Investigation into the Effects of Backrest Angle and Stick Location on Female Strength

Objectives: The purpose of this study was to investigate the effects of backrest angle and hand maneuver direction on maximum hand strength and to recommend a strength value for the hand-controlled stick of an aircraft. Methods: Forty-eight female subjects were recruited to perform simulated forward–backward and adduction–abduction maneuvers using control sticks. Each subject was free from musculoskeletal disorders and pain. The independent variables included four control maneuvers (forward, backward, adduction, abduction), two right-hand control stick locations (central, side), and three backrest angles (90°, 103°, 108°). The dependent variable was maximum hand strength. Results: The maximum strength for forward maneuvers with both central and side sticks was strongest at a 90° backrest angle (p < 0.001). The maximum strength for adduction maneuvers with both central and side sticks was also strongest at a 90° backrest angle (p < 0.001). On the other hand, the highest strength was observed at a 108° backrest angle when pulling the stick backward (p < 0.001). The abduction strength was significantly stronger than the adduction strength with a central stick (p < 0.001), but the adduction strength was significantly stronger than the abduction strength with a side stick (p < 0.001–p = 0.017). The forward and abduction strength were significantly different in different locations (p < 0.001). The recommended strength in the Code of Federal Regulations (CFR) by the US FAA is higher than the strength values observed in this study. Conclusions: The backrest angle, directions, and location affected the muscular strength. The recommended values should be reevaluated and adjusted for Taiwanese pilots.

The Effect of Microbes and Fly Ash to Improve Concrete Performance

This paper presents the application of�fly ash�combining with microbes in concrete to reduce cement content.�A class F fly ash as cement replacementwas applied with ratios of 20%, 30%, 40%, and 50% to reduce hydration heat. Microbes from bacterial consortium were applied to as the filler to increase concrete compressive strength. The concrete mix design from SNI 03�2834�2000 was applied for a compressive strength target of 30 MPa. The mechanical test was carried out consisting compressive and tensile test.�Concrete�workability�and the heat hydration measurement were performed for fresh concrete.�The results showed that the maximum strength of 45.10 MPa was obtained from specimens with 30% fly ash content.�Application of microbes associated with�fly ash content of 40% showed the maximum strength of 48.47 MPa.�It was found that the tensile strength also increased with the application of�fly ash�and microbes.�Hydration temperature of concrete decreased with the increase of�the ash�content.�This proves that the application of�fly ash�and microbes in concrete can reduce the cement as well as increasing the concrete performance.

Study on the Behavior of Rigid Pavement Using Quarry Dust as a Partial Replacement of Sand and Sulfonated Naphthalene Formaldehyde (SNF) as an Admixture

Quarry dust is considered as a possible source of natural sand or fine aggregate in concrete construction work. This could reduce the problem of dumping of quarry dust as a byproduct from stone crusher factory. The experimental work investigates the optimum quarry dust percentage which can be adopted as replacement of fine aggregate in concrete mainly for rigid pavement. The quarry dust is added at different percentages of 0%, 20%, 40%, 60%, 80%, and 100% replacement of fine aggregate for M35 grade concrete thereby to find out the optimum content of quarry dust that can give better strength in concrete. Mix design has been developed for M35 grade of concrete as per IRC 044 – 2017(Mix Design for Concrete Pavement) and mix design ratio is found as 1: 1.6: 2.62 by using Sulfonated naphthalene formaldehyde (SNF) as an admixture at 1%, and 2%. The required water cement ratio was obtained as 0.39 according to table no.9 of IRC 044 for the target strength of 42.5 N/mm2. Optimum strength and workability test values of concrete made up for various proportions of quarry dust along with SNF are compared with conventional concrete of natural fine aggregate after 7 days and 28 days curing. It is found that the strength increased with the increase in curing time and the maximum strength at 28 days curing and 60% quarry dust replacement with 2% addition of SNF. The maximum strength of quarry replaced concrete is obtained as 40.3MPa, 5.6MPa, and 5.1MPa for compressive, flexural, and split tensile respectively.

Partial replacement of fine aggregate with Copper slag and marble dust powder in geo-polymer concrete: A review

-As of late the ascent of substantial creation costs has consistently been a worry of substantial makers and customers. Using current waste to override concrete and some poIn ongoing years the ascent of substantial creation costs has consistently been a worry of substantial makers and buyers. Using present day waste to override concrete and some bit of all out can diminish its cost and environmental dirt of all out can decrease its cost and natural tainting. The mark to the purpose of this paper to audit the shot at powder made from marble dust close by the copper slag as an in part substitution to fine aggregate all out in geo-polymer concrete. Marble dust powder was used in mix in comprise copper slag as in part substitution to fine aggregate in level of 10%, 20%, 30%, 40% and 50%. The strength of geo-polymer concrete was tested after 7 & 28 days. Result shows that compressive strength is increased after the replacement of 60% of copper slag and marble dust powder to fine aggregate and also flexural strength and split tensile strength increases strength upto 60% and 80% after replacement. These discoveries of the examination express that powdered marble dust will be utilized as the conceivable substitution material to fine aggregate to give maximum strength copper slag geo-polymer concrete.

Experimental verification tests of isokinetic equipment used in sport and rehabilitation

Abstrakt The paper deals with experimental verification of selected types of tests on isokinetic, diagnostic IsoForce2 training equipment. The isokinetic device provides accurate and immediate information about the developed strength in the exerciser's movement. The main criterion is its versatility when used in sport or rehabilitation. Therefore, it was necessary to create a portable adjustable structure that allows all the movements to be carried out and must meet other specific requirements. An important information is the amount of data collected, which is collected through the measurement system and then analyzed. The first test was elbow flexion, which was verified in arm-wrestling. The second test was knee flexion, which tested patients in rehabilitation after knee surgery to determine the difference in maximum strength between the lower limbs. The results of measurements are accurate, repeatable and provide athletes, patients, coaches and physiotherapists with immediate information about the level of strength abilities in a given type of test or movement.

Optimization of FSW Process Parameters to Yield Maximum Shear Fracture Load of AA2024 Aluminum Alloy Joints

AA2024 Aluminum alloy has predominantly been used for making aircraft engine parts and frames. The normal welding process does not apply to join aluminum alloy. Because Al and its alloy have a low melting point and high thermal conductivity, which can easily lead to porosity and partially melting; as a result, Friction Stir Welding (FSW) has been employed to solve these issues. This work focused on the parameter’s optimization to the conceived maximum strength of AA2024 aluminum alloy. Four major parameters viz., tilt angle, shoulder diameter, welding speed, and rotational speed were selected. The formulation of empirical relationship was made using statistical tool design of experiment, and analysis of variance has been used to check the developed model’s adequacy. Furthermore, the response surface graphs were used to identify the maximum strength and its corresponding FSW parameters. The joint obtained the full power from the experimental results at a tilt angle of 1.5 deg., traverse speed of 15 mm/min, speed of tool 1100 rpm, and diameter of shoulder 24 mm.

A Comparative Study between the Usages of Differently Sized Waste Rubber Obtained From Tires over the Strength Performance of Rigid Road Pavements

In this research work, waste rubber obtained from tires is mainly used as a fractional substitution of natural coarse aggregate to improve the strength aspects of the concrete. 3 dissimilar sizes of waste rubber obtained from tires aggregates were used that is of 4mm, 10 mm and 16 mm. Depending upon all three sizes all the waste rubber obtained from tires aggregate were used at 3 different percentages that are at 10 percent, 20 percent and 30 percent. Then several concrete samples were prepared depending upon the shape and percentage of the waste rubber obtained from tires aggregate. Then all these samples were cured and tested after 7 days and 28 days. Depending upon the results obtained after these above-discussed test various conclusions has been drawn which are as follows. It was found that the maximum strength was obtained at 20 percent usage of 4mm sized waste rubber obtained from tires aggregate, the strength obtained at 20 percentage with 4mm size was maximum as compared to all other concrete samples, so it can be concluded that the compressive strength depends upon both the size as well as on the percentage of waste rubber obtained from tires aggregate and with the decrease in size of the waste rubber obtained from tires aggregate the strength was increasing. From the test results of the split tensile strength test and flexural strength test, it was found that the maximum strength was obtained at 20 percent usage of 4mm sized waste rubber obtained from tires aggregate and with the increase in size and percentage the strength was declining. So therefore it can be concluded that both split tensile strength and flexural strength depends upon the size of waste rubber obtained from tires aggregate and the percentage of waste rubber obtained from tires aggregate. From the obtained test results it can be concluded that with the addition of the waste tire rubber the overall internal micro-structure of the concrete improves which further leads to enhanced mechanical strength of the concrete. This was due to the physical properties and the chemical composition of the waste tire rubber particles which fills the internal pores in a broader way and lead to improved mechanical strength.