Flat Head Research Articles

Analysis of TB2 rivet forming quality and mechanical properties of thin sheet riveted joints based on different riveting methods

The riveting of high-strength rivets (such as TB2 (Ti-5Mo-5V-8Cr-3Al)) faces difficulties in forming. This article compares the electromagnetic riveting (EMR) and the hot riveting (HR) joints of two typical TB2 rivets (the flat cone head rivet and the countersunk head rivet). The interference and hardness distributions of the rivets were measured, and the strength of the joints was tested. Moreover, the microstructures of rivets after riveting and the fractured surfaces after the shear and pull-out tests were both observed. The results indicate that the interference of the EMR joints is greater and more uniform than that of the HR joints. The deformation of the EMR driven head is more severe than that of the HR. Higher hardness is measured in the driven head and the rivet shank at the positions of severe deformation. The hardness of the EMR driven head and rivet shank is higher than that of the HR. Additionally, it will not cause a decrease and even slightly improve in the mechanical properties of the joint when using the EMR riveting TB2. The pull-out strength of flat cone head rivet joints is significantly higher than that of countersunk rivet joints due to the influence of the structure strength of the manufactured head. The fracture mode of all joints is mixed fracture. However, the failure mode of joint varies greatly due to the influence of rivet structure and riveting method. When using the EMR instead of the HR to rivet the TB2 rivets, it will not cause a decrease in the mechanical properties of the joint. Therefore, it is indicated that the EMR can be used to replace the HR.

Polystemma stevensii (Apocynaceae, Asclepiadoideae), a new species from Michoacán, Mexico

Polystemma stevensii, a new species from Michoacán, Mexico, is described and illustrated. It grows in tropical deciduous forest in the Balsas Depression at elevations from 350 to 750 m. Polystemma stevensii is similar to P. viridiflorum but differs by having a gynostegial corona with five lobes fused at the base to form a discontinuous flat ring (vs. not forming a discontinuous flat ring), an internal corona with two deltate lobes (vs. with one ligulate lobe), and globose style head (vs. flat style head). A distribution map of the new species and a key to determine the Polystemma species of Michoacán are provided. Following IUCN Red List guidelines, it is assigned a preliminary category of endangered, EN B1ab(i,ii,iii)+2ab(i,ii,iii). Polystemma now includes eight species, of which five are endemic to Mexico.

Effect of lamination sequence and warhead shape on impact resistance of fiber‐metal laminates

AbstractIn this work, the failure mode and ballistic protection capability of the carbon fiber aluminum alloy laminated target plate under the impact of high‐speed projectile body were studied by ballistic impact test. The effects of the lamination sequence and warhead shape difference on the impact resistance of the laminated aluminum alloy and carbon fiber laminates were analyzed. Two kinds of projectile bodies, flat and oval head, were used to carry out multiple high‐speed impact experiments on four groups of targets with different stacking sequences. By analyzing the result, it is found that the lamination sequence of the target plate has a significant effect on the anti‐impact performance only when the flat head projectile impacts, while the ovoid projectile has almost no effect. In the fiber‐metal composite configuration, the aluminum plate placed in front of the carbon fiber plate showed the best resistance to flat head bullet impact, the ballistic limit speed reached 135 m/s, and the overall impact resistance improved by up to 26% compared with other configurations. Unlike the shear failure caused by flat head projectile, ovoid projectile impact can cause serious tensile and tear damage. Based on the experimental results, it is clear that the laminated structure has better penetration resistance against the flat head projectile, and the placement of aluminum plate on the impact surface can change the failure mode of carbon fiber laminates and improve the energy absorption level of composite plates.Highlights Unlike traditional fiber‐metal laminates, the target plate used in this experiment does not use adhesive, which makes the deformation of the two materials will not affect each other, which is conducive to the study of its own impact resistance. The mechanical behavior and damage failure mode of the target plate under high speed impact load were studied. The impact of ovoid projectile changes the damage failure mode of the target plate. For the configuration of fiber‐metal laminates, the ballistic limit value is as low as 100 m/s, and the energy absorption value fluctuates in the range of 145–190 J with the change of impact velocity. Compared with ovoid projectile, laminated material has stronger impact resistance to flat head projectile. The metal plate arranged on the impact surface can change the damage mode from shear failure to tensile failure, thus greatly improving the ballistic limit and impact resistance, overall impact resistance can be improved by up to 26%.

Clinical outcomes of primary Latarjet technique in recurrent shoulder dislocation using BioLatarjet® LCS cannulated flat head screws

Background: The Latarjet technique is an effective procedure that reconstructs and augments the glenohumeral joint instability. It improves stability by increasing the glenoid width and using the sling effect. The aim of the study was to assess the functional outcomes of the primary Latarjet treatment with BioLatarjet® LCS cannulated flat head screws in cases of recurrent shoulder dislocation. Methods: In this retrospective study, 30 patients were treated with the primary Latarjet technique. Rowe score, visual analog scale (VAS), Quebec back pain disability scale (QDS), and, American shoulder and elbow surgeon score (ASES), and range of motion (ROM) were evaluated in the selected population at the time point of 6-week, 3-month, and 6-month after surgery for the determination of the functional outcomes in them. Results: The results showed that all patients had excellent or good functional outcomes with significant improvements in Rowe score, VAS score, QDS, and ASES scores (p<0.0001). The ROM in patients for forward elevation, cross body adduction, external rotation by side of body/neutral, and internal rotation by side of body/neutral were related to better clinical outcome and less movement of recurrent instability with optimal graft placement. Conclusions: These findings have clinical significance in that they demonstrate the effectiveness of the Latarjet technique in improving stability without significantly increasing the risk of complications. The BioLatarjet® LCS cannulated flat head screws were found to be safe and efficient for primary Latarjet surgeries, providing appropriate graft healing and a low recurrence of instability, with a good return-to-sports rate.

Effects of the launch parameters on trans-phase stability performance and mechanism for submarine-launched missiles model

The impact of missile head shape, launch angle, and Fr number on the stability of trans-phase missiles was investigated, providing both experimental and theoretical support for designing diverse ballistic trans-phase weapons and aircraft. Through water-to-air trans-phase experiments and numerical calculations of missiles, deflection angle, velocity, and trajectory are obtained, while statistical and flow-field analyses reveal associated stability mechanisms. The research results indicate a good agreement between the experimental and numerical results. As the Fr number increases for the same head shape, the variations in transient deflection angle decrease. The deflection angle shows notable variations for different head shapes under the same Fr number. Specifically, the flat head demonstrates the highest deflection angle, followed by the 120° conical head, the 90° conical head, and finally the round head shape. Different head shapes lead to varying water film deformations and turbulent kinetic energy dissipations, resulting in differences in shedding vortex intensity and frequency. Launch angles cause variable component wall shear forces and fluid resistances, while changing the Fr number affects initial kinetic energy and energy dissipation, leading to missile model stability differences.

The electro-mechanics of piezoelectric coating structure under frictional contacts

In papers of the piezoelectric coating/substrate system under smooth spherical contact (DOI: 10.1177/1081 286519 865773), conical contact (DOI: 10.1016/j.ijsolstr.2019.08.031), and cylinder flat head contact (DOI: 10.1007/s11012-019-01085-1), Green’s function method has been applied to solve the problem of piezoelectric friction contact. We deduced the analytical expression of piezoelectric coating structure, which is expressed by elementary functions. The numerical results highlight the best thickness to maintain a higher potential difference and a critical potential difference. This study has guiding significance for the future research and analysis of friction signals in intelligent manufacturing, such as piezoelectric tactile sensors.

Erratum: Eyestalk Ablation to Increase Ovarian Maturation in Mud Crabs.

Erratum: Eyestalk Ablation to Increase Ovarian Maturation in Mud Crabs.

In-situ fabrication of repairing layers for large structures using follow-up hot-hammering-assisted wire arc additive manufacturing

The development of a spherical hammer head follow-up hot-hammering-assisted (FH) hybrid wire arc additive manufacturing enables the application of the hammering-assisted process to the in-situ repair of large-scale structural parts. This process allows for large deformation in the deposited weld bead with lower energy input at higher temperatures, resulting in less work hardening. A thermal, mechanical and plastic deformation coupled finite element model is established to analyze the plastic strain distribution with different shapes of hammer heads and different deformation history. Compared with the flat hammer head, the spherical hammer head is more likely to produce large plastic deformation in deposited weld bead under the same force and energy conditions, and obtain more uniform microstructure. Different hammering temperatures higher than austenite recrystallization temperature with the spherical hammer head, are selected to study the effect on grain refinement of repairing layers. The OM, XRD, SEM and EBSD are used for grain, texture evolution and strengthening mechanism analysis. The results show that by introducing the spherical hammer head FH process at 980 °C slightly higher than the austenite recrystallization temperature, the grain size decreases gradually from the bottom repairing layer to the top one, showing a genetic evolution law. The topmost repairing layer grain size is refined from 353 μm to 30 μm, the average grain size of repairing layers is refined from 361 μm to 62 μm, and the strong {100} texture of the topmost repairing layer is reduced to be approximately random. The grain refinement is attributed to the combined influence of recrystallization and co-generation crystallization. Meanwhile, the yield strength is significantly improved, and the main strengthening mechanisms are grain refinement strengthening and dislocation strengthening, and the contributions are 42.0 MPa and 101.4 MPa.

Aviation Rivet Classification and Anomaly Detection Based on Deep Learning

The shortage of personnel and the high cost have become a major pain point in the current safety supervision work of the inspectors. Aiming at the problem that the aircraft maintenance inspector could not visit the scene in person during the epidemic, a remote safety supervision platform was built based on intelligent glasses and 5G network, and the real-time monitoring of the aircraft skin rivet status was realized. And a method of aviation rivet classification and anomaly detection based on deep learning algorithm was proposed. Firstly, according to the appearance of rivet head, the aviation rivet is classified, the data set of aviation rivet is made, and the aviation rivet classification and anomaly detection model are constructed. Evaluate the detection results from such indicators as confidence, precision, recall rate, and mAP and compare the algorithm with the detection results of Yolox-s, Yolox-m, Yolov5-s, Yolov5-m, and Yolov4. The results show that (1) the algorithm proposed in this paper can realize the classification of aviation rivets and the detection of abnormal conditions, the confidence of the detection results is more than 90%, and the average precision, recall, and AP value are above 95%, 85%, and 88%, respectively. (2) The order of rivet classification and abnormal detection effect from good to bad is Philips screws, round head rivets, flat head rivets, countersunk head rivets, blind rivets, and abnormal condition. (3) Compared with other algorithms, the aviation rivet classification abnormal target detection based on deep learning has absolute advantages in accuracy and speed.

Selective-area growth of GaN and AlGaN nanowires on N-polar GaN templates with 4° miscut by plasma-assisted molecular beam epitaxy

In this study, selective area growth (SAG)s of AlGaN/GaN nanowires (NWs) on miscut N-polar GaN templates were studied and compared with that grown on Ga-polar templates using plasma-assisted molecular beam epitaxy (MBE). The SAG of N-polar AlGaN/GaN NWs demonstrated higher growth rate and more growth selectivity than that of Ga-polar AlGaN/GaN NWs. Additionally, lateral growth rate of N-polar NWs was significantly lower than Ga-polar NWs. Compared to the pyramidal shaped top surfaces of Ga-polar NWs, the N-polar GaN NWs had flat head top surfaces. The combination of higher growth selectivity, larger growth window, negligible lateral growth, and flat head, makes N-polar (Al,Ga)N NWs attractive for a variety of applications including UV LEDs and detectors as well as quantum sensing.

Analysis of Plane Displacement of Pressure Vessels with Defects

Aiming at the problem that the internal defects of the pressure vessel are not easy to detect, the out-of-plane displacement method is used to study it. The out-of-plane displacement field of circular flat plate heads with defects is obtained by the method of elastic theory analysis and compared with the finite element method to verify the accuracy of the finite element method. Based on the finite element method, the effects of vessel material, pressure load, defect shape, and defect size on the first-order out-of-plane displacement derivative are studied. The results show that the material of the container has little effect on the out-of-plane displacement. The first derivative of out-of-plane displacement increases linearly with the increase of pressure, and this relationship will not change with the increase of pressure. With the increase of defect aspect ratio, the maximum value of the first derivative of out-of-plane displacement increases gradually. When δ ˃ 9, the defect is detectable. The research results lay a theoretical foundation for the internal defect detection of pressure vessels based on digital speckle shearing interferometry.

The Quality and Readability of Online Patient Information on Positional Head Shape Conditions.

Families increasingly use online resources to acquire medical information about their child's condition with little understanding of the legitimacy of the source of information or of the information itself. We evaluate the quality and readability of online information related to positional head shape conditions and identify unmet needs for healthcare providers to improve online patient education. The search terms "flat head baby," "brachycephaly," and "plagiocephaly" were queried on the Google search engine and the first 20 websites for each were reviewed. Included websites were evaluated for quality using the DISCERN Instrument and readability using the Flesch-Kincaid Reading Grade Level (FKGL) and Flesch Reading Ease Score (FRES). Websites were categorized by upload source and results were compared using one-way ANOVA. 38 websites met inclusion criteria. There was no significant correlation between DISCERN score and Google search rank between the three search terms. Professional organizations provided websites with the highest mean DISCERN score (56.3) and commercial websites with the lowest score (36.6, P = .003), indicating "good" and "poor" quality content, respectively. Readability assessments showed an overall average FKGL of 9.9 and FRES of 54.4, suggesting "fairly difficult". Hospitals provided the most website results and tended to publish lower quality information, yet are the most readable. High quality websites written at an appropriate reading level for the general public are lacking. A review of online resources for positional head shape conditions can be used to derive recommendations to improve the content of online patient education for pediatric healthcare.

Living apart together: Morphological, spatial, and genetic differentiation of three sympatric rock lizard species (Lacertidae: Darevskia) of the Caucasus

Three rock lizard species (genus Darevskia) occur in the same mountain gorge of the Greater Caucasus mountains located in Northern Georgia. Whereas Darevskia caucasica and Darevskia derjugini belong to the same phylogenetic clade known as “caucasica”, Darevskia rudis is associated to the “rudis” clade. The mountain lizards differed interspecifically in their scalation and ventral colouration patterns, but the body proportions of D. caucasica and D. rudis were more similar to each other than to D. derjugini as both had flatter heads and longer limbs than D. derjugini. Females of all three species had longer trunks and shorter limbs than males. We hypothesized that hybrids occur more likely between D. derjugini and D. caucasica rather than between species belonging to different clades. However our analysis of microsatellite genotyping clearly revealed no traces of hybridisation and/or gene flow among any of the coexisting lizard species. The absence of individuals with intermediate morphological and genetic features reflects the presence of strong reproductive barriers at the prezygotic level.

Advanced turbulence and combustion modeling for the study of a swirl-assisted natural gas spark-ignition heavy-duty engine

Increasing demands on higher performance and lower fuel consumption and emissions have led the path for internal combustion engine development; this race is nowadays directly related to CO2 emissions reduction. To drive engine development and reduce the time-to-market, the employment of numerical analysis is mandatory. This requires a continuous improvement of the simulation models toward real predictive analyses able to reduce the experimental R&D efforts. In this framework, 1D numerical codes are fundamental tools for system design, energy management optimization, and calibration. The present work is focused on the improvement of the phenomenological turbulence model, originally conceived to describe turbulence evolution in tumble-promoting engines. The turbulence model is developed with reference to a SI heavy-duty CNG engine derived from a diesel engine. In this architecture, due to the flat cylinder head, turbulence is also generated by swirl and squish flow motions, in addition to tumble motion. The presented turbulence model is validated against 3D CFD results, demonstrating to properly predict turbulence and swirl/tumble evolution under two different operating conditions, without the need for any case-dependent tuning. The developed turbulence model is coupled to a phenomenological combustion model based on the fractal geometry theory applied to the flame front surface, where the turbulence is assumed to support flame propagation through an enhancement of the flame front area with respect to the laminar counterpart. The combustion model is validated against an extensive experimental dataset, composed of 25 operating points at different engine rotational speeds and loads. The numerical/experimental comparisons of global performance parameters are satisfactory, leading to maximum errors around ±2% for the BSFC, ±2° for the main combustion events, and ±1 bar for the in-cylinder peak pressure. Burn rate profiles are very well captured by the combustion model at changing operating conditions, not requiring any case-dependent tuning. The presented results demonstrate that the turbulence/combustion models could constitute a reliable virtual test facility, contributing to supporting and driving experimental activities.

마스크와 모자 개발을 위한 20∼24세 남성의 얼굴 및 머리 유형 분석

This study attempted to analyze the face and head shape of 20∼24 aged males using the 8th Size Korea Survey and classify the types to find out the characteristics of each type. Through this, it was intended to provide data to help develop fashion items that span the face and head, such as masks and hats. A total of 39 items of data were analyzed with the SPSS 26.0 program. Among the measurement items on the face and head of men in 20∼24, the items with the largest standard deviation were Head Circumference, Bitragion Coronal Arc, Sagittal Arc of Head, Bitragion Cellion Arc, Bitragion Chin Arc, Menton to Occiput Length, etc. There are many items related to the vertical length of the face and head, indicating that men in 20∼24 have a large individual difference in the vertical length of the face and head. The face and head parts of 20∼24 aged males were classified into six categories: face and head vertical, face front width, face, and head thickness, eye spacing, under-eye vertical, and face protrusion. There were four types: short lower face & short face type, long lower face-flat face and thick head type, long-big face and flat head type, and wide-protruding face and thick head type. When developing a mask pattern, the mask

Cloth face mask fit and function for children part two: Material Selection

The second component of this three-paper series studying cloth face masks for children ages 4 to 6 years old concentrates on optimizing aerosol capture and air permeability through fabric selection. Material choices were evaluated in two modes: Flat Filter (FF) and Head Form (HF). FF isolates material factors while HF simulates the performance of the constructed masks on a 3D printed child head form. In FF mode, higher filtration efficiency correlated to lower air permeability in both reusable commercial and experimental face masks regardless of fiber contents, fabric structures, and number of layers. Our prototype face mask developed in design exploration successfully captured 37 ± 12% of 0.3 μm, 87 ± 3% of 0.5 μm, and 87 ± 2% of 1.0 μm particles while maintaining good air permeability, moisture capture, and aerosolized salt capture in HF mode. Sealing masks to minimize outward leakage reduced particle capture up to 64%. Particle leakage data captured at the eye level of the head form illuminated the synergy between mask design, material choice, and fit.

The influence of calcium carbonate and its modifications on the extrusion process and selected functional properties of polypropylene cast films

The purpose of the article was to determine the influence of calcium carbonate and its modification (with stearic acid) on selected properties of composite polypropylene films and their processing. Polypropylene composites containing, respectively, 5, 10, 20 and 30 wt% filler, were made in twin-screw extrusion process with cold granulation. Films, on the other hand, were produced in single-screw extrusion process (an extruder with a screw with diameter d = 20 mm and ratio l/d = 24) using a flat head (so-called cast films) and a chill roll type cooling and pull-back device. The pull-back rotational speed was selected so as to obtain films of a thickness of approx. 120 µm, irrespectively of the composite being processed. The assessment of the effect of the addition of applied fillers on the magnitude of the melt volume-flow rate (MVR) of polypropylene and the processing characteristic of extrusion process was made (the flow resistance and the variations in volumetric flow rate were determined). It was demonstrated how variations in the processability of polymeric material determined the correction of extrusion process setup parameters (pull-back system speed). The processability of composite films under extensional flow conditions was also determined by evaluating the extensional viscosity (ηE) of the composites. The strength values of composite films were determined under static tension conditions and in puncture tests. The effect of the content and modification of CaCO3 on the film haze and gloss was also assessed. The investigation carried out has demonstrated a direct effect of the addition of calcium carbonate and its modification on the processability and selected functional properties of composite films. The study has also proved that stearic acid is an effective modifier of processing properties, not only in shear flow conditions, but also under extensional flow conditions – smaller ηE values are exhibited by films containing modified calcium carbonate.

Role of Head Position in Stroke Outcome: An Observational Study from Tertiary Care Hospital in Pakistan

Background and Aim: Acute ischemic stroke patients mainly rely on cerebral blood flow (CBF) to sustain penumbral tissue perfusion in turn depend on arterial blood pressure in affected cerebral autoregulation. Head positioning either sitting-up or lying flat allows gravitational force to enhance leptomeningeal circulation and collateral blood flow. The present study aimed to determine the role of head position in acute ischemic stroke patients. Methodology: This prospective observational study was conducted on 500 stroke patients in the Department of Neurology and Medical department of Fauji Foundation Hospital, Rawalpindi from January 2020 to December 2021. Patients with acute ischemic stroke receive care in either a lying flat on bed or sitting-up position with elevated head position at 30 to 45 degrees. The designated position was established shortly after hospital admission and was held for 24 hours. Outcomes such as pneumonia, aspiration pneumonia, and increased hospital stay, disability, and mortality were associated with flat head position and elevated head position. Modified Rankine scale (0-6) was used for assessing the degree of disability as a primary outcome in three months. Rankine scale higher score indicates the greater disability and maximum score 6 indicate mortality. Results: The average time from initiation of assigned position and onset of ischemic stroke symptoms was 14 hours (IQR 5-35). Patients in the sitting position group (93%, p<0.001) were more likely than the lying-flat group (82%, p<0.001) in maintaining their position for 24 hours. Based on a modified Rankine scale, both lying flat and sitting-up position groups had no significant differences in a proportional-odds model in terms of 90-days disability outcomes distribution. The mortality rate in lying flat and sitting-up position was 6.8% and 6.9% (p=0.79). Also, both groups had no significant differences in terms of severe outcomes including pneumonia. Conclusion: The present study found that disability outcomes in acute stroke patients were similar irrespective of their position either flat or sitting position with head elevated at 30 to 45 degree for 24 hours. The prevalence of AIS was 95.6%. Keywords: Head position, Acute ischemic stroke, Outcomes

Feasibility Study for Catfish Farming Business in A Bucket in Kp Biru, Malang, East Java, Indonesia

The Covid-19 pandemic that occurred in Indonesia has had a negative impact on various sectors such as health, economy, and others. There needs to be a strategic solution to survive. There are various ways people survive and win against the Covid-19 pandemic. The community's economy is destroyed. This is certainly a trigger for people to do anything to survive. The emergence of household-scale businesses. Creative ideas are emerging. One of them is damber catfish cultivation in kp Biru, Malang, East Java. The author is interested in making this damber catfish cultivation object. business feasibility study research. Catfish is one type of fish that can live in high density. This fish has a good conversion rate of feed into body weight. With these properties, catfish farming will be very profitable if done intensively. Catfish (Clarias sp) is one type of freshwater fish consumption. Catfish is a type of catfish or in other words a fish that has a mustache. Catfish are raft and caninal. The characteristics of catfish are elongated and slightly rounded body shape, on the pectoral fins there are hard and sharp spines (patil), striped body color with a flat head and there is a mustache and slippery because it does not have scales. This fish has an additional breathing apparatus in the form of a modification of its gill arc, namely arborescent. This catfish has a fairly complete nutritional content. The chemical and nutritional content of catfish are fat, protein, vitamins (BI, B). The study used descriptive qualitative methods and participatory methods, observations and interviews. The study also used SWOT analysis to map strengths, opportunities, weaknesses and threats. The SWOT method can be used to determine strategies, fix deficiencies and can also read competitors. The final result of this damber catfish business feasibility study can be an indicator of how to run this business better from the management aspect including product, management, HR, marketing and financial aspects. Good business management will increasingly provide promising benefits. The purpose of this research is to encourage people to be more active, creative and productive and to continue to innovate to create something different. The harvest can be developed for processed products so that they become added value and become various kinds of processed innovations. With the innovation of this catfish processed product, it is hoped that it can change the community's economy to be stronger. Be more independent and Isa will create a new strong businessman

Finite Element Analysis of Piston for Structural Assessments

This paper presents the assessment of different piston head geometry made of aluminum and magnesium alloy. ANSYS finite element analysis is used to analyze the piston under static and transient conditions. Round and flat piston head is constructed using SOLIDWORK software and the exported to ANSYS WORKBENCH. According to static analysis, it is found that flat head piston produced higher stress compared with round head piston. Similar trend is observedwhen transient analysis is conducted where round piston head capable to produce almost stress consistency with respect to time.