Traditional Sawing Research Articles

Surface acoustic wave bound state in the continuum for 1200 °C high temperature sensing

The langasite (LGS) SAW are often used in high temperature wireless passive sensing above 1000 °C. And the about 400 nm thick metal electrodes film such as platinum-rhodium (Pt-Rh) are usually used to avoid high-temperature melting, however it could seriously pull down the quality factor and sensitivity of SAW sensors because the heavy metal electrodes result in high reflection coefficient and mass loading effect. In order to satisfy the thick electrode and the high-quality factor of SAW sensors simultaneously, this paper developed a new mode SAW which is based on the bound states in the continuum (BIC) on (0, 138.5°, θ) LGS wafers. The BIC-mode SAW sensor with a 410 nm thick Pt-Rh show an extremely high Q factor, which is four times to traditional SAW. The high temperature testing verified this BIC-state SAW sensor can maintain high quality (Q) factor after 1200 °C for 3 h.

Bone Ablation Depth Estimation From Er:YAG Laser-Generated Acoustic Waves

Using a laser for cutting bones instead of the traditional saws has been shown to improve a patient’s healing process. Additionally, the laser has the potential to reduce the collateral damage to the surrounding tissue if appropriately applied. This can be achieved by building additional sensing elements besides the laser itself into an endoscope. To this end, we use a microsecond pulsed Erbium-doped Yttrium Aluminium Garnet (Er:YAG) laser to cut bones. During ablation, each pulse emits an acoustic shock wave that is captured by an air-coupled transducer. In our research, we use the data from these acoustic waves to predict the depth of the cut during the ablation process.We use a Neural Network (NN) to approximate the depth, where we use one or multiple consecutive measurements of acoustic waves. The NN outperforms the base-line method that assumes a constant ablation rate with each pulse to predict the depth. The results are evaluated and compared against the ground-truth depth measurements from Optical Coherence Tomography (OCT) images that measure the depth in real-time during the ablation process.

Machinability improvement in three-dimensional (3D) ultrasonic vibration assisted diamond wire sawing of SiC

Ultrasonic vibration assisted (UVA) cutting has been proven to be an effective method for improving machining behavior in processing hard and brittle materials. However, there is no investigation on three-dimensional (3D) UVA diamond wire sawing (DWS). In this paper, a novel 3D vibration assisted DWS system is developed. A theoretical model is established for predicating sawing forces. Experiments have been carried out on DWS of silicon carbide (SiC) ceramics. The effects of ultrasonic vibration assistance, input vibration direction and cutting parameters on sawing forces, surface morphologies and tool wear are studied respectively. The simulation results indicate that elliptical motion in 3D space can be obtained for the diamond abrasive. The experimental results reveal that the proposed model has sufficient accuracy to predict sawing forces. It is demonstrated that sawing forces can be reduced by ultrasonic vibration assistance either in vertical direction or in longitudinal direction. However, 3D ultrasonic vibration condition provides the lowest sawing force because of the combined advantages. Due to intermittent cutting mode, sawing forces are decreased by 31%, 40% and 29.8% in X, Y and Z direction, respectively. Because debris can be removed more easily from the contact surface and large ductile smooth area can be obtained, 3D ultrasonic vibration assistance generates higher surface integrity than that of traditional sawing process. Moreover, the wear of diamond wire saw can be effectively decreased.

Using of versine and sagitta calculations for log sawing optimization, part 1: Circular cross-section

Log sawing can be defined as a problem with obtaining squares from a cylindrical shaped raw material, log. There are traditional sawing methods such as live, cant, quarter, etc. for sawmills. However, they cant generally obtain maximum yield due to log and lumber variables for each log. Therefore, many mathematical approaches and computer programs were improved for log sawing. In this study, suitability of two geometrical calculations, versine and sagitta, were tried for log sawing process. Logs were assumed having cylindrical shape and circular cross section. The estimation accuracy of calculations were tested for live and cant sawing methods with in a drawing software. The results showed that one of versine equations works almost as well as the real dimensions. It is suggested that the equation can be used inside of algorithms for log sawing optimization. However, the real log defects such as taper, irregular cross-section, curvature, etc. should be considered for more realistic yield and accuracy

Establishing empirical relationship between welding current and weld metal deposition rate for submerged arc welding process

Any increase in the productivity of the SAW process will immensely benefit the welding industry, as this process is widely used. Since the traditional single wire DCEP SAW system is extensively used even today, any enhancement using this system will benefit the industry in a big way, if this traditional SAW system is part of the improvisation process. This paper establishes a relationship between welding current and productivity (deposition rate), for the three common sizes of both solid wires and metal cored tubular wires at different current values over its full range, through bead-on-plate experimentation. At each preset current value, the weld bead was optimized for acceptable visual quality, by adjusting arc travel speed and voltage, then the wire feed rate-making optimized bead was noted. The weld metal deposition rate was calculated for establishing A vs WMDR empirical relationships. From the results, ten progressive strategies have been established which can improve welding productivity from 21 to 211% from baseline. The established relationships, strategies can be effectively used, to estimate/optimize the productivity based on the welding current values, for each wire type and diameter.

Sawn timber and rotary veneer processing and grade recovery investigation of northern Australian plantation grown African mahogany

Over half of the large African mahogany plantation estate in northern Australia has reached the mid-point of the target rotation length of 20 to 25 years. As such, there is increasing interest in understanding the potential volume and grade qualities recovered from these young trees using different processing methods. The objective of this study was to compare the recovery rates and product grade quality for rotary veneer using spindleless lathe technology and sawn boards using traditional sawing techniques. Net veneer recovery ranged between 42% and 55% of log volume, with most veneers being limited to D-grade. Compression, surface roughness, and grain breakout were the most prominent defects limiting veneer grade. The sawn-dried-dressed recovery was low, with less than 20% of the log volume representing a potential saleable product. The small log diameter combined with defects including wane, heart shake, pith, and knots reduced the potential recovery. A high presence of sawn board distortion was observed that negatively impacted the efficiency of sawn timber processing along with product recovery. While low, the recovery of veneers and sawn timber from young African mahogany was like other young plantation grown hardwoods.

Experimental investigation on cutting mechanisms in fixed diamond wire sawing of bone

Bone sawing has been widely used in performing bone surgery. However, thermal necrosis, loss of cutting precision and surface damage may occur in cutting process. The primary objective of this research is to improve cutting performance of bone by advantages of diamond wire sawing. Mechanism of material removal, cutting force, temperature and surface quality are analyzed based on experimental results. It is indicated that wire sawing provides small depth of cut, which is effective to obtain ductile material removal mode. Due to small material removal rate per abrasive, thermal energy is low and most of the heat can be taken away by the cyclic wire and bone chips. Consequently, cutting force and temperature in cutting zone are lower than that of traditional sawing. Due to the high efficiency of chip ejection, burrs and fracture are reduced and a significant improvement in surface quality is achieved. Based on cutting experiments with various values of cutting parameters, it is observed that better performance is achievable at higher wire speeds. These results provide a valuable basis for application of wire sawing and understanding of bone cutting mechanisms.

A novel design method for SAW temperature sensor with monotonic and linear frequency-temperature behavior in wide temperature range

In this work, a novel method was proposed to achieve linear temperature dependent frequency in SAW temperature sensors. The designed SAW temperature sensor can operate in a wide temperature range without the limitation originated from the large second-order frequency-temperature coefficient of traditional SAW resonators. An SAW temperature sensor which consists of two SAW resonators was designed with the proposed method. The frequency characteristics of the SAW resonators were measured from room temperature up to 600 °C. The resonance frequency shows good linearity as the function of the temperature. This novel design method can be widely applied in the SAW temperature sensors based on the piezoelectric substrates with large second-order frequency-temperature coefficient.

Research on Supplier Evaluation in a Green Supply Chain

The supplier is considered to be attractive under green supply chain management; supplier evaluation is also confronted with a serious challenge. Based on this background, this paper studies green supplier evaluation and selection with weights unknown in hesitant fuzzy sets and presents evaluation indexes by the DEMATEL method. On the basis of the Euclidean distance, hesitancy degree is used to construct the improved type signed distance. At last, the paper calculates relative closeness to rank green suppliers by the improved TOPSIS method and compares the results of the traditional algorithm and SAW method. The result of the example shows that the algorithm has practicability and a dipartite degree.

A NUMERICAL STUDY OF THE EFFECT OF GREEN-STATE MOISTURE CONTENT ON STRESS DEVELOPMENT IN TIMBER BOARDS DURING DRYING S Florisson, S Ormarsson, J Vessby

Timber boards manufactured with a traditional sawing pattern often contain both heartwood and sapwood. The difference in moisture content between heartwood (30-60%) and sapwood regions (120-200%) result in a radial moisture variation that can cause internal constraints during drying. However, the green state moisture content is seldom considered when evaluating kiln drying schedules. The developed numerical model is able to simulate stress development in timber boards, which are dried from green state to equilibrium moisture content. The model studied the effect of initial moisture content on stress development in timber boards during drying. The model operates on continuum level and consists of a coupled transient non-linear orthotropic moisture flow analysis, while a stress analysis considers elastic, hygroscopic and mechano-sorptive strain behaviour with use of the finite element method. The simulations were performed on four different timber board configurations, each defined by a unique pith location. The study shows that the green state moisture content does not necessarily lead to significant constraints, but has a positive effect on the maximum tensile stress found in tangential direction at the exchange surfaces in the beginning of the drying process. In this stage, stress development is mainly governed by shrinkage close to the surface, which is partly prevented due to regions still above the fibre saturation point. The initial MC can also influence the time when the maximum stress occurs, but not necessarily the location.

Comparison of processing methods for small-diameter logs: Sawing versus rotary peeling

Currently there are limited markets in Australia for small-diameter native forest logs. This has resulted in much of this resource being underutilized and regarded as sub-optimal in quality and of low value. This is despite the fact that the wood properties are favorable for a wide range of high-value products. Traditional processing approaches either have not been able to accommodate small-diameter logs or the resulting product recovery is too low for profitable production. Alternative processing approaches are necessary to enable the efficient recovery of wood from this resource in a form that is usable for high-value product manufacturing. Processing small-diameter spotted gum (Corymbia citriodora) and white cypress pine (Callitris glaucophylla) logs into rotary veneer using new spindleless veneering technology has been demonstrated to yield more acceptable recoveries compared with more traditional sawing approaches. The veneer processing approach was also found to be less impacted by the diameter than sawing, with more consistent recovery rates across the three small-diameter log groups included in this study. The resulting veneer, especially the spotted gum veneer, had visual qualities and mechanical properties well suited to the manufacturing of veneer-based engineered wood products.

Micromixing using swirling induced by three-dimensional dual surface acoustic waves (3D-dSAW)

Abstract Efficient mixing in a microfluidic system is difficult to achieve, since it is dependent solely on molecular diffusion due to low Reynolds number. In this paper, we newly propose a novel mixing technique using three-dimensional dual surface acoustic waves (3D-dSAWs) generated from two interdigitated transducers of top and bottom piezoelectric substrates. By using the 3D-dSAW, internal swirling in a single direction is induced, which can facilitate more efficient mixing of a fluorescent particle suspension and deionized water. Therefore, by using the 3D-dSAW mixer, higher efficiency mixing performance can be achieved compared to the single SAW mixer at the same flow rate and applied voltage. With the applied voltage of 14 V, 3D-dSAW mixing device could achieve 100% mixing efficiency at the flow rate of 50 μl/min, while the mixing efficiency of the traditional single SAW mixer was approximately 38%. Moreover, the throughput of 3D-dSAW mixing device could be enhanced up to 120 μl/min with the applied voltage of 18 V, at which the measured temperature was lower than 40 °C and the efficiency could reach approximately ∼95.6%.

Efecto del sistema de aserrío tradicional en las características de la madera de encinos

El proceso de aserrío de encinos se considera una fase importante de su industrialización y de la calidad de la madera generada. Se analiza el control de calidad del proceso de aserrío, el sistema de corte tradicional con el radial y su efecto en los coeficientes de aprovechamiento, en los tiempos de procesamiento y en la proporción de dimensiones en anchos de la madera generada. Se utilizaron trozas de Quercus laurina, Q. candicans y Q. acutifolia, que se procesaron en un aserradero banda de 8 plg de ancho, con sierras tradicionales para pino. La variación del corte (St) fue de 3,93 mm, que se considera alta y refleja una mala calidad del aserrío, la media fue de 25,36 mm y la dimensión óptima de corte de 28,71 mm, la diferencia indica que un porcentaje considerable de las tablas producidas (80 %) no se puede clasificar en el espesor de la categoría de 3/4 plg. Los coeficientes de aserrío del sistema tradicional fueron de 55,83 % y en el radial de 52,31 %. El tiempo de aserrío para procesar 1 000 pies tablas en el sistema tradicional fue de 73 minutos y en el radial de 103 minutos, lo que representa un 41 % más del tradicional. Con el sistema se aserrío radial, se generó una proporción alta (77 %) de tablas angostas (4 plg y 6 plg), y un porcentaje bajo (23 %) de tablas con anchos mayores de 8 plg. Con el aserrío tradicional, las proporciones se invierten significativamente, para los anchos mayores a 8 plg representaron un 88 %.

Comparison of piezosurgery and traditional saw in bimaxillary orthognathic surgery

PurposeInvestigators have hypothesised that piezoelectric surgical device could permanently replace traditional saws in conventional orthognathic surgery. MethodsTwelve consecutive patients who underwent bimaxillary procedures were involved in the study. In six patients the right maxillary and mandible osteotomies were performed using traditional saw, whilst the left osteotomies by piezoosteotomy; in the remaining six patients, the surgical procedures were reversed. Intraoperative blood loss, procedure duration time, incision precision, postoperative swelling and haematoma, and nerve impairment were evaluated to compare the outcomes and costs of these two procedures. ResultsCompare to traditional mechanical surgery, piezoosteotomy showed a significant intraoperative blood loss reduction of 25% (p = 0.0367), but the mean surgical procedure duration was longer by 35% (p = 0.0018). Moreover, the use of piezoosteotomy for mandible procedure required more time than for the maxillary surgery (p = 0.0003). There was a lower incidence of postoperative haematoma and swelling following piezoosteotomy, and a statistically significant reduction in postoperative nerve impairment (p = 0.003). ConclusionsWe believe that piezoelectric device allows surgeons to achieve better results compared to a traditional surgical saw, especially in terms of intraoperative blood loss, postoperative swelling and nerve impairment. This device represents a less aggressive and safer method to perform invasive surgical procedures such as a Le Fort I osteotomy. However, we recommend the use of traditional saw in mandible surgery because it provides more foreseeable outcomes and well-controlled osteotomy. Further studies are needed to analyse whether piezoosteotomy could prevent relapse and promote bony union in larger advancements.

Single-Use Instruments, Cutting Blocks, and Trials Increase Efficiency in the Operating Room During Total Knee Arthroplasty: A Prospective Comparison of Navigated and Non-Navigated Cases

The purpose of this prospective controlled trial was to determine if efficiency increases could be achieved in non-navigated and navigated total knee arthroplasties by replacing traditional saws, cutting blocks, and trials with specialized saws and single-use cutting blocks and trials. Various timing metrics during total knee arthroplasty, including operating room preparation times and specific intra-operative times, were measured in 400 procedures performed by eight different surgeons at 6 institutions. Efficiency increases were the result of statistically significant reductions in combined instrument setup and cleanup times as well as in adjusted surgical episode times in navigated total knee arthroplasties. Single-use instruments show promising benefits, but adequate patient follow-up is needed to confirm safety and efficacy before they can be widely adopted. Nevertheless, the authors believe that the use of single-use instruments, cutting guides, and trial implants for total knee arthroplasty will play an increasing role in improving operating room efficiency.

Single-Use Instrumentation, Cutting Blocks, and Trials Decrease Contamination during Total Knee Arthroplasty: A Prospective Comparison of Navigated and Nonnavigated Cases

The purpose of this prospective controlled trial was to determine whether decrease in contamination could be achieved in nonnavigated and navigated total knee arthroplasties by replacing traditional saws, cutting blocks, and trials with specialized saws and single-use cutting blocks and trials. Various tray wrapping metrics during total knee arthroplasty were measured in 400 procedures performed by 8 different surgeons at 6 institutions. Instrumentation contamination was determined by counting the number of tray sterility indicators, pans, and instruments that were compromised. The results show that a decrease in contamination was evident in 57% (nonnavigated) and 32% (navigated) fewer compromises of tray sterility indicators, pans, and instruments. Single-use instruments show promising benefits, but further study is needed to confirm safety and efficacy before they can be widely adopted. The authors believe that the use of single-use instruments, cutting guides, and trial implants for total knee arthroplasty will play an increasing role in decreasing operating room contamination and potential deep infections.

SAW Sensors and RF ID Tags without a Reference Channel

A new approach for design of SAW sensors and tags is discussed. We propose to use a two-path SAW oscillator as a sensor. This structure does not require a reference channel as a traditional SAW sensor does. Also we show that the use of fan-shaped transducers in sensors and RF ID tags allows one to utilize different frequency bands in the same propagation path for reference and code parts of the signal. In the article we present prototypes of SAW chemical alarm sensor and SAW RF tag.

Nano-resonators for RF-enabled networked-control

Several types of microfabricated mechanical filters are analyzed for RF communications applications and their advantages over the traditional SAW or FBAR filters are described. GHz frequency operation requires sub-micron dimensions. This work focuses on the modeling of a filter with torsional mode vibration. Ansys finite element simulation has been performed to make comparison with the analytical modelling. These devices enable a networked approach to control along with a specific application to velocity estimation in servocontrol.

DNA immobilization and SAW response in ZnO nanotips grown on LiNbO/sub 3/ substrates

DNA immobilization enhancement is demonstrated in a structure consisting of ZnO nanotips on 128 degrees Y-cut LiNbO3. The ZnO nanotips are grown by metalorganic chemical vapor deposition (MOCVD) on the top of a SiO2 layer that is deposited and patterned on the LiNbO3 SAW delay path. The effects of ZnO nanotips on the SAW response are investigated. X-ray diffraction and scanning electron microscopy are used to analyze the ZnO nanotips, which are of single crystalline quality, and they are uniformly aligned with their c-axis perpendicular to the substrate surface. The photoluminescence (PL) spectrum of the ZnO nanotips shows strong near bandedge transition with insignificant deep level emission, confirming their good optical property. DNA immobilization enhancement is experimentally validated by radioactive labeling tests and SAW response changes. The ZnO nanotips enhance the DNA immobilization by a factor of 200 compared to ZnO film with flat surface. DNA hybridization with complementary and noncomplementary second strand DNA oligonucleotides is used to study the selective binding of the structure. This device structure possesses the advantages of both traditional SAW sensors and ZnO nanostructures.

Distortion and visible crack formation in green and seasoned timber: influence of annual ring orientation in the cross section

This work describes distortion (bow, crook, twist, cup) and the formation of visible cracks in green and seasoned timber of Scots pine and Norway spruce. Distortion and crack formation have been evaluated according to the original location in the cross section of the log. The purpose is to describe differences in distortion and crack formation between sawn timber taken from star sawing and from traditional sawing patterns. Bow and crook develop in the green timber immediately after sawing as a result of growth stress release. Drying and conditioning in general lead to a marginal increase in bow, but crook may show a large percentage increase depending on the location of the wood in the cross section. Twist and cup do not occur directly after sawing, but arise during seasoning of the wood. In sawn wood, the juvenile wood has a major influence on the twist. This means that timber sawn close to the pith shows a greater twist than timber sawn away from the pith. This is a consequence of the fibre orientation in this timber. Cupping increases with decreasing radius of curvature of the annual rings in the cross section of the timber. Cracks occur in timber before seasoning. The pattern of crack formation is the same in both pine and spruce; timber sawn close to the pith or with pith enclosed exhibits a considerably larger number of visible cracks than timber sawn away from the pith. Cracks occur mainly on surfaces orientated to the pith, a fact that becomes clearer when timber is observed close to the pith. Seasoned star-sawn timber with a rectangular cross section has bow and crook of the same extent as or less than that of timber sawn according to traditional sawing patterns. Seasoned star-sawn timber with a triangular cross section has high bow, but the crook is low. Star-sawn timber does not show any cup and has a good shape stability according to the geometrical shape in the cross section. It also has a very small twist and shows very few visible cracks after seasoning.