In order to investigate the seismic performance of prestressed concrete rocking frame (PCRF), a theoretical model based on rigid body is established for a one-story single-span PCRF. The PCRF studied ...in this paper has the connecting interfaces set at the column feet and at the inner faces of the beam–column joints, allowing the columns to be uplifted with the accompanying separation of the beam–column interface and rotation of the beam and column around the interface. The tendons are arranged along the centerline of the beam and columns. The connections between the beam and columns and the anchoring of columns are accomplished by prestressing the tendons. The theoretical model consists of a rigid beam, rigid columns and elastic tendons. The governing motion equation of the PCRF is derived based on the model and a numerical solution of the equation of motion is obtained. The energy dissipation of the PCRF is analyzed and the calculation method for the coefficient of restitution is derived. Time history analysis and parameter analysis of seismic response of the PCRF are conducted and the results show that the PCRF has promising seismic behavior.
When searching for a dynamic target in an unknown real world scene, search efficiency is greatly reduced if users lack information about the spatial structure of the scene. Most target search ...studies, especially in robotics, focus on determining either the shortest path when the target’s position is known, or a strategy to find the target as quickly as possible when the target’s position is unknown. However, the target’s position is often known intermittently in the real world, e.g., in the case of using surveillance cameras. Our goal is to help user find a dynamic target efficiently in the real world when the target’s position is intermittently known. In order to achieve this purpose, we have designed an AR guidance assistance system to provide optimal current directional guidance to users, based on searching a prediction graph. We assume that a certain number of depth cameras are fixed in a real scene to obtain dynamic target’s position. The system automatically analyzes all possible meetings between the user and the target, and generates optimal directional guidance to help the user catch up with the target. A user study was used to evaluate our method, and its results showed that compared to free search and a top-view method, our method significantly improves target search efficiency.
Thin film thermocouples (TFTCs) can provide more precise in situ temperature measurement for aerospace propulsion systems without disturbance of gas flow and surface temperature distribution of the ...hot components. ITO
/
PtRh:PtRh TFTC with multilayer structure was deposited on alumina ceramic substrate by magnetron sputtering. After annealing, the TFTC was statically calibrated for multiple cycles with temperature up to 1000 °C. The TFTC with excellent stability and repeatability was realized for the negligible variation of EMF in different calibration cycles. It is believed that owing to oxygen diffusion barriers by the oxidation of top PtRh layer and Schottky barriers formed at the grain boundaries of ITO, the variation of the carrier concentration of ITO film is minimized. Meanwhile, the life time of TFTC is more than 30 h in harsh environment. This makes ITO/PtRh:PtRh TFTC a promising candidate for precise surface temperature measurement of hot components of aeroengines.
Digital technology plays a crucial role in advancing sustainable farming and ensuring food security, especially in developing countries. This study evaluates the impact of Internet technology usage ...on technical efficiency in crop productivity, using data from 600 wheat farmers in rural Pakistan. It addresses the imperative need to enhance agricultural practices within the context of sustainable food production. To achieve this, a matched sample of Internet users and non-users was formed through propensity score matching. The study employs the stochastic frontier method with sample selection adjustment, ensuring a robust evaluation of technical efficiency between these groups. The findings reveal a positive influence of Internet usage on efficiency, persisting even after mitigating self-selection bias from observed and unobserved factors. Internet users exhibit a technical efficiency score of 0.62, surpassing the 0.55 score of non-users. Quantile regression analysis exposes varying impacts of Internet usage on technical efficiency, with less efficient farmers experiencing substantial improvements. Widespread Internet adoption holds the potential to significantly enhance agricultural production for growers. The research underscores the role of promoting Internet utilization to stimulate growth and improve farming efficiency within the evolving digital economy. Policymakers are advised to promote the adoption of modern technology to enhance crop production and support economic growth.
When a user walks freely in an unknown virtual scene and searches for multiple dynamic targets, the lack of a comprehensive understanding of the environment may have a negative impact on the ...execution of virtual reality tasks. Previous studies can help users with auxiliary tools, such as top view maps or trails, and exploration guidance, for example, automatically generated paths according to the user location and important static spots in virtual scenes. However, in some virtual reality applications, when the scene has complex occlusions, and the user cannot obtain any real-time position information of the dynamic target, the above assistance cannot help the user complete the task more effectively.
We design a virtual camera priority-based assistance to help the user search dynamic targets efficiently. Instead of forcing users to go to destinations, we provide an optimized instant path to guide them to places where they are more likely to find dynamic targets when they ask for help. We assume that a certain number of virtual cameras are fixed in virtual scenes to obtain extra depth maps, which capture the depth information of the scene and the locations of the dynamic targets. Our method automatically analyzes the priority of these virtual cameras, chooses the destination, and generates an instant path to assist the user in finding the dynamic targets. Our method is suitable for various virtual reality applications that do not require manual supervision or input.
A user study is designed to evaluate the proposed method. The results indicate that compared with three conventional navigation methods, such as the top-view method, our method can help users find dynamic targets more efficiently. The advantages include reducing the task completion time, reducing the number of resets, increasing the average distance between resets, and reducing user task load.
We presented a method for improving dynamic target searching efficiency in virtual scenes by virtual camera priority-based path guidance. Compared with three conventional navigation methods, such as the top-view method, this method can help users find dynamic targets more effectively.
Precise control of casting velocity and effective throwing kinetic energy conversion efficiency in blasting engineering are challenges. To provide a theoretical basis and reference for the ...implementation plan and fine construction of the cast blasting project, we study the problems of casting velocity and energy consumption ratio of broken rock under the impact load of explosions in this manuscript. The calculation methods of casting velocity and throwing energy of broken rock under two blasting modes of spherical charge and cylindrical charge are established by using the theory of dimensional analysis and rock breaking by blasting. A large number of model tests are carried out by using high-speed photography. The results indicate that the casting velocity of broken rock after explosive initiation has two evident stages: instantaneous acceleration to a certain value and subsequent fluctuation; the velocity presents an ordinary distribution law with the step height, and the fitting correlation of high-speed photography results is more than 91%. With the minimum burden increasing from 0.12 m to 0.2 m, the energy consumption decreases from 1306.88 J to 747.49 J and the proportion of energy consumption decreases from 14.77% to 8.45%.
•The image fusion task is cast into a regression problem and we formulate the problem in a hierarchical Bayesian manner incorporating with the TV penalty.•The fusion weights of each pixel is adaptive ...to the input sources without manual adjustment.•This model is efficiently inferred by the EM algorithm.•In comparison with other methods, the novel model can generate better fused images with highlighting targets and rich texture details.
Infrared and visible image fusion has been a hot issue in image fusion. In this task, a fused image containing both the gradient and detailed texture information of visible images as well as the thermal radiation and highlighting targets of infrared images is expected to be obtained. In this paper, a novel Bayesian fusion model is established for infrared and visible images. In our model, the image fusion task is cast into a regression problem. To measure the uncertainty in a better manner, we formulate the model in a hierarchical Bayesian manner. Aiming at making the fused image satisfy the human visual system, the model incorporates the total-variation (TV) penalty. Subsequently, the model is efficiently inferred by the expectation-maximization (EM) algorithm, where the fusion weight can be automatically inferred and adaptive to the source images. The performance of our algorithm is investigated and compared with several state-of-the-art approaches on TNO and NIR image fusion datasets. In comparison with other methods, the novel model can generate better fused images with highlighting targets and rich texture details, which may potentially improve the reliability of the target automatic detection and recognition system.
Human-customer service chatbot interaction has had mixed effects on customer satisfaction in sales-related services. To dissect these conflicting results, three 2 (temporal cues: instant versus ...anthropomorphic delayed response) × 2 (conversational cues: task- versus social-oriented) between-group experiments were conducted. The results revealed the complex effects of temporal cues, conversational cues, and their interactions on perceived warmth, perceived competence, and satisfaction. And, perceived warmth and competence mediated the effects of temporal and conversational cues on satisfaction. Furthermore, the product attribute type (functional versus experiential) affected the relationships between these variables. These findings provide two explanatory perspectives (temporal and conversational cues) for dissecting the mixed effects of human-customer service chatbot interaction on customer satisfaction, and provide practical insights for improving customer service chatbots and enhancing customer satisfaction.
•Temporal cues, conversational cues, and their interactions had mixed effects on warmth, competence, and satisfaction.•Perceived warmth and competence mediated the effects of temporal and conversational cues on satisfaction.•The product attribute type affected the relationships between the above variables.
Infrared and visible image fusion (IVIF) expects to obtain images that retain thermal radiation information from infrared images and texture details from visible images. In this paper, a model-based ...convolutional neural network (CNN) model, referred to as Algorithm Unrolling Image Fusion (AUIF), is proposed to overcome the shortcomings of traditional CNN-based IVIF models. The proposed AUIF model starts with the iterative formulas of two traditional optimization models, which are established to accomplish two-scale decomposition, i.e., separating low-frequency base information and high-frequency detail information from source images. Then the algorithm unrolling is implemented where each iteration is mapped to a CNN layer and each optimization model is transformed into a trainable neural network. Compared with the general network architectures, the proposed framework combines the model-based prior information and is designed more reasonably. After the unrolling operation, our model contains two decomposers (encoders) and an additional reconstructor (decoder). In the training phase, this network is trained to reconstruct the input image. While in the test phase, the base (or detail) decomposed feature maps of infrared/visible images are merged respectively by an extra fusion layer, and then the decoder outputs the fusion image. Qualitative and quantitative comparisons demonstrate the superiority of our model, which can robustly generate fusion images containing highlight targets and legible details, exceeding the state-of-the-art methods. Furthermore, our network has fewer weights and faster speed.
In this study, we fabricated a unique core–shell structure of PB@MoS2 microcubes for the first time (PB stands for Prussian blue) and examined the microwave absorption performance in the frequency ...range of 2–18 GHz. The results showed the hybrid PB@MoS2 core–shell structure has an excellent microwave absorbing property. The minimum reflection loss value was found to be −42.83 dB with a thickness of 2.1 mm at 16.46 GHz and −42.06 dB at a frequency of 11.44 GHz with a thickness of 2.5 mm for the 40 wt % loading of PB@MoS2/wax. The effective absorbing bandwidth (less than −10 dB) could reach 7.31 GHz at 2.4 mm, 7.44 GHz (9.82–17.26 GHz) at a thickness of 2.5 mm, and 7.17 GHz at a thickness of 2.6 mm. The results indicated that the hybrids of PB@MoS2 core–shell microcubes were promising microwave-absorbing materials formed using an inexpensive and facile synthesis process, which can be an excellent candidate for efficient electromagnetic wave-absorbing applications.
PDF
