Cut Thickness Research Articles

Optimisation of machining parameters in high-speed end milling of hardened AISI H13 die steel by integrating RSM and GA

ABSTRACT This study explores the potential of high-speed hard-end milling as a cost-effective alternative to the time-consuming grinding process for Chromium-molybdenum steel (AISI H13), widely used in cold and hot work tooling. The research aims to optimize machining parameters for achieving desired surface roughness, comparable to grinding and polishing. Cutting depth (0.4 - 0.8 mm), feed rate (1 - 4 μm per tooth), and cutting speed (80 - 140 m/min) were varied, and soybean oil replaced conventional lubricants. Employing Titanium Aluminum Nitride (TiAlN) coated end mills (3 mm diameter, 2 μm coating thickness) and response surface method (RSM) with Design Expert software, the study aimed at reducing tool wear and enhancing surface quality through multi-criteria optimization. Surface roughness analysis led to a streamlined surface by lowering mass flow rate and increasing cutting speed. The optimization approach predicted an optimal surface roughness value of 0.217475 μm at a cutting speed of 110 m/min, a feed rate of 1 μm/tooth, and a cut depth of 0.4 mm using genetic algorithm (GA), closely aligned with RSM’s ideal value of 0.215 μm. Both values converge around the 0.4 mm cut thickness.

Femoral cartilage thickness measured on MRI varies amongindividuals: Time to deepen one of the principles of kinematic alignment in total knee arthroplasty. A systematic review.

Kinematically aligned total knee arthroplasty (KA TKA), as a pure resurfacing procedure, is based on matching implant thickness with bone cut and kerf thickness, plus cartilage wear. However, the assumption of a consistent 2 mm femoral cartilage thickness remains unproven. This study aimed to systematically review the available literature concerning magnetic resonance imaging (MRI) assessment of femoral cartilage thickness in non-arthritic patients. Our hypothesis was that cartilage thickness values would vary significantly amongindividuals, thereby challenging the established KA paradigm of 'one-cartilage-fits-all'. Systematic literature searches (Pubmed, Scopusand Cochrane Library) followed PRISMA guidelines. English-language studies assessing distal and posterior femoral cartilage thickness using MRI in non-arthritic adults were included. Studies lacking numerical cartilage thickness data, involving post-operative MRI, considering total femoro-tibial cartilage thickness, or failing to specify the compartment of the knee being studied were excluded. Overall, 27 studies comprising 8170 MRIs were analysed. Weighted mean femoral cartilage thicknesses were: 2.05 ± 0.62 mm (mean range 1.06-2.6) for the distal medial condyle, 1.95 ± 0.4 mm (mean range 1.15-2.5) for the distal lateral condyle, 2.44 ± 0.5 mm (mean range 1.37-2.6) for the posterior medial condyleand 2.27 ± 0.38 mm (mean range 1.48-2.5) for the posterior lateral condyle. Femoral cartilage thickness varies significantly across patients. In KA TKA, relying on a fixed thickness of 2 mm may jeopardize the accurate restoration of individual anatomy, leading to errors in implant coronal and rotational alignment. An intraoperative assessment of cartilage thickness may be advisable to express the KA philosophy at its full potential. Level IV.

Numerical study on a new spiral fin heat Exchanger's thermal-hydraulic performance

This study presents a numerical investigation of a novel spiral finned heat exchanger (SFHE). The primary objective is to optimize the heat transfer efficiency of micro gas turbine recuperators by employing a spiral fin model. Through computational simulations (CFD), the study examines the variations in the Colburn j factor and Fanning friction f factor as the spiral fins alter. The results demonstrate that the SFHE exhibits superior heat transfer capacity and overall heat transfer performance compared to wavy fin models. At a Reynolds number of 1000, the JF factor of the spiral fin 35_125 is 70.47 % higher than that of a wavy fin at the same Reynolds number, and 34.03 % higher when the Reynolds number increases to 5000. The study also reveals that the cutting thickness of the top and bottom, denoted as C1, does not significantly impact the variable j, f. However, increasing the cut thickness C2 on the left and right sides results in a more compact model, leading to higher values of f, but the j-factor is almost unchanged. While decreasing the wavelength of the spiral fins can improve heat transfer efficiency, it also increases pressure loss, necessitating careful selection of wavelength for optimal SFHE design.

Глубинное строение Северо-Востока России, закономерности размещения и прогноз рудного золота

The principal gold-bearing zone of the Kolyma-Chukotka fold belt is controlled by the Yana-Kolyma downfold of the earth's crust identified on the basis of gravity prospection data; it involves thick (25 km) terrigenous formations and their underlying migmatites as well as the lower layers of the earth's crust and asthenosphere. The Yana-Kolyma downfold is formed under the influence of the protogenic asthenospheric ultramafic magma chamber. According to the analysis of the most important ore-controlling factor (the thickness of the erosion cut), the structures of the deep Yano-Kolyma downfold are the least eroded, and, consequently, the rich placers of the principal gold bearing zone might have been formed from very rich gold motherlodes. This conclusion determines inferred resources in the principal zone and conforms with the calculated ratio of motherlode reserves exceeding placer reserves. The gold ore ratio of 2.6 is used for the prognostic evaluation of the ore gold mineragenic potential of the Kolyma-Chukotka fold belt, which makes 6 000 t.

The impact of 3-dimensional humeral planning and standard transfer instrumentation on reconstruction of native humeral anatomy for anatomic total shoulder arthroplasty

BackgroundPreoperative three-dimensional CT-based planning for anatomic total shoulder arthroplasty (TSA) has grown in popularity in the past decade with the primary focus on the glenoid. Little research has evaluated if humeral planning has any effect on the surgical execution of the humeral cut or the positioning of the prosthesis. MethodsThree surgeons performed a prospective study utilizing 3D-printed humeri printed from CTs of existing patients, which were chosen to be -3, -1, 0, 1 and 3 standard deviations of all patients in a large database. A novel 3D printing process was utilized to 3D print not only the humerus, but also all four rotator cuff tendons. For each surgical procedure, the printed humerus was mounted inside a silicon shoulder, with printed musculature and skin, and with tensions similar to human tissue requiring standard retraction and instruments to expose the humerus. Three phases of the study were designed: Phase 1: Humeral neck cuts were performed on all specimens without any preoperative humeral planning, Phase 2: 3D planning was performed, and the cuts and implant selection were repeated, Phase 3: A neck shaft angle guide and digital calipers were used to measure humeral osteotomy thickness to aid in the desired humeral cut. All humeri were digitized. The difference between the prosthetic center of rotation (COR) and ideal COR was calculated. The percentage of patients with a varus neck shaft angle (NSA) was calculated for each phase. The difference in planned and actual cut thickness was also compared. ResultsFor both 3D change in COR and medial to lateral change in COR, use of preoperative planning alone and with standard transfer instrumentation resulted in a significantly more anatomic restoration of ideal COR. The deviations from planned cut thickness decreased with each phase: Phase 1: 2.6±1.9 mm, Phase 2: 2.0±1.3 mm, Phase 3: 1.4±0.9 mm (p = 0.041 for Phase 3 vs Phase 1). For NSA, in Phase 1: 7/15 (47%) cases were in varus, in Phase 2: 5/15 (33%) were in varus and Phase 3: 1/15 (7%) were in varus (p =0.013 for Phase 3 vs Phase 1). ConclusionsUse of preoperative 3-D humeral planning for stemless anatomic TSA improved prosthetic humeral center of rotation, whether performed with or without standard transfer instrumentation. The use of a neck-shaft angle cut guide and calipers to measure cut thickness significantly reduced the percentage of varus humeral cuts and deviation from planned cut thickness.

Pre-milling technique improves the accuracy of posterior femoral condyle cut and reduces the tibial recut in Oxford unicompartmental knee arthroplasty.

Recuts are sometimes needed in UKA because of inadequate posterior tibial cut thickness. We investigated the efficacy of a pre-milling technique (the first milling is done prior to the posterior condylar cut) in Oxford unicompartmental knee arthroplasty to enhance bone cut thickness and to minimize tibial recuts. Between January 2021 and January 2023, a posterior condyle cut was made before milling in 213 knees in 152 patients (conventional group), while the pre-milling technique was used in 198 knees in 140 patients (pre-milling group). The thickness of the posterior condyle and the rate of tibial recuts were compared between the groups. The bone cut thickness was thinner in the conventional group than in the pre-milling group in small-size (4.7mm ± 0.6mm and 5.0mm ± 0.6mm, P = 0.0001) and in medium-size (5.1mm ± 0.5mm and 5.4mm ± 0.5mm, 0.0001) femoral components, whereas there was no difference in large-size femoral components. However, the thickness was still less than the component thickness (5.17mm for small, 5.57mm for medium and 6.17mm for large) in both groups. Tibial recuts were more prevalent in the conventional group than in the pre-milling group (14 knees, 7%, 3 knees 2%, P = 0.002). The pre-milling technique was found to increase the bone cut thickness in small and medium femoral components, reducing the need for tibial recuts. Further research is warranted to optimize the pre-milling technique and to investigate its long-term impact on patient outcomes.

78 Assessment of the Scalpel Blade as a Calibration Tool for Measuring Dermatome Cut Thickness

78 Assessment of the Scalpel Blade as a Calibration Tool for Measuring Dermatome Cut Thickness

Enhanced CT imaging artificial neural network coronary artery calcification score assisted diagnosis.

The study of coronary artery calcification (CAC) may assist in identifying additional coronary artery problem protective factors. On the contrary side, due to the wide variety of CAC as individuals, CAC research is difficult. Due to this, evaluating data for investigation is becoming complicated. To use a multi-layer perceptron, we investigated the accuracy and reliability of synthetic CAC coursework or hazard classification in pre or alors chest computerized tomography (CT) of arrangements resolutions in this analysis. Photographs of the chest from similar individuals as well as calcium-just and non-gated pictures were incorporated. This cut thickness ordered CT pictures (bunch A: 1 mm; bunch B: 3 mm). The CAC rating was determined utilizing calcification score picture information, and became standard for tests. While the control treatment's machine learning program was created using 170 computed tomography pictures and evaluated using 144 scans, group A's machine learning algorithm was created using 150 chest CT diagnostic tests. 334 external related pictures (100 μm: 117; 0.5 mm x: 117) of 117 individuals and 612 inside design organizing (1 mm: 294; mm3: 314) of 406 patients were surveyed. Pack B had 0.94, however, tests An and b had 0.90 (95% CI: 0.85-0.93) ICCs between significant learning and gold expenses (0.92-0.96). Dull Altman plots agreed well. A machine teaching approach successfully identified 71% of cases in category A is 81% of patients in section B again for cardiac risk class. Regression risk evaluation algorithms could assist in categorizing cardiorespiratory individuals into distinct risk groups and conveniently personalize the treatments to the patient's circumstances. The models would be based on information gathered through CAC. On both 1 and 3-mm scanners, the automatic determination of a CAC value and cardiovascular events categorization that used a depth teaching approach was reliable and precise. The layer thickness of 0.5 mm on chest CT was slightly less accurate in CAC detection and risk evaluation.

Reasonable top coal thickness for large cross-section open-off cut in lower-layer mining

The thickness of top coal is the main factor affecting the stability of the large cross section open-off cut under the goaf. The 1-2 lower 203 cross section open-off cut of the Huojitu Coal Mine was used as the background to investigate the top coal rational thickness of the large cross section open-off cut under the goaf in slicing mining. The top coal above the cut was simplified into a beam model to calculate its plastic zone range with the elastoplastic theory under the influence of the upper slicing mining and the lower slicing cut excavating. The deformation law of the top coal of the large cross section open-off cut under different top coal thicknesses was studied with both a simulation experiment and numerical simulation. The displacement, stress, and top coal structure of the surrounding rock of the cut were observed in situ using several observation methods. The results show that the plastic zone of the floor in the upper slicing face and the influence of the cut excavation are 2.02 m and 1.43 m, and the maximum plastic zone of the top coal is 3.45 m. A top coal thickness of more than 3.45 m is conducive to maintaining the stability of the large cross section open-off cut. The top coal of the cut can be divided into the roof-fall hazard zone and roof-fall warning zone according to the results monitored by distributed optical fiber. When the top coal thickness is 3.0 m, 3.5 m, and 4.0 m, the deformation law changes from an exponential deformation to a linear and then to a logarithmic relationship in the roof-fall hazard zone and from a linear to a logarithmic relationship in the roof-fall warning zone. When the thickness of top coal is 3.5 m and 4.0 m, the subsidence trend of the top coal visibly decreases, and the subsidence is only 56% and 39% of the subsidence of that of a thickness of 3 m. The deformation law of top coal measured using the DIC (Digital Image Correlation, DIC) is consistent with that of distributed optical fiber. The average thickness of the top coal reserved in the 1-2 lower 203 large cross section open-off cut is 4.0 m. The maximum surface subsidence of the top coal cut hole is 12 mm in the field monitoring. The maximum internal subsidence is 6 mm, and the maximum shed beam strain is –416 με. The deformation of the top coal is slight, indicating that the top coal thickness of 3.5–4.0 m is reasonable.

Biomechanical behavior of deep anterior lamellar keratoplasty: a finite element analysis

Deep Anterior Lamellar Keratoplasty (DALK) is a surgical procedure used to restore sight and manage corneal diseases by replacing cloudy corneal tissue with allogeneic normal corneal tissue or artificial corneal material. However, the limited availability and mechanical defects of artificial corneal materials pose challenges in DALK. To predicting postoperative mechanical behavior of Deep Anterior Lamellar Keratoplasty (DALK), a three-dimensional finite element model of the postoperative DALK cornea with suture holes was developed. The postoperative corneal displacement and von Mises (VM) stress changes were also simulated under varying depths of cut (DOC: 0.16-0.26 μm), intraocular pressure (IOP: 12, 15, 18 mmHg), and central corneal thickness (CCT: 420-620 μm). The model indicated that higher IOP and CCT were associated with improved postoperative corneal stability. The postoperative corneal displacement increased from the edge to the center, while the maximum VM stress value occurs at the corneal suture hole. Corneal displacement and VM stress decrease with increasing CCT and decreasing IOP. DOC has a slight effect on corneal displacement and VM stress, with an overall positive relationship. The model has potential application in the preoperative assessment of risk in keratoplasty.

Prediction of gap balancing based on 2-D radiography in total knee arthroplasty for knee osteoarthritis patients

BackgroundTo investigate the influence of osteophytes on postoperative gap balancing, and to work out a predictive model of the relationship between osteophyte size and gap gaining in primary total knee replacement.MethodsOne hundred and ten patients were enrolled in the study. Pre- and postoperative radiographs were collected and analyzed. They were assigned to the training dataset and test dataset randomly at a ratio of 9:1 by using the statistical package R (version 4.0.5). Size and marginal distances of osteophytes, planned bone cut planes, predicted bone cuts and joint gaps were labeled on the preoperative standing anteroposterior and lateral views, while actual bone cuts and joint gaps were recorded on the postoperative plain films, respectively. Statistical analysis was performed.ResultsActual joint gaps were significantly related to the distances of medial and lateral predictive bone cutting lines, bone cut thickness on tibial side and posterior condylar, as well as size and marginal distances of osteophytes (P < 0.05). A predictive equation was generated, with a root mean square error (RMSE) of 3.4761 in validation. A 2-D planning system with adjustable input parameters and dim predictive outputs on joint gap was developed. The equation is S left(Joint Gapright)=1.82+0.15*y+0.552*Tibial cut+0.953*Femoral cut+0.197*Post CondyleConclusionPostoperative joint gap can be predicted on the basis of preoperative measurements on 2-D plain films. Larger sample size may help improve the effectiveness and accuracy of the predictive equation.

Investigation on the ultra-precision diamond turning of ZnSe aspheric surfaces using straight-nosed cutting tools

Theoretical and experimental investigations on the machining performance and mechanisms in single-point diamond turning (SPDT) of ZnSe aspheric surfaces using straight-nosed cutting tools have been carried out. Analyses of the chip formation process have shown that using straight-nosed cutting tools can significantly reduce the cut thickness by about 60 % compared with using round-nosed cutting tools for facilitating the ductile-mode material removal and reducing surface damages. The analyses have also shown that the height of residual feed marks can be reduced by using the straight-nosed cutting tools by about 80 %, which can further improve the machined surface integrity. Experiments on the machining performance of using straight-nosed and round-nosed cutting tools were conducted to verify the analytical deductions. It has been shown that nano-scale surface finish with surface roughness Ra ∼ 1.5 nm can be achieved by using straight-nosed cutting tools, which is significantly improved comparing with that by the round-nosed cutting tools (Ra ∼ 7.8 nm) and is consistent with the analytical results. Needle-like chip with periodical layered structure was collected from the SPDT processes using straight-nosed cutting tools, indicating a relatively continuous chip formation process under the ductile-mode material removal. Raman spectroscopy has shown increased metallization of ZnSe occurred during the machining with straight-nosed cutting tools, which is considered to reduce the brittle fractures along with the chip formation process. It has been further found that the straight-nosed cutting tool can reduce work adhesion and micro-edge chipping of cutting tools for extending the cutting tool life.

Does measuring the medial gap before bone resection in total knee arthroplasty provide optimum gap adjustment and prevent bone recutting?

This study aimed to demonstrate that measuring the medial gap before bone resection during total knee arthroplasty (TKA) provides an optimum gap adjustment in varus knees. In this study, patients were separated into two groups. Group 1 included patients whose medial joint gap was measured before bone resection and Group 2 included patients who underwent conventional technique without measuring. The medial joint gap was measured with a custom-made gap measuring device up to the point that the knee was corrected and aligned along its mechanical axis. Medial joint gap distances, distal medial femoral bone cut thicknesses, amounts of tibial resection calculated; gap internal distances measured after cutting and the thicknesses of the trial inserts were recorded. A comparison was made between the groups concerning the number of patients requiring an additional tibial bone cut and the distribution of insert thicknesses. Extra tibial bone resections were performed in two (5.7%) patients in Group 1 and 10 (28.6%) patients in Group 2. In Group 1, where the medial joint gap was measured, the need for an additional bone resection was statistically less (p=0.018). In comparing the distribution of insert size by group, the number of patients on whom an 8 mm insert had been used was significantly greater in Group 1 (p=0.024). The findings obtained in this study suggest that measuring the medial joint gap before bone resection in total knee arthroplasty may prevent repeated bone recutting and additional bone resections.

Study on fresh processing key technology and quality influence of Cut Ophiopogonis Radix based on multi-index evaluation.

The purpose of this study was to ascertain the fresh processing technology of Cut Ophiopogonis Radix using a multi-index evaluation. This study comprehensively evaluated the fresh processing technology of sliced Cut Ophiopogonis Radix by investigating the cutting methods, cutting thickness, and drying conditions, and referring to The Chinese Pharmacopoeia 2020 edition. The appearance traits, internal quality (extract, total saponins, total flavonoids, total polysaccharides), and drying efficiency were used as evaluation indexes. The physical attributes of Cut Ophiopogonis Radix were found to vary based on the processing techniques employed. The shape, surface characteristics, texture, and color were observed to differ across the different methods. Notably, the apparent quality of Cut Ophiopogonis Radix was superior in samples processed using A1B1C1, A1B2C2, and A3B1C3 techniques. Drying time and energy consumption of Cut Ophiopogonis Radix produced by the A1B2C2 and A2B1C2 processes were less than those of other treatments, making them the optimal process for fresh processing Cut Ophiopogonis Radix. The impact of the cutting method and thickness on the extract was found to be statistically insignificant (P > 0.05). However, the drying method was observed to have a significant impact on the extract (P < 0.05). The cutting method, Cut thickness, and drying method did not affect the total saponin content (P > 0.05), but they had significant effects on the total polysaccharide and flavonoid contents (P < 0.01). Total polysaccharides were most affected by the cutting method, while total flavonoids were most affected by the drying condition. Based on the characteristics and internal quality, the fresh processing technology for Cut Ophiopogonis Radix was determined: fresh Ophiopogonis Radix was sliced to a thickness of 2-4 mm and dried at 55°C or a low temperature. The feasibility of Cut Ophiopogonis Radix is improved through its fresh processing. According to the evaluation indices, it is recommended to utilize the novel processing technique involving "fresh Ophiopogonis Radix" with fresh cuts, a cut thickness ranging from 2 to 4 mm, and drying at a temperature of 55℃ or through low-temperature drying. The Cut Ophiopogonis Radix exhibited favorable appearance and internal characteristics, thereby furnishing a scientific basis and innovative insights for the production of ophiopogon decoction slices.

The Deep-MCL Line: A Reliable Anatomical Landmark to Optimize the Tibial Cut in UKA.

The extramedullary guides for the tibial resection during medial unicompartmental knee arthroplasty (UKA) are inaccurate, with an error risk in coronal and sagittal planes and cut thickness. It was our hypothesis that the use of anatomical landmarks for the tibial cut can help the surgeon to improve accuracy. The technique described in this paper is based on the use of a simple and reproducible anatomical landmark. This landmark is the line of insertion of the fibers of the deep medial collateral ligament (MCL) around the anterior half of the medial tibial plateau called the "Deep MCL insertion line". The used anatomical landmark determines the orientation (in the coronal and sagittal planes) and the thickness of the tibial cut. This landmark corresponds to the line of insertion of the fibers of the deep MCL around the anterior half of the medial tibial plateau. A consecutive series of patients who underwent primary medial UKA between 2019 and 2021 were retrospectively reviewed. A total of 50 UKA were included. The mean age at the time of surgery was 54.5 ± 6.6 years (44-79). The radiographic measurements showed very good to excellent intra-observer and inter-observer agreements. The limb and implant alignments and the tibial positioning were satisfying, with a low rate of outliers and good restoration of the native anatomy. The landmark of the insertion of deep MCL constitutes a reliable and reproducible reference for the tibial cut axis and thickness during medial UKA, independent of the wear severity.

Анализ влияния радиуса зерна и критического переднего угла на критическую толщину среза при шлифовании древесных материалов

Обработка заготовок и деталей из древесины и древесных материалов абразивными инструментами является наиболее сложным по описанию и моделированию процессом. Закономерности износа абразивного инструмента непосредственно связаны с работой единичных абразивных зерен. В основе механизма износа лежат явления адгезии, диффузии, абразивного разрушения, пластического течения тончайших поверхностных слоев, размягченных под действием высоких контактных температур и давлений, химического воздействия на абразив окружающей среды и обрабатываемого материала. Под действием механических и температурных напряжений происходит растрескивание, скалывание режущих кромок, выкрашивание из связки отдельных абразивных зерен и целых комплексов. В ходе экспериментальных исследований процесса калибрования-шлифования древесных материалов было выявлено, что в некоторых случаях на поверхности образца появляются контактные разрушения, имеющие вид точек, рисок, пятен, покрытых ворсом. Ранее считалось, что основным дефектом механической обработки резанием древесных материалов являются прижоги поверхностного слоя, однако необходимо обратить внимание на то, что контактные разрушения поверхностных слоев наблюдается задолго до появления прижогов и оказывают первоочередное влияние на качество обработанной поверхности. Целью настоящего исследования является объяснение механизма образования контактных разрушений при помощи анализа процесса микрорезания древесных материалов единичным абразивным зерном, а также определение условий резания, не допускающих появления контактных разрушений. Поскольку из экспериментальных исследований известно, что на образование контактных разрушений оказывают влияние такие режимные факторы, как скорость резания и подачи, зернистость абразива, глубина шлифования и толщина среза,необходимо вывести математическую зависимость, отражающую влияние этих факторов на качественные показатели процесса шлифования для того, чтобы получить возможность заранее рассчитывать оптимальные режимы резания, не допуская появления на обработанной поверхности контактных разрушений. The processing of blanks and parts made of wood and wood materials with abrasive tools are the most difficult process in terms of description and modeling. The patterns of wear of an abrasive tool are directly related to the work of individual abrasive grains. The wear mechanism is based on the phenomena of adhesion, diffusion, abrasive destruction, plastic flow of the thinnest surface layers softened under the action of high contact temperatures and pressures, chemical impact on the abrasive of the environment and the material being processed. Under the action of mechanical and thermal stresses, cracking, chipping of the cutting edges, chipping of individual abrasive grains and entire complexes from the bond occurs. In the course of experimental studies of the process of calibrating-grinding wood materials, it was revealed that in some cases contact damage appears on the surface of the sample, in the form of points, scratches, spots covered with pile. Previously, it was believed that the main defect of mechanical processing by cutting wood materials is the burns of the surface layer, however, it is necessary to pay attention to the fact that contact destruction of the surface layers is observed long before the appearance of burns and has a primary effect on the quality of the machined surface. The objective of this study is to explain the mechanism of formation of contact damage by analyzing the process of microcutting wood materials with a single abrasive grain, to determine the cutting conditions that do not allow the appearance of contact damage. In the course of experimental studies of the process Since it is known from experimental studies that the formation of contact fractures is influenced by such regime factors as cutting speed and feed, abrasive grain size, grinding depth and cut thickness, it is necessary to derive a mathematical dependence reflecting the influence of these factors on the quality indicators of the process. Grinding in order to be able to pre-calculate the optimal cutting conditions, preventing the appearance of contact damage on the machined surface.

Optimizing hydrogen purification performance by membrane from industrial waste of methanol production

There is an increasing interest to migrate from fossil fuel energy dependency to a greener hydrogen economy. In order to meet this challenge, hydrogen should be made cheap and readily available for both industrial and public consumption. In this research, polyetherimide membrane was used to achieve highly purified hydrogen from methanol purge gas (MPG) containing hydrogen, carbon dioxide, nitrogen, carbon monoxide and methane gas. The novelty of this research stems from the development of semi-empirical models for correlating the membrane's characteristics and operating condition with purity and recovery of hydrogen from penta-nary MPG components and optimizing the membrane's purification process to achieve maximum hydrogen purity and recovery. Results from the study suggest that membrane area was one of the important factors affecting the hydrogen purity in the permeate. Keeping stage cut and membrane thickness constant at 0.340 and 0.25 µm, respectively, hydrogen purity was increased from 86.00% to 99.00% by increasing membrane area from 55.4 to 80.0 cm2. Membrane thickness was found to affect the hydrogen recovery in permeate significantly. By reducing the thickness from 25.00 to 1.00 µm, the hydrogen recovery was increased from merely 3.00% to 43.00% at a constant stage cut of 0.3400 and membrane area of 55.4 cm2. When the membrane parameters were optimized at 80.0 cm membrane area, 0.25 um membrane thickness and 0.3395 stage cut, the maximum hydrogen purity and recovery from this model achieved 99.99% and 53.89%, respectively.

Tibial Tubercle Osteotomy With Distalization for the Treatment of Patella Alta

One of the most common osseous abnormalities associated with patellar instability and patellofemoral osteochondral disease is patella alta, characterized by an Insall–Salvati ratio ≥1.2 or a Caton–Deschamps Index ≥1.2. Despite being the most common surgical treatment option for patella alta, tibial tubercle osteotomy with distalization raises concerns due to the complete detachment of the tubercle, which may lead to damage of local vascularity from periosteal detachment and increased mechanical stress at the attachment site. These factors are related to greater risk of complications, such as fractures, loss of fixation, delayed union, or nonunion of the tuberosity. We describe a technique for tibial tubercle osteotomy with distalization that aims to minimize these complications through care with the osteotomy, stabilization, bone cut thickness, and local periosteum.

Resonance properties of shear-horizontal surface acoustic waves on Ca3TaGa3Si2O14 at room and high temperatures

The resonance properties of shear-horizontal surface acoustic waves on Ca3TaGa3Si2O14 (CTGS) with Au or Al interdigital transducers (IDTs) were investigated. IDT-type resonators were fabricated on CTGS (0°, 134° or 155°, 90°) using Au- or Al-IDT, and the strong resonance properties and near-zero temperature coefficient of frequency (TCF) were measured at a certain electrode film thickness. From the measured and simulated results, an effective coupling factor of approximately 1.2% and zero TCF can be simultaneously obtained by using not only a high-density Au-IDT but also an Al-IDT and by adjusting the cut angle and electrode film thickness. Moreover, the resonance properties on Au-IDT/CTGS were evaluated at temperatures up to 570 °C. From the cut-angle dependences of the frequency shift calculated using the determined second-order temperature coefficients of the elastic constants, the potential for sensor applications that measure not only temperature but also pressure in such high-temperature environments can be expected.

Determining the force formulas while orthogonal shaped turning by tools with convex radial cutting edge

Orthogonal shaped turning is a non-free cutting process, because the main geometric and force parameters are variable while radial infeed of a tool: side cutting edge angle (SCEA), width and thickness of cut, rake angle and flank angle etc.. In this regard, the existing force dependencies, which are used for stationary conditions of cutting, are not applicable. Analytical dependences for calculating variable cutting forces while orthogonal turning are obtained on the basis of experimental studies in this work. This approach takes into account the cutting areas and corresponding specific pressures using correction coefficients for changing cutting conditions during machining. The obtained calculated dependences are universal and can be used for a free cutting process, i.e. while cutting with a constant value of radial infeed. The obtained analytical dependences make it possible to calculate the energy parameters in the cutting process: power, torque and work in conditions of orthogonal shaped turning.