MetaDreamer: Efficient Text-to-3D Creation With Disentangling Geometry and Texture

Generative models for 3D object synthesis have seen significant advancements with the incorporation of prior knowledge distilled from 2D diffusion models. Nevertheless, challenges persist in the form of multi-view geometric inconsistencies and slow generation speeds within the existing 3D synthesis frameworks. This can be attributed to two factors: firstly, the deficiency of abundant geometric a priori knowledge in optimization, and secondly, the entanglement issue between geometry and texture in conventional 3D generation methods.In response, we introduce MetaDreammer, a two-stage optimization approach that leverages rich 2D and 3D prior knowledge. In the first stage, our emphasis is on optimizing the geometric representation to ensure multi-view consistency and accuracy of 3D objects. In the second stage, we concentrate on fine-tuning the geometry and optimizing the texture, thereby achieving a more refined 3D object. Through leveraging 2D and 3D prior knowledge in two stages, respectively, we effectively mitigate the interdependence between geometry and texture. MetaDreamer establishes clear optimization objectives for each stage, resulting in significant time savings in the 3D generation process. Ultimately, MetaDreamer can generate high-quality 3D objects based on textual prompts within 20 minutes, and to the best of our knowledge, it is the most efficient text-to-3D generation method. Furthermore, we introduce image control into the process, enhancing the controllability of 3D generation. Extensive empirical evidence confirms that our method is not only highly efficient but also achieves a quality level that is at the forefront of current state-of-the-art 3D generation techniques.Comment: arXiv admin note: text overlap with arXiv:2306.17843, arXiv:2209.14988 by other author

Buckling Instability Behavior of Steel Bridge under Fire Hazard

Failure of buckling instability will most likely occur before the displacement reaches the allowable value of the code when a tanker burns under the steel bridge. This research focuses on critical buckling stress of bridge under fire hazard and a thermal analysis model of a steel bridge is established by FDS (Fire Dynamics Simulator). Thermal parameters of the steel are determined by the polynomial fitting method. Temperature field and elastic modulus of the bridge changing with time are calculated by determining the heat release rate function of tanker. Critical buckling stress of the bridge web and bottom floor changing with time is calculated according to steel floor buckling theory. Finite element software ANSYS is used to verify the result. Results show that when a tanker is burning for 17 minutes, critical buckling stress of steel web will be reduced to τcrl,lw(T) = 19.1 MPa and σcrl,lw(T) = 38.8 MPa, which is less than the web stress (τ = 19.6 MPa, σ = 39.8 MPa) caused by dead and live load. So steel web will be the first to show shear flexural bending buckling failure. Displacement in the midspan will reach 35.4 mm at this time, which was less than the allowable displacement (50 mm) set by standard. The best rescue time of the bridge under fire hazard is within 15 minutes

Enhanced Multiple-Object Tracking Using Delay Processing and Binary-Channel Verification

Tracking objects over time, i.e., identity (ID) consistency, is important when dealing with multiple object tracking (MOT). Especially in complex scenes with occlusion and interaction of objects this is challenging. Significant improvements in single object tracking (SOT) methods have inspired the introduction of SOT to MOT to improve the robustness, that is, maintaining object identities as long as possible, as well as helping alleviate the limitations from imperfect detections. SOT methods are constantly generalized to capture appearance changes of the object, and designed to efficiently distinguish the object from the background. Hence, simply extending SOT to a MOT scenario, which consists of a complex scene with spatially mixed, occluded, and similar objects, will encounter problems in computational efficiency and drifted results. To address this issue, we propose a binary-channel verification model that deeply excavates the potential of SOT in refining the representation while maintaining the identities of the object. In particular, we construct an integrated model that jointly processes the previous information of existing objects and new incoming detections, by using a unified correlation filter through the whole process to maintain consistency. A delay processing strategy consisting of the three parts - attaching, re-initialization, and reclaiming - is proposed to tackle drifted results caused by occlusion. Avoiding the fuzzy appearance features of complex scenes in MOT, this strategy can improve the ability to distinguish specific objects from each other without contaminating the fragile training space of a single object tracker, which is the main cause of the drift results. We demonstrate the effectiveness of our proposed approach on the MOT17 challenge benchmarks. Our approach shows better overall ID consistency performance in comparison with previous works

Core promoter-specific gene regulation: TATA box selectivity and Initiator-dependent bi-directionality of serum response factor-activated transcription

Gene-specific activation by enhancers involves their communication with the basal RNA polymerase II transcription machinery at the core promoter. Core promoters are diverse and may contain a variety of sequence elements such as the TATA box, the Initiator (INR), and the downstream promoter element (DPE) recognized, respectively, by the TATA-binding protein (TBP) and TBP-associated factors of the TFIID complex. Core promoter elements contribute to the gene selectivity of enhancers, and INR/DPE-specific enhancers and activators have been identified. Here, we identify a TATA box-selective activating sequence upstream of the human β-actin (ACTB) gene that mediates serum response factor (SRF)-induced transcription from TATA-dependent but not INR-dependent promoters and requires the TATA-binding/bending activity of TBP, which is otherwise dispensable for transcription from a TATA-less promoter. The SRF-dependent ACTB sequence is stereospecific on TATA promoters but activates in an orientation-independent manner a composite TATA/INR-containing promoter. More generally, we show that SRF-regulated genes of the actin/cytoskeleton/contractile family tend to have a TATA box. These results suggest distinct TATA-dependent and INR-dependent mechanisms of TFIID-mediated transcription in mammalian cells that are compatible with only certain stereospecific combinations of activators, and that a TBP-TATA binding mechanism is important for SRF activation of the actin/cytoskeleton-related gene family

The effect of applications of different nitrogen types and potassium on seed quality and AR37 endophyte presence at different spikelet and floret positions of perennial ryegrass cv. Halo

Nitrogen has been considered as an important nutrient in the terrestrial system. In the seed production of ryegrasses, one of the most popular pastures used in New Zealand and other temperate-zone areas, the application of nitrogen is responsible for improving seed yield and seed quality. Novel fungal endophytes are also now commonly used in perennial ryegrass pasture systems. The effect of different forms of nitrogen on seed quality and endophyte infection frequency and alkaloid concentration including spikelet/floret positional effects is also of interest to researchers. This study was designed to determine the effects of three nitrogen forms and potassium treatments (six in total) on the seed quality (purity, thousand seed weight (TSW), and germination) and AR37 endophyte presence in the offspring seedlings of the perennial ryegrass cv. Halo at three spikelet positions (top, middle and bottom). Also the effect of two nitrogen forms (nitrate and ammonium) at different floret positions was investigated. The two nitrogen forms (urea and nitrate) with potassium had a poorer seed quality compared with the control and all nitrogen treatments applied without potassium. Nitrogen application (any form by itself) did not affect TSW of ‘Halo’, but a reduction was found under urea or nitrate with potassium. Also, seed germination percentages were not affected by nitrogen type when compared with the control, but urea with potassium gave a lower germination than the three nitrogen forms alone; and nitrate with potassium was lower than just the urea treatment. In the purity test, urea applied alone had a higher pure seed percentage than the control and the other nitrogen forms applied alone, but, again, the nitrogen with potassium application had the poorest performance in the test. On the other hand, none of these seed quality parameters differed among the three spikelet positions (top, middle and bottom). Both nitrogen and potassium application and different spikelet positions did not affect endophyte content in the offspring seedlings of ‘Halo’.In the minor experiment, where seven floret positions and only two nitrogen forms (ammonium (NH4+)and nitrate (NO3-)) were compared, the individual seed weights of Halo in florets3, 4, and 7 under nitrate application were higher than that under ammonium. The seed weight in floret 7 wasthe only position lower than floret 1 and 2 when ammonium was applied. The germination percentages were not affected by the two nitrogen forms, nor were different floret positions. Further, nitrogen application also did not alter empty seed percentages (in frequency), but the basal florets produced less empty seeds. Differences in endophyte content between ammonium and nitrate applications were found only in floret position 1 where nitrate reduced endophyte. Also amongst florets under nitrate there was higher endophyte content in floret positions 2, 4 and 7

Enhanced Multiple-Object Tracking Using Delay Processing and Binary-Channel Verification

Tracking objects over time, i.e., identity (ID) consistency, is important when dealing with multiple object tracking (MOT). Especially in complex scenes with occlusion and interaction of objects this is challenging. Significant improvements in single object tracking (SOT) methods have inspired the introduction of SOT to MOT to improve the robustness, that is, maintaining object identities as long as possible, as well as helping alleviate the limitations from imperfect detections. SOT methods are constantly generalized to capture appearance changes of the object, and designed to efficiently distinguish the object from the background. Hence, simply extending SOT to a MOT scenario, which consists of a complex scene with spatially mixed, occluded, and similar objects, will encounter problems in computational efficiency and drifted results. To address this issue, we propose a binary-channel verification model that deeply excavates the potential of SOT in refining the representation while maintaining the identities of the object. In particular, we construct an integrated model that jointly processes the previous information of existing objects and new incoming detections, by using a unified correlation filter through the whole process to maintain consistency. A delay processing strategy consisting of the three parts—attaching, re-initialization, and re-claiming—is proposed to tackle drifted results caused by occlusion. Avoiding the fuzzy appearance features of complex scenes in MOT, this strategy can improve the ability to distinguish specific objects from each other without contaminating the fragile training space of a single object tracker, which is the main cause of the drift results. We demonstrate the effectiveness of our proposed approach on the MOT17 challenge benchmarks. Our approach shows better overall ID consistency performance in comparison with previous works