow-up, 3 hips were excellent, 11 hips were good, 3 hips were acceptable, 5 hips were poor. Two hips of L2 type progressed to ARCO ⅢB stage and continued to be observed, 2 hips of L2 type and 2 hips of L3 type progressed to ARCO Ⅳ stage, and received total hip replacement, and 1 hip infection at 3 months after surgery was given a cement spacer. Based on CJFH classification, collapse can be predicted to a certain extent according to the area, volume, location and human biological characteristics of osteonecrosis, and the main mechanical support points are found on this basis to prevent collapse.

Generative Artificial Intelligence Using Machine Learning on Wireless Ad Hoc Networks

In this article, we discuss the use of Generative Artificial Intelligence (GenAI) to improve the efficiency and performance of access to wireless points located in various spaces and specific places, which allows interaction with wireless mesh networks and enables the use of mobile devices to access all types of information in internal environments. Furthermore, we propose the use of generative neural networks, which are one of the pillars of GenAI, since they use a methodology from the perspective of Machine Learning that allows analysis of a large amount of data and detection of certain types of patterns that help in the better placement of access points for improved reception and connectivity. Images (heat maps), access point locations, positioning points, and bandwidth are analyzed, allowing new information to be created. On the other hand, to understand and model the general architecture of the wireless Ad-Hoc network, we use two processes that are part of neural networks, such as Multilayer Perceptron (MLP), and the Radial Basis Function (RBF), which is a function of predictors or independent variables or input variables that allows the prediction error in the output variables of the wireless network architecture to be reduced. Using these two processes does help reduce blind spots in those internal places where the wireless signal does not reach, resulting in a signal drop. Improving internal scenarios with wireless Ad-Hoc networks is what is required for better functioning and performance of the network infrastructure.

Kritik Arsitektur terhadap Aspek Inklusif Aksesibilitas Hubungan Horizontal Antar Ruang atau Antar Bangunan Studi Kasus: Selasar RSP (Rumah Sakit Paru) Dr. H. A. Rotinsulu Bandung

Hallway of the Lung Hospital DR. H. A. Rotinsulu is one of the facilities that functions as the accessibility of relationships between spaces or between buildings. Tues as referred to in the Lung Hospital DR. H. A. Rotinsulu is a means of connecting circulation pathways between rooms or between buildings outside a building that is not limited by walls or limited by at most 1 (one) side wall. The object of Architectural Criticism is the hall of Dr. Lung Hospital. H.A Rotinsulu Bandung. Architectural criticism is carried out in the form of observations and measurements in the field on several walkway segments, based on the steepness of the contours that have been measured influenced by the long span of each walkway segment, which has been divided into observations according to the existing conditions of the walkways of Dr. Lung Hospital. H. A Rotinsulu Bandung, then a study was carried out in the form of an evaluation of the existing conditions of the walkway according to Ministerial Regulation PUPR No. 14 of 2017 concerning Requirements for Building Facilities and Law no. 8 of 2016 concerning Persons with Disabilities. The aspects studied are: 1. Needs for space for movement of users, 2. Circulation, 3. Guiding paths 4. Placement of gathering points, 5. Waiting area or right of way in transit to the hall rest. The basic dimensions of space and related facilities according to the object of observation refer to the Universal Design principle or the principle of inclusive design so that each user can move easily, safely, comfortably and independently.

Kritik Arsitektur terhadap Aspek Keselamatan Sarana Penyelamatan Jiwa Bangunan Gedung Studi Kasus: Gedung Pusat Antar Universitas (PAU) ITB Bandung

Safety at the building is a safe condition physically, socially, spiritually, psychologically and other threats that endanger humans. Building Safety not only focus on active fire protection, but also need to concern about passive protection. Regarding from that safety aspect, the aspect of building life saving is a prevention for building users so that they have time for evacuation process until they leave the building. The aspect of saving lives is reviewed from the fulfillment of criteria such as distance between buildings, fire fighting access routes, pavement layers or hardstanding, fire fighting access inside buildings, access to exit facilities (corridors), access to exit facilities (doors), lighting on evacuation routes. , Signage, Placement of assembly point. So that an evacuation plan is created along with the fulfillment of protect users in saving lives at the building.

A seed point placement method for generating streamlines in context regions

A seed point placement method for generating streamlines in context regions

Effect of tillage and precision nutrient placement on growth and productivity of maize (Zea mays)

The experiment was conducted at ICAR-Indian Agricultural Research Institute, New Delhi during rainy season of 2022 to asses the effect of tillage and precise nutrient placement on maize (Zea mays L.) growth. Employing a split-plot design with 3-tillage methods in main plots, viz. T1 , (conventional tillage); T2 , (once rotavator as minimum tillage) and T3 , (zero tillage) and 4, precision nutrient application options N1 , 50% RDF as point placement; N2 , 75% RDF as band placement; N3, 100% RDF as band placement and N4, 100% RDF as broadcasting were tested in subplots. Results indicated that tillage and precision nutrient placement practices improved the plant height and LAI of maize. Minimum tillage recorded significantly higher crop growth indices, viz. CGR (1.92 g/m2/day), RGR (26.80 g/g/day) and dry matter accumulation (204.58 g/plant) over other tillage practices at 60 to 90 Days after sowing (DAS). Root attributes also improved under minimum tillage. The grain yield was significantly higher with minimum tillage (6.22 t/ha) over other tillage practices. Among the precision nutrient application options, 100% RDF as band placement recorded significantly higher grain yield (6.20 t/ha) over N2 and N4 but remained statistically at par with 50% RDF point placement (6.06 t/ha). The findings suggested that adopting minimum tillage and precise nutrient point placement could significantly enhance maize growth and yield in kharif seasons, offering 50% reduction in fertilizer consumption.

Encuentros desde el rizoma entre el Saber Pedagógico y el Currículo en las Escuelas Normales Superiores de Antioquia

The purpose of this paper is to analyze the inter-critical dialogue scenarios from the rhizomatic encounters between pedagogical knowledge and the curriculum in some Higher Teacher Training Colleges of Antioquia. To strengthen the points of epistemic placement, the category "Knowledge" is addressed first, followed by a theoretical journey on the conception of pedagogy as a disciplinary and professional field. In this field, pedagogical knowledge derived from teaching practices is produced, which is put into conversation from the curricular field. Finally, the methodological path is presented, which is based on a historical-hermeneutic look, a rhizome-sensitive map and a biographical-narrative methodological tool.

Dosimetric Impact of Prescription Point Placement in Heterogeneous Medium for Conformal Radiotherapy Dose Calculation with Various Algorithms.

The aim of the study is to compare the accuracy of dose calculation for different dose calculation algorithms with different prescription points (air, tissue, air-tissue interface in carcinoma lung patients and bone, tissue, and bone-tissue interface in carcinoma buccal Mucosa tumors). Forty-one patients with carcinoma lung and buccal mucosa were retrospectively selected for this study. A three-dimensional conformal radiotherapy reference plan was created using the prescription point in the tissue with Monte Carlo (MC) algorithms for both the groups of patients. The reference plan was modified by changing the prescription point and algorithms in the tissue, air, air-tissue interface for lung patients and tissue, bone, and bone-tissue interface for buccal mucosa patients. The dose received by the target volume and other organs at risk (OAR) structures was compared. To find out the statistical difference between different prescription points and algorithms, the statistical tests were performed with repeated measures ANOVA. The target volume receiving 95% dose coverage in lung patients decreased to -3.08%, -5.75%, and -1.87% in the dose prescription point at the air-tissue interface with the dose calculation algorithms like MC, collapsed cone (CC), and pencil beam (PB), respectively, compared to that of the MC tissue. Spinal cord dose was increased in the CC and PB algorithms in all prescription points in patients with lung and buccal mucosa. OAR dose calculated by PB in all prescription points showed a significant deviation compared to MC tissue prescription point. This study will help demonstrate the accuracy of dose calculation for the different dose prescription points with the different treatment algorithms in radiotherapy treatment planning.