Virtual prototyping with surface reconstruction and freeform geometric modeling using level-set method

More and more products with complex geometries are being designed and manufactured by computer aided design (CAD) and rapid prototyping (RP) technologies. Freeform surface is a geometrical feature widely used in modern products like car bodies, airfoils and turbine blades as well as in aesthetic artifacts. How to efficiently design and generate digital prototypes with freeform surfaces is an important issue in CAD. This paper presents the development of a Virtual Sculpting system and addresses the issues of surface reconstruction from dexel data structures and freeform geometric modeling using the level-set method from distance field structure. Our virtual sculpting method is based on the metaphor of carving a solid block into a 3D freeform object using a 3D haptic input device integrated with the computer visualization. This dissertation presents the result of the study and consists primarily of four papers --Abstract, page iv

Exploring novel ligands interacting with RuBisCO.

Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is pivotal in photosynthesis, facilitating the conversion of carbon dioxide into organic compounds within the CalvinBenson-Bassham (CBB) cycle, vital for life on Earth. RuBisCO's abundance suggests potential as a food source. Previous research has delved into its biochemical mechanisms, unveiling different ligands that modulate its activity and several studies have elucidated the structural and functional aspects of its phosphate binding sites. This study aimed to identify new RuBisCO ligands; screening close to 500 small molecular compounds via differential scanning fluorimetry. The RuBisCO enzyme utilized in this project was purified from spinach, a commonly employed source. The screening identified ligands that potentially stabilise RuBisCO, suggesting binding interactions. By adjusting ligand concentrations, melting temperature trends were analyzed to estimate the affinity data, corroborated by isothermal titration calorimetry (ITC). Two compounds showed promising binding in ITC, albeit weak compared to RuBisCO's known substrates. The study also probed ligand binding under different RuBisCO activation states and employed spectrophotometry to gauge RuBisCO’s activity in the presence of ligands, revealing novel positive and negative effectors compared to negative controls. Future investigations might discover additional small molecules modulating activity of RuBisCO. This research sets the stage for exploring RuBisCO's interactions with diverse small molecule metabolites, enhancing our understanding of its binding and catalytic mechanisms. Such insights could spur endeavours to boost crop efficiency or utilize RuBisCO in food or pharmaceutical applications in future

Lüders banding and its effects on structures under tension/compression and cyclic bending loads

Lüders banding is a material instability that leads to localized deformation during the initial yielding of the material. This research project investigates how this material instability affects the response of tubular structures under bending and cyclic bending. Tension/compression experiments are first performed on steel rods exhibiting Lüders banding. Special attention is given to how a specimen behaves when the initial loading is interrupted with part of it Lüders deformed and the rest of the specimen still remaining elastic. Digital image correlation reveals that both sections unload elastically, but upon reverse loading, the previously elastic zone develops Lüders strain of the opposite sign, while the plastically deformed zone traces Bauschinger rounding. A custom constitutive model is developed to capture this complex behavior, encompassing a J2-type softening material response and nonlinear kinematic hardening for reverse loading. The constitutive model is subsequently used to study the effect of Lüders banding on tubes under cyclic bending. Under bending, tubes progressively develop inclined bands of higher strain organized in periodic diamond-shaped patterns. Upon unloading, the diamond patterns gradually disappear, but simultaneously local secondary patterns of higher strain develop in the hitherto elastic zones between the original diamonds. When completing the cycle, the secondary patterns are progressively erased and the diamond patterns reappear. The sensitivity of this structural behavior to several problem variables including the extent of Lüders strain, the level of Lüders stress, and diameter-to-thickness ratio of the tube is examined in parametric studies. The constitutive model is subsequently implemented in a large-scale numerical analysis of the winding/unwinding of a pipeline with Lüders bands on a large diameter reel. During winding, inclined Lüders bands organize into clusters separated by elastic sections. During unwinding and straightening, the intensity of Lüders patterns is gradually reduced and secondary patterns develop in the previously undeformed zones. This appearance, erasure, and reappearance of Lüders patterns is repeated in subsequent wind/unwind cycles. Ovality accumulates during each cycle and may lead to local buckling and collapse. The effect of problem variables such as the level of back tension, reel diameter, extent of Lüders strain, steel yield strength and diameter-to-thickness ratio is examined in a parametric study.Engineering Mechanic

A New Contour Reconstruction Approach from Dexel Data in Virtual Sculpting

This paper presents a novel method of contour reconstruction from dexel data solving the shape anomalies for the complex geometry in virtual sculpting. Grouping and traversing processes are developed to find connectivity between dexels along every two adjacent rays. After traveling through all the rays on one slice, sub-boundaries are connected into full boundaries which are desired contours. The complexity of the new method has been investigated and determined as O(n). We also demonstrate the ability of the described method for viewing a sculpted model from different directions

Cross‐Scale Decoupling Kinetic Processes in Lithium‐Ion Batteries Using the Multi‐Dimensional Distribution of Relaxation Time

To non‐destructively resolve and diagnose the degradation mechanisms of lithium‐ion batteries (LIBs), it is necessary to cross‐scale decouple complex kinetic processes through the distribution of relaxation times (DRT). However, LIBs with low interfacial impedance render DRT unreliable without data processing and closed‐loop validation. This study proposes a hierarchical analytical framework to enhance timescale resolution and reduce uncertainty, including interfacial impedance reconstruction and multi‐dimensional DRT analysis. Interfacial impedance is reconstructed by eliminating simulated inductive and diffusive impedance based on a high‐fidelity frequency‐domain model. Multi‐dimensional DRT decouples solid electrolyte interphase (SEI) and charge transfer (CT) processes by the reversibility of electrochemical reactions with state of charge (SOC) to characterize electrode kinetic evolution driven by SOC and temperature through timescales and peak area. The findings reveal that reconstructed impedance improves the accuracy of identified time constants by ≈20%. Cross‐scale DRT results reveal that SOCs below 10% at 25 °C effectively distinguish electrode kinetics due to the high correlation between cathodic CT and SOC. Kinetic metrics characterize that anodic SEI or CT are different control steps limiting the low‐temperature performance of different cells. This work underscores the potential of the proposed framework for non‐destructive diagnostics of kinetic evolution

Investigation on the Behavior of Tensile Damage Evolution in T700/6808 Composite Based on Acoustic Emission Technology

T700/6808 composite has been widely used in aerospace field and the damage in composite will seriously influence the safety of aircraft. However, the behavior of damage evolution in T700/6808 composite when it suffered from tensile loading is seldom researched. In this paper, the acoustic emission (AE) technology is employed to research the process of damage evolution in T700/6808 composite under tensile loading. Results show that the damage in T700/6808 composite is small in the initial stage of tensile loading, and main damage is the matrix cracking. The composite has serious damage in the middle stage of tensile loading, which mainly includes the matrix cracking and the interface damage as well as the fiber breakage. The number of fiber breakages decreases rapidly in the later stage of tensile loading. When it comes into the stage of load holding, the composite has relatively smaller damage than that in the stage of tensile loading, and the fiber breakage rarely occurs in the composite. Analysis of damage modes shows that the criticality of the matrix cracking and the interface damage is higher than the fiber breakage, which illustrates that the reliability of T700/6808 composite could be improved by the optimization of matrix and interface

Intralayer Negative Poisson's Ratio in Two-Dimensional Black Arsenic by Strain Engineering

Negative Poisson's ratio as the anomalous characteristic generally exists in artificial architectures, such as re-entrant and honeycomb structures. The structures with negative Poisson's ratio have attracted intensive attention due to their unique auxetic effect and many promising applications in shear resistant and energy absorption fields. However, experimental observation of negative Poisson's ratio in natural materials barely happened, although various two-dimensional layered materials are predicted in theory. Herein, we report the anisotropic Raman response and the intrinsic intralayer negative Poisson's ratio of two-dimensional natural black arsenic (b-As) via strain engineering strategy. The results were evident by the detailed Raman spectrum of b-As under uniaxial strain together with density functional theory calculations. It is found that b-As was softer along the armchair than zigzag direction. The anisotropic mechanical features and van der Waals interactions play essential roles in strain-dependent Raman shifts and negative Poisson's ratio in the natural b-As along zigzag direction. This work may shed a light on the mechanical properties and potential applications of two-dimensional puckered materials.Comment: 23 pages, 4 figure

Soloist: Distributed SNARKs for Rank-One Constraint System

Distributed SNARKs enable multiple provers to collaboratively generate proofs, enhancing the efficiency and scalability of large-scale computations. The state-of-the-art distributed SNARK for Plonk, Pianist (S\&P \u2724), achieves constant proof size, constant amortized communication complexity, and constant verifier complexity. However, when proving the Rank-One Constraint System (R1CS), a widely used intermediate representation for SNARKs, Pianist must perform the transformation from R1CS into Plonk before proving, which can introduce a start-up cost of $10\times$ due to the expansion of the statement size. Meanwhile, existing distributed SNARKs for R1CS, e.g., DIZK (USENIX Sec. \u2718) and Hekaton (CCS \u2724), fail to match the superior asymptotic complexities of Pianist. We propose $\textsf{Soloist}$, an optimized distributed SNARK for R1CS. $\textsf{Soloist}$ achieves constant proof size, constant amortized communication complexity, and constant verifier complexity, relative to the R1CS size $n$. Utilized with $\ell$ sub-provers, its prover complexity is $O(n/\ell \cdot \log(n/\ell))$. The concrete prover time is~$\ell\times$ as fast as the R1CS-targeted Marlin (Eurocrypt \u2720). For zkRollups, $\textsf{Soloist}$ can prove more transactions, with $2.5 \times$ smaller memory costs, $2.8\times$ faster preprocessing, and $1.8\times$ faster proving than Pianist. $\textsf{Soloist}$ leverages an improved inner product argument and a new batch bivariate polynomial commitment variant of KZG (Asiacrypt \u2710). To achieve constant verification, we propose a new preprocessing method with a lookup argument for unprescribed tables, which are usually assumed pre-committed in prior works. Notably, all these schemes are equipped with scalable distributed mechanisms

Chinese herbal retention enema combined with magnetic vibration magneto-electric therapy: a promising therapeutic strategy for chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS)

Background: Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a common urological condition characterized by complex etiology, high incidence and limited treatment options. Despite extensive research, its pathogenesis remains poorly understood and high-quality, effective therapies are lacking. Methods: This propensity score-matched study assessed 92 patients by evaluating symptom scores, complications, and prognostic outcomes using the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI), International Prostate Symptom Score (IPSS), and Hospital Anxiety and Depression Scale (HADS), with patients stratified based on baseline characteristics for outcome comparison. Results: The total clinical effective rate was significantly higher in the combination therapy group (91.30%) compared to the control group (76.09%, p < 0.05); the treatment process was uneventful in both groups, and four weeks after treatment, the total NIH-CPSI score and its subscales were significantly lower in the combination therapy group (−17.24 (6.84) vs. −12.54 (7.18), p < 0.05), with a more pronounced reduction in the IPSS score (−6.70 (2.54) vs. −3.87 (2.03), p < 0.05) and superior improvements in both peak and average urine flow rates—especially the latter—while neither regimen produced a significant improvement in mood scores. Conclusions: The combination of Chinese herbal retention enema and magnetic vibration magneto-electric therapy is more effective than magnetic vibration magneto-electric therapy alone in alleviating the primary symptoms of CP/CPPS, suggesting significant potential for broader clinical application. Clinical Trial registration: This study was registered on itmctr.ccebtcm.org.cn. And the registration number is ITMCTR2024000191