Application of the liquid bridges theory to find the melt menisci shape when growing cylindrical crystals

A vertical liquid bridge of small volume between a conical shaper and a convex crystallization front was investigated. Two variants of the front crystallization shape selection are considered: a conical and a spherical fronts. A variational statement of the original problem is given. As the boundary conditions we used the condition of engagement at the edge of the shaper and a given growth angle at the crystallization front. The Bond number was assumed to be small, and to find a solution of the problem the asymptotic approach was applied. The calculations are carried out for small diameter cylindrical sapphire crystals, grown from the melt by the Stepanov method. The results of the menisci shapes calculations are presented. The comparison of the results of calculations for conical and spherical crystallization fronts is carried out.

A Study on the Shape Selection of Mechanical Fastening for the Repair of Fighter Wing

A study on optimal shape selection of a mechanical fastening for the repair of crack defect of ROK Air Force F-5 fighter wing was conducted. The crack defect occurred in the spar of the wing, and the technical manual does not specify the repair method. However, ROK Air Force decided to develop a repair technology for this defect in consideration of various logistic conditions. Three repair shapes for the proper repair were devised and the finite element analysis was performed to examine the structural safety of these three connection members. As a result of the structural safety review, two connection members except one were structurally safe with safety margins over zero because the calculated stress values were at or below the yield strength level. Therefore, two connection members were determined to be able to use for repair under the condition that the aircraft operated within the design limit load. The results of this study would be very useful if the same defect occurs in long-term aircraft operated by the ROK Air Force.

Screening of Parkinson’s Disease Using Geometric Features Extracted from Spiral Drawings

Conventional means of Parkinson’s Disease (PD) screening rely on qualitative tests typically administered by trained neurologists. Tablet technologies that enable data collection during handwriting and drawing tasks may provide low-cost, portable, and instantaneous quantitative methods for high-throughput PD screening. However, past efforts to use data from tablet-based drawing processes to distinguish between PD and control populations have demonstrated only moderate classification ability. Focusing on digitized drawings of Archimedean spirals, the present study utilized data from the open-access ParkinsonHW dataset to improve existing PD drawing diagnostic pipelines. Random forest classifiers were constructed using previously documented features and highly-predictive, newly-proposed features that leverage the many unique mathematical characteristics of the Archimedean spiral. This approach yielded an AUC of 0.999 on the particular dataset we tested on, and more importantly identified interpretable features with good promise for generalization across diverse patient cohorts. It demonstrated the potency of mathematical relationships inherent to the drawing shape and the usefulness of sparse feature sets and simple models, which further enhance interpretability, in the face of limited sample size. The results of this study also inform suggestions for future drawing task design and data analytics (feature extraction, shape selection, task diversity, drawing templates, and data sharing).

The Shaped PDC Cutter and Special Bit Element Utilization to Improve Overall Drilling Performance in Hard Massive Carbonate: A Case Study of ERD Horizontal Well In Offshore East Java, Indonesia

Drilling through hard massive carbonate formation combined with naturally induced torsional vibration due to bit-formation interaction is often resulting in unnecessary down time caused by downhole tool failures, sub-optimal drilling performance and extra trip to change out worn out bit. The torsional vibration is also well known as as stick and slip. To address the challenge, special PDC bit with advanced cutter technology were utilized in ERD well in Offshore East Java. The key focus when selecting the bit was on PDC cutter shape selection to improve drilling efficiency and utilization of higher strength material elements to improve stability and impact durability of the cutting structure critical in drilling hard and harsh rocks. The bit record, bit type configuration, QA/QC process, hydraulic & stability analysis and secondary cutter materials consideration were also specifically analysed when selecting this bit to improve bit performance further and ensure the bit could be repairable & reusable after being used. The first field run of the bit incorporating all this technology mentioned above was performed on last two (2) ERD well drilled in East Java Offshore area, at the 8.5in hole section with 7 bladed, 16mm cutter. The bit successfully drilled total of 3,029 ft interval through massive carbonate formation for both wells. The bit reached target depth without bit change. The bit had proven to reduce drilling torsional vibration stick & slip from severe to medium level. Both bit run also had set considerably remarkable slip-to-slip Rate of Penetration (ROP) for ERD wells category, which had significantly improved by 69.35% compared to previous ERD well drilled in same carbonate formation with ERD profile. When on surface, the bit was observed still in excellent condition for this application. The enhanced PDC bit selection had proven to enable drilling into more challenging torsional vibration induced formation in massive Carbonate formation and challenging ERD trajectory thus improving overall drilling performance and achieve actual rig time & cost saving compared to plan.

Selection on heritable social network positions is context-dependent in Drosophila melanogaster

Social group structure is highly variable and can be important for nearly every aspect of behavior and its fitness consequences. Group structure can be modeled using social network analysis, but we know little about the evolutionary factors shaping and maintaining variation in how individuals are embedded within their networks (i.e., network position). While network position is a pervasive target of selection, it remains unclear whether network position is heritable and can respond to selection. Furthermore, it is unclear how environmental factors interact with genotypic effects on network positions, or how environmental factors shape selection on heritable network structure. Here we show multiple measures of social network position are heritable, using replicate genotypes and replicate social groups of Drosophila melanogaster flies. Our results indicate genotypic differences in network position are largely robust to changes in the environment flies experience, though some measures of network position do vary across environments. We also show selection on multiple network position metrics depends on the environmental context they are expressed in, laying the groundwork for better understanding how spatio-temporal variation in selection contributes to the evolution of variable social group structure.

2D material programming for 3D shaping

Two-dimensional (2D) growth-induced 3D shaping enables shape-morphing materials for diverse applications. However, quantitative design of 2D growth for arbitrary 3D shapes remains challenging. Here we show a 2D material programming approach for 3D shaping, which prints hydrogel sheets encoded with spatially controlled in-plane growth (contraction) and transforms them to programmed 3D structures. We design 2D growth for target 3D shapes via conformal flattening. We introduce the concept of cone singularities to increase the accessible space of 3D shapes. For active shape selection, we encode shape-guiding modules in growth that direct shape morphing toward target shapes among isometric configurations. Our flexible 2D printing process enables the formation of multimaterial 3D structures. We demonstrate the ability to create 3D structures with a variety of morphologies, including automobiles, batoid fish, and real human face.