Cut Position Research Articles

Investigating the Tear Fracture of Elastomeric Skins in Morphing Wings: An Experimental and Computational Study

Morphing wings covered with elastomeric skin have emerged as a promising technique for enhancing the performance and efficiency of unmanned aerial vehicles (UAVs). These morphing wings can change shape in flight, enabling UAVs to adapt to evolving aerodynamic conditions, fly more efficiently, maneuver more effectively and perform a broader range of missions. The durability of such elastomeric skins that cover the wings, on the other hand, is a critical issue that requires careful consideration. During the flight, elastomeric skins are subjected to a variety of mechanical stresses, including tear and fracture, which can significantly impact the performance and reliability of elastomeric morphing wings. To ensure the long-term durability of the morphing wings, a comprehensive understanding of the tear fracture of elastomeric skins is essential. This study employs a multi-faceted approach of experimental and computational research to investigate the tear fracture of elastomeric skins in morphing wings. Initially, the fracture properties of three materials — Latex, Oppo and Ecoflex — are evaluated experimentally for various cut positions. Subsequently, a continuum physics-based tear fracture model is derived to numerically simulate the mechanical behavior of elastomeric skins. The Griffith criterion, a well-established method, is adopted to investigate mode-III fracture tests, specifically the trousers test, which involves pulling two legs of a cut specimen horizontally apart. Finally, the derived tear fracture model is validated by comparing model solutions to tear test data obtained experimentally. The study suggests that adjusting the stretch ratio and cut position can significantly impact the stress distribution of elastomeric skins, the ability to resist fracture and the stretching behavior of elastomeric morphing wings.

A Novel Polyvinyl Alcohol‐Based Hydrogel with Ultra‐Fast Self‐Healing Ability and Excellent Stretchability Based on Multi Dynamic Covalent Bond Cross‐Linking

AbstractA novel self‐healing poly(vinyl alcohol) (PVA)‐based hydrogel is developed by cross‐linking PVA chains through multi dynamic covalent bonds by use of a small cross‐linker composed by 4‐formylphenylboric acid (FPBA) and lysine (Lys). The dynamic borate‐imine‐imine‐borate bond structure between PVA chains endows the hydrogel excellent stretchability and ultra‐fast self‐healing ability without external stimulation. The self‐healing efficiency can attain 94% and the elongation at break can reach up to near 1000% after only 3 min healing. Moreover, the self‐healing of the hydrogel through the contact of two faces from both the same cut position and different cut positions has similar excellent efficiency. The hydrogel with the unusual self‐healing performance and stretchability is used as an ideal material in strain sensors monitoring human movement and tiny vibrations caused by human voice. Interestingly, the sensor can continue to function normally after self‐healing for only ≈3 s. It is expected that this simple strategy of fabricating self‐healing hydrogels with multi dynamic bonds will provide new opportunities in the design and preparation of PVA‐based hydrogels to expand their potential applications in sensors and other various fields.

Welfare indicators for stunning versus non‐stunning slaughter in sheep and cattle: A scoping review

While most cattle and sheep in the United Kingdom are stunned before slaughter, non-stun methods are permitted to supply meat to specific consumers. This study aimed to identify the existing literature that compared animal welfare indicators during stun and non-stun slaughter, using a scoping review framework. Following a structured search strategy, including the establishment of a PICO (population, intervention, comparator and outcomes) question, a comprehensive literature search of the CAB Abstracts, MEDLINE and PubMed databases, was conducted. A total of 962 papers were identified, of which 16 were selected for data extraction. Fourteen papers concluded that welfare at slaughter was negatively impacted at non-stun slaughter in comparison to stun slaughter; two papers were inconclusive. Welfare indicators identified included biochemical parameters, brain activity and visual signs of consciousness. Limitations regarding inconsistent restraint method, neck cut position and non-standardised measures of welfare at slaughter are highlighted. This study provides further evidence that stunning is an effective method to improve the welfare of sheep and cattle at slaughter. Animal welfare advisors, politicians, religious communities and others interested in animal welfare could use the findings to further discuss and establish new dialogues for producing updated guidance on animal welfare at slaughter.

Constitutive modeling for the tear fracture of artificial tissues in human-like soft robots

Artificial tissues made of fiber-reinforced polymeric materials typically show biological tissue-like mechanical properties, which motivates its usage in designing and constructing human-like soft robots. Inspired by nature, soft robots aimed to perform a wide range of human-like motions and work cordially with the human environment effectively. In some applications, soft robots may be torn or damaged for unknown reasons. In this regard, this work presents the constitutive modeling for the tear fracture and its impact on the mechanical behavior of artificial tissues used in the novel field of soft robotics. Firstly, a continuum mechanics-based deformation model for artificial tissue is developed and experimentally validated to justify that tissues have inherent anisotropic behavior, which cannot be neglected while modeling such materials. Secondly, the tear fracture model is derived to investigate the effect of concerning physical parameters linked with the tearing phenomenon of artificial tissues. A well-known Griffith criterion is adopted to investigate a particular fracture test of mode-III, namely the trousers test, where two legs of a cut specimen are pulled horizontally apart. The findings of the proposed model solution indicate that a significant impact on the cut position due to the stretch gradient arises during the gradual transition through one leg to another. Additionally, the fracture toughness of artificial tissue increases with increasing fiber inclination and limiting chain extensibility, corresponding to a given critical driving force.

Effects of a narrative template on memory for the time of movie scenes: automatic reshaping is independent of consolidation

Memory for time is influenced by reconstructive processes, but the underlying mechanisms remain unclear. The present study investigated whether the effect of schematic prior knowledge on temporal memory for movie scenes, produced by the incomplete presentation (cut) of the movie at encoding, is modulated by cut position, retention interval, and task repetition. In a timeline positioning task, participants were asked to indicate when short video clips extracted from a previously encoded movie occurred on a horizontal timeline that represented the video duration. In line with previous findings, removing the final part of the movie resulted in a systematic underestimation of clips' position as a function of their proximity to the missing part. Further experiments demonstrate that the direction of this automatic effect depends on which part of the movie is deleted from the encoding session, consistent with the inferential structure of the schema, and does not depend on consolidation nor reconsolidation processes, at least within the present experimental conditions. We propose that the observed bias depends on the automatic influence of reconstructive processes on judgments about the time of occurrence, based on prior schematic knowledge.

Influence of Axial Depth of Cut and Tool Position on Surface Quality and Chatter Appearance in Locally Supported Thin Floor Milling.

Thin floor machining is a challenging and demanding issue, due to vibrations that create poor surface quality. Several technologies have been developed to overcome this problem. Ad hoc fixtures for a given part geometry lead to meeting quality tolerances, but since they lack flexibility, they are expensive and not suitable for low manufacturing batches. On the contrary, flexible fixtures consisting of vacuum cups adaptable to a diversity of part geometries may not totally avoid vibrations, which greatly limits its use. The present study analyses the feasibility of thin floor milling in terms of vibration and roughness, in the cases where milling is conducted without back support, a usual situation when flexible fixtures are employed, so as to define the conditions for a stable milling in them and thus avoid the use of ad hoc fixtures. For that purpose, the change of modal parameters due to material removal and its influence on chatter appearance have been studied, by means of stability lobe diagrams and Fourier Transform analysis. Additionally, the relationship between surface roughness and chatter frequency, tooth passing frequency, and spindle frequency have been studied. Ploughing effect has also been observed during milling, and the factors that lead to the appearance of this undesirable effect have been analyzed, in order to avoid it. It has been proven that finish milling of thin floors without support in the axial direction of the mill can meet aeronautic tolerances and requirements, providing that proper cutting conditions and machining zones are selected.

Grid order prediction of ephemeral gully head cut position: Regional scale application

Predicting ephemeral gully (EG) location is essential for many land management decisions and for accurate application of widely used soil erosion models. Topographic indexes are widely used for identifying EG head locations, even though the calibration of the topographic index models limits their use for broad scales. The objective of this research was to test the accuracy and usability of grid order in predicting EG head locations at the regional scale compared to other topographic indexes commonly used for this purpose. Three hundred fifty-three EGs in eight watersheds located within different landforms (Major Land Resource Areas) in Iowa, USA, were visually digitized, georeferenced, and analyzed using 3-meter LiDAR-derived elevation datasets and orthoimages. The location prediction accuracy, spatial location prediction error stability, and the variation of grid order critical threshold (CT) values were compared to predictions from four commonly used topographic indexes, specific contributing drainage area (As), Compound Topographic Index (CTI), Stream Power Index (SPI), and a variation of Stream Power Index (AS2). Results indicate that using As, CTI, SPI, and AS2 to identify flow length upstream from predicted EG head locations would require careful calibration for each watershed or substantial errors in prediction accuracy would occur. In contrast, the accuracy of using grid order was acceptable at the regional scale even without model calibration with Nash Sutcliff Efficiency estimates ranging from 0.29 to 0.59; the distance between surveyed and predicted EG head locations was within 20 m for all studied EGs. The grid order value of 4 was the best CT value when the slope gradient was less than 10%, and 3 for steeper slopes. These results could be easily applied for different landforms across wider areas. The result of this research supports the prediction of EGs using automated systems without calibration at a broad scale where quality DEMs are available.

Key technologies and engineering practices for soft-rock protective seam mining

Severe gas disasters in deep mining areas are increasing, and traditional protective coal seam mining is facing significant challenges. This paper proposes an innovative technology using soft rock as the protective seam in the absence of an appropriate coal seam. Based on the geological engineering conditions of the new horizontal first mining area of Luling Coal Mine in Huaibei, China, the impacts of different mining parameters of the soft-rock protective seam on the pressure-relief effect of the protected coal seam were analyzed through numerical simulation. The unit stress of the protected coal seam, which was less than half of the primary rock stress, was used as the mining stress pressure-relief index. The optimized interlayer space was found to be 59 m for the first soft-rock working face, with a 2 m mining thickness and 105 m face length. The physicochemical characteristics of the orebody were analyzed, and a device selection framework for the soft-rock protective seam was developed. Optimal equipment for the working face was selected, including the fully-mechanized hydraulic support and coal cutter. A production technology that combined fully-mechanized and blasting-assisted soft-rock mining was developed. Engineering practices demonstrated that normal circulation operation can be achieved on the working face of the soft-rock protective seam, with an average advancement rate of 1.64 m/d. The maximum residual gas pressure and content, which were measured at the cut hole position of the protected coal seams (Nos. 8 and 9), decreased to 0.35 MPa and 4.87 m3/t, respectively. The results suggested that soft-rock protective seam mining can produce a significant gas-control effect.

Optimization Analysis of Over-Sized Section Open-Off Cut Failure and Support

The open-off cut section of 1105 working face in Zhaogu II mine is the largest in China, causing considerable difficulties to the support work. The failure process of surrounding rock deformation, stress field, and stress state under original support of open-off cut is analyzed using FLAC3D numerical simulation analysis software. Analysis results show the large displacement of the bottom heave and two sides of the roadway. Furthermore, the vertical stress of open-off cut is greater than the horizontal stress, whereas horizontal stress is larger in the upper roof part. The shearing failure range of the open-off cut surrounding rock is large, indicating that the original support scheme possesses weak restraint capability to the surrounding rock and fails to effectively control deformation. Based on analysis and research results, the technical scheme of coordinated support for super-long anchor rod and anchor cable of over-sized section open-off cut with high-stress broken surrounding rock is put forward. The field industrial test shows that the coordinated support scheme of super-long anchor rod and anchor cable is reasonable and safe under a 9.2 m open-off cut section. With improvement of the working face, the deep rock layer on the roof at the open-off cut position of goaf first occurs evidently, whereas the shallow rock layer is unremarkable, indicating the stable rock formation in the anchorage area of the shallow super-long anchor. The super-long anchor rod plays a satisfactory role in support, and the control effect of broken surrounding rock is similarly satisfactory. Such condition can achieve large deformation of broken surrounding rock with high stress and super large section.

Coupling silica waveguides to photonic crystal waveguides through a multilayered Luneburg lens

We present a detailed analysis of a coupler based on the Luneburg lens to couple a silica waveguide to a photonic crystal (PhC) waveguide. The dependence of coupling efficiency on the lens’s truncation, cut position of the PhC structure, coupler tip width, and misalignment are investigated with a two-dimensional finite element method. We implement the lens with a concentric ring-based multilayer structure. We also present a method to replace layers with very narrow widths by layers of predetermined minimum widths in the structure of the lens. The coupling loss of the designed 2.7-µm-long coupler, connecting a 2.79-µm-wide silica waveguide to a PhC structure with a rod-type square lattice, is lower than 0.49 dB in the C-band. The average coupling loss in the entire S, C, L, and U bands of optical communications is 0.70 dB.

Experimental and computational analysis of a cyclone separator with a novel vortex finder

Simulations and experimental methods were used to evaluate the performance of notched vortex finders in a cyclone separator with a tangential inlet. The vortex finder was cut obliquely. Four types of cyclone separators with different vortex finder structures were studied. One of the separators did not have a cut at the vortex finder, while the other separators had cuts located at 45°, 135°, and 225° opposite to the inlet of the separator. An unsteady Reynolds stress transport model (RSM) was implemented for the gas-phase flow field, and a discrete phase model (DPM) was adopted for the particle phase. Considering the asymmetric flow field in the separator with a tangential inlet, the distribution of axial velocity, tangential velocity, and radial velocity along the circumference were discussed, and the effect of the notched vortex finder on the flow field in the separator was shown in detail. The grade efficiencies of the four models were compared. The simulation results show that the separation performances of the cyclone separators with notched vortex finders were greatly improved over the separation performance of the original separator. When the cut position was located 225° opposite to the inlet, the separation performance of the cyclone separator improved most obviously. Experiments were carried out to confirm the advantages of notched vortex finders. The experimental results show that a separator with a notched vortex finder at 225° can remove particles greater than 3.5μm in diameter, while a normal separator can remove only particles greater than 8μm in diameter. Furthermore, the total separation efficiency of the original separator is 0.73, while the total separation efficiency of the improved separator is 0.76.

A Time Domain Estimation Algorithm for Speech Signal Pitch Period

In speech recognition and speech synthesis, accurate estimation of the pitch period is an important part of speech processing. The traditional direct peak estimation method and the autocorrelation function method are both effective time domain estimation algorithms. The autocorrelation method is a pitch period estimation algorithm suitable for low SNR. Both algorithms need to get accurate peak position estimation. In this paper, a multi-line cut method which is a method for judging the position of the peak point is proposed. The multi-line cut method is used to intercept the sampled data of the waveform by using multiple cut lines. The median value is calculated by the starting and ending points of the cut line position, and the peak position is indirectly evaluated. By minimizing the impact of interference on the peak estimate, the likelihood of falling into local extreme points is reduced, therefore a more accurate peak point estimate than the direct search for peak points can be obtained. The simulation results show that compared with the traditional direct peak estimation method, the performance of peak estimation by the multi-line cut method can be greatly improved, and the multi-line cut method can be used to estimate the peak value in the autocorrelation method, and also achieve a certain performance improvement. In addition, the number of cut lines is directly related to performance, and the more the number is, the better the performance is. The complexity of this method is not high and easy to implement.

Gene co-expression network analysis reveals pathways associated with graft healing by asymmetric profiling in tomato

BackgroundThe ability of severed rootstocks and shoots to re-establish vascular connections is used to generate grafted plants that combine desirable traits from both scions and rootstocks. Clarifying the mechanisms of graft healing is essential for its further application. We performed RNA sequencing of internodes near the cut position, making a distinction between separated or grafted tissues above and below the cut, in order to obtain a genetic description of graft union formation.ResultsUsing weighted gene co-expression analysis, variable transcripts were clustered into 10 distinct co-expression networks (modules) based on expression profiles, and genes with the most “hubness” (“hub” genes show the most connections in a network) within each module were predicted. A large proportion of modules were related to Position, and represent asymmetric expression networks from different pathways. Expression of genes involved in auxin and sugar transport and signaling, and brassinosteroid biosynthesis was increased above the cut, while stress response genes were up-regulated below the cut. Some modules were related to graft union formation, among which oxidative detoxification genes were co-expressed along with both wounding response and cell wall organization genes.ConclusionsThe present work provides a comprehensive understanding of graft healing-related gene networks in tomato. Also, the candidate pathways and hub genes identified here will be valuable for future studies of grafting in tomato.

Assessing marbling scores of beef at the 10th rib vs. 12th rib of longissimus thoracis in the slaughter line using camera grading technology in Germany

Internationally, different Video Image Analysis Systems (VIAS) are established to enable categorization of beef carcasses according to a marbling score as determining part of trading categories. Different established standardized cutting positions of longissimus thoracis, among other reasons, hamper the use of VIAS in European countries. The objective of the study was to explore the potential of a VIAS-based grading system VBG 2000 for the estimation of marbling of carcasses cut according to German standards.The correlation coefficient between the camera assessed marbling scores (n = 354 halves of carcasses) at the 10th rib section at the left and right side achieved 0.89 (P < .01) and 0.80 (P < .01) for camera assessed marbling scores between the right 12th/13th and 10th/11th rib interface of longissmus thoracis. Thus, modification of the cut position towards the US standard provides comparable results, and assessing VIA based marbling scores at the 10th rib is correlated to the 12th rib.

The RecB helicase-nuclease tether mediates Chi hotspot control of RecBCD enzyme.

In bacteria, repair of DNA double-strand breaks uses a highly conserved helicase–nuclease complex to unwind DNA from a broken end and cut it at specific DNA sequences called Chi. In Escherichia coli the RecBCD enzyme also loads the DNA strand-exchange protein RecA onto the newly formed end, resulting in a recombination hotspot at Chi. Chi hotspots regulate multiple RecBCD activities by altering RecBCD’s conformation, which is proposed to include the swinging of the RecB nuclease domain on the 19-amino-acid tether connecting the helicase and nuclease domains. Here, we altered the tether and tested multiple RecBCD activities, genetically in cells and enzymatically in cell-free extracts. Randomizing the amino-acid sequence or lengthening it had little effect. However, shortening it by as little as two residues or making substitutions of ≥10 proline or ≥9 glycine residues dramatically lowered Chi-dependent activities. These results indicate that proper control of RecBCD by Chi requires that the tether be long enough and appropriately flexible. We discuss a model in which the swing-time of the nuclease domain determines the position of Chi-dependent and Chi-independent cuts and Chi hotspot activity.

Do patient-specific instruments (PSI) for UKA allow non-expert surgeons to achieve the same saw cut accuracy as expert surgeons?

IntroductionHigh-volume unicompartmental knee arthroplasty (UKA) surgeons have lower revision rates, in part due to improved intra-operative component alignment. This study set out to determine whether PSI might allow non-expert surgeons to achieve the same level of accuracy as expert surgeons.Materials and methodsThirty-four surgical trainees with no prior experience of UKA, and four high-volume UKA surgeons were asked to perform the tibial saw cuts for a medial UKA in a sawbone model using both conventional and patient-specific instrumentation (PSI) with the aim of achieving a specified pre-operative plan. Half the participants in each group started with conventional instrumentation, and half with PSI. CT scans of the 76 cut sawbones were then segmented and reliably orientated in space, before saw cut position in the sagittal, coronal and axial planes was measured, and compared to the pre-operative plan.ResultsThe compound error (absolute error in the coronal, sagittal and axial planes combined) for experts using conventional instruments was significantly less than that of the trainees (11.6°±4.0° v 7.7° ±2.3º, p = 0.029). PSI improved trainee accuracy to the same level as experts using conventional instruments (compound error 5.5° ±3.4º v 7.7° ±2.3º, p = 0.396) and patient-specific instruments (compound error 5.5° ±3.4º v 7.3° ±4.1º, p = 0.3). PSI did not improve the accuracy of high-volume surgeons (p = 0.3).ConclusionsIn a sawbone model, PSI allowed inexperienced surgeons to achieve more accurate saw cuts, equivalent to expert surgeons, and thus has the potential to reduce revision rates. The next test will be to determine whether these results can be replicated in a clinical trial.

Evolution of the Fractured Zone Above a Coal Face with a Large Mining Height: A Case Study of the Dahuangshan Coalmine, China

The characteristic of the distribution and evolution of the fractured zone has important guiding significance for gas drainage design. In this paper, the 2ZW11 face of the Dahuangshan coal mine was chosen as an engineering example, and the evolution of the fractured zone was analysed using physical and numerical simulations. The results showed that in the vertical direction, the heights of the fractured zone and the caved zone tended to be stable after the face advanced to 200 m. The heights of the two zones drawn from the physical and numerical simulations were supported by the field test. The traditional empirical formula may not be appropriate for predicting the heights of the two zones of working faces with large mining heights. In the horizontal direction, the bed-separated ratio of the overburden strata above the face position was slightly higher than that of the overburden strata above the open-off cut position. Finally, a high-level drainage was designed and undertaken in the 2ZW11 face.

English

The study of pollen dispersal and mode of fertilization of Vernonia amygdalina and Vernonia calvoana is a prerequisite to the understanding of genetic diversity and elaboration of improvement programs for the Vernonia genus. In this study, precise experimental designs were made for morphological and biological observations on Vernonia species capitulum in order to assess the distinctive effects of each of the three possible pollen transportation agents (insects, wind and rain water) on pollination. Results obtained show that the exclusive mode of pollen dispersal is entomophilous. Even though allogamy and autogamy are observed as two possible modes of fertilization in Vernonia spp., some arguments tend to favour allogamy. However, there is no clear cut position on the issue, hence the need for confirmation by further experimentation in controlled pollination. This study paves the way for the establishment of a genetic improvement program for this genus based on the results on pollen dispersal. Key words: Vernonia species, allogamy, autogamy, pollination agent.

From path integrals to tensor networks for the AdS/CFT correspondence

In this paper, we discuss tensor network descriptions of AdS/CFT from two different viewpoints. First, we start with an Euclidean path-integral computation of ground state wave functions with a UV cut off. We consider its efficient optimization by making its UV cut off position dependent and define a quantum state at each length scale. We conjecture that this path-integral corresponds to a time slice of AdS. Next, we derive a flow of quantum states by rewriting the action of Killing vectors of AdS3 in terms of the dual 2d CFT. Both approaches support a correspondence between the hyperbolic time slice H2 in AdS3 and a version of continuous MERA (cMERA). We also give a heuristic argument why we can expect a sub-AdS scale bulk locality for holographic CFTs.

Bacteriophage SPP1 pac Cleavage: A Precise Cut without Sequence Specificity Requirement

In many tailed bacteriophages, DNA packaging is initiated by recognition and cleavage of a specific sequence pac by the small (TerS) and large (TerL) terminase subunits. It was previously shown that the SPP1 pac region has two sequences where TerS binds (pacR and pacL), flanking the segment where TerL cleaves the SPP1 DNA (pacC). However, the pac-specific sequences required to achieve this endonucleolytic cut were not established. Their characterization is essential to understand the underlying mechanism. We show that the pacR sequence localized within 35bp downstream of the pac cut can be extensively degenerated, including its c1 and c2 repeats, and that only a disruption of a 5-bp polyadenine tract impairs the pac cleavage. This result together with deletion analysis of pacL shows that the specific DNA sequences required for targeting the terminase for pac cleavage are considerably shorter than the large region bound by TerS. Furthermore, extensive degeneration of the 6-bp target sequence within pacC where pac cleavage occurs reveals that TerL maintains, remarkably, its precise position of cleavage. Studies with SPP1-related phages show the conservation of the cut position, irrespective of the sequence variation in pacC and in pacR or the changes in pacL–pacC distance. Mechanistically, our data are compatible with a model in which TerS interactions with part of the pacL sequence and a poly-A tract in pacR are sufficient to orient very accurately the TerL nuclease to a defined pacC position. They also demonstrate that the resulting precise cut at pacC is independent of the targeted DNA sequence.