Stroke Length Research Articles

DEVELOPMENT AND MATERIAL OPTIMIZATION OF 0.67HP PETROL GENERATOR CYLINDER BLOCK USING TAGUCHI DESIGN AND FINITE ELEMENT ANALYSIS

The development of 0.67Hp gasoline generator cylinder block and the material optimization of the component using Taguchi Design and Finite Element Method were carried out successfully. The cylinder block is known to create an avenue for the piston to carry out its reciprocating effect on the crankshaft for onward transmission for the machine output. The designed cylinder block had an engine power of 5.11kw which drove piston through a bore and stroke length of 46.10mm and 51.20mm respectively. The determined clearance volume of 9.46cm 3 was contained in a cylinder wall thickness and block length of 3.04mm and 58.88mm respectively. The designed values were found to be in consonance with recommended values obtained in standard engineering text. The developed mathematical model was determined to be adequate with a statistical Coefficient of determination (R 2 ) of 98.62% and the Adjusted coefficient of determination (Adj R 2 ) was found to be 97.79%. The comparison of optimal values developed from the Taguchi design and genetic algorithm optimizations showed that obtained values from both methods were noticed to be very close as only a difference of about 0.0005 existed among the input parameters. The genetic algorithm result was seen as a kind of validation for the Taguchi design optimization. The Finite element analysis result showed that the temperature output result recorded the highest temperature of 100 o C around the cylinderical bore axis while the lowest temperature of 51.97 o C was found on the cooling fins of the component. Keywords: Optimization, Taguchi Design, Genetic Algorithm and Finite Element Analysis. DOI: 10.7176/JIEA/12-1-04 Publication date: March 31 st 2022

Changing Oar Rotation Axis Position Increases Catch Angle During Indoor and In-Field Para-Rowing: A Randomized Crossover Trial Verified by a Repeated Measurement Trial

A long rowing stroke length is crucial for adequate rowing performance. Therefore, the relocation of the oar from traditional “in front” (NORM) to “behind the rotation axis” (GATE) may increase (para) rowing performance. Thus, 15 able-bodied rowers (21.4 ± 3.6 years; 187 ± 8 cm; 85.4 ± 8.2 kg) completed indoor TANK rowing 2 min TimeTrials (2 min-TT) of GATE and NORM in a randomized order. Additionally, one elite Paralympic oarsman (37 years, 185 cm, 67 kg) performed a multiple single case in-field BOAT testing (24x2min-TT of GATE and NORM in a randomized order). GATE revealed significantly larger catch angles during TANK (+97.1 ± 120.4%; p = 0.001, SMD = 0.84) and BOAT (+11.9 ± 3.2%; p < 0.021; SMD = 2.69; Tau-U = 0.70) compared to NORM. While total stroke length, rowing power, and work per stroke increased in GATE during TANK (p < 0.010, SMD > 0.634), no such significant changes of these performance parameters between GATE and NORM were observed during BOAT (p > 0.021; SMD < 0.58; Tau-U < 0.29). Rowing economy-related parameters (power or speed per oxygen uptake) and boat speed also showed no significant differences between GATE und NORM during BOAT (p > 0.61; SMD < 0.31; Tau-U < 0.19). The shape of the force–angle curve (position of peak force and ratio between average and maximal force) remained unaffected from GATE during both TANK (p > 0.73, SMD < 0.1) and BOAT (p > 0.63; SMD < 0.60; Tau-U < 0.27). In conclusion, GATE shifted the entire rowing stroke towards the catch (+6.6 ± 1.8°) without notably affecting relevant performance parameters during BOAT. Particularly during crew rowing, the minimization of detrimental boat movements for perfect synchrony should be aimed for. Accordingly, the combined application of GATE and NORM (for different athletes in crew boats) may be beneficial for rowing synchronization.

How Anthropometrics of Young and Adolescent Swimmers Influence Stroking Parameters and Performance? A Systematic Review.

The purpose of this systematic review was to investigate the relationship between anthropometric characteristics, biomechanical variables and performance in the conventional swimming techniques in young and adolescent swimmers. A database search from 1 January 2001 to 30 June 2021 was done according to the PRISMA statement, with 43 studies being selected for analysis. Those manuscripts were divided in butterfly, backstroke, breaststroke and front crawl techniques as main categories. The results showed the importance of the anthropometric variables for the performance of the young swimmer, although there was a lack of variables common to the studies that analysed the butterfly, backstroke and breaststroke techniques. For the front crawl technique there is a consensus among studies on the advantage of having higher height and arm span values, variables that concurrently with high body mass and lean body mass values, contribute positively to better stroke length and stoke index values.

The Impact of a Swimming Training Season on Anthropometrics, Maturation, and Kinematics in 12-Year-Old and Under Age-Group Swimmers: A Network Analysis.

Understanding fluctuations and associations between swimming performance-related variables provide strategic insights into a swimmer's preparation program. Through network analysis, we verified the relationships between anthropometrics, maturation, and kinematics changes (Δ) in 25-m breaststroke (BREAST) and butterfly (FLY) swimming performance, before and after a 47-week swimming training season. Twenty age-group swimmers (n =11 girls: 10.0 ± 1.3 years and n = 9 boys: 10.5 ± 0.9 years) performed a 25-m all-out swim test (T25) in BREAST and FLY techniques, before and after 47 weeks. Three measures of centrality, transformed into a z-score, were generated: betweenness, closeness, and strength. Data were compared (t-test) and effect sizes were identified with Hedges' g. Large effect sizes were observed for swimming performance improvements in BREAST (32.0 ± 7.5 to 24.5 ± 3.8 s; g = 1.26; Δ = −21.9 %) and FLY (30.3 ± 7.0 to 21.8 ± 3.6 s; g = 1.52; Δ = −26.5 %). Small to moderate effect sizes were observed for anthropometric changes. Moderate effect size was observed for maturity offset changes (−2.0 ± 0.9 to −1.3 ± 1.0; g = 0.73; Δ = 50.9 ± 281 %). Changes in maturity offset, stroke rate (SR), and stroke length for both BREAST and FLY swimming speeds were highlighted by the weight matrix. For betweenness, closeness, and strength, changes in arm span (AS) (BREAST) and stroke length (FLY) were remarkable. The dynamic process of athletic development and the perception of complexity of fluctuations and associations between performance-related variables were underpinned, particularly for simultaneous swimming techniques in age-group swimmers.

Effect of breakout phase on the stroke kinematics and coordinative swimming variables

ABSTRACT The first complete upper and lower limbswimming cycle after the underwater segment of start and turns represents the breakout phase in competitive swimming. The aim of the present research was to examine the effect of the breakout movements on the stroking variables and coordinative patterns of competitive swimmers. Thirty-three national-level male swimmers performed 4 x 25 m maximal efforts (one of each stroke in random order) from a push start and were recorded by two sequential cameras in the sagittal plane. The average velocity, stroke length, and stroke frequency; the relative duration (%) of the stroke phases; and the inter-limb discrete relative phases were calculated using direct linear transformation algorithms for the breakout and free-swimming phases. In general terms, swimming velocity during breakout was faster (δ 0.27 ± 0.04 m/s, p < 0.001, ES = 0.33) than free swimming (in all strokes but breaststroke), not because of a faster previous underwater kicking or a modified coordinative swimming pattern, but because of an increase in the stroke rate (δ 4.68 ± 0.79 cycles/min, p < 0.001, ES = 0.36). These results indicate how swimmers manage the changing constraints during breakout from underwater to surface swimming.

Biomechanics of Double Poling in Paralympic Cross-Country Skiing-A Cross-Sectional Study Comparing the Standing and Sitting Positions in Healthy Male Subjects.

Background and Objectives: Double poling is an important fundamental skill required for cross-country skiing in able-bodied athletes and in those with physical disabilities. Meanwhile, the performance improvement and injury prevention related to double poling requires a thorough assessment, whereas the scapular and shoulder kinematics in different postural conditions remain to be clarified. The main purpose of this study was to evaluate the biomechanics during cross-country ski double poling in the standing and sitting positions. Materials and Methods: Eleven participants underwent kinematic assessments of the shoulder girdle during double poling on a ski ergometer with an electromagnetic tracking device. The cycle rate, stroke length, stroke speed, thorax motion relative to pelvis, scapular motions relative to thorax, humeral motions relative to thorax, and humeral motions relative to scapula were calculated for five double-poling cycles. Results: In the sitting position, the angles of humerothoracic elevation were 18 degrees larger and glenohumeral elevation 13 degrees larger than in the standing position at the upward point and range of motion. Conclusions: The study revealed that double poling in the sitting condition increased the humerothoracic and glenohumeral elevation angle to secure the poling margin. If these are excessive, there is a risk of shoulder injuries such as subacromial impingement.

The Effects of 12 Weeks In-Water Training in Stroke Kinematics, Dry-Land Power, and Swimming Sprints Performance in Master Swimmers

Background: Master swimming is becoming increasingly popular, but research related to the training process and its effect on this population is scarce. The aim of this study was to investigate the effects of 12 weeks in-water training in stroke kinematics, dry-land power, and swimming sprints performance in master swimmers, and the relationships between these variables in this sports population. Methods: 15 healthy and physically active male master swimmers (age 32.3 ± 5.1 years, height 1.81 ± 0.04 m, body mass 77.0 ± 6.5 kg, training experience of 11 ± 4 years and average swimming training volume ~2.5 km/day, 3 times a week) participated in the study. Previously and after the intervention program, entirely water-based, swimmers were tested in a dry-land environment to assess their upper and lower body limbs (UL and LL) strength through power measurements, namely countermovement jumps (CMJ), seated 3 kg medicine ball throwing (MBT) and maximal isometric strength with handgrip (HG). In-water 50 m maximal front crawl swimming test was also completed. Swimming performance at 15, 25, and 50 m (T15, T25, and T50) was determined, and the associated stroke kinematics. During the intervention program period, swimming training comprised three sessions per week (7.5 ± 0.9 km per microcycle), with low- to high-intensity aerobic and anaerobic swimming series and technical drills. Results: T25 significantly decreased after 12 weeks of training (18.82 ± 2.92 vs. 18.60 ± 2.87 sec, p = 0.02), the same was observed in the case of T50 (40.36 ± 7.54 vs. 38.32 ± 6.41 sec, p = 0.00). Changes in stroke rate (SR), stroke length (SL) and stroke index (SI) in swimming performance at 15 m were not observed, contrarily to 25 and 50 m, where SL and SI significantly increased. MBT and HG improved, but not CMJ, and improvements in T15, T25 and T50 were mostly related to kinematic proficiency improvement. Conclusions: 12 weeks of in-water training in master swimmers significantly enhance performance time in 25 and 50 m front crawl swimming. SL and SI are also improved and are the variables that most influence T15, T25 and T50 when compared to SR and dry-land power variables. Centering the training process not only in in-water tasks in master swimmers seem to be of relevant interest since age influences stroke kinematic and power variables.

The Impact of Assisted Swimming on Front Crawl Performance

Background: In the present study, we aimed to clarify the impact of the Assisted swim (A-swim; towing from propulsion direction) on front crawl performance at maximum and sub-maximum effort levels. Methods: Fourteen male collegiate swimmers (age, 21.0 ± 2.0 years; height, 1.73 ± 0.05 m; weight, 67.1 ± 7.1 kg) participated. Participants swam 25-m front crawl at maximal (Max) and submaximal intensity (Submax (80% of the max stroke rate (SR))) with and without an assist (assisted swimming with a towing device and normal swim (N-swim) without the device) for a total of four lengths. In addition to swim velocity (V), SR, and stroke length (SL), one stroke cycle was broken down into four phases—glide, pull, push, and recovery—and analyzed the duration of each phase. Results: A significant interaction of level of efforts and presence/absence of towing was confirmed in V, SR, and SL. V and SL showed a significant increase in A-swim compared to N-swim at both Max and Submax. SR was significantly higher in A-swim than in N-swim only at Max. Each phase of stroke showed a significant difference in recovery at Submax and push at Max. Conclusions: Despite considering the impact of propulsion from towing, A-swim increased SR, in addition to the V and SL, of swimmers compared with N-swim.

Optimal race analysis parameters of freestyle swimming events: A case study

Introduction: During the swim meet, race analysis is a common practice to provide insight into each event. This case study explores the variables of swimming performance using the video analysis method.Purpose: To determine the best indicator from a set of swim variables (digitised from video) for competitive swim races by one Malaysian freestyle swimmer in preparation for the Tokyo Olympic Games 2020.Methods: Race video footage was analysed retrospectively to determine the key parameter for each event distance. The following variables were calculated: start time, end time (ET), turn time (TT), stroke count, stroke length, stroke rate, average velocity (AV) and stroke index. Differences were subsequently assessed among the parameters within the same event style.Results: The results from the correlation test between the eight digitised variables and final time (FT) showed that for both 200 and 400 m events the variables AV (respectively, r = −0.96 and r = −0.94) and TT (respectively, r = 0.89 and r = 0.83) were significantly correlated. In addition, for the 200 m events, the ET also significantly correlated (r = −0.94) with FT.Conclusion: This swimmer and over this period of Olympic qualifiers competitions, AV and TT were the best indicators for swim performance. Regarding the 200 m events, the end (sprint) time may also be an indicator.

200-m front crawl performance over a training season in 12 years and underage-group swimmers: growth and kinematics effects

Aims: analyze kinematics, anthropometrics, and maturation during a training season in 12 y and underage-group swimmers, quantifying changes and estimating their contributions to the 200-m maximal front crawl time trial test (T200) (time trial/fixed distance), as an event representative of the swimming performance. Methods: Nineteen age-group swimmers (11 girls and 8 boys; age 10.0 ± 1.3 y and 10.6 ± 1.0 y) performed a T200 four times during the training season. Changes in kinematic and anthropometric variables throughout the season were calculated. We applied generalized estimating equations to compare the variables over the four experimental tests. Multiple linear regressions were applied to identify the most influential variables and the relative contribution of anthropometrics and kinematics to swimming performance of T200 at baseline (pre-season) and after (using delta values) each macrocycle. Results: Large improvements (d = 1.76) were observed in the T200's performance (from 85.5 ± 38.2 at pre-season to 175.2 ± 50.1 FINA points at the end season). A gender effect was not identified. Stroke rate, stroke length, and stroke index explained, respectively 59, 23, and 17% of the T200 performance changes along the season (R2 = 0.81; F = 26.9; p < 0.001; Durbin-Watson: 1.5). Anthropometric was not related to performance changes, with kinematic being the most determinant factor. Conclusion: Kinematical approaches must be carefully considered by coaches when planning 12 y and underage-group swimmers training programs.

Case Study: Comparison of Swimsuits and Wetsuits Through Biomechanics and Energetics in Elite Female Open Water Swimmers

The authors investigated how the Arena Powerskin R-EVO Closed Back swimsuit and Arena Carbon Triwetsuit (full-sleeve wetsuit), both approved by the Fédération Internationale de Natation (FINA) regulations, affect biomechanics and energetics of 3 elite female open water (OW) swimmers at maximal and 4 submaximal swimming intensities. Three elite female OW swimmers (OW1 = 24y, 1.64m, 60kg; OW2 = 23y, 1.69m, 65kg; OW3 = 27y, 1.63m, 64.5kg) were tested 1 week prior to a FINA/CNSG (China National Sports Group) Marathon Swim World Series event and 40 days before the 18th FINA World Championships 2019. Each OW swimmer completed 2 identical testing sessions, one with a swimsuit and other with a wetsuit, involving shoulder flexion power output assessed from medicine-ball throw, maximal performance and drag coefficient assessment, and an incremental intermittent swim test at 4 different relative intensities. Estimated peak oxygen uptake was 4.4L·min-1 for OW1, 5.6L·min-1 for OW2, and 5.0L·min-1 for OW3. Despite a distinct behavior observed on index of coordination for OW3, a null index of synchronization, increased stroke rate (mean difference = 2%-8%), reduced drag factor (minimum = -14%; maximum = -30%), lower energy cost (mean difference = -2% to -6%), and faster performance (mean difference = 2% to 3%) were observed with the wetsuit compared with swimsuit for all elite OW swimmers. The wetsuit enhances submaximal swimming performance, and this increase is dependent on the OW swimmer's characteristics. The higher stroke rate and lower stroke length detected with wetsuit could be related to movement constraints imposed by the suit.

Valve efficiency at depth pumps

Oil extraction by deep pumping uses bottom hole pumps whose efficiency depends on several parameters like: surface stroke length, stroke rate, pump depth, pump clearance. Pump valves play an important role in the efficiency of deep pumping. They wear out quite frequently, especially when the pumped oil contains mechanical suspensions. Choosing the right valves increases the pumping efficiency and prolongs the service life of the pump.

Effect of temperature on the lubrication ability of two ammonium ionic liquids

The tribological properties of ionic liquids (ILs) have been widely investigated, and their excellent performance has been acknowledged by many researchers. However, their lubricity is closely linked to operating conditions. For wider applications, the complexity of their behavior must be understood. In this study, we compared the tribological properties of ILs at temperatures of 30 °C and 80 °C. Two ammonium ILs with different cation side-chain lengths, methyl-trioctylammonium [N1888] and tributylmethylammonium [N4441] and the same anion bis(trifluoromethylsulfonyl)imide [NTf2] were selected. Their tribological properties were investigated in the lubrication of three different friction pairs: bearing steel–bearing steel E 52100, bearing steel–stainless steel 304, and bearing steel–aluminum alloy 6082 T6. Tribotests were performed using a ball-on-plate reciprocating tribometer for 30 min at 4 N, 15 Hz, and a 1 mm stroke length. The worn surfaces were analyzed using optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results indicated diminished lubricity at higher test temperatures. The performance difference between the investigated temperatures depended on the friction pair, being almost negligible in bearing steel–bearing steel friction pairs and significantly different for bearing steel–aluminum friction pairs. The wear reduction ability was more sensitive to the test temperature than friction did. The investigated ILs were superior to the 5W–40 motor oil at both temperatures.

A Novel Reciprocating Tribometer for Friction and Wear Measurements with High Contact Pressure and Large Area Contact Configurations

There are many moving machine assemblies with conformal tribological contacts at very high contact pressures, e.g., sliding bearings, propeller shaft bearings and machine guideways. Furthermore, applications such as trunnion and guide vane bearing in Kaplan turbines have very low sliding speeds and oscillatory types of motion. Although there is a vast selection of tribology test rigs available, there is still a lack of test equipment to perform friction and wear tests under high contact pressure, reciprocatory sliding and large area contact. The aim of this work is thus to develop a novel reciprocating tribometer and test method that enables friction and wear tests under low-speed reciprocatory sliding with contact pressures up to 90 MPa in a flat-on-flat contact configuration. First, a thorough description of the test rig design is given. Secondly, the influence of contact pressure and stroke length on the tribological properties of a stainless steel and polymer composite material combination is studied. The significance of considering creep, friction during the stroke and contact temperature is specifically highlighted. The novel tribometer can be used to screen different bearing and shaft material combinations and to evaluate the friction and wear performance of self-lubricating bearings for the specific operating conditions found in Kaplan turbines.

Effect of pin generatrix on the elastohydrodynamic lubrication performance of pin-bush pair in industrial roller chains

For industrial roller or bush chains, the bush swings relative to the pin at working condition. If proper lubrication is maintained, an elastohydrodynamic lubrication contact is formed between the pin and the bush. In this study, a custom-made pin was used to replace the steel ball of a ball-disk test rig and optical interferometric experiments were carried out to study the effect of pin generatrix on the lubrication performance. The effects of generatrix shape, stroke length and oil supply condition on the lubrication state were explored. It is found that the change of the generatrix has an important influence on the oil film thickness, especially under rare oil supply condition.

Feasibility and Potential Impact of Heart Transplantation From Adult Donors After Circulatory Death

BackgroundA shortage of donation after brain death (DBD) donors for heart transplantation (HT) persists. Recent improvements in organ procurement from donation after circulatory death (DCD) donors and promising early results of DCD-HTs from Europe and Australia have renewed interest in DCD-HT. ObjectivesThe current study evaluated donor and recipient characteristics, early outcomes, and potential impact of adult DCD-HT in the United States. MethodsThe United Network for Organ Sharing registry was used to identify and compare adult DCD donors based on their use for HT between January 2020 and February 2021. Adult DCD-HTs with available post-HT outcomes data were compared with contemporary adult DBD-HTs during study period using Cox-regression analysis and propensity-matching. ResultsOf the 3,611 adult DCD donors referred during the study period, 136 were used for HT. DCD donors used for HT were younger (median age 29 years), and most were male (90%), and blood type O (79%). On comparing DCD-HT (n = 127) and DBD-HT (n = 2,961) meeting study criteria and with available data on post-HT outcomes, there was no significant difference in 30-day or 6-month mortality, primary graft failure up to 30 days, or other outcomes including in-hospital stroke, pacemaker insertion, hemodialysis, and post-HT length of hospital stay. Results were similar in propensity matched DCD-HT and DBD-HT cohorts. The number of potential adult DCD donors referred has increased substantially (n = 871 in 2010 to n = 3,045 in 2020), and the authors estimated that widespread adoption of DCD-HT could lead to approximately 300 additional adult HTs in the United States annually. ConclusionsThis preliminary analysis of adult DCD-HTs from the United States showed favorable early outcomes and suggested a potential for substantial increase in adult HT volumes with use of DCD donors.

Pulmonary Hypertension as a Predictor of Early Outcomes of Mitral Valve Replacement: A Study in Rheumatic Heart Disease Patients.

AimMitral valve pathology in rheumatic heart disease patients is a common cause of secondary pulmonary hypertension (PH). Our aim was to evaluate pulmonary hypertension severity as a predictor of in-hospital mortality and early complications following mitral valve replacement.MethodsA retrospective review of rheumatic heart disease patients who underwent mitral valve replacement between January 2017 and August 2020 was performed. Systolic pulmonary artery pressure (sPAP) was used to classify patients as no PH (<35 mmHg), mild PH (35-44 mmHg), moderate PH (45-59 mmHg) or severe PH (>60 mmHg). Patients subjected to additional cardiac procedures (such as aortic valve replacement and coronary artery bypass grafting) were excluded from the study sample.ResultsThe study group was composed of 159 patients (mean age: 40; 73 male, 86 female) categorized as no PH (n = 32; 20.1%), mild PH (n = 14; 8.8%), moderate PH (n = 65, 40.9%) and severe PH (n = 48, 30.2%) groups. Patient demographic data and preoperative comorbidities were comparable among the four groups. Use of intraoperative and postoperative blood products was similar in all the groups. Severe PH patients had similar in-hospital mortality (4.2%; p = 0.74) as in groups with lesser degrees of pulmonary hypertension. Likewise, increasing severity of pulmonary hypertension did not confer any significant increase in early postoperative complications, namely prolonged ICU stay (10.4%; p = 0.41), prolonged ventilation (2.1%; p = 0.70), reintubation (4.2%; p = 0.90), reopening for bleeding tamponade (6.3%; p = 0.39), new-onset renal failure (6.3%; p = 0.91), postoperative stroke (4.2%; p = 0.52) or prolonged length of stay (mean: 5.6 + 2.8 days; p = 0.49).ConclusionsIncreasing severity of pulmonary hypertension does not appear to have a significant impact on in-hospital mortality or early postoperative outcomes of patients undergoing mitral valve replacement.

Productivity improvement in honing machining process

In the past few years, legislation regarding fuel consumption and its emission levels for the automotive industry has become increasingly comprehensive. The friction generated in the engine should be minimum to reach the demands for automotive manufacturers. The cylinder liner is considered to be one of the most critical engine components regarding friction and different surface texture. Honing is one of the best machining processes to create efficient cylinder liners. In this research paper, the key parameters have been identified in the process control connected to surface roughness by optimizing the honing process in cylinder liner manufacturing in the automobile industry. Furthermore, the aim is to find an optimal setting of the machine to produce the demanded surface texture. After viewing the results of the test, it has been noticed that plateau honing plays an important role in the surface texture quality. The factors which affected the honing process were namely honing force, stroke length, reciprocating speed, expansion point and rpm. Out of all these, for a given situation, the required important parameter is identified to achieve stipulated cycle time and required surface quality.

Nonlinear observer for electromagnetic position estimation using active current control

This paper proposes a novel electromagnetic position estimation system suitable for piston-cylinder actuators using active current control. The inexpensive non-contacting position measurement system is composed of an electromagnet on the stationary cylinder and a magnetic sensor on the piston rod. The measured amplitude of an alternating magnetic field is used to estimate piston position. The current supply to the electromagnet needs to be actively controlled so as to increase monotonically with piston position, allowing for sufficient magnetic sensitivity along the whole stroke length. Since the position itself is unknown, this poses a challenging coupled estimation-control problem. A nonlinear state observer is designed based on Lyapunov theory to ensure both asymptotically stable position estimation and current modulation. The desired current profile is optimized using a direct trapezoidal collocation method to achieve accurate position estimation even for regions with low magnetic sensitivity. The active position system is experimentally validated using a piston-cylinder setup with 20 cm stroke length. Experimental results show that the active position estimation system can achieve 1% measurement accuracy all through the stroke length while a system with constant current consuming the same average power shows nearly twice the estimation error. Through active control of the current supply, the electromagnetic position estimation system offers the potential to either improve measurement accuracy at locations with weak sensitivity, extend the overall position sensing range, or to save electrical energy cost.

Experimental Modal Analysis of a Linear Reciprocating Tribometer for Maximum Reciprocating Frequency

This work demonstrates estimation of critical reciprocating frequency of a fabricated linear pin-on-reciprocating plate tribometer by modal analysis. Experimental investigation by impact testing and numerical analysis using ANSYS Work bench 14 were performed to extract the modal parameters of individual subsystems. The authors could not find reported literature on of estimation of critical reciprocating frequency of pin-on-reciprocating plate tribometer. Authors developed a pin-onreciprocating plate tribometer that can simulate friction and wear under reciprocating sliding conditions for stroke lengths up to 150 mm. The developed pinon- reciprocating plate tribometer had a loading sub system, transmission subsystem and measurement subsystem. From experimental and numerical estimation of modal parameters, transmission subsystem found to had the lowest modal frequency of 18 Hz. Maximum frequency of reciprocation then fixed at 30% of the lowest modal frequency of 18 Hz that is 5 Hz. Confirmatory friction tests were then conducted on the tribometer and found that identification of maximum frictional force was difficult when the reciprocating frequency of plate of tribometer exceeded 4 Hz due to vibrations in measuring system and agreed with the reported literature. This work addresses the need of methodology for establishing critical reciprocating frequency of tribometer. This paper elaborates the modal analysis of a fabricated linear reciprocating tribometer. Resonance of subsystems in reciprocating tribometer affects experimental estimate of coefficient of friction (CoF). Subsystems have their own individual modal frequencies. Hence, modal analysis of all subsystems becomes obligatory. Tribometer developed for this study can simulate reciprocating friction and wear for stroke lengths up to 150 mm. Experimental and numerical analysis utilized to identify modal frequency of individual subsystems. Tests identified that transmission subsystem had the lowest modal frequency of 18 Hz. Maximum frequency of reciprocation then fixed at 4Hz. This is 25% of the lowest modal frequency of 18 Hz as delineated in literature. Confirmatory friction tests then conducted on the tribometer. Resolving maximum frictional force along the stroke length was impossible over 4 Hz of reciprocating frequency. This is 25% of the lowest modal frequency of structure and agreed with the reported literature. Authors sincerely hope the methodology used in this paper will guide fellow researchers for modal analysis of reciprocating tribometer.