A scan-line hidden surface removal procedure for constructive solid geometry

We consider schemes for recursively dividing a set of geometric objects by hyperplanes until all objects are separated. Such a binary partition is naturally considered as a binary tree where each internal node corresponds to a division and the leaves correspond to the resulting fragments of objects. The goal is to choose the hyperplanes properly so that the size of the binary partition, i.e., the number of resulting fragments of the objects, is minimized. We construct binary partitions of size O(n log n) for n edges in the plane, and of size O(n) if the edges are orthogonal. In three dimensions, we obtain binary partitions of size O(n2) for n planar facets, and prove a lower bound of O(n3/2). Two applications of efficient binary partitions are given. The first is an O(n2)-sized data structure for implementing a hidden-surface removal scheme of Fuchs, Kedem and Naylor [5]. The second application is in solid modelling: given a polyhedron described by its n faces, we show how to generate an O(n2)-sized CSG (constructive-solid-geometry) formula whose literals correspond to half-spaces supporting the faces of the polyhedron (see Peterson [9] and Dobkin et al. [3]). The best previous results for both of these problems were O(n3).

Significant effort has been recently devoted to modeling visual relations. This has mostly addressed the design of architectures, typically by adding parameters and increasing model complexity. However, visual relation learning is a long-tailed problem, due to the combinatorial nature of joint reasoning about groups of objects. Increasing model complexity is, in general, illsuited for long-tailed problems due to their tendency to overfit. In this paper, we explore an alternative hypothesis, denoted the Devil is in the Tails. Under this hypothesis, better performance is achieved by keeping the model simple but improving its ability to cope with long-tailed distributions. To test this hypothesis, we devise a new approach for training visual relationships models, which is inspired by state-of-the-art long-tailed recognition literature. This is based on an iterative decoupled training scheme, denoted Decoupled Training for Devil in the Tails (DT2). DT2 employs a novel sampling approach, Alternating Class-Balanced Sampling (ACBS), to capture the interplay between the long-tailed entity and predicate distributions of visual relations. Results show that, with an extremely simple architecture, DT2-ACBS significantly out-performs much more complex state-of-the-art methods on scene graph generation tasks. This suggests that the development of sophisticated models must be considered in tandem with the long-tailed nature of the problem.

Volume-based approaches to construct solid models from orthographic views have several advantages over the traditional bottom up approach that has been popular thus far. The main advantages are—there is a valid solid model that is consistent with the input views always available at any point in the solution and there is no need for the intermediate wireframe. The first enables user intervention in complex drawings and the second eliminates the ambiguities due to the wireframe that have to be resolved to obtain a valid solid model. A major limitation of volume-based approaches that have been proposed thus far has been the limited domain of objects that they can handle. This is because these approaches typically use either pre-defined primitives or identify only entities (loops of edges) that can be extruded. This paper aims at extending the capabilities of the volume-based construction approaches by proposing a procedure to identify entities in the views that correspond to axis-aligned volumes of revolution and using these to construct the corresponding primitive volumes. Results of implementation are presented and further work has been identified.

The discusser would like to thank the author for presenting an improved nonlinear Muskingum model with a variable exponent parameter and would like to draw attention to some points. The need to consider a variable exponent parameter for a nonlinear Muskingum model has been pointed out by the author. The variable exponent parameter accounts for the nonlinearity of flood wave and clearly produces better model performance than that with the constant exponent parameter. The author found that even a small number of inflow levels result in an improvement in model performance. As mentioned by the author, as the number of inflow levels increase, model performance improves, but the improvement was found to be small beyond five levels in different case studies. The variable exponent parameter proposed by the author accounts for the nonlinearity of flood wave in a disaggregate manner. When five inflow levels are used, the number of model parameters will be seven making it a highly overparameterized model. Additional parameters should not be added to a model unless the increased accuracy justifies the increase in model complexity. Also, model complexity can sometimes lead to an undesirable loss of predictive power. In a regression model, accuracy needs to be balanced against complexity, and slight improvements in accuracy do not compensate for the additional complexity. As it will be shown in this discussion, considering a suitable continuous functional form for exponent parameter of nonlinear Muskingum model results in a substantial improvement in model performance. The proposed general functional form has five parameters and thus will be comparable with the case of five inflow levels proposed by the author. The author and most of the previous researchers have used inaccurate explicit Euler’s method [Tung’s method (Tung 1985)] along with the manipulated discharge equation to get a better fit for observed data. This manipulation [using It−1 rather than It in Eq. (6) of the original paper] is not acceptable from a mathematical viewpoint. All explicit solution methods will produce similar results for small size of the time interval, Δt, but in practice for historical field data, the size of the time interval is fixed and may not be small enough, and thus a suitable solution method with sufficient accuracy should be used. As shown by Vatankhah (2010, 2014), fourth-order Runge-Kutta method is an accurate and suitable solution method among the explicit solution methods for solving the Muskingum model which will be used in this discussion.

Some important trends in geometric modeling are the reliance on solid models rather than surface-based models and the enhancement of the expressive power of models, by using free-form objects in addition to the usual geometric primitives and by incorporating physical principles. An additional trend is the emphasis on interactive performance. In this paper, we integrate all of these requirements into a single geometric primitive by endowing the tri-variate tensor-product free-form solid with several important physical properties, including volume and internal deformation energy. Volume preservation is of benefit in several application areas of geometric modeling, including computer animation, industrial design and mechanical engineering. However, previous physics-based methods, which have usually used some form of "energy", have neglected the issue of volume (or area) preservation. We present a novel method for modeling an object composed of several tensor-product solids while preserving the desired volume of each primitive and ensuring high-order continuity constraints between the primitives. The method utilizes the Uzawa algorithm for non-linear optimization, with objective functions based on deformation energy or least squares. We show how the algorithm can be used in an interactive environment by relaxing exactness requirements while the user interactively manipulates free-form solid primitives. On current workstations, the algorithm runs in real-time for tri-quadratic volumes and close to real-time for tri-cubic volumes.

Background and Aims: This article aims to examine the current implementation of the dual system of education in Zhengzhou, analyzing the existing problems and the reasons behind them. By studying successful cases of dual system education from both domestic and international vocational colleges, this research will explore the development of school-enterprise cooperation from various perspectives, including national policy, government, vocational colleges, and enterprises. The focus of the study will be on students from Zhengzhou Railway Vocational and Technical College, using questionnaire surveys and interviews to assess the impact of dual education management on their competitiveness. Methodology: This research employs a mixed-methods approach, combining both qualitative and quantitative techniques, to explore the dual system vocational education model implemented in Zhengzhou, Henan Province. The study primarily focuses on the impact of the dual system on vocational education management and its effect on student competitiveness, with an emphasis on the local economic development of Zhengzhou and the Central Plains region. Results: Proposed Solutions and Recommendations. Based on the analysis of the data collected, the study will propose targeted recommendations for improving the dual education management system in Zhengzhou. These recommendations will focus on enhancing the cooperation between schools and enterprises, improving the role of vocational colleges, and creating supportive policies and frameworks to strengthen the dual education system. Suggestions will also include the establishment of long-term mechanisms, such as the development of special funds and policy incentives, to ensure sustainable growth and development of the dual education model. Conclusion: In conclusion the study highlights the need to improve the dual education management system in Zhengzhou to boost student competitiveness and local economic growth. Recommendations include enhancing school-enterprise cooperation, strengthening vocational colleges, and creating supportive policies. Establishing long-term mechanisms like dedicated funds will ensure sustainable development. These solutions aim to create a dynamic, resilient vocational education system benefiting both students and the community.

This paper addresses the bottom-up influence of local image information on human eye movements. Most existing computational models use a set of biologically plausible linear filters, e.g., Gabor or Difference-of-Gaussians filters as a front-end, the outputs of which are nonlinearly combined into a real number that indicates visual saliency. Unfortunately, this requires many design parameters such as the number, type, and size of the front-end filters, as well as the choice of nonlinearities, weighting and normalization schemes etc., for which biological plausibility cannot always be justified. As a result, these parameters have to be chosen in a more or less ad hoc way. Here, we propose to learn a visual saliency model directly from human eye movement data. The model is rather simplistic and essentially parameter-free, and therefore contrasts recent developments in the field that usually aim at higher prediction rates at the cost of additional parameters and increasing model complexity. Experimental results show that—despite the lack of any biological prior knowledge—our model performs comparably to existing approaches, and in fact learns image features that resemble findings from several previous studies. In particular, its maximally excitatory stimuli have center-surround structure, similar to receptive fields in the early human visual system.

In low light environment, photographs taken with a high ISO setting suffer from significant noise. In this paper, we propose to use a near infrared (NIR) flash image, instead of a normal visible flash image, to enhance its corresponding noisy visible image. We build a hybrid camera system to take an visible image and its NIR counterpart simultaneously. We introduce a new method to denoise an visible image and enhance its details using its corresponding NIR flash image. Experimental results show the superiority of our method compared with previous image denoising and detail enhancement methods.

A spatially-segmented solids database — justification and design

The article outlines the organizational foundations of dual education in European Union countries, focusing on the integration of learning and practical work experience within national vocational education and training systems. It examines different models of combining theoretical instruction with work-based learning, commonly referred to as alternating or dual systems. These models include comprehensive apprenticeship systems, programs in which internships are combined with other forms of vocational education, vocational schools with a significant proportion of workplace training, and predominantly school-based VET programs. Special attention is paid to the structural features of the educational process and the roles of the state, social partners, and employers in ensuring the quality of vocational training. The article analyzes how legislative frameworks, national curriculum standards, and professional qualification regulations contribute to the effectiveness and reliability of dual education systems. Comprehensive apprenticeship systems in countries such as Austria, Denmark, and Germany are highlighted as examples where practical training is fully integrated with theoretical instruction and closely aligned with labor market needs. In these systems, apprenticeship is legally regulated, supported by employers and public institutions, and widely recognized and valued by young people. Participants receive paid internships that complement their formal education, enabling them to develop comprehensive professional competencies and achieve qualifications acknowledged across the labor market. These programs offer opportunities for both general and vocational learning, contributing to the overall personal and professional development of students. The organizational foundations of dual education are based on a collaborative relationship between the state, social partners, and education institutions. The state establishes standards for curricula and theoretical instruction, while employers and professional associations are primarily responsible for practical training and quality assurance. This model ensures flexibility and adaptability to labor market demands, allowing vocational education to respond to changing economic conditions and sectoral requirements. Furthermore, dual education provides alternative pathways for students, reducing early school leaving and supporting social inclusion. By combining structured workplace experience with formal education, these systems help young people transition smoothly into the labor market, enhancing employability and career prospects. The dual model also fosters close cooperation between businesses and schools, encouraging mutual accountability and continuous improvement of training standards.

Cancer metastases have been difficult to treat and to control. The nature of tumor growth and metastases depends on many elements including the tumor microenvironment and cellular and vascular components to sustain viability and dissemination of cancer cells. Tumors themselves release signals that can alter resident endothelial cells (ECs) to form aberrant vessels to sustain tumor growth. Here we report the use of a novel, endothelial cell therapy (PVS-30200) that is delivered locally and able to control tumor growth and inhibit metastases. It promotes homeostasis and acts as a paracrine regulator of the tumor and its microenvironment to prevent growth and limit cancer invasion and metastasis. PVS-30200 comprises allogeneic ECs cultured on a gelatin substrate; this unique setting maintains the quiescent nature of the ECs and resists tumor alteration of the quiescent endothelial phenotype. A similar local EC therapy is entering a Phase 3 clinical trial for enhancing blood vessel repair and promoting vascular health in hemodialysis patients and has demonstrated a safe and tolerant profile.In vitro proliferation assays that cultured MDA-MB-231 breast and A549 lung carcinoma cells with EC-conditioned media reduced growth by approximately 40% (p < 0.001 for both cell lines). Migration and invasion were measured in a dual chamber culture system. Culture in EC-conditioned media significantly reduced in vitro invasiveness of both cancer lines. Analysis of the conditioned media showed the presence of anti-inflammatory, and anti-tumorigenic factors, such as TGF-β1, heparan sulfate proteoglycan and tissue inhibitors of matrix metalloproteinases. In vivo studies were performed to confirm the anti-proliferative and invasiveness activity. A spontaneously metastasizing orthotopic prostate (PC-3M-Luc) tumor model was utilized to determine the therapeutic potential of this treatment. Progression of the tumor and distant metastases were monitored using bioluminescent in vivo imaging (BLI). These studies demonstrated that a single injection of 500 μL PVS-30200 to the area surrounding the tumor prevented distant chest metastases and inhibited primary tumor growth. Twenty-nine days after tumor inoculation and 15 days post PVS-30200 treatment, the metastatic BLI measurements were 2.1-, 8.8-, and 11.8-fold greater than the initial day 0 BLI measurements for PVS-30200, vehicle, and untreated groups, respectively. Statistical significance was observed using a Kruskal-Wallis comparison of the group median BLI measurements for primary tumor growth (p=0.0386) and distant chest metastases (p=0.0387). This safe and novel cell therapy has demonstrated promising utility in the treatment of local cancers and in the reduction of metastases. This therapy is being explored in other in vivo solid tumor models to further assess the effects on tumor growth and metastases. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-423. doi:10.1158/1538-7445.AM2011-LB-423

InfraGAN: A GAN architecture to transfer visible images to infrared domain

We show that the WZW model on the Heisenberg Lie group H4 has Poisson–Lie symmetry only when the dual Lie group is A2⊕2A1. In this way, we construct the mutual T-dual sigma models on Drinfel'd double generated by the Heisenberg Lie group H4 and its dual pair, A2⊕2A1, as the target space in such a way that the original model is the same as the H4 WZW model. Furthermore, we show that the dual model is conformal up to two-loop order. Finally, we discuss D-branes and the worldsheet boundary conditions defined by a gluing matrix on the H4 WZW model. Using the duality map obtained from the canonical transformation description of the Poisson–Lie T-duality transformations for the gluing matrix which locally defines the properties of the D-brane, we find two different cases of the gluing matrices for the WZW model based on the Heisenberg Lie group H4 and its dual model.

Infrared and visible image fusion using fuzzy logic and population-based optimization

Neural Architecture Search for compressed sensing Magnetic Resonance image reconstruction