Rod Diameter Research Articles

Measurement of conductivity and diameter of metallic rods using eddy current testing

The conductivity and radius are significant parameters for metallic rods, which are associated with metal composition, hardness and microstructure. Accurate conductivity and radius measurement can reflect internal structure status of metallic rod, so as to prevent accidents. The method in this paper aims at simultaneously estimating the conductivity and diameter using sweep-frequency eddy current testing (ECT). This method is an extension of the analytical solution we proposed previously. Specifically, the peak frequency of the imaginary part of the self-inductance variation has the inverse relationship with conductivity. However, the peak frequency is also affected by rod diameter. In order to decouple the conductivity and diameter of metallic, the real part of self-inductance variation have been proved to be only related to the diameter of the metallic rod under high frequency. Combining the peak frequency and real part of self-inductance variation under high frequency, the conductivity and radius can be simultaneously obtained. The experiments using standard specimen are implemented to- verify the feasibility of the method. Results illustrate the average relative errors are within 1.4%.

Microstructure and mechanical properties in additive manufacturing by friction surfacing of AA6061 alloy

This present study uses a novel solid-state additive manufacturing method based on friction surfacing as a mechanism for layer-upon-layer deposition. This utilizes severe plastic deformation to create a homogeneous fine-grain microstructure without melting to avoid solidification-related defects. The deposition of AA6061-T6 aluminum alloy was achieved by rotating a 20 mm diameter rod on top of a substrate at 1000 RPM and applying a 300 mm/min transverse speed with an axial feed rate of 50 mm/min. Advanced macro/microstructural techniques characterized the grain and precipitate structures in the deposited material, i.e., electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) analyses, along with micro-hardness and tensile testing of the mechanical properties. The multi-layer deposition contains a refined grain size in the range of 5–10 μm and sub-grains less than micron size, while a reasonable reduction in mechanical properties compared to the as-received rod was observed; in which hardness was reduced from 114 HV to 49 HV, and the tensile strength was reduced from 333 MPa to 161 MPa. These reductions are largely attributed to the dissolution of precipitates in the original rod due to the high temperatures imposed by friction and deformation. Achieving metallurgical bonding between the layers while suppressing porosity is critical to additive manufacturing, and this feasibility study of friction surfacing demonstrates this can be achieved along with superior isotropic mechanical properties. Based on the results, it was observed that additive manufacturing by friction surfacing is particularly suitable for metals that are sensitive to heat during deposition, though parameter optimization and secondary treatment may be required to enhance properties further.

Mechanical behavior of glued-in GFRP rod in glubam: Experimental and analytical study

Fiber reinforced polymer (FRP) rod is a reasonable alternative to steel rod used in glued-in rod engineered bamboo structures, mainly attributed to its significantly higher strength-weight ratio and excellent corrosion resistance, while this field of study is almost empty. To fill this research gap, a total of 95 glued laminated bamboo (glubam) joints with single glued-in glass FRP (GFRP) rod were tested in a pull-pull tension loading program, aiming to shed light on the influence of anchorage length, rod diameter, bonding length-diameter ratio, glue-line thickness and rod-to-grain angle on the mechanical behavior. Particular emphasis was placed on the initial stiffness analysis and the explanation of the bond-slip mechanism based on the strain distribution of GFRP rod. Approximately 30% and 65% of the glued-in glubam joints can be categorized as the pure bonding failure at the glubam-adhesive interface and the shear failure in the glubam, respectively. It is found that the shear strength and initial stiffness of glubam joint decrease with increasing of the bonding length, the bonding length-diameter ratio, and the glue-line thickness, but the two indexes increase with increasing of GFRP rod diameter. The shear strength and initial stiffness exhibit an initial upward and then downward trend when the rod-to-main fiber direction angle varied from 0° to 90°. The analysis results reveal that the distribution of the local slip stiffness is non-uniform along the bonding length, also meaning that the local bond-slip relationships are varied at different locations. Based on the single-parameter correlation analysis, a strength model and an initial stiffness model are proposed for predicting the mechanical performance of glubam joints with glued-in GFRP rod for a potential application in evaluating actual glubam joints.

The coarsening behavior of strengthening particles in an Al–Cu–Mg–Ag alloy during creep

The coarsening behavior of strengthening particles has been studied in a peak-aged Al–Cu–Mg–Ag alloy during creep at 150 °C and 165 °C. The average {111}Al Ω plate thickness and diameter were observed to strongly depend on creep time and less on the applied stress levels and total plastic strain accommodated during creep. The volume fraction (FV) of Ω particles increased during long-term creep up to values exceeding that after peak-aging. The S-phase (Al2CuMg, Cmcm) fragments independently nucleate along dislocations and then intergrowth each other to form precipitate complexes together with the θ′-phase (Al2Cu, I4‾m2). The complex particle size including the θ′ plate thickness and the S rod diameter are sensitive to the total plastic strain level achieved at different applied stresses during creep.

Ultra-high output hybrid nanogenerator for self-powered smart mariculture monitoring and warning system

Remote monitoring of distributed mariculture based on Internet of Things (IoT) has become an important part of smart marine agriculture, however, attaining stable and long-lasting power supply from conventional commercial batteries remains challenging, which significantly restricts the development of blue economic toward intelligent and diversified. Herein, a self-powered monitoring and warning system (SMWS) for smart mariculture based on a nodding duck structured multi-layer hybrid triboelectric-electromagnetic generator (MHTEG) is developed that endows improved electrical output performances and energy conversion efficiency. The structure of multi-electrode pairs is investigated with various ratios of nylon rod diameter to electrode width for optimizing the charge transfer efficiency of MHTEG. A peak output power density of 20.9 W/m3, ultra-high output energy of 39.6 mJ and excellent energy conversion efficiency of 22.61% can be achieved by the MHTEG with a high charge transfer efficiency of over 88%. Moreover, combining the MHTEG with an anti-theft and seawater sensor module, the remote SMWS is designed for monitoring and providing early-warning in marine farming. Such a design renders a practicable strategy and generic energy solution for efficient ocean wave energy scavenging and enabling distributed mariculture with intelligence.

Concave rod first vs. convex rod first in AIS instrumentation with differential rod contouring: computer modeling and simulations based on ten AIS surgical cases.

To assess biomechanical differences between AIS instrumentations using concave vs. convex rod first. Instrumentations of ten AIS patients were simulated first with major correction maneuvers using the concave rod then with convex rod. Correction maneuvers were concave/convex rod translation, followed by apical vertebral derotation and then convex/concave rod translation. The concave/convex rods were 5.5/5.5 and 6.0/5.5mm diameter Co-Cr and contoured to 35°/15°, 55°/15°, 75°/15° and 85°/15°, respectively. Differences in simulatedthoracic Cobb angle (MT), thoracic kyphosis (TK) and apical vertebral rotation (AVR) were less than 5° between the two techniques; mean bone-screw force difference was less then 15N (p > 0.1). Increasing differential contouring angle from 35°/15° to 85°/15°, the MT changed from 14 ± 7° to 15 ± 8°, AVR from 12 ± 4° to 6 ± 5°, TK from 23 ± 4° to 42 ± 4°, and bone-screw forces from 159 ± 88N to 329 ± 170N (P < 0.05). Increasing the concave rod diameter from 5.5 to 6mm, the mean MT correction improvement for both techniques was less than 2°, the AVR correction was improved by 2°, the TK increased by 4° and bone-screw force increased by about 25N (p < 0.05). There was no significant difference in deformity corrections and bone-screw forces between the two techniques. Increasing differential contouring angle and rod diameter improved AVR and TK corrections with no significant effect on the MT Cobb angle. Although this study simplified the complexity of a generic surgical technique, the main effects of a limited number of identical steps were replicated for each case in a systematic manner to analyze the main first-order effects.

Additively Manufactured Parts from AA2011-T6 Large-Diameter Feedstocks Using Friction Stir Deposition.

The current work investigates the possibility of fabricating additive manufacturing products in solid-state form, from AA2011-T6 of 40 mm diameter rods as a feedstock, using an additive friction stir deposition (A-FSD) technique. The use of large diameter feedstocks, especially high-strength aluminum alloys (2XXX series), is a challenge, as it necessitates high power and the critical selection of the optimal A-FSD parameters, such as feed rate and spindle rotation speed. The study included applying a wide range of spindle rotation speeds, ranging from 400 to 1200 rpm, at three levels of feeding rates of 1, 3, and 5 mm/min. The AA2011-T6 friction stir deposited parts (FSDPs) were visually evaluated. This was followed by an examination of macrostructures through the thickness of the fabricated specimens. The characterization of microstructures was also carried out using optical microscopy and a scanning electron microscope equipped with advanced EDS analysis. Furthermore, the mechanical properties in terms of hardness and compressive strength of the AA2011-T6 base material (BM) and deposited materials were evaluated. Sound, additively manufactured products were successfully fabricated from 40 mm diameter AA2011-T6 feedstocks using the suggested deposition variables of 600 and 800 rpm spindle speeds and feeding rates of 1, 3, and 5 mm/min. The results indicated that the spindle speed and feeding rate govern the quality of the FSDPs. Furthermore, the axial load during the A-FSD process increased with increasing these parameters. In comparison to the AA2011-T6 BM, the additively deposited materials showed a refined grain structure and uniform dispersion of the fragment precipitates in their continuous multi-layers. The reduction ratio in grain size attains 71.56%, 76%, and 81.31% for the FSDPs processed at 800 rpm spindle speed and feeding rates of 1, 3 and 5 mm/min, respectively, compared to the grain size of BM. The Al2Cu and Al7Cu2Fe intermetallics are detected in the AA2011-T6 BM, and their deposited parts are in different shapes of spherical, almost spherical, irregular, and rod-like shapes. The compressive strength and hardness of the deposited parts increased with increasing spindle speed and feeding speeds. At a spindle speed of 800 rpm and a 5 mm/min feeding rate, the higher hardness and compressive strength gained were 85% and 93%, respectively, from that of the AA2011-T6 feedstock.

Invasion of Endophytic Bacteria by Using Microencapsulation Technology as Stimulant in Cocoa Plants (Theobroma cacao L)

Fertilization is an important process in the growth of cocoa (Theobroma cacao L). Fertilizing cocoa usually used inorganic fertilizers. Using of inorganic fertilizers continuously could degrading soil fertility. One of the efforts to replace inorganic fertilizers was using endophytic bacteria as biofertilizers. Some endophytic bacteria are abundant in healthy plant tissues. The aim of this research was to obtain endophytic auxin-producing bacteria in cocoa plants and determine the effect of seed immersion and microcapsules addition of endophytic bacteria on cocoa plant growth. The research design used was Complete Randomized Design (CRD), 16 treatments and 3 replications. The first factor was immersion of cocoa seed using endophytic bacteria suspension consisting of S0= 0 hours; S1= 5 hours; S2= 6 hours and S3= 7 hours and the second factor was microcapsules addition consisting of B0= 0 gr; B1= 5 gr; B2= 10 gr; B3= 15 gr. Isolation from the roots and stems of cocoa obtained 5 isolates endophyte bacteria. Auxin assays showed that five isolates were able to produce auxin. Observations on plant height showed the best treatment was treatment B1 (32.49 cm). Observation of total leaves showed S3 treatment was the highest data (11.83 strands). Observation rod diameter parameter, highest data was S3 treatment (4.01 mm). For leaf area parameter, highest value was B1 treatment (66.64 cm2). For wet weight parameter, highest data was S3 treatment (18.41 g). Root length parameter, highest data was B3 treatment (15.78 cm). Test results showed that the application of suspension and microcapsules of endophytic bacteria significantly increased growth of cocoa.

The Correlation Between Scatter Detector Performance and Spatial Resolution in a Ring-Shaped Compton Imaging System

Whole gamma imaging (WGI) is a new concept that combines PET and Compton imaging by inserting a scatter detector ring into a PET ring. We developed a WGI prototype and demonstrated three-dimensional tomographic Compton imaging of a 89Zr-injected mouse. However, improving the scatter detector performance, i.e. crystal pitch and energy resolution, was required for high resolution Compton imaging. Therefore, we investigated the correlation in Geant4 simulations using 909 keV gamma rays emitted from 89Zr. Three WGI geometries consisting of the scatter detector ring with different GAGG crystal sizes (0.9 W 0.9 W 6 mm3, 1.45 W 1.45 W 6 mm3 and 2 W 2 W 6 mm3) were modeled. The energy resolutions were obtained experimentally for application to the simulation data. Also, the values were virtually halved and 1.5 times degraded. Simulations of a point-like source were carried out varying the pixel pitch in the scatter detector and images were reconstructed. For a source placed at the center of the system, a spatial resolution of 1.7, 1.9 and 2.3 mm was obtained with pixel pitches of 0.9, 1.45 and 2 mm, respectively. The spatial resolution of the system obtained with the 0.9 mm scatterer was improved to 1.4 mm for the halved energy resolution and it was deteriorated to 2.1 mm for the 1.5 times degraded energy resolution. In the hot-rod-like phantom simulation, 2 mm diameter rods were separated in the reconstructed images with the 0.9 mm scatterer. The separation became clearer for the halved energy resolution.

Features of coolant movement at the boundary of jacketless fuel assemblies with fuel rods of various diameters

Features of coolant movement at the boundary of jacketless fuel assemblies with fuel rods of various diameters

Bistability in the wake of a circular cylinder with passive control using two leeward rods

This paper presents an experimental investigation on the flow around a circular cylinder controlled by a pair of rods placed close to the separated shear layers from the leeward face of the cylinder. Past research of Cicolin et al. (2021) has shown that one control rod, placed at specific positions, induces a late flow separation on the main cylinder’s surface in a typical occurrence of the Coandă effect. As a result the control rod reduced the mean drag acting on the cylinder but also produced a net mean lift force. We now present an extension of the aforementioned study to consideration of a pair of symmetrically arranged control rods, aimed at eliminating the mean lift force whilst maintaining a drag reduction. The experiments were carried out at a Reynolds number Re=20,000 based on the diameter of the main cylinder D, with the diameter of the control rods being ten times smaller than that of the cylinder. The centre-to-centre distances between each control rod and the cylinder was 0.7D, and the angular position of the rods varied from θ=120∘ to 125∘, where θ is measured from the front stagnation point. Time-resolved PIV velocity fields and hydrodynamic forces were measured for the different setups. Results show that the mean flow is asymmetric in spite of the symmetry of the geometric model and position of the rods. The pair of control rods induces a bistable flow, induced by the imbalance of two colliding jets in the near wake. The dynamics were found to be random, with the average switching time between stable states depending on the position of the rods. The mean drag force was reduced by up to 15%, and the mean lift force was reduced by 80% compared to the cases with a single control rod. It was also observed that the control rod can induce two different types of flow separation from the main cylinder, one in which the flow separates from the main cylinder only once and one in which a small separation bubble forms in proximity to the control rod before reattaching and then permanently separating. These distinct features play an important role in the dynamics of the bistability and hint at a possible extension of the total drag reduction to 30% if the bistability is suppressed.

Fuel lifetime extension for the KLT-40S small modular reactor by means of thorium-uranium fuel cycle

This paper demonstrates the results of the Monte Carlo simulation conducted with MCU-PTR software for a small modular pressurized water reactor KLT-40S. Four dispersed fuel compositions, (U238 + U235)O2, (U238 + Pu239)O2, (Th232 + U235)O2, and (Th232 + U233)O2, were examined for fuel lifetime and fuel burnup calculations.The transition to the (Th232 + U233)O2 fuel composition extends fuel lifetime by 50% and fuel burnup by 44% at design value of the fuel rod diameter. If the fuel rod diameter for (Th232 + U233)O2 fuel composition is increased to 7.2 mm, fuel lifetime is extended by 105%, and fuel burnup is extended by 38% compared to the design values.

Experimental Investigation on the Penetrability Mechanism of Gel Slug During Well Completion Processes.

Reservoir formation damage is an essential problem which troubled oil and gas well production, a smart packer is a promising technology to maintain sustainable development for the oil and gas fields. Currently, the "gel valve" technology has been proved to be feasible with gel slug to seal casing and descend the completion pipe string, while the systemic performance of ideal gel is still not clear. In the underbalanced completion stage with the gel valve, the downward completion string needs to penetrate the gel slug to form an oil and gas passage in the wellbore. The penetration of rod string to gel is a dynamic process. The gel-casing structure often shows a time-dependent mechanical response, which is different from the static response. In the process of penetration, the interaction force between the rod and gel is not only related to the properties of the interface between gel and string but also affected by the moving speed, rod diameter, and thickness of the gel. The dynamic penetration experiment was carried out to determine the penetrating force varied with depth. The research showed that the force curve was mainly composed of three parts, the rising curve of elastic deformation, decline curve for the surface worn out, and another curve of the rod wear into. By changing the rod diameter, gel thickness, and penetration speed, the change rules of forces in each stage were further analyzed, which would provide a scientific basis for a well completion design with a gel valve.

Distal fusion in Duchenne scoliosis: the relevance of preoperative pelvic obliquity. A case series study.

The aim of this study was to determine clinical and radiographic outcomes for Duchenne Muscular Dystrophy (DMD) patients who underwent posterior spinal fusion from T2/3 to L5 (without pelvic fixation), at this single centre. From January 2012 to January 2020, 29 consecutive DMD scoliosis patients underwent posterior spinal fusion using pedicle screws from T2/3 to L5 in a single center with a minimum of 3years follow-up (FU). Radiologic measurements and chart review were performed. Twenty nine patients aged 14 ± 1.5years were included. No patient was lost to FU. All patients had significant correction in Cobb angle, pelvic obliquity (PO) and lumbar lordosis (LL), without loss of correction at last FU. The mean values for preoperative, immediate postoperative and last FU were CA 62o, 15o and 17o, PO: 21o, 8o and 9o; and LL 10o, -41o and -41o respectively. Correction in CA was independent of any variable analysed including implant density, rod diameter, traction, or bone density. Regarding PO, it was inversely related to age and independent of all other variables. Factors associated with postoperative complications were age and respiratory function. It appears from our results that pelvic fixation might not always be required in DMD scoliosis surgery, when using pedicle screws with lowest instrumented vertebra at L5. However, larger preoperative PO values can be related with residual PO. It seems that probably related to the underlying condition, early surgery may decrease incidence of complications. IV.

Noise reduction performance of a deep learning-based reconstruction in brain computed tomography images acquired with organ-based tube current modulation.

We aimed to evaluate the image quality of brain computed tomography (CT) images reconstructed using deep learning-based reconstruction (DLR) in organ-based tube current modulation (OB-TCM) acquisition. An anthropomorphic head phantom and a cylindrical low-contrast phantom were scanned at the standard dose level for adult brain CT in axial volume acquisition without OB-TCM. Moreover, image acquisition with OB-TCM was performed. The radiation dose on the eye lens was measured using a scintillation fibre-optic dosimeter placed on the anthropomorphic phantom's eye surface. The task transfer function (TTF), contrast-to-noise ratio (CNR), and low-contrast object specific CNR obtained from low-contrast phantom images reconstructed with filtered back projection (FBP), hybrid iterative reconstruction (HIR), and two types of DLR (DLRCTA and DLRLCD) were compared. In result, OB-TCM achieved a 32.5% dose reduction in the eye lens. Although HIR, DLRCTA, and DLRLCD showed lower TTF than FBP, the difference in TTF at the highest contributing spatial frequency corresponding to the contrast rod diameter was < 10%. Despite the OB-TCM acquisition, DLRCTA and DLRLCD achieved significantly lower noise and a higher CNR than FBP without OB-TCM (p < 0.05). However, low-contrast object specific CNR was equivalent among all reconstruction methods for the objective diameter of 5mm and slightly improved in DLRLCD for the objective diameter of 7mm. DLR with OB-TCM acquisition enabled dose reduction for the eye lens and high CNR image appearance, whereas the low contrast detectability evaluated by low-contrast object specific CNR did not always improve.

Reducing scan time in 177 Lu planar scintigraphy using convolutional neural network: A Monte Carlo simulation study.

The aim of this study was to reduce scan time in 177 Lu planar scintigraphy through the use of convolutional neural network (CNN) to facilitate personalized dosimetry for 177 Lu-based peptide receptor radionuclide therapy. The CNN model used in this work was based on DenseNet, and the training and testing datasets were generated from Monte Carlo simulation. The CNN input images (IMGinput ) consisted of 177 Lu planar scintigraphy that contained 10-90% of the total photon counts, while the corresponding full-count images (IMG100% ) were used as the CNN label images. Two-sample t-test was conducted to compare the difference in pixel intensities within region of interest between IMG100% and CNN output images (IMGoutput ). No difference was found in IMGoutput for rods with diameters ranging from 13 to 33mm in the Derenzo phantom with a target-to-background ratio of 20:1, while statistically significant differences were found in IMGoutput for the 10-mm diameter rods when IMGinput containing 10% to 60% of the total photon counts were denoised. Statistically significant differences were found in IMGoutput for both right and left kidneys in the NCAT phantom when IMGinput containing 10% of the total photon counts were denoised. No statistically significant differences were found in IMGoutput for any other source organs in the NCAT phantom. Our results showed that the proposed method can reduce scan time by up to 70% for objects larger than 13mm, making it a useful tool for personalized dosimetry in 177 Lu-based peptide receptor radionuclide therapy in clinical practice.

Optimum depth of a lower concrete grade at the tension zone in a two-layer reinforced concrete beam

This paper presents the results of an investigation into the optimum depth of the lower concrete grade (LCG) at the tension region in a two-layer reinforced concrete beam. A total of nine (9) simply supported two-layer RC beams (1100 x100 x150 mm) were studied. Two 8 mm and two 6 mm diameter rods were used as reinforcement at the bottom and top of each two-layer beam, respectively. The beam samples were grouped into two: the first group comprises two-layer RC beams produced with 1:2:4 as the higher grade and 1:3:6 as the lower grade; the second group comprises two-layer RC beams cast with 1:2:4 as the higher grade and 1:4:8 as the lower grade. The depth of LCG adopted for each group is 25 mm to 100 mm at a step of 25 mm out of the total beam depth of 150 mm. The beams were subjected to two-point static loading to evaluate the load resistance and deflection. The results show that the greater the depth of the layer under compression, the stiffer the beam. The two-layer RC beam has an equal loading carrying capacity as the beam made entirely of higher grade. The depth of the layer of RC beam under tension in two-layer beams should be kept between 40 and 50% of the overall beam depth, which would be desirable structurally.

(470) Malleable Penile Implant Rod Diameter Predicts Complications And Patient Satisfaction

Abstract Introduction One of the most common complaints after malleable prosthesis implantation (MPI) is thinning of the penis and decreasing girth. Some surgeons try to insert the largest diameter they can to improve patient satisfaction Objective To investigate if malleable rod diameter (MRD) has an impact on outcome and patient satisfaction Methods Consecutive malleable prosthesis implanation (MPI) was assessed in a high volume center over one year. The same preoperative, intraoperative, and postoperative protocols were used for all patients and one brand of the malleable device was used only. We recorded MRD and length for all patients. All patients had data on comorbidities including glycated hemoglobin (HbA1c) and clinical Peyronie’s disease (PD). Revision cases and those who lost for follow up were excluded from the study. We also excluded patients operated on by low volume surgeons. All complications, minor (edema, ecchymosis, pain), and major (infection and erosion) were recorded. After 1-year, patients were assessed and given a Likert scale from 1-5 where 1 is dissatisfied and 5 is most satisfied with their MPI. We stratified patients according to MRD into two groups: group A for diameter 9.5 and 11 mm and group B for 13 mm. Results 183 patients had full data and filled the questionnaire after 1 year follow up. All patients had Coloplast, Genesis penile implants. Major complications rate (infection, erosion, and removal) was significantly higher in group B 11% versus 1.2% in group A (P=0.016). At 4 weeks postoperative visit, 90 % of group A showed no complications versus 60 % only in group B that was statistically significant (p=0.0003). Satisfaction rate was more in patients in group A (88.6%) compared to patients in group B (75.7%)but this did not reach to be statistically significant (P=0.0519). See Table 1. Conclusions Larger diameter of malleable penile implants are not always associated with higher patient satisfaction as there are other predictors like postoperative complications and concealement. The best implant size for a certain patient is the best fitting, neither the oversize nor the undersize. Disclosure No

基于 EDEM 的顶杆输送带式取苗机构优化设计

In the seedling extraction mechanism of the ejection type, because the ejector rod is in direct contact with the seedling substrate, the fragmentation rate of the seedling is high, the success rate is low, and the seedling effect is poor. In order to solve this problem, combined with the interaction between the ejector rod and the bowl seedling, this paper analyzes the working principle of the ejector rod conveyor belt seedling harvesting mechanism, and optimizes the design of the ejector rod conveyor belt seedling harvesting mechanism. By using the method of EDEM simulation analysis and orthogonal experiment, taking the breaking rate and success rate of bowl seedling as the test response index, the effects of ejector rod end form, ejector rod diameter and seedling extraction speed were studied, and the results were analyzed by range analysis and variance analysis to analyze the influence law of the interaction of various factors on bowl seedling extraction. The simulation results show that the crushing rate of bowl seedlings increases with the increase of seedling speed and the decrease of ejector diameter. Among the three different types of ejectors, the effect of round head ejector is the best. The best parameter combination of the seedling mechanism is the diameter of the ejector rod 10mm, the seedling speed 2m/s, and the ejector rod in the form of round head ejector rod. The verification experiment shows that the seedling extraction effect of the optimized seedling extraction mechanism is better than that of the original seedling extraction mechanism. The results show that when the best combination of working parameters is used to collect seedlings, the qualified rate of seedlings is not less than 90%, the fragmentation rate is not higher than 20%, and the seedling performance is relatively stable. The optimized seedling extraction mechanism can be used in the automatic dryland bowl seedling transplanter to meet the operational requirements of the automatic transplanter.

Numerical modeling investigation of cross-laminated timber connections consisting of multiple glued-in rods

Glued-in rods are stiff and high-capacity connections that are used in timber structures. Regardless of the many advantages of glued-in rods, research on the glued-in rods in CLT is limited, especially on numerical modeling. This paper provides the numerical modeling principles, validation details, and parametric studies of glued-in rods embedded on the edge of CLT. The numerical modeling was performed on a 3D finite element basis, and the cohesive surface method was used to define the bond lines along the rods. To validate the numerical models, 24 replica experiments were performed and investigated the effect of the rod diameter and of the embedment length on the pull-out strength of rods embedded perpendicular, parallel, and on the boundary of two cross-wised layers. The numerical models were validated according to the maximum load, stiffness, as well as the failure mode of the glued-in rods. The numerical models showed high reliability in simulating the experiments and predicted the strength of the glued-in rods with a maximum of 4% difference. After validation of the numerical models, the parametric study covered the pull-out strength investigation of rods with 20, 24, and 30 mm diameter and anchorage lengths of 250, 350, and 450 mm embedded in the perpendicular, parallel, and on the boundary of cross-wised layers on the edge of 5 and 7 layer CLT panels. The findings showed that increasing the embedment length and rod diameter enhanced the pull-out strength of the glued-in rods, regardless of where the rod was positioned on the CLT's edge. Rods embedded perpendicular to the grain showed the highest pull-out strength, and two rods with 30 mm diameter and 450 mm embedment lengths reached 961 kN pull-out strength. Numerical models showed that for the same diameter and embedment length of two rods embedded on the parallel and on the boundary of two cross-wised layers reached 836 and 738 kN pull-out strength, respectively. Finally, A design equation is provided to determine the pull-out strength of the glued-in rods embedded in CLT based on the shear strength of the bondline.