Mesh Efficiency Research Articles

Influence of gear tooth addendum and dedendum on the helical gear optimization considering mass, efficiency, and transmission error

In this study, the effects of the gear tooth addendum and dedendum on the optimization results for gear macro geometry design were evaluated. First, gear optimization using macro design variables was performed, excluding tooth addendum and dedendum parameters. Subsequently, the optimization, including the addendum and dedendum variables, was performed by applying the same addendum and dedendum lengths to the pinion and wheel. Finally, the gear optimization using different addendum and dedendum lengths for the pinion and wheel was completed. The gear mass, gear mesh efficiency, and transmission errors were considered as objective functions for optimization. The optimization results were min-max normalized, and the average values of the total scores were compared. The results show that the average score of the optimization considering only the main design variables was 2.7085 points and that considering the addendum and dedendum was 2.7829 and 2.8830 points, respectively, from a maximum possible score of 3.000 points. Hence, a gear macro design with better performance could be established by considering the tooth addendum and dedendum.

Thermal Investigations of Double Pass Solar Air Heater with Two Types of Porous Media of Different Thermal Conductivity

This study describes an experimental investigation of the thermal efficiency of stainless steel mesh and steel wool as a porous medium in the lower channel of a double pass solar air heater. An experimental setup was planned and developed. Various types of porous media with high thermal conductivity and with different porosities have been tested. The effects of the porosity of wire mesh, the thermal conductivity of porous media, mass flow rate, and the intensity of radiation have been studied. Experimental results show that thermal efficiency with using porous media is greater than without using porous media. When used steel wool as a porous medium, the thermal efficiency reached 79.82 percent while it can be achieved 76. The percent by using stainless mesh as porous material. The reduction in porosity increasing thermal efficiency. The thermal efficiency of multi-pass solar air collector when used steel wool as porous media is 6, 12.6 and31.7percent higher than without porous media at porosity 98.75, 97.5, and 96.25percent. While it can increase 8.1 and 28.5 percent at porosity 97.875 and 95.75 percent when using stainless steel as porous media.

End Colostomy With or Without Mesh to Prevent a Parastomal Hernia (GRECCAR 7): A Prospective, Randomized, Double Blinded, Multicentre Trial.

To evaluate whether systematic mesh implantation upon primary colostomy creation was effective to prevent PSH. Previous randomized trials on prevention of PSH by mesh placement have shown contradictory results. This was a prospective, randomized controlled trial in 18 hospitals in France on patients aged ≥18 receiving a first colostomy for an indication other than infection. Participants were randomized by blocks of random size, stratified by center in a 1:1 ratio to colostomy with or without a synthetic, lightweight monofilament mesh. Patients and outcome assessors were blinded to patient group. The primary endpoint was clinically diagnosed PSH rate at 24 months of the intention-to-treat population. This trial was registered at ClinicalTrials.gov, number NCT01380860. From November 2012 to October 2016, 200 patients were enrolled. Finally, 65 patients remained in the no mesh group (Group A) and 70 in the mesh group (Group B) at 24 months with the most common reason for drop-out being death (n = 41). At 24 months, PSH was clinically detected in 28 patients (28%) in Group A and 30 (31%) in Group B [P = 0.77, odds ratio = 1.15 95% confidence interval = (0.62;2.13)]. Stoma-related complications were reported in 32 Group A patients and 37 Group B patients, but no mesh infections. There were no deaths related to mesh insertion. We failed to show efficiency of a prophylactic mesh on PSH rate. Placement of a mesh in a retro-muscular position with a central incision to allow colon passage cannot be recommended to prevent PSH. Optimization of mesh location and reinforcement material should be performed.

Metric-based, goal-oriented mesh adaptation using machine learning

This paper presents a machine-learning approach for determining the optimal anisotropy in a computational mesh, in the context of an output-based adaptive solution procedure. Artificial neural networks are used to predict the desired element aspect ratio from readily accessible features of the primal and adjoint solutions. Whereas the sizing of the element is still based on an adjoint-weighted residual error estimate, the network augments this information with element stretching magnitude and direction, at lower computational and implementation costs compared to a more rigorous approach: mesh optimization through error sampling and synthesis (MOESS). The network is trained to provide anisotropy information in the form of a normalized metric field, computed from primal, adjoint, and error indicator features. MOESS-optimized meshes for a variety of steady aerodynamic flows governed by the Reynolds-averaged Navier-Stokes equations in two dimensions provide data for training several multi-layer perceptron networks, which differ in size and inputs. The networks are then deployed and tested by driving complete mesh adaptation sequences, and the results show improvements in mesh efficiency compared to pure primal Hessian-based anisotropy detection and in many cases to MOESS itself.

Feasibility of basalt and glass FRP mesh for strengthening and confinement concrete damage due to ASR-expansion

This research compares the efficiency of basalt fiber reinforcement polymer mesh (BFM) and glass fiber reinforcement polymer mesh (GFM) to suppress ASR-Expansion and enhance the mechanical properties of ASR-damaged concrete. BFM has not often been utilized for concrete confinement but is significantly less expensive than GFM. Results showed that the level of the expansion of damaged concrete prior to strengthening would dominate the performance rather than the materials. Early application of BFM and GFM resulted in a 25% reduction in expansion. In addition, an increase in compressive strength in the range from 4.6% to 39% and from 6.5% to 50% for BFM and GFM, respectively, depending mainly on the expansion at the time of strengthening and time since strengthening. An increase in modulus of elasticity by about 14% and a decrease in the Poisson’s ratio by about 23% compared with control specimens were obtained.

Influence of the DIN 3962 Quality Class on the Efficiency in Honed Powder Metal and Wrought Steel Gears

To increase the efficiency of a gearbox, research on gear mesh loss is of importance. Britton et al. concluded that the surface finishing method affects the gear mesh efficiency. The efficiency benefits of superfinishing a surface and reducing the surface roughness have been reported by Kahraman. A novel method for calculating the bearing loss torque was proposed by Tu et al. Andersson et al. found that the efficiency can vary between 2 and 5% during repeated efficiency tests due to variations in the assembly process. This work investigates how the honing surface finishing process and DIN 3962 quality class affect the gear mesh efficiency by performing tests in an FZG back-to-back test rig. Two materials, a powder metal and a wrought steel, were tested. All gears were finished using a honing process and sorted according the measured quality class. Powder metal gears of class 6, 7, 8, and ≥9 and wrought steel gears of class 6, 7, and ≥9 were tested. The efficiency were calculated from measuring the torque required to maintain a constant velocity of the FZG test rig. The results from the efficiency tests showed no significant difference in efficiency between the wrought steel and powder metal steel gears. In addition, no obvious correlation between the DIN 3962 quality class and the gear mesh efficiency could be found. When examining the wrought steel material it was found that the reproducibility of the efficiency was comparable to the assembly error of the test rig, despite the variation in quality class.

Improving water harvesting efficiency of fog collectors with electrospun random and aligned Polyvinylidene fluoride (PVDF) fibers

People worldwide suffer from poor access to water, with more than 3 billion lacking basic handwashing facilities and more than 2 billion without water services at their homes. This global problem needs new, cost-effective and efficient solutions that can be employed in places with scarce water sources. One potential sustainable solution is fog water collection, inspired by the way nature harvests water from humid air via condensation processes or from fog. Currently, a common medium to collect fog with the highest water collection efficiency is the Raschel mesh. By incorporating electrospun polyvinylidene fluoride (PVDF) fibers we improved water collecting efficiency of commercial Raschel mesh by more than 300%. We show a relatively simple to implement and inexpensive system that builds on top of already applied solutions and expands the capabilities of existing designs.

Synthesis of Durable Superhydrophobic Coating and Its Applications in Oil/Water Separation

Superhydrophobic surfaces have received enormous attention thanking to their potential applications in the areas of anti-icing, anti-contamination, and oil/water separation. Herein, we have successfully prepared superhydrophobic surfaces, which were synthesized by using the polydimethylsiloxane (PDMS) as adhesive and the magnesium palmitate (Mg-P) were evently coated to form roughness on the surfaces of glass, textile, stainless steel mesh, and paper. The as-fabricated superhydrophobic surfaces possessed excellent water-resistance, self-cleaning properties, durability, and robustness. Remarkably, in the actual oil/water separation, the water contact angle and oil collection efficiency of the superhydrophobic mesh were still more than 150° and 91% even after separation over 10 cycles, respectively. Thus, the superhydrophobic coating has applications potential in self-cleaning, anti-contamination, and oil/water separation fields.

A 2D finite element analysis of the effect of numerical parameters on the reliability of Ti6Al4V machining modeling

The numerical analysis, based on the finite element modeling (FEM), presents nowadays an efficient computational tool. It allows a better understanding of several thermo-mechanical phenomena involved during the machining process. However, its reliability heavily depends on the accurate definition of the numerical model. In this regard, a FE analysis focused on the 2D modeling of the Ti6Al4V dry orthogonal machining was carried out in this study. The relevance of different numerical meshing approaches and finite elements topologies was studied. The effect of the friction coefficient on the numerical chip morphology, its geometry, the cutting and the feed forces was investigated. The adequacy of several compared adaptive meshing approaches, in terms of the modeling of severe contact conditions taking place around the cutting-edge radius, was underlined in the current study. However, numerical serrated chips, closer to the experimental ones, were only predicted when the pure Lagrangian formulation was adopted and a proper determination of the failure energy was carried out. The definition of different mesh topologies highlighted the efficiency of the 4-node quadrangular mesh, with a suitable edge length, in increasing the agreement with the experimental data, while reducing the computing times.

Features of the Engagement of the Nutation Speed Reducer

This paper discusses the development of a Nutating Speed Reducer (NSR), which is characterized by high reduction ratio, high tooth contact ratio, very high torque to weight/ volume ratio, quiet and smooth operation under load and very high efficiency. All of these advantages are due to the presence of conjugate face-gear pairs, which incorporate each other, which is called nutating/rotating gear mechanism. Details of the NSR, its kinematics, gear tooth load capacity, and mesh efficiency are explained. The general formulae for calculating the reduction ratio and main design parameters of the novel gear drive are developed. The smooth running of the NSR is examined without applying any load. The operability of the NSR under load is carried out in a virtual simulation environment to verify the transmission theory and the smoother transmission between pairs of teeth of the nutation speed reducer.

Morbidity and Efficiency of Transobturator Polypropylene Mesh in Treatment of Urinary Incontinence A 12 years experience

Urinary incontinence is a socio-economic problem with a major impact on quality of life. Although there are multiple non-surgical and drug solutions, surgical treatment remains the most effective method for stress urinary incontinence. Placement of transobturator polypropylene tape is a safe method with minimal intraoperative and postoperative complications. This study had a minimal rate of complications at a one-year follow-up; the biggest problem is represented by de novo overactive bladder (20.26%) that responded successfully to conservative treatment in most cases. The surgical treatment cure rate was 97.8%. TOT is a safer method with less intraoperative complications than TVT, at the same time the success rate is comparable to TVT.

Kinematical analysis of the nutation speed reducer

This paper discusses the development of a Nutating Speed Reducer (NSR) which is characterized by high reduction ratio, high tooth contact ratio, very high torque to weight/volume ratio, quiet and smooth operation under load and very high efficiency. All of these advantages are due to the presence of conjugate face-gear pairs, which incorporate each other, which called nutating/rotating gear mechanism. Details of the NSR, its kinematics, gear tooth load capacity, and mesh efficiency are explained. The NSR component speeds and speed reduction ratios of the NSR are calculated. Effect of the varying nutation angles on the geometry of the NSR is discussed and compared.

Towards constant mesh stiffness helical gears: The influence of integer overlap ratios

This work presents the development and dynamic analysis of Constant Mesh Stiffness Gears. First, a study of the contact length variation between gears is conducted since it has great influence on the gear mesh stiffness. Following that, an algorithm capable of generating Constant Mesh Stiffness Gears (CMSGears) was developed while considering the gears’ safety factors and mesh efficiency. The dynamic performance of these gears was evaluated resorting to a single degree of freedom dynamic model which considered teeth contact loss. The CMSGears created respect the gear design principles and both the gear safety factors and gear mesh efficiency were successfully taken into account. With regard to the dynamic behavior of these gears, they ended up revealing great potential in the reduction of noise, vibration and dynamic overload.

In-situ growth hierarchical and superhydrophobic flower-like Cu3(PO4)2·2H2O nanosheets based on copper mesh for efficient oil–water separation

Superhydrophobic porous membranes with interconnected open structures for effective treatment oily wastewater have gradually drawn researchers’ attentions owing to frequent occurrence of organics leakage accidents. In this paper, we successfully fabricated superhydrophobic flower-like Cu3(PO4)2·2H2O nanosheets on copper mesh surface via in-situ growth strategy and silane coupling agent (A151) hydrophobic modification. Specifically speaking, commercial copper mesh served as substrate and Cu could react with (NH4)2S2O8 and Na2HPO4, forming flower-like micro-nanostructure. As-synthesized materials were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD). In addition, chemical, mechanical stability and durability of as-prepared materials were also investigated under different condition. The relevant experiment results demonstrated that flower-like Cu3(PO4)2·2H2O nanosheets successfully grew on copper mesh surface, resulting in the formation of rough structure. Modified copper mesh showed superhydrophobic and superoleophilic properties simultaneously with water contact angle (CA) of 151.24° and oil contact angle of 0°, respectively. The as-prepared materials could be used to separate oily wastewater with high separation efficiency (above 95.0%). The mechanism of oil–water separation was investigated in detail based on positive and negative capillary effect. High separation efficiency, excellent stability and durability of superhydrophobic copper mesh make it one of best promising separation candidates for wastewater treatment.

Оценка влияния неравномерности размеров ячейки на эффективность фильтровальных сеток

Оценка влияния неравномерности размеров ячейки на эффективность фильтровальных сеток

Oil/water separation on structure-controllable Cu mesh: Transition of superhydrophilic-superoleophilic to superhydrophobic-superoleophilic without chemical modification

Four different surface morphologies, including needle-like, bamboo leaf-like, pine needle-like, and peony flower-like structures, were prepared on Cu mesh surface, and the existence of these different surface morphologies were due to the formation of Cu(OH)2 or CuO microstructures by controlling the oxidation time and oxidation temperature of the chemical reaction. These freshly prepared Cu meshes all exhibit superhydrophilic-superoleophilic after dried with a hair dryer. They all have excellent separation efficiency, and the separation efficiency for oil-remove (~96%) is higher than that of water-remove (~94%). Interestingly, these meshes with four different surface morphologies can transform from superhydrophilic-superoleophilic to superhydrophobic-superoleophilic just after storage in air for >20 days without any further chemical modification. This is because oxygen adsorption on the mesh surface contributes to air trapped into the microstructures. These superhydrophobic-superoleophilic copper meshes have good durability. According to the investigation of separation efficiency of the superhydrophobic-superoleophilic mesh, we find that the separation efficiency for oil-remove of the superhydrophobic-superoleophilic mesh (~99%) is higher than that of the superhydrophilic-superoleophilic mesh (~96%).

Thermo-mechanical characteristics of high-speed and heavy-load modified gears with elasto-hydrodynamic contacts

Abstract The thermo-mechanical characteristics of high-speed and heavy-load modified gears in non-Newtonian transient micro thermo-elasto-hydrodynamic contacts are investigated. The synthetic stiffness model is developed from the stiffness of both the oil film and gear pair. Scuffing prediction and mesh efficiency are determined by the total contact temperature and frictional loss ratio respectively. By utilizing the verified numerical procedure, effects of geometric parameters on aforementioned thermo-mechanical characteristics are discussed. The results show that crown modification and the increase of tooth number, module, and pressure angle contribute to vibration and impact reduction of gear drive. Larger tooth number and module are beneficial to scuffing resistance and efficiency improvement. It indicates that gear system can achieve high-performance transmission by rationally matching geometric parameters.

Preloop trial: study protocol for a randomized controlled trial

BackgroundA temporary loop ileostomy, which is used to decrease the risk of symptomatic anastamotic leakage after anterior resection and total mesorectal excision (TME), is traditionally closed without any mesh. However, as 44% of incisional site hernias need further repair after stoma closure, attention has increasingly been paid to the use of mesh. Research on the prevention of these hernias is scarce, and no studies comparing different meshes exist.Method/DesignThe Preloop trial (Clinical Trials NCT03445936) is a prospective, randomized, controlled, multicenter trial to compare synthetic mesh (Parietene Macro™, Medtronic, Minneapolis, MN, USA) and biological implants (Permacol™, Medtronic) at a retromuscular sublay position for the prevention of incisional site hernias after loop-ileostomy closure. The main endpoints in this trial are infections at 30-day follow-up and the incidence of hernias clinically or on CT scan at 10 months after closure of the stoma. The secondary endpoints are other complications within 30 days of surgery graded with the Clavien-Dindo classification, reoperation rate, operating time, length of stay, quality of life measured with RAND-36, and incidence of hernia over a 5-year follow-up period. A total of 100 patients will be randomized in a 1:1 ratio.DiscussionThis is a pilot trial that will be undertaken to provide some novel evidence on the safety profile and efficiency of both synthetic mesh and biological implants for the prevention of incisional hernias after closure by temporary loop ileostomy. The hypothesis is that synthetic mesh is economical but equally safe and at least as effective as biological implants in hernia prevention and in contaminated surgical sites.Trial RegistrationClinicalTrials.gov, NCT03445936. Registered on 7 February 2018.

Immediate Vicryl mesh insertion after lumpectomy, advantage overview

Background: oncoplastic surgical treatment is defined as mix of excision of a tumor, with proper margin consisting of lumpectomy or mastectomy and prompt reconstruction of the bust, this may require applying mesh to stabilize the structure beneath the skin. Objective: we discussed the efficiency of Vicryl mesh and it usage in surgery after lumpectomy. Method: we searched in detailed following electronic databases; (PubMed, Embase, Google scholar) for relevant studies published in English language with human subject only up to July,2018.Results: absorbable surgical mesh is the most current method in oncoplastic surgery. The simpleness of the time-preserving method that is comfortably appropriate has actually been reported to have substantial benefits for specialists in addition to a fairly affordable and acceptable aesthetic end results. Conclusion: elimination of just the area of cancer by lumpectomy intends to keep most of the bust tissue, is much less of a modification to your body compared to mastectomy and has a healing time of a couple of weeks. Immediate Vicryl mesh insertion is a simple approach. Additionally, surgeons ought to think about mesh use when constructing patients who are mosting likely to or have actually obtained radiotherapy to the bust; vicryl mesh is a reliable choice to acellular dermal matrix in non-irradiated bust reconstruction and is accessible at approximately one twentieth the expenses. Acellular dermal matrix or complete muscular tissue coverage could be preferable in irradiated reconstructions.

Immediate Vicryl mesh insertion after lumpectomy, advantage overview

Background: oncoplastic surgical treatment is defined as mix of excision of a tumor, with proper margin consisting of lumpectomy or mastectomy and prompt reconstruction of the bust, this may require applying mesh to stabilize the structure beneath the skin. Objective: we discussed the efficiency of Vicryl mesh and it usage in surgery after lumpectomy. Method: we searched in detailed following electronic databases; (PubMed, Embase, Google scholar) for relevant studies published in English language with human subject only up to July,2018.Results: absorbable surgical mesh is the most current method in oncoplastic surgery. The simpleness of the time-preserving method that is comfortably appropriate has actually been reported to have substantial benefits for specialists in addition to a fairly affordable and acceptable aesthetic end results. Conclusion: elimination of just the area of cancer by lumpectomy intends to keep most of the bust tissue, is much less of a modification to your body compared to mastectomy and has a healing time of a couple of weeks. Immediate Vicryl mesh insertion is a simple approach. Additionally, surgeons ought to think about mesh use when constructing patients who are mosting likely to or have actually obtained radiotherapy to the bust; vicryl mesh is a reliable choice to acellular dermal matrix in non-irradiated bust reconstruction and is accessible at approximately one twentieth the expenses. Acellular dermal matrix or complete muscular tissue coverage could be preferable in irradiated reconstructions.