Simultaneous tailoring of pulsed thermography experimental and processing parameters for enhanced defect detection and sizing in adhesive bonds in carbon fibre composites

Thermographic inspection provides opportunity to tailor non-destructive evaluation to specific applications. The paper discusses the opportunities this presents through consideration of adhesive bonds between composites, such as those joining structural members and outer skins, where access is restricted to a single side. To date, literature focusses on the development of either an experimental procedure or data processing approach. This research aims to demonstrate the importance of tailoring both of these aspects to an application to obtain improved defect detection and robust quantification. Firstly, the heating stimulus is optimised to maximise the thermal contrast created between defect and non-defect regions using a development panel. Traditional flash heating is compared to longer square pulse heating, using a developed shutter system, compromising between experimental duration and heat input. A pulse duration of 4 seconds using two 130 W halogen bulbs was found double the detection depth from 1 mm to 2 mm, revealing all defects in the development panel. Temporal processing was maintained for all data using thermal signal reconstruction. Spatial defect detection routines were then implemented to provide robust defect/feature detection. Spatial defect detection encompassed a combination of image enhancement and edge detection algorithms. A two-stage kernel filter/binary enhancement method followed by the use of Canny edge detection was found most robust, providing a sizing error of 1.8 % on the development panel data. This process was then implemented on adhesive bonds with simulated bond line defects. The simulated defects are based on target detection threshold of 10 mm diameter void found at 1- 2 mm depth. All simulated void defects were detected in the representative bonded joint down to the minimum diameter tested of 5 mm. By considering the tailoring of multiple aspects of the inspection routine independently, an overall optimised approach for the application of interest has been defined.

Mechanical performance analysis and experimental study of soft-bodied bird-billed pneumatic gripper

Purpose Flexible mechanical gripper has better safety and adaptability than a rigid mechanical hand. At present, there are few soft grippers for small objects on a millimeter scale. Therefore, the purpose of this paper is to design a soft pneumatic gripper for grasping millimeter-scale small and fragile objects such as jewelry and electronic components. Design/methodology/approach By simulating the clamping action of the bird’s mouth and combining the high flexibility of the soft material, the bird’s beak soft pneumatic gripper is designed. First, the internal cavity of the gripping end of the gripper is determined by bending deformation calculation, and the brief manufacturing process of the gripper is outlined. Then, the single finger of the soft gripper is modeled mechanically, and the relationship between air pressure and bending deformation of the single finger is obtained. Finally, the experimental platform of the soft mechanical gripper is built, and the gripping performance of silicone rubber material is tested by comparison test, bending deformation test, stability test, adaptability test and gripping accuracy test. Findings The designed gripper has the advantages of simple structure, convenient operation, easy grasping of different small objects of millimeter-scale and good adaptability. It can grasp the precise dispensing needle with a minimum diameter of 0.19 mm, and its accuracy meets daily use. Originality/value A new type of soft pneumatic, the mechanical gripper is proposed and manufactured. According to the shape of the bird’s beak and the calculation of bending performance, a hollow finger gripper with better bending performance is designed. Various test results show that the gripper has a significant clamping effect on millimeter small objects, which supplements the research field of millimeter small object gripper.

Biodiversity Conservation Potential of Forests and Trees On Farms In the Agricultural–Forest Mosaic Landscape of Catacamas, Honduras

Biodiversity decline in the tropics requires the implementation of comprehensive landscape management where agricultural systems are necessarily an integral element of biodiversity conservation. This study evaluates the potential for biodiversity conservation within an intensive livestock-agricultural-forest mosaic landscape in Catacamas, Honduras. Tree sampling was performed in 448 plots set up within different forest and agricultural land uses: secondary forests, agroforestry coffee plantations, agriculture, pastures, live fences and riparian forest. All trees with a minimum diameter at breast height of 10 cm were identified and measured. We characterized their tree structure and diversity, and compared tree diversity between the different uses. The results indicate a high degree of tree species diversity: 375 species identified, belonging to 74 families among the 15,096 trees inventoried across 84.2 hectares, including many rare species (40% of the species registered three individuals or fewer). Biodiversity indices for agroforestry coffee were found equivalent to those for natural secondary forests in the Catacamas landscape. Combining biodiversity conservation and agricultural production is possible in human-pressured tropical landscapes through tree cover maintenance. Enrichment practices combining local producers and technical knowledge may improve tree diversity in agricultural landscapes by prioritizing a mix of forest and introduced tree species (rare and with multiple uses).

A Pneumatic Novel Combined Soft Robotic Gripper with High Load Capacity and Large Grasping Range

Pneumatic soft grippers have been widely studied. However, the structures and material properties of existing pneumatic soft grippers limit their load capacity and manipulation range. In this article, inspired by sea lampreys, we present a pneumatic novel combined soft gripper to achieve a high load capacity and a large grasping range. This soft gripper consists of a cylindrical soft actuator and a detachable sucker. Three internal air chambers of the cylindrical soft actuator are inflated, which enables them to hold objects. Under vacuum pressure, the cylindrical soft actuator and the detachable sucker can both adsorb objects. A finite element model was constructed to simulate three inflation chambers for predicting the grasping range of the cylindrical soft actuator. The validity of the finite element model was established by an experiment. The mechanism of holding force and adsorption force were analyzed. Several groups of experiments were conducted to determine adsorption range, holding force, and adsorption force. In addition, practical applications further indicated that the novel combined soft gripper has a high load capacity (10.85 kg) at a low pressure (16 kPa) and a large grasping range (minimum diameter of the object: d = 6 mm), being able to lift a variety of objects with different weights, material properties, and shapes.

Y90 Radioembolization of Liver Tumors via Radial approach – Correlation Between Common Femoral artery and Radial Artery Size

PurposeTypically, before Y90 radioembolization procedure undergoes, a CT is completed and the Barbeau test followed by radial artery ultrasound is used to determine if the artery is sufficiently large for vascular access [1-4]. 2.5 mm is the average radial artery diameter, and a vessel measurement of 2.0 mm is the recommended minimum diameter for safe vessel access, but a diameter of 1.5–2.0 mm can be accessed [4-9]. Our study explores using common femoral artery measurements from the pre-procedure CT abdomen/pelvis to assess in a binary manner if the vessel is sufficiently large to use for radial artery access. Materials and MethodsAll computed tomography scans of yttrium-90(Y90) radioembolization of the liver tumor procedures from January 1, 2015 - December 31, 2019 were retrospectively reviewed. Medical records were used from 47 procedures to gather patients' age, gender, Avastin use, femoral artery size (mm), administer Y90 (%), history of diabetes, and smoking status were recorded. ResultsThe minimum femoral artery size in patients who underwent transradial artery Y90 liver tumor radioembolization was 6 mm, with a mean femoral artery size of 10 mm. A comparative analysis of Y90 liver tumor uptake revealed no significant difference in radioembolization tumor uptake based on the initial site of procedure, transfemoral or transradial artery, (p > 0.81229). ConclusionThe study suggests that femoral arteries can predict radial artery diameter and that a femoral artery diameter of 10 mm should yield high confidence that the patient will be a candidate for transradial approach.

690 Acute post-implantation enlargement of transcatheter self-expandable valve: insights from a single-centre prospective registry

Aims Transcatheter implantation of a balloon-expandable aortic valve is associated with an acute stent recoil . Conversely, the acute effects of nitinol-based stent frame- self expandable valve on post-deployment dimensions have not been reported. Accordingly, the aim of this study was to assess the occurrence and degree of acute prosthetic dimension changes after Evolute R valve implantation. Methods A total of 58 consecutive patients undergoing transcatheter aortic valve intervention (TAVI) with a widely used nitinol based self-expandable device (Evolute R, Medtronic, Minneapolis, USA) were included in this study. We measured valve diameters at three different sections: a) distal (aortic) level, b) central (annulus) level, and c) proximal (ventricular) level. Valve expansion was calculated as the difference between the diameters calculated immediately after valve deployment (A) and at the end of the procedure (B). The absolute and relative acute stent recoil were defined as B-A and (B-A)/B*100, respectively. A linear regression model was performed to test the association between the degree of valve extension, with baseline, as well as procedural characteristics. Results Final stent diameters were significantly higher compared to those achieved immediately after valve implantation in proximal (20.87±3.20 mm versus 20.37±3.27 mm, P <0.001), central (19.58±1.63 mm versus 19.12±1.75 mm, P <0.001) as well as distal (26.99±1.53 mm versus 26.41±1.57 mm, P <0.001) segments. The mean absolute and relative enlargement of the valve was respectively 0.50±0.51 mm and 2.48±2.57% in the proximal, 0.46±0.57 mm and 2.39±2.96% in the central and 0.58±0.59 mm and 2.14±2.14% in the distal segment. Among baseline and procedural characteristics assessed in the logistic regression model no association was observed between pre-dilation and valve expansion across all the segments (proximal: r2=0.004, P=0.885, central: r2=0.004, P=0.637, and distal r2=0.05, P=0.10). Of interest, post dilation affected only the expansion of the central segment (r2=0.241, P<0.001), while no association was observed for the proximal (r2=0.059, P=0.065) and distal (r2=0.0002, P=0.916) parts. The expansion of the proximal segment was associated with higher maximum/minimum diameter ratio measured by CT (r2=0.08, P=0.045), while no association was observed for the central (r2= 0.020; P=0.992) and distal (r2=1.111, P=0.683) segments. Conclusions This is the first study that documented a significant degree of post-deployment recoil of the Evolute R self-expandable valve, that was consistent across all the segments. The stent-valve expansion of the proximal segment was associated with a greater annulus dissymmetry reported by the maximum and minimum diameter ratio assessed by CT scan. However, further studies are required to assess the short and long-term time-course of self-expandable valve enlargement and the clinical relevance of this finding.

Effect of Material Type and Minimum Diameter of Specimens on the Fatigue Life

The obstacle faced during the fatigue test is the waiting time which is quite long and inefficient, especially for test specimens made of ductile metal with waiting times of up to several days. The research method includes reducing the specimen radius to obtain a flexural stress approaching 400 MPa which was originally 229 MPa from a radius of 254 mm to 240 mm with the results of turning the original specimen obtained a minimum diameter of 8.6 mm is reduced to 7.3 mm at a maximum loading of 10 kg. Results of the research are brass specimens C3604BD type with a minimum diameter of 8.6 mm at a flexural stress of 298 MPa showing a fatigue life of 2455546 cycles with a test duration of 1754 minutes and a minimum specimen diameter of 7.3 mm at a flexural stress of 299 MPa showing a fatigue life of 684311 cycles with a test duration of 489 minutes which means that with a minimum specimen diameter of 7.3 mm the fatigue life is 3.59 times shorter than a minimum specimen diameter of 8.6 mm. Meanwhile, for aluminium AA1101 type with a minimum specimen diameter of 7.3 mm at a flexural stress of 182 MPa, the fatigue life is 422117 cycles with a test duration of 278 minutes and with a minimum specimen diameter of 8.6 mm at a flexural stress of 183 MPa, the fatigue life is 389232 cycles with a test duration of 302 minutes which means that with a minimum specimen diameter of 7.3 mm the fatigue life is 1.05 times shorter than the minimum specimen diameter of 8.6 mm or almost the same.

Geometric, kinematic and dynamic parameters of the disc ripper

Introduction. The unit of continuous action for the formation of the underlying layer is designed to increase labour productivity in the construction of roads and other objects, for the construction of which it is necessary to remove the upper layer of soil. For loosening of soil in the unit used bit-like working bodies. Often, disc working bodies are used to cut the soil. Therefore, the expediency of using passive discs in road-building technical means, in particular, in the unit of continuous action for the formation of the underlying layer of highways, is of practical interest. Despite the large number of works, a detailed analysis of the operation of passive disks was not made. Therefore, in order to compare the energy costs for cutting the soil with passive discs and chisel-shaped working bodies, it is necessary to make a theoretical analysis of the operation of passive disks. Analysis of the energy costs of the disk ripper cannot be carried out without having the approximate values of its geometric, kinematic and dynamic parameters.The method of research. As part of a continuous unit to form the underlying layer of roads, each disc would be clamped with soil on both sides and carried out clamped cutting. Therefore, a disk ripper is adopted for analysis, aggregated with a separate energy device. On the basis of the constructive layout, rational geometric parameters of the disk ripper are revealed. The method of calculation of its kinematic and dynamic parameters is developed. In particular, the method of determining the weighted average circumferental velocity of the disk, the angular velocity of the disk and the circumferental velocity of the point on the edge of the disk blade is considered. The modes of cutting the soil by various parts of the disk are considered.Results. On the basis of the developed technique, the dependence of the minimum diameter of the disk on the depth of soil development was revealed. The moment of resistance of the soil to the rotation of the disks is calculated. The horizontal and vertical component of soil resistance to the front disc carrying out clamped cutting and subsequent discs carrying out semi-clamped cutting of the soil are determined. The necessary thrust force of the energy device for cutting the soil with a disk ripper and the dependence of the thrust force of the energy device for cutting the soil on the depth of soil development were revealed. The performance of the unit, including the power device and the disk ripper, is calculated.Conclusion. Since as part of the unit of continuous action for the formation of the underlying layer of roads, the disks will carry out clamped cutting of the soil, for preliminary loosening of the soil with disks, it is more expedient to use a separate unit, including an energy device and a disk ripper. On the basis of the theoretical studies carried out, the necessary thrust force of the energy device for cutting the soil and the total traction force necessary to move the disc ripper were revealed. The performance of the unit is calculated. To compare the energy costs for cutting the soil with passive discs and chisel-shaped working bodies, it is necessary to make a theoretical analysis of the energy costs for the operation of passive disks.

Clinical and CT Radiomics Nomogram for Preoperative Differentiation of Pulmonary Adenocarcinoma From Tuberculoma in Solitary Solid Nodule

AimTo investigate clinical and computed tomography (CT) radiomics nomogram for preoperative differentiation of lung adenocarcinoma (LAC) from lung tuberculoma (LTB) in patients with pulmonary solitary solid nodule (PSSN).Materials and MethodsA total of 313 patients were recruited in this retrospective study, including 96 pathologically confirmed LAC and 217 clinically confirmed LTB. Patients were assigned at random to training set (n = 220) and validation set (n = 93) according to 7:3 ratio. A total of 2,589 radiomics features were extracted from each three-dimensional (3D) lung nodule on thin-slice CT images and radiomics signatures were built using the least absolute shrinkage and selection operator (LASSO) logistic regression. The predictive nomogram was established based on radiomics and clinical features. Decision curve analysis was performed with training and validation sets to assess the clinical usefulness of the prediction model.ResultsA total of six clinical features were selected as independent predictors, including spiculated sign, vacuole, minimum diameter of nodule, mediastinal lymphadenectasis, sex, and age. The radiomics nomogram of lung nodules, consisting of 15 selected radiomics parameters and six clinical features showed good prediction in the training set [area under the curve (AUC), 1.00; 95% confidence interval (CI), 0.99–1.00] and validation set (AUC, 0.99; 95% CI, 0.98–1.00). The nomogram model that combined radiomics and clinical features was better than both single models (p < 0.05). Decision curve analysis showed that radiomics features were beneficial to clinical settings.ConclusionThe radiomics nomogram, derived from unenhanced thin-slice chest CT images, showed favorable prediction efficacy for differentiating LAC from LTB in patients with PSSN.

Sealing Behavior in Transcatheter Bicuspid and Tricuspid Aortic Valves Replacement Through Patient-Specific Computational Modeling

Background: Patient-specific computer simulation of transcatheter aortic valve replacement (TAVR) can provide unique insights in device-patient interaction.Aims: This study was to compare transcatheter aortic valve sealing behavior in patients with bicuspid aortic valves (BAV) and tricuspid aortic valves (TAV) through patient-specific computational modeling.Methods: Patient-specific computer simulation was retrospectively performed with FEops HEARTguide for TAVR patients. Simulation output was compared with postprocedural computed tomography and echocardiography to validate the accuracy. Skirt malapposition was defined by a distance larger than 1 mm based on the predicted device-patient interaction by quantifying the distance between the transcatheter heart valve (THV) skirt and the surrounding anatomical regions.Results: In total, 43 patients were included in the study. Predicted and observed THV frame deformation showed good correlation (R2 ≥ 0.90) for all analyzed measurements (maximum diameter, minimum diameter, area, and perimeter). The amount of predicted THV skirt malapposition was strongly linked with the echocardiographic grading of paravalvular leakage (PVL). More THV skirt malapposition was observed for BAV cases when compared to TAV cases (22.7 vs. 15.5%, p < 0.05). A detailed analysis of skirt malapposition showed a higher degree of malapposition in the interleaflet triangles section for BAV cases as compared to TAV patients (11.1 vs. 5.8%, p < 0.05).Conclusions: Patient-specific computer simulation of TAVR can accurately predict the behavior of the Venus A-valve. BAV patients are associated with more malapposition of the THV skirt as compared to TAV patients, and this is mainly driven by more malapposition in the interleaflet triangle region.