Conventional Space Research Articles

Maxwell equations in Schwarzschild black hole with topological defects and the gravitational magnetoelectric effect

Maxwell equations in Schwarzschild black hole with topological defects and the gravitational magnetoelectric effect

Electromagnetic fields in topologically charged traversable wormholes

In this research paper, we focus on analyzing the electromagnetic fields within the framework of a traversable wormhole that incorporates a cosmic string. We then extend our investigation to a traversable wormhole with a global monopole charge, addressing the same problem in this new context. To facilitate our study, we compute the electromagnetic field tensor and derive Maxwell’s vacuum field equations, which govern the behavior of the electric and magnetic fields. Using an analytical approach, we obtain solutions for the electromagnetic fields and compare them with the results from conventional Minkowski flat space. Our study demonstrates significant deviations in the electromagnetic fields, and thus, changes the behavior of electromagnetic waves in the presence of a cosmic string and a global monopole charges within this wormhole background.

Posthumanism in ecofeminist literature: Transgressions in Kazuo Ishiguro's Klara and the Sun

This paper establishes a critical place of conversation between an ecofeminist type of contravening patriarchal and masculine-centered discourse and posthumanist attempts to problematize boundary-setting systems assembled around the conceit of speciesism and human privilege. Kazuo Ishiguro's novel Klara and the Sun (2021) supplies this conversational groundwork centered around the novel's main protagonist, Klara, an Artificial Friend (AF). The literary presence of Klara is designed to infract a conventional social space (dominated by humans), technically eroding the human/non-human and nature/culture duality. Such erosion implies a transgression, portrayed in posthuman studies as a transcendence of the human and in ecofeminist studies as a deconstruction of the often-oppressive essentialist relationships of women and the environment. Transgression is the boundary-crossing mediation among actants. The novel permits us to see multivalent frames, each thematizing a posthuman future in terms of gender differences, the posthuman/human intricate gravitation towards loneliness, and, most of all, love. Through the examination of this work, an interrogation of the technological trajectory of the near future also suggests repositioning the role of posthumans concerning their environments.

Practical Teaching Case: Experimental Eye-Tracking Study on Library Virtual Space Design

Eye-tracking experiments can be used to evaluate the popularity of design spaces. In this thesis, eye-tracking experiments are employed in the practical teaching of the “Ergonomics” course to provide feedback on the feasibility of library virtual space design. Firstly, in the course teaching, research subjects were selected and two virtual library spaces were built for eye-tracking experiments, with results showing that applying eye-tracking technology to space design is feasible, and participants prefer conventional library virtual spaces. Meanwhile, it is further confirmed that the use of design experiment feedback in practical teaching reform can improve students' subjective enthusiasm.

A novel simulation of space charge decay dynamics after removing the voltage in epoxy resin composites

Abstract Epoxy resin serves as a critical insulating component in ultra-high voltage dry direct current bushings. However, the accumulation of space charges within the epoxy resin, a byproduct of charge mobility, poses a significant risk to the reliability and operational safety of bushings. Conventional space charge attenuation models, especially after voltage removal, have limited use in simulations aimed at understanding this phenomenon. This study introduces an improved model integrating the bipolar charge transport mechanism with space charge decay based on the hopping conduction mechanism and Schottky’s theorem, establishes a theoretical framework for predicting the space charge behavior following voltage removal, and conducts a simulation to investigate the decay process within the internal structure of epoxy resin and measure the residual charges after voltage removal using the pulsed electro-acoustic method. The experimental data validate the accuracy of the proposed model and theoretical assumptions. The findings show that the remaining negative charges after voltage removal are not enhanced by the field enhancement; the anodic positive and cathodic positive charges are distributed in two-segment discontinuous traps, whereas the negative charges are distributed in one-segment traps. The model identifies two distinct trapping sites for anodic and cathodic positive charges, and one trapping site for negative charges. After voltage removal, when the field strength exceeded 40 kV mm−1, positive charges exist near the upper and lower electrodes, and negative charges exist near the center of the specimen. The consistency between the simulated predictions and experimental data proves the effectiveness of the proposed model in accurately simulating the space charge decay in epoxy materials after voltage removal.

Multidisciplinary space shield origami composite: Incorporating cosmic radiation shielding, space debris impact protection, solar radiative heat shielding, and atomic oxygen erosion resistance

Origami composites have been extensively utilized in space structures with constrained payload volumes due to their capability to efficiently transform compact structures into larger surface area or volume configurations. The proposed origami composite incorporates hydrogen-rich benzoxazine polymers known for their high radiation shielding capability and ultra-high-molecular-weight polyethylene fibers known for their high ballistic performance, radiation shielding capability, and flexibility. The proposed origami composite and manufacturing method can enhance bonding strength by achieving precise origami shapes and utilizing the same matrix for both flexible and rigid components. Membrane sheets are manufactured at a low curing temperature to provide flexibility, while rigid facets are separately manufactured at a high curing temperature to increase rigidity. The integration of a polyimide protection layer significantly enhances space environment resistance and reduces mass loss due to atomic oxygen erosion. Despite a slight decrease in ballistic performance after exposure to space conditions, the proposed origami composite maintains superior ballistic performance compared to conventional space materials and conventional origami composites. Compared to existing origami composites or conventional space materials, the proposed origami composite exhibited superior radiation shielding performance. The laminated structure of the proposed origami composite can offer some solar radiation shielding capability. The proposed origami composite offers a multifunctional origami solution as a membrane-space shield material, fulfilling requirements for high ballistic performance, cosmic radiation shielding, solar radiative heat shielding, and space environmental resistance.

SMALL OBJECT DETECTION APPROACH BASED ON ENHANCED SINGLE-SHOT DETECTOR FOR DETECTION AND RECOGNITION OF INDONESIAN TRAFFIC SIGNS

The detection and recognition of traffic signs are crucial components of advanced driving assistance systems (ADAS) that enhance road safety. Current traffic sign detection and recognition model technology is proficient in identifying and interpreting traffic signs. However, for accurate detection and recognition, the traffic sign in the image must be of a certain minimum pixel size or distance from the driver's sight line for proper detection. The ADAS system should be capable of detecting and recognizing road traffic signs from a considerable distance as they come into the driver's line of vision. The higher the vehicle speed, the greater the distance required for the sign to be detected and recognized, allowing the driver sufficient time to react according to the sign's meaning. Addressing these challenges, this research proposes an enhanced version of the single shot detector (SSD) algorithm, commonly used in object detection, to improve the algorithm's ability to detect small objects. The proposed method involves adding an auxiliary layer module to the original SSD architecture to increase the feature map resolution and expand the conventional layer's receptive space. With the Enhanced SSD algorithm, the detection capability of the SSD can be significantly enhanced in terms of accuracy. The limitations of this study are related to the influence of occlusion and clutter, which might affect the performance of object detection, especially for small objects, which are more susceptible to being influenced by various factors. The research results demonstrate that Enhanced SSD improves object detection accuracy compared to the original SSD, with a mean average precision (mAP) of 97.87 compared to 95.35 for detecting 21 traffic signs in Indonesia.

M3D‐DPWM strategy for three‐phase four‐leg inverter with higher harmonic suppression capability

AbstractThree‐phase four‐leg inverters are widely used in power systems due to their inherent ability to handle unbalanced loads. However, with conventional 3D space vector pulse width modulation (3D‐SVPWM), high harmonics of large amplitude exist in the output voltage around the switching frequency and its integer multiples leading to noise in the load motor and limiting the application range of the inverter system. The passband amplification of conventional sinusoidal filters and their cutoff frequency vary with the load, so it is particularly important to investigate the regulation strategy with harmonic suppression. In this study, an improved 3D discontinuous pulse width modulation (M3D‐DPWM) strategy is proposed based on 3D‐SVPWM. By reducing the conventional 3D‐SVPWM switching segments and changing the vector synthesis sequence of the last half switching cycle, the output phase voltage period is reduced to half of the original one, which achieves the purpose of suppressing the output voltage at the switching frequency and its odd multiple high harmonics without changing the fundamental characteristics and adding additional circuits. In contrast, the conventional 3D‐SVPWM switching frequency is increased to 20 kHz to achieve similar performance. Finally, the effectiveness of the proposed strategy is verified by simulation and experiment.

Thermal comfort driven space heating control via hierarchical state machine strategy interacting with multiphysics simulation

Improving energy efficiency of space heating systems is as important as adopting emerging clean energy technologies for decarbonising heating. While exploring strategies for reducing energy consumption, the space occupants’ expectations to thermal comfort should not be sacrificed. Conventional space heating control systems are often developed under the hypothesis of uniform temperature distribution in a bounded space and the heating system controller is primarily operated based on the information from the temperature sensor at a fixed position. That is, the measured temperature does not represent the temperature surrounding the occupant’s location. This paper explores a new control method; the heating system control is led by the occupant’s thermal experience, expressed by the temperature surrounding the occupant. A new hierarchical state machine control strategy interacting with a Multiphysics simulation model to dynamically estimate the temperature at the point of the occupant is developed. The accuracy of the Multiphysics simulation model is verified based on the corresponding experimental test room data. A co-simulation platform is built to allow COMSOL and SIMULINK to communicate in real-time for control strategy realisation. The experimental results show that the maximum and average mean square error between the measured and simulated temperature under different operating modes is less than 0.21℃ and 0.06℃, respectively. The simulation results indicate that energy consumption could be potentially reduced around 20% with an improved thermal comfort of the occupant by 30%, compared with the conventional fixed sensor control method.

Comparative Study of Mechanical Properties and Microstructure Between Conventional and Infinite z-Axis Fused Deposition Modeling Printers

Additive Manufacturing (AM) has emerged as a critical technology in shaping manufacturing strategies, offering versatility and efficiency in designing complex structural components. Extensive literature exists on small- to mid-sized product production. However, a significant knowledge gap exists in manufacturing elongated products, such as wind turbine blades and constructional beams. Current AM technology faces limitations in this context, primarily due to the constraints imposed by the conventional 90-degree nozzle head and limited bed space. This study introduces an innovative AM approach called Infinite z-Axis Printing. This novel technique utilizes a belt-driven heated bed and a 45-degree nozzle head to 3D print objects of infinite length. The study compares this groundbreaking approach and the traditional 90-degree nozzle head Fused Deposition Modeling (FDM) method and the associated results. The findings of this research demonstrate that the Infinite z-Axis Printing methodology yields a significant improvement of up to 20% in tensile and compressive strength compared to the currently used FDM process. This advancement can potentially revolutionize on-site operations by enabling the efficient production of elongated structural components, thus contributing significantly to the construction and renewable energy sectors.

Fracture Resistance of Space Maintainers Produced Using 3D Printable Materials.

This study aimed to evaluate the fracture resistance of space maintainers (SMs) produced using 3D-printable materials (metal, resin and polyetheretherketone [PEEK]) after thermal aging and compare them with conventional space maintainers. A standardised typodont model for paediatric dentistry was utilised, and band and loop space maintainers were designed digitally using computer-aided design (CAD) technology. Four groups were established: Conventional, 3D printed metal, 3D printed resin, and 3D printed PEEK. Fracture resistance was assessed after 10,000 thermal cycles, simulating oral conditions. Fracture tests were conducted using a universal testing machine, applying vertical force to the band and loop junction until fracture. Statistical analyses were performed using one-way ANOVA and the Tukey HSD test (P<0.05). Although the fracture resistance values showed that metal, resin, and PEEK 3D printed band and loop space maintainers can be acceptable clinically, the permanent resin may be preferable to printable material because of their aesthetic properties.

Critical local well-posedness of the nonlinear Schrödinger equation on the torus

In this paper, we study the local well-posedness of nonlinear Schrödinger equations on tori \mathbb{T}^{d} at the critical regularity. We focus on cases where the nonlinearity |u|^{a}u is nonalgebraic with small a&gt;0 . We prove the local well-posedness for a wide range covering the mass-supercritical regime. Moreover, we supplementarily investigate the regularity of the solution map. In pursuit of lowering a , we prove a bilinear estimate for the Schrödinger operator on tori \mathbb{T}^{d} , which enhances previously known multilinear estimates. We design a function space adapted to the new bilinear estimate and a package of Strichartz estimates, which is not based on conventional atomic spaces.

A Comparative Evaluation of Real-Time Guided Dynamic Navigation and Conventional Techniques for Post Space Preparation During Post Endodontic Management: An In Vitro Study.

The three-dimensional (3D) dynamic navigation system (DNS; Navident, ClaroNav Technology, Toronto, ON) is a revolutionary technique in endodontics that offers superior precision and efficiency compared to existing techniques for post space preparation. The aim is to evaluate and contrast the efficacy and efficiency of the DNS with conventional post space preparation techniques. This assessment considers severalparameters, notably canal deviation (global coronal and apical deviation and angular deflection), duration of the procedure, and total volumetric loss of instrumented root canal and volumetric loss of instrumented root canal above 4 mm from the apex. Freshly extracted maxillary central incisors were chosen for this study. A total sample size of 60 (n) was included. The extracted teeth samples were divided into two groups: 3D DNS (group I; n = 30)and conventional techniques (group II; n = 30). The samples were taken, and 50% of the crown structure was reduced for post space preparation to ensure standardization between thetwo groups. The samples were root canal-treated and mounted in a 3D-printed maxillary cast. Preoperative micro-computed tomography (micro-CT) and cone-beam computed tomography (CBCT) were taken for both groups.For group I, post space preparation was conducted with the DNS, which provided comprehensive guidance. The procedure was stopped when post space preparation was 4 mm short of the apex, as indicated in the system display. For group II, post space preparation was done without the guidance of DNS. Time taken for the procedure was assessed using a timer; canal deviation was evaluated using CBCT analysis, and volumetric loss was estimated using micro-CT analysis. The dynamic navigation group achieves significantly more precise outcomes in post space preparation than the conventional technique. The DNS group has significantly lesser global coronal and apical deviation and angular deflection compared to the conventional group (p < 0.05). The DNS group has reduced the volumetric loss of instrumented root canals compared to the conventional group (p < 0.05). Furthermore, the DNS group requires significantlyless time than the conventional method, with a mean difference of about 10.567 minutes (p < 0.05). Implementing dynamic navigation improves precision in post space preparation, with a notable reduction in canal deviation and volumetric loss and a decrease in procedure time compared to the conventional method.

Electric Field Gradient Calculations for Ice VIII and IX Using Polarizable Embedding: A Comparative Study on Classical Computers and Quantum Simulators.

We test the performance of the polarizable embedding variational quantum eigensolver self-consistent field (PE-VQE-SCF) model for computing electric field gradients with comparisons to conventional complete active space self-consistent-field (CASSCF) calculations and experimental results. We compute quadrupole coupling constants for ice VIII and ice IX. We find close agreement of the quantum-computing PE-VQE-SCF results with the results from the classical PE-CASSCF calculations and with experiment. Furthermore, we observe that the inclusion of the environment is crucial for obtaining results that match the experimental data. The calculations for ice VIII are within the experimental uncertainty for both CASSCF and VQE-SCF for oxygen and lie close to the experimental value for ice IX as well. With the VQE-SCF, which is based on an adaptive derivative-assembled problem-tailored (ADAPT) ansatz, we find that the inclusion of the environment and the size of the different basis sets do not directly affect the gate counts. However, by including an explicit environment, the wavefunction and therefore the optimization problem become more complicated, which usually results in the need to include more operators from the operator pool, thereby increasing the depth of the circuit.

Effect of Laser Treatment of Root Dentine on Retention of Dental Fiber Post in Endodontically Treated Teeth: An In Vitro Study.

Introduction: The most common causes of fiber post-failure are inadequate restorations and dislodgement. This study aimed to evaluate fiber post-bond strength to dentin following Er,Cr:YSGG laser irradiation. Methods: A total of 65 human mandibular premolars with single roots were included. The 14 mm root length was instrumented with the rotary system using the crown-down technique. Gutta-percha was used for obturation, followed by conventional post space preparation. The samples were divided into two major groups: control (A) and Er,Cr:YSGG (2780 nm) laser group (B). The laser group was subdivided into (B1) 1.25 W, (B2) 1.5 W, and (B3) 1.75 W. All laser groups were set at 20 Hz, 10% and 30% water/air ratio. Fiber posts were cemented with selfadhesive cement. Each sample was divided horizontally into two slices, coronal and apical. The universal testing equipment was used to conduct a push-out test. All groups were examined by SEM and temperature changes. The statistical analysis was performed by using one-way ANOVA and Tukey HSD tests. Results: SEM images of all laser groups revealed the elimination of the smear layer and opened dentinal tubules, which was particularly noticeable in the apical region with no thermal risk to the periodontal tissue. In the push-out test, all laser groups had highly significant (P<0.001) increases in the bond strength of fiber post to dentin. The failure mode of the control group was a predominantly adhesive failure, whereas the laser groups were a predominantly mixed type. Conclusion: The three laser protocols can be used safely in the surface treatment of the fiber post space of endodontically treated teeth. Laser help to increase the bond strength of fiber post to dentin, especially in the apical area.

Assessment of Knowledge and Utilization of Prefabricated Band and Loop Space Maintainers in Primary Dentition Among Dentists: A Cross-Sectional Questionnaire Study.

Preserving primary dentition is essential for maintaining optimal oral health and development in children. Premature loss of primary teeth due to caries, infection, crowding, or trauma can necessitate orthodontic intervention and lead to various complications. Space maintainers are critical for preserving arch space until the eruption of permanent teeth, thereby preventing issues such as ectopic eruption, crowding, and malocclusion. Despite their advantages, prefabricated space maintainers (PSMs) are underutilized. This study aims to evaluate the knowledge, attitudes, and practices of Indian dentists regarding PSMs in primary teeth. A cross-sectional questionnaire survey was conducted among 100 dental practitioners in Chennai. A 10-item self-administered questionnaire, developed based on a comprehensive literature review and expert consultations, assessed demographics, knowledge of PSM indications and techniques, current practices, perceived barriers, and preferences for continuing education. The questionnaire's reliability was confirmed with a Cronbach's alpha value of 0.85. Descriptive statistics, including frequencies andpercentages, were used to summarize the participants' demographic characteristics, knowledge levels, and current practices related to PSMs. Of the 100 respondents, 86 (86%) were males and 14 (14%) were females. Only 19 (19%) reported using PSMs, while 36 (36%) used conventional space maintainers. A significant proportion (42 (42%)) of the respondents held a master's degree in dental surgery, yet only 11 (11%) had participated in Continuing Dental Education (CDE) programs on space maintainers. The perceived benefit of PSMs being a single appointment procedure was acknowledged by 82 (82%) of the respondents, whereas 76 (76%) participants identified cost as a major drawback. Notably, 45 (45%) practitioners did not consider PSMs necessary. This survey highlights notable obstacles in the adoption of PSMs among Indian dentists, emphasizing the need for focused educational initiatives. Improving knowledge and practices related to PSMs can enhance pediatric dental care and oral health outcomes in India.

3D-Printed Models for Optimizing Tactile Braille & Shape Display.

Existing market-available refreshable Braille displays (RBDs) offer limited functionality at a high cost, hindering accessibility for individuals with blindness and visual impairment for teaching and learning purposes. This motivates us to develop a multi-functional, compact, and affordable RBD tailored for educational institutes to enhance teaching and learning experiences. We propose the development of BLISS (Braille Letters and Interactive Shape Screen), a novel RBD, that BLISS presents a unique configuration arrangement of Braille cells that accommodates up to six letters at a time and shapes by reusing the Braille pins. To determine the optimal specifications, including size, Braille cell spacing, and pin configuration, we fabricated and evaluated 3D-printed sets, mimicking how BLISS would display letters and shapes. We tested 36 variants of 3D-printed sets with 8 individuals with blindness and visual impairment and found that conventional Braille spacing is insufficient for accurately representing shapes. Hence, BLISS will introduce a novel design that uses a pin configuration to raise the extra pins to present shapes and lower them for Braille letters, providing dual-mode operation. Our findings show the potential of BLISS to display both Braille letters and shapes on the same refreshable display, offering a novel, compact, and cost-effective solution.

Analytic Modelling of 2-D Transient Heat Conduction with Heat Source Under Mixed Boundary Constraints by Symplectic Superposition

Abstract Many studies have been conducted on 2-D transient heat conduction, but analytic modelling is still uncommon for the cases with complex boundary constraints due to the mathematical challenge. With an unusual symplectic superposition method, this paper reports new analytic solutions to 2-D isotropic transient heat conduction problems with heat source over a rectangular region under mixed boundary constraints at an edge. With the Laplace transform, the Hamiltonian governing equation is derived. The applicable mathematical treatments, e.g., the variable separation and the symplectic eigenvector expansion in the symplectic space, are implemented for the fundamental solutions whose superposition yields the ultimate solutions. Benchmark results obtained by the present method are tabulated, with verification by the finite element solutions. Instead of the conventional Euclidean space, the present symplectic-space solution framework has the superiority on rigorous derivations without pre-determining solution forms, which may be extended to more issues with the complexity caused by mixed boundary constraints.

Exploring the Correlation between Morpho-physiological Traits and Growth Attributes Associated with Yield Characteristics in Rice (Oryza sativa L.)

This study aimed to identify the morpho-physiological and growth attributes, and yield associated with yield in rice genotypes. The experiment included 120 rice genotypes and 3 checks, conducted in an alpha lattice design with two replications at the Research Cum Instructional Farm in the Department of Plant Physiology, Indira Gandhi Krishi Vishawavidyalaya, Raipur, Chhattisgarh, during the two consecutive Kharif seasons of 2021-22 and 2022-23. Conventional spacing of 15 x 20 cm and recommended cultural practices were employed. The objective is to improve the overall efficiency and productivity of rice cultivation to meet the needs of a growing population. It is crucial to emphasize the comprehension and enhancement of the fundamental features associated with canopy structure and growth attributes. Improving these morpho-physiological traits is pivotal for boosting rice yield. By studying and refining the arrangement and growth of the rice plant's leaf canopy, the goal is to enhance the efficiency and productivity of rice cultivation. The results indicated that productive tillers (0.335**) and flag leaf area (0.213*) were positively correlated with higher yields. While leaf angles, specific leaf area, and days to panicle initiation showed negative correlations with yield. The leaf area index at flowering was positively correlated with specific leaf area (0.382***) but negatively with grain yield (-0.199*). Specific leaf weight was positively correlated with yield per hectare (0.178*). Understanding these relationships can guide the selection and breeding of rice genotypes with optimal traits for enhanced grain yield and crop performance.

Effect of Microbial Fuel Cell, fertilizer, and plant spacing on nitrogen dynamics in paddy soil

&lt;p&gt;Nitrogen is one of the primary nutrients required for growing rice. Still, the efficiency of urea fertilizer application is very low (20-40%) due to the nitrogen loss process, one of which is denitrification. This study aims to determine the effects of combining Microbial Fuel Cell (MFC), plant spacing, and fertilization on nitrogen dynamics in paddy fields. The combination of treatments are expected to reduce the nitrogen loss in paddy fields, and plants can absorb it efficiently. A total of six treatments included Microbial Fuel Cell (MFC) (2 levels: without MFC and with MFC), plant spacing (2 levels: conventional spacing 25 cm × 25 cm and &lt;em&gt;jajar legowo&lt;/em&gt; spacing 25 cm × 12.5 cm × 50 cm), and fertilization (2 levels: without fertilizer and with 500 kg ha&lt;sup&gt;-1&lt;/sup&gt; of NPK fertilizer), with three replications for each combination. The observed parameters included total soil nitrogen, nitrate, nitrogen uptake, chlorophyll, nitrogen-fixing and denitrifying bacteria, and N&lt;sub&gt;2&lt;/sub&gt;O gas emissions. The results showed that combining MFC, conventional spacing, and NPK fertilizer in the paddy fields resulted in a high total soil nitrogen (0.44%). The results showed different effects on total soil nitrogen in the MFC and fertilization treatments, leading to increased nitrate levels, nutrient uptake, and chlorophyll. Increasing total soil nitrogen significantly contributes to leaf development and significantly aids photosynthesis. The integration of MFC and fertilization observed in this study resulted in a real impact on nitrogen dynamics in paddy fields. This combined treatment effectively reduces total nitrogen loss due to denitrification in paddy fields, thereby increasing the efficiency of uptake by plants.&lt;/p&gt;