Trapezoidal Pattern Research Articles

Numerical Simulation of Overburden Deformation Mechanism and Surface Settlement Characteristics Induced by Underground Coal Mining: A Case Study

ABSTRACTUnderground mining in mountainous regions presents a significant geological hazard, characterised by the occurrence of land subsidence and movement of overlying strata. To aggrandise the theory of mine rock mechanics, we conducted a systematic investigation into the deformation and failure mechanisms of overlying strata as well as the patterns of surface subsidence in mountainous regions. With the method of engineering mechanics and theoretical analysis, supplemented by the universal distinct element code (UDEC) numerical simulation, the mining status of Songzao mine was simulated effectively. Herein, the results revealed that the nonlinearity of the overlying strata failure field occurred during mining, as evidenced by an increase in the failure field when the coal approached the seam roof. The subsidence curve of the underlying lower strata exhibits an inverted trapezoid pattern, while that of the overlying upper overburden displays a funnel‐shaped trend. Additionally, the upward transmission displacement velocity was significantly attenuated due to the shielding effect exerted by the key stratum in the overburden, resulting in a greater spatial separation from the underlying strata. The critical stratum fractures as the working face advanced to 120 m, subsequently leading to an increase in vertical displacement and cessation of surface subsidence. The surface subsidence value and speed, however, exhibited a gradual increase as the coal seam mining progressed. Due to the influence of mountain surface landforms, the subsidence value of convex landforms surpasses that of concave landforms, thereby expediting the rate of subsidence and resulting in geological hazards.

Influence of post-processing methods on bond-slip behavior of nonlinear Fe-SMA lap-shear joints

Prestressed bonded strengthening for structures employing iron-based shape memory alloy (Fe-SMA) has been proven promising. Analyzing adhesively bonded joints necessitates a thorough understanding of the bond-slip behavior. However, when examining the bond-slip behavior of Fe-SMA-to-steel joints comprising nonlinear adhesives, the “forward” and “backward” post-processing methods, representing the current state-of-the-art, produce a trilinear and a trapezoidal bond-slip pattern, respectively, which is inconsistent. To address this inconsistency, the current study investigates the bond behavior of Fe-SMA-to-steel joints, with a particular focus on the bond-slip behavior. Two finite element (FE) joints, one featuring a linear adhesive and the other comprising a nonlinear adhesive, are modeled and compared against physical tests from literature. The “forward” and “backward” processing methods are used to analyze the bond behavior of the two FE joints. Eventually, the aforementioned inconsistency is resolved; a triangular and a trapezoidal bond-slip pattern are characterized for Fe-SMA-to-steel lap-shear joints with linear and nonlinear adhesives, respectively. The trilinear bond-slip behavior is concluded as a result of error accumulation and propagation during the “forward” processing. A hybrid post-processing method, which takes the advantages of both the “forward” and “backward” processing methods, is further proposed for inferring the full-range behavior; the resulting experimental behaviors closely align with simulations using a trapezoidal bond-slip model as input. A comparison against carbon fiber reinforced polymer (CFRP) lap-shear joints demonstrates similar bond-slip characteristics between Fe-SMA and CFRP lap-shear joints.

Mathematical Modeling of SOIC Package Dynamics in Dielectric Fluids during High-Voltage Insulation Testing

The efficient testing and validation of the high-voltage (HV) insulation of small-outline integrated circuit (SOIC) packages presents numerous challenges when trying to achieve faster and more accurate processes. The complex behavior these packages when submerged in diverse physical media with varying densities requires a detailed analysis to understand the factors influencing their behavior. We propose a systematic and scalable mathematical model based on trapezoidal motion patterns and a deterministic analysis of hydrodynamic forces to predict SOIC package misalignment during automated high-voltage testing in a dielectric fluid. Our model incorporates factors known to cause misalignment during the maneuvering of packages, such as surface tension forces, sloshing, cavity formation, surface waves, and bubbles during the insertion, extraction, and displacement of devices while optimizing test speed for minimum testing time. Our model was validated via a full-factorial statistical experiment for different SOIC package sizes on a pick-and-place (PNP) machine with preprogrammed software and a zero-insertion force socket immersed in different dielectric fluids under controlled thermal conditions. Results indicate the model achieves 99.64% reliability with a margin of error of less than 4.78%. Our research deepens the knowledge and understanding of the physical and hydrodynamic factors that impact the automated testing processes of high-voltage insulator SOIC packages of different sizes for different dielectric fluids. It enables improved testing times and higher reliability than traditional trial-and-error methods for high-voltage SOIC packages, leading to more efficient and accurate processes in the electronics industry.

A Smart Manufacturing Process for Textile Industry Automation under Uncertainties

Most textile manufacturing companies in the world heavily rely on manual labor, particularly in the fabric inspection section, especially for cotton fabric. Establishing smart manufacturing systems like industrial automation in the textile industry for cotton fabric inspection is important for error-free inspection. The proposed make-to-order (MTO) inventory model focuses on the strategic development of a supply chain network under fuzzy uncertainty. The distinctiveness of this research lies in integrating a methodology that involves human and machine interaction, along with allocating resources to investment in smart manufacturing. This article presents a case study of the Jagatjit Cotton Textiles (JCT) manufacturing company in Punjab, India, as an example to validate the model and check the performance of SMT in the fabric inspection process in cotton TC mills. This paper contributes by developing four distinct textile supply chain models with industrial automation under triangular and trapezoidal fuzzy demand. A numerical analysis is conducted to verify the effectiveness of installing automated fabric inspection machines in the cotton plant. This article proposes an iterative solution algorithm (KDPMG) to obtain the global optimum for the proposed model. A comparative study of the proposed algorithm, KDPMG, and the genetic algorithm (GA) is presented in this study to verify the credibility of the obtained results. It is observed that KDPMG provides more appropriate solutions to the problem compared to the GA. Moreover, the computational time of KDPMG is significantly less than that of the GA. The rigorous analysis reveals that maximum profit can be achieved under trapezoidal fuzzy demand with fully automated fabric inspection technology. Using a triangular fuzzy demand pattern, the model with fully automated smart manufacturing achieves an 8.62% higher profit compared to a traditional system. Similarly, in the case of a trapezoidal fuzzy demand pattern, the adoption of automation in cotton plants can achieve an 8.69% higher profit. Hence, the implementation of smart manufacturing systems in the mending section of the cotton textile industry proves to be more profitable compared to the traditional inspection process.

Performance evaluation of geosynthetic reinforced marginal material as base layer over weak subgrade

ABSTRACT The availability of quality materials for construction has been an issue in some regions. This scarcity obliged using marginal materials reinforced with geosynthetic materials as one of the quests for sustainability in the pavement industry. In this study, an attempt was made to stabilize the marginal materials by incorporating geosynthetics. The different geosynthetics used in the study are geogrid, geocell, double geogrid, and geocell + geogrid. A series of unreinforced (UR) and geosynthetic reinforced (GR) pavement prototypes were constructed in the laboratory with landslide debris as base material underlain by black cotton soil subgrade. Large-scale cyclic plate load (CPL) tests were performed on test prototypes constructed in the laboratory under cyclic loading following the trapezoidal loading pattern with 0.77 Hz frequency. The efficacy of geosynthetic reinforcement was quantified concerning permanent deformation (PD), resilient deformation (RD), Rut depth reduction (RDR), Traffic improvement ratio (TIR), and reduction in vertical stresses transmitted to the subgrade and reduction in base layer thickness. The test results indicate that the GR significantly reduced the rut depth and improved the traffic capacity. In addition, over all types of GRs, the combination of geogrid and geocell outperformed in terms of permanent deformation and rut depth reduction.

STensile behaviour of T-stub to hollow section column using elliptical-head one-side bolts

The Elliptical-head one-side bolt (EOB) is a typical representative of the third generation for one-side bolts, relying on its elliptical head and bolt hole to achieve orthogonal anchorage, and the application scenario is mainly the bolted connection of closed-section members. Studies have been reported for the shear performance of EOBs bolted lap connections and the tensile behaviour of concrete-filled steel tubes, but there is still a lack of the tensile performance of EOBs connecting Hollow section columns (HSCs), which is necessary for the application of the component method for the beam-column joints design. Therefore, numerical simulation and theoretical analysis methods were employed in this paper to demonstrate the feasibility of adopting EOBs for this type of connection, including typical failure modes, novel yield line pattern in the HSC wall, comparison with the Conventional high-strength bolt (CHB) connections, analysis of the parameters related to the elliptical bolt head and hole, and the establishment and validation of the methodology for calculating the HSC bearing capacity. The results show that: The novel trapezoidal yield line pattern tended to show in the HSC wall with the smaller bolt pitch distance and larger gauge distance; The yield strength of the EOBs bolted T-stub to HSC connections was reduced by about 15% compared to the CHBs bolted ones; Vertical layout of bolt holes, accuracy of rough assembly, rotation deviation of bolt shank within 20° and avoidance of bolt offsets in bolt hole were recommended for EOB connections; The novel yield line pattern established in this paper predicted the yield strength of the connections, and the accuracy and stability were verified by comparing with finite element modelling (FEM) results.

Centrifuge and analytical modeling of counterweight retaining walls under translation mode

Counterweight retaining walls (CRWs) are a variant of gravity-retaining walls that feature a pressure relief platform (RP) on the backfill side to reduce total earth pressure, offering a cost-effective option compared to traditional forms. However, the intricate interactions between CRWs and backfill, coupled with the lack of clear design guidelines, have restricted their use. This study examines the behavior of CRWs in translation mode using three different centrifuge model tests, each with varying fill heights. Observations show a slightly concave slip surface through the wall heel and a nearly planar slip surface extending from the edge of the RP to the back of the wall in an active limit state. Backfill movement can be classified into translation, sliding, and stable zones. Earth pressure distribution on the upper wall follows a trapezoidal pattern, whereas the pressure on the lower wall exhibits a triangular distribution. Earth pressure on the RP is approximately linear, peaking near the RP’s edge. Introducing a friction angle mobilization factor for the potential first slip surface improves accuracy in calculating earth pressure. The tests were replicated to validate the analytical model for earth pressure calculations, using the adaptive finite-element limit analysis method.

Laboratory Evaluation of Marginal and Industrial Waste Material in Geocell-Reinforced Pavements under Cyclic Loading

Abstract The availability of quality materials for the construction of pavements has been a problem in some regions. This scarcity enforced geosynthetic materials as one of the quests for su1stainability in the pavement industry. This study attempted to stabilize marginal (tunnel muck, reclaimed asphalt pavement material) and industrial waste (zinc slag) materials by employing high density polyethylene geocell to appraise the effectiveness of geosynthetic reinforcement in enhancing the characteristics of pavement materials and mitigating their rutting. The cyclic plate load tests are performed on marginal and industrial waste material with geocell-reinforced and unreinforced base layers over black cotton soil as the subgrade. The tests were conducted following the trapezoidal loading pattern with a 0.77-Hz frequency. The geocell-reinforced pavement performance was evaluated for resilient deformation, accumulated permanent deformation, rut depth reduction, traffic benefit ratio, and base layer thickness reduction. The mechanistic empirical pavement design guide (MEPDG) permanent deformation performance (PDP) model framework was used to predict the accumulated permanent deformation in unbound granular layers and to differentiate the rutting performance in geocell-reinforced and unreinforced sections. This study determined the material constants of the MEPDG PDP model for marginal and industrial waste materials used in the pavement section for quantifying the reduction in base layer thickness.

Effect of trapezoidal pattern on deflection of sandwich panel with corrugated core

Effect of trapezoidal pattern on deflection of sandwich panel with corrugated core

Guided mode resonances for angular and spectral filtering

The development of devices based on compact waveguides is a rapidly evolving field. A unique variation of such devices is the Fano-like resonance dielectric spectral and spatial filtre, made from a dielectric conformal thin film on a surface relief grating. It can be used in a normal (or oblique) angle-of-incidence configuration. This device facilitates directional selectivity, which is useful for transverse-mode cleaning in short optical cavities. It can also be enhanced by using leaky-mode effects to produce even sharper spectral features. However, a perfect spatial filtre should be as invariant as possible in the spectral and enhanced angular domains. Here, we solved the inverse design problem to produce such an effect. Numerically, we tuned the surface profile of the substrate grating, assuming a conformal layer on top. This resulted in trapezoidal relief patterns followed by narrow flat-top angular features. The combination of leaky mode effect and enhanced device topology will enable efficient and useful devices with a bandwidth of 50 nm and even more in the future.

Defining Hereditary Pyropoikilocytosis (HPP) in the Molecular Diagnostic Era

Misconceptions continue in distinguishing hereditary elliptocytosis (HE) with hemolysis in early perinatal period and hereditary pyropoikilocytosis (HPP). In 1975, Zarkowsky and colleagues described a group of children with transfusion dependent congenital hemolytic anemia with the unique morphology of “microspherocytes, measuring 2-3 microns in diameter, and cells with blunted projections or triangular in shape”, a morphology resembling the heat induced damage to normal erythrocytes - hence the name hereditary pyropoikilocytosis (HPP). Subsequently, similar cases were described with or without demonstrable heat sensitivity (Ravindranath & Johnson, 1985). Regardless, the common denominators were 1) transfusion dependency early in infancy - resolved with splenectomy, 2) severe microcytosis, often <60 fL, and 3) a decrease in membrane bound spectrin (decreased spectrin/band3 ratio). Family studies showed normal RBC morphology in both parents (Ravindranath & Johnson, 1985) or in some cases, one parent with HE (Zarkowsky et al., 1975). Protein chemistry studies showed decreased tetramer formation and tryptic digests showed mutations within the n-terminal alpha 1 domain of alpha spectrin - the dimer/dimer interaction site. Thus, homozygosity or double heterozygosity of mutations in the dimer/dimer interaction site of alpha spectrin (alpha 1 domain of alpha spectrin) defined HPP while classical HE cases showed heterozygous mutations in the alpha 1 domain. A fact unexplained was how this results in spectrin deficiency, specifically, alpha spectrin deficiency (Ravindranath & Johnson, 1985). Using the molecular analytical tool AnemiaID (courtesy of Agios Pharmaceuticals, Inc.), we show that HPP is defined by the co-inheritance of two SPTA1 mutations and Alpha-LeLy polymorphism ( αLeLy rs28525570; SPTA1[c.5572C>G;c.6531-12C>T]) in one or both alleles, thus explaining the increased propensity for red cell fragmentation and the spectrin deficiency noted on acrylamide gels [Table: Clinical and molecular characteristics of our cases]. Of note, homozygosity for αLeLy polymorphism and one SPTA1 variant did not result in clinical HPP phenotype [HE-2 in Table]. At a clinical laboratory level, the extreme microcytosis in HPP is evident in the markedly diminished band3 content on eosin-5'-maleimide (EMA) binding test- mean channel fluorescence (MCF) of <275.0 (control: 473.0-549.0) while HE (including neonatal HE with hemolysis) show a double peak pattern in EMA (the minor peak representing the fragmented cells while the major peak had MCF higher than control MCF) and the characteristic trapezoid pattern on osmotic gradient ektacytometry (not shown).

A novel approach for enhancing the bond performance of bamboo reinforced concrete by surface treatment and corrugation

In the quest for sustainable development and to address the challenges of urbanization, researchers are exploring alternative sources of materials for construction and bamboo has emerged as a promising alternative to steel reinforcement in concrete construction due to its impressive weight-to-strength ratio. The goal of the present work is to investigate the bond properties of three different corrugation patterns in surface-treated bamboo alongside non-corrugated and epoxy-treated bamboo samples through pull-out testing. Bamboo corrugation is advocated as an ingenious mechanism to foster a robust interlocking effect between bamboo and concrete, effectively bolstering cohesion and optimizing skin friction to amplify the overall bond strength significantly. The findings revealed significant improvements in bond strength for rectangular corrugation, V-notch corrugation, and trapezoidal corrugation patterns, with strength enhancements of 46%, 85%, and 81% respectively, compared to plain bamboo. Furthermore, a theoretical bond model was developed for each corrugation pattern, which has been successfully validated against the experimental results with a notable accuracy ranging from 78.7% to 95.6%. Finally, the theoretical model was suggested as a tool for estimating the bond between bamboo and concrete. These findings underscore the potential of using corrugated bamboo reinforcement as a sustainable solution for enhancing bond performance in concrete.

Sagittal Orientation and Variabilities of the Anatomical Insertional Footprint of the Achilles Tendon: A Cadaveric Study

Category: Hindfoot; Sports Introduction/Purpose: New surgical techniques for Achilles tendon insertional pathology are evolving rapidly. Whether via open surgery, minimally invasive, or endoscopic approaches, more information about the Achilles' insertional footprint is needed to help surgeons with decision making. This study investigated the footprints of the Achilles insertion in sagittal orientation to delineate the anatomical landmarks, safe zones for bone resection3-down surgeries in treating insertional Achilles tendinopathies. Methods: Twenty fresh frozen cadavers were selected excluding insertional Achilles tendon pathology on lateral view x-rays. The calcanei were dissected maintaining the Achilles tendon insertion intact. Dimensions of the posterior tuberosity were recorded and marked to plan for three sagittal cuts (medial, middle, and lateral) (Fig 1 A). Using an oscillating saw (Fig 1 B.), the posterior tuberosity was cut into four pieces (Fig 1 C,E). A trapezoid shape (Fig 1 D) was reconstructed demonstrating relative location of the footprints of the Achilles insertion compared to the boundaries of the tuberosity on each piece (A, most superior point in the posterior tuberosity; B, most superior point in the Achilles insertion; C, most inferior point in the Achilles insertion; D, most inferior point in the posterior tuberosity). Data regarding footprints of the Achilles tendon insertion in the sagittal orientation was analyzed and compared within each trapezoid region and among different regions. Results: AB (calcaneal tuberosity tip to the upper limit of the Achilles insertion) was shortest at the medial cut (9.35mm) and longest at the lateral cut (12.15mm). However, the tendon thickness at the insertion (the distance from the proximal to the distal limits) represented by BC was shortest at the lateral cut (13.19mm) and longest at the middle cut (14.04mm). AD, the distance from the highest to the lowest point of the calcaneal tuberosity, was the longest at the middle cut (41.20mm). AB:BC ratio was highest at the lateral cut and lowest at the medial cut, indicating the safe amount of bone to be resected at the Achilles insertion. Tendon thickness relative to the whole calcaneal tuberosity (BC:CD) was highest at the medial wall (Table1). Conclusion: The sagittal orientation and variability of the Achilles tendon insertion is an under-studied topic in the literature. It needs to be addressed given recent trends towards minimally invasive procedures in treating insertional Achilles pathology. This study precisely delineated the footprint in each region of the insertion by creating a trapezoid pattern to compare the coordinates across these areas. This could lead to future three-dimensional reconstruction of the Achilles insertional footprint and patient- specific instrumentation software directed towards optimizing the management of Insertional Achilles pathology.

Permeability evolution and production characteristics of inclined coalbed methane reservoirs on the southern margin of the Junggar Basin, Xinjiang, China

The thick and steeply inclined coal seams of the Junggar Basin of Xinjiang, China, are unique with dip angles generally >50° but over the range 0°–85°. Initial and evolving permeability and pressures change drastically around wells down-dip within the steeply inclined reservoir as a result of the depth differential. Hence, the evolution of permeability and fluid pressures during drainage exhibits significant differences from those of flat-lying or even slightly inclined reservoirs. We apply a hydro-mechanical model to evaluate the interaction of two-phase flows of gas and water in the inclined system. The influence of different reservoir inclinations (15°, 30°, 45°, 60°, and 75°) on the evolution of permeability, reservoir pressure, and gas production are explored through finite element modeling of this system. The results show that: 1) Reservoir inclination induces differences in permeability, reservoir pressure, gas content and methane production between the shallower updip reservoir and deeper downdip reservoir. The difference in permeability between the updip and downdip reservoirs is amplified as the dip angle increases and as drainage proceeds in the presence of the varying stress gradient. 2) An apparent asymmetric distribution of reservoir pressures results for wells along dip. The difference in reservoir pressure between the updip and downdip reservoirs intensifies as the inclination increases but lessens with the progress of drainage. The larger the dip angle, the smaller the final reservoir pressure. 3) The pressure reduction in the updip reservoir is larger than that in the downdip reservoir, resulting in the unsynchronized desorption of methane in the updip and downdip reservoirs. Methane within the updip reservoir desorbs preferentially over that in the downdip reservoir. For reservoir dip angles <45° a single peak in methane production rate is apparent but this is supplanted by dual peaks for inclinations >45°. The time gap in gas desorption between the updip and downdip reservoirs results in the “dual-peak” on gas production profile. 4) A larger well spacing along the dip of a more highly inclined reservoir results in more efficient water drainage and gas production. An inverted trapezoidal well pattern is recommended to facilitate the drainage and gas production of reservoirs with significant dip angles.

Improving the T-stub component behavior tied to a rigid base

An improvement in the behavior of the T-stub component as the vital element in the bolted connections is significant. Therefore, the present research aims to enhance the T-stub behavior by refining the bolt pattern under static load. In order to observe the effect of the bolt pattern resulting in suitable T-stub behavior, both experimental and numerical studies were performed on the specimens including one-row and two-row bolts with rectangular and trapezoidal patterns. The major aim of the experimental study was to monitor the failure mode of the specimens besides their load–displacement curves. Then, after verifying experimental results with ABAQUS software, numerical study on not only the mechanical behavior of the specimens but also the bolt behavior were conducted. Based on the results, a novel failure mode in the subgroup of failure mode 1 was observed. Furthermore, the bolt type had direct effect on the kind of the bolt rupture in failure mode 2. The last but not least, modifying just the bolt pattern without varying the remaining parameters enhanced the T-stub and bolt behavior in each of the failure modes. Therefore, without increasing the weight and cost of the connection considerably, an appropriate behavior can be reached.

New landscape-perspective exploration of Moso bamboo forests under on/off-year phenomena and human activities

On-year and off-year phenomena is an unique spatiotemporal characteristics of Moso bamboo forests (MBFs), the combination of multiple sources data to assess the impact of on-/off-year phenomena and human activities is a new perspective to better understand MBFs. There is an urgent need to explore how to characterize the spatial variability of MBFs, whether there is a pattern in the spatial distribution of MBFs boundary lines, and whether the causes of the boundary lines are directly related to human activities. In this paper, Anji County, with a large MBF area, was selected as the study area. Based on Sentinel-2 time-series data, topography and impermeability data, the on-year/off-year status and boundary lines of MBFs were determined, and the Integrated Moso bamboo On-off year Differentiation Index (IMODI) was proposed to evaluate spatial differentiation. Spatial heterogeneity, the shape pattern of boundary lines, and the impact of human activities on the MBFs were quantitatively analyzed, and 631.5 km2 of MBFs and 140 on-off boundaries were accurately obtained. The on-year and off-year MBFs and boundaries were mainly distributed in mountainous areas, especially at elevations of 100–400 m and on slopes of 10–35°. The patterns in elevation can be categorized as stable, single-change, ascending-descending and descending-ascending patterns. The patterns in slope can be summarized as stable, single-change, and trapezoidal patterns. The newly proposed IMODI shows the best performance in reflecting the spatial differentiation of MBFs, and the on-year and off-year phenomenon of MBFs was closely related to human activities because the boundary lines were mostly concentrated within 2 km of villages. The results of this paper provide a new perspective to understand landscape of MBFs and the integrated management of carbon sequestration and sinks.

Trocar number and placement for laparoscopic sleeve gastrectomy and comparison of single-incision and conventional laparoscopic sleeve gastrectomy: a systematic review and meta-analysis.

Conventional laparoscopic sleeve gastrectomy (CLSG) has been conducted in multiple centers for treating morbid obesity, however, there are no standard criteria for (1) placing the trocar; and (2) how many trocars should be used. Single-incision laparoscopic sleeve gastrectomy (SLSG), a newly emerged technique in 2008, has been proposed as an alternative to CLSG in recent years, however, there is no definite evidence for this. A systematic literature search was performed using the PubMed, Embase, Web of Science, and Cochrane Library databases for laparoscopic sleeve gastrectomy cases from January 2006 to October 2022. We then summarized the trocar numbers and placement patterns among these studies. A meta-analysis was conducted to compare the difference between SLSG and CLSG in the perioperative and postoperative indices. A total of 61 studies involving 20180 patients who underwent laparoscopic sleeve gastrectomy for treating morbid obesity were included in the systematic review, including 11 on SLSG, 35 on CLSG, and 15 studies comparing SLSG and CLSG. A systematic review showed that the trocar number varied in different CLSG studies, mainly using four or five trocars. The trocars were mainly placed in position, presenting an inverted trapezoid pattern and a left-predominant pattern. Meta-analysis showed that the operative time in the SLSG was significantly higher than that in the CLSG, and the pain Visual Analog Scale rating on postoperative day 1 in the CLSG was significantly higher than in the SLSG. There were no statistical significances in the other complications or surgical efficiency. In the CLSG, the majority of the trocars were arranged in an inverted trapezoid pattern and were of the left-predominant type. Although SLSG is a feasible technique in selected patients, there is insufficient evidence to recommend its widespread use compared with CLSG. High-quality randomized controlled trials with large study populations and long follow-up periods will be required in the future.

An Optimal Control Approach to the Minimum-Time Trajectory Planning of Robotic Manipulators

Trajectory planning is a classic problem in robotics, with different approaches and optimisation objectives documented in the literature. Most of the time, the path is assumed, i.e., pre-defined, and optimisation consists of finding the timing of motion under a number of constraints. The focus of this work is on the minimum-time manoeuvring of robotic manipulators. A nonlinear optimal control approach is proposed that does not require the provision of either a pre-defined path or a pre-defined control structure and allows the inclusion of dynamic constraints. The solution (path and timing of motion) is obtained by transforming the optimal control problem into a nonlinear programming problem. The proposed approach is applied to a two-link manipulator for illustration purposes. The optimisation is carried out both without and with obstacles. The minimum-distance and minimum-time solutions are compared, and some classic results are obtained, including the trapezoidal pattern of the joint velocity and the bang–bang structure of the control torques. The effects of limitations on the jerks of actuators and the rate of change in torque inputs are discussed. The application to a four-link manipulator is also included to show the ‘scalability’ of the approach, together with a comparison with a classic path-and-motion-planning method, to highlight the characteristics and performance of the proposed approach. Finally, the possibility of enforcing a number of via-points along the path is demonstrated. The proposed method allows the computation of the path and motion simultaneously with the computation time, which is 1–30 times the manoeuvre time, on a standard PC with the current implementation.

Development of a flexible high-friction pressure sensor with structural colors for soft gripper fingers

For energy-efficient and lightweight sensor applications, structural colors were utilized to sense the pressure applied to the surface. However, conventional structural color sensors have been usually fabricated with nanoscale features focusing on high pressure sensitivity with small load limits. In this study, a flexible surface with high frictional force and wide pressure-sensing capability was fabricated by ultra-precision machining for soft gripper applications. Friction and grip detection are very important for gripping performance and sensors for soft grippers are required to cope with loads of over 1 kg. Here, microscale three-dimensional trapezoidal patterns were fabricated and transferred to a polymer to increase the contact area for higher friction and improve structural color expression. The effects of pattern geometry on structural color changes due to the varying loads were analyzed using the hue, saturation, and brightness (HSB) model. The hues of the patterned surfaces decreased with loads. Clear color changes were apparent as the pattern width and depth varied; patterns with blue colors (hue of ~240) at no-load status sensed pressure most effectively. Based on the experimental results, a sensor was designed to have a clear color change in terms of pressure and then was applied to soft gripper fingers. Significant color changes were evident as the pressure changed during gripping even under large loads of up to 1200 g; the high friction (compared to that of a plain surface) also improved gripping performances. The sensor provides intuitive information detectable by the naked eye, and there is no need for any power source, wire, or data acquisition system. This research can contribute to the development of multi-functional, lightweight energy-efficient systems.

Notch-dependent Abl signaling regulates cell motility during ommatidial rotation in Drosophila.

A collective cell motility event that occurs during Drosophila eye development, ommatidial rotation (OR), serves as a paradigm for signaling-pathway-regulated directed movement of cell clusters. OR is instructed by the EGFR and Notch pathways and Frizzled/planar cell polarity (Fz/PCP) signaling, all of which are associated with photoreceptor R3 and R4 specification. Here, we show that Abl kinase negatively regulates OR through its activity in the R3/R4 pair. Abl is localized to apical junctional regions in R4, but not in R3, during OR, and this apical localization requires Notch signaling. We demonstrate that Abl and Notch interact genetically during OR, and Abl co-immunoprecipitates in complexes with Notch in eye discs. Perturbations of Abl interfere with adherens junctional organization of ommatidial preclusters, which mediate the OR process. Together, our data suggest that Abl kinase acts directly downstream of Notch in R4 to fine-tune OR via its effect on adherens junctions.