Simulation Study of Dynamic Characteristics of Hot Pepper Harvester

Purpose Determining the safety conditions of a hot pepper harvester to mechanize harvesting. Methods The dynamic characteristics of a hot pepper harvester were analyzed with the dynamic simulation program RecurDyn. Results The pepper harvester can climb a maximal slope of 25° under full loading conditions; the maximal allowable height of an obstacle over which the harvester can drive is 450 mm; the minimal rotation radius during a spin turn is 870 mm. Conclusions Considering its dynamic characteristics, the harvester can be applied on over 95% of domestic upland fields. The safety accident rate can be decreased with the use of the spin turn method. In conclusion, the dynamic characteristics are sufficiently safe for the domestic upland fields.

CFD Simulation on Workability of a Seaweed Harvesting Boat Due to Wake-Wash

In the present study, a 2-ton class seaweed harvesting boat was optimized by employing a W-shape hull form to reduce roll motion due to wake-wash from passing boats. A series of numerical simulations were conducted using Star-CCM+, a commercial CFD (computational fluid dynamics) software, to improve workability by optimizing the hull form from the conventional design (original hull form). The 2-dimensional roll decay motion of various hull forms with W-shape midsection were simulated and the hull form with the best performance in free roll decay test was selected. To evaluate stability of each hull in wake-wash, the original or optimized hull was alternately located at the middle of a computational domain as a target ship while an advancing ship (original hull) moved forward generating Kelvin waves which impact the original or optimized boat. Two kinds of working conditions, i.e., ballast and full loading conditions, of the target ship were considered with and without initial roll angle. It was observed through the comparison of motion between the original and optimized hulls a decrement of roll motion for the optimized ship demonstrating the effectiveness of the W-shape hull. Decrement of roll motion was observed for both working conditions. Additionally, the optimized W-shape hull showed an extraordinary performance under the ballast condition without initial roll angle.

Effects of Tension–Compression Asymmetry on Bending of Steels

Stainless steels (SUS) and dual-phase (DP) steels have tension-compression asymmetry (TCA) in mechanical responses to full loading cycles. This phenomenon can significantly influence sheet metal forming of such metals, however, it is difficult to describe this behaviour analytically. In this research, a novel analytical method for asymmetric elastic-plastic pure bending using the Cazacu–Barlat 2004 asymmetric yield function is proposed. It only uses material parameters in tension along with an asymmetry coefficient related to the yield function. Bending operations of SUS304 and DP980 are investigated as two case studies. In the pure bending for both SUS304 and DP980, moment–curvature diagrams are analytically obtained. Furthermore, linear and nonlinear springback behaviours of SUS304 are analytically investigated. Moreover, using the analytical model as a user-defined material, a numerical model is developed for both steels under pure bending. In the V-bending case of SUS304 with and without TCA effects, the springback behaviours of the material are investigated numerically. In addition, considering friction effects, the analytical method is further modified for predicting springback behaviours in the V-bending of 16 types of SUS304 with various strengths are determined. All the analytical and numerical results have good agreement with those experimental results from literature for validation.

Study on Transverse Strength of the Deck-Container Ships due to Laying All Containers on Deck

The strength of transversal structure of the ship has a great effect on the safety of ship. Shipswill experience conditions that affect the strength of the ships structure. A deck-container ships are the ships that all container are loaded on deck such as MV. Khendaga Nusantara series ships. The transversal strength of the ships is loaded mainly by the weight of cargolaying on deck.. This research aims to determine the transverse strength of a deck-container ship due to the all container loads on deck. The research was done by usingfinite element method throughmodeling transverse ship structure, the simulation is conducted by varying the amount and lay-out of containers on dec). The loads appliedto the model are side loads, bottomloads, and deck loads in according to BKI rules. The results shows that the stress that occurred in the web frame was 140,63 N/mm2due to the placement of the entire container on the deck(full loading). For ship structure response, a deformation of 2,86 mm occurred in the web frame area at maximum loading. Stress ratio that occurs in all ship’s structuredoes not exceed 1 in other words the working stress does not exceed the allowedstress according to BKI rules.

Vibration Analysis and Experimental Validation of Multiple Launch Rocket System Based on MSTMM

Natural vibration characteristics and dynamics response of multiple launch rocket system (MLRS) are of fundamental importance from the viewpoint of vibration levels, firing dispersion, and stability. In this study, a new launch vehicle-supports-rockets coupling dynamic model for a practical MLRS is established. Rui method, namely the transfer matrix method for multibody systems (MSTMM) is a new and efficient method for multibody system dynamics (MSD) and is used to obtain the vibration characteristics and dynamics response. The dynamics model, the topology figure of dynamics model, the transfer equations of elements, the overall transfer equation, the eigenfrequency equation, the body dynamics equations, the generalized coordinate equations, and the dynamics simulation system for the MLRS are established. Based on the advantages of MSTMM in studying MSD, the vibration characteristics and dynamics response of complex MLRS are computed rapidly. Finally, the new model is validated in three ways: (1) modal experiment of MLRS, (2) launch dynamics experiment of non-full loading rockets, and (3) launch dynamics experiment of full loading rockets. The results show that the proposed model can not only simulate the natural vibration characteristics of the MLRS but also effectively perform dynamic simulations of the MLRS during launching process.

Test Dynamics Method of Non-Full Loading Firing for Multiple Launch Rocket System Using Transfer Matrix Method for Multibody Systems

This paper studies test dynamics method of non-full loading firing for multiple launch rocket system (MLRS) and provides a new test method for reducing rocket consumption in MLRS firing precision test. Based on the theories of launch dynamics and Rui method, namely the transfer matrix method for multibody systems (MSTMM), launch dynamics model, characteristic equations and dynamics response equations of MLRS are established. The launch and flight dynamic simulation system for MLRS is developed combining the Monte Carlo simulation technology. The simulated results of vibration characteristics, rocket initial disturbance, and firing precision are verified by modal test, pulse thrust test and firing test, which show the simulation system can more accurately reflect the dynamic characteristics of the actual system and its dynamics computation has sufficient accuracy. The relationship between the initial state of MLRS and the mean value and median error of the impact points are established. Based on the idea of equal initial disturbance, non-full loading firing test dynamics method is presented for reducing the rocket consumption in firing precision test, by optimizing the loading position, firing orders and firing intervals of the rockets. For a practical MLRS, a seven-shot test scheme is designed and tested. The experimental results show that the amount of the rockets in firing precision test is reduce by 61% compared with the conventional test method, which saves a lot of testing costs.

Performance Evaluation of a Solar Tunnel Dryer For Around The Year Use

This study was done to evaluate the performance of a walk-in type solar tunnel dryer for around the year use. In the present study, the performance of solar tunnel dryer was evaluated at no load and at full load conditions. Full loading was done with garlic, chili, fenugreek and aonla candy according to their seasonal availability in Hisar, India. At no load condition, performance was evaluated during three seasons i.e summer, winter, and autumn. During full load, the dryer reduces the moisture content of garlic from 65% (w.b.) to about 8.5% (w.b.) in 8 days, chilli from 77%(w.b.) to 7% (w.b.) in 7 days, fenugreek from 86% (w.b.) to 7.2% (w.b.) in 5 days and aonla candy from 44% (w.b.) to a safe moisture content of 16%(w.b.).The thermal efficiency of the dryer was also measured and was found between 8.89% to 17.63%. A temperature of 15-30 ºC higher than the atmospheric temperature was recorded inside the dryer. Products dried were hygienic and their sensory evaluation showed that they were of good quality and highly acceptable.

Are postnatal ampicillin levels actually related to the duration of intrapartum antibiotic prophylaxis prior to delivery? A pharmacokinetic study in 120 neonates

ObjectiveTo assess ampicillin levels according to the duration of intrapartum antibiotic prophylaxis (IAP).DesignProspective cohort single-centre study.SettingTertiary care centre (Modena, Italy).Patients120 neonates≥35 weeks’ gestation exposed to IAP.InterventionsNeonates were divided into four groups, according to the duration of IAP prior to delivery: group 1 (n=30; <1 hour), group 2 (n=30; ≥1 and <2 hours), group 3 (n=30; ≥2 and <4 hours) and group 4 (n=30; ≥2 doses, ≥4 hours).Main outcome measuresBlood samples were collected at delivery (from the umbilical cord) and at age 4 hours (from a peripheral vessel).ResultsMedian duration of IAP was 121 min (range 7–2045 min). Median ampicillin levels in umbilical cord blood were 10.4 µg/mL (IQR 6.4–14.9) and in peripheral blood were 4.7 µg/mL (IQR 2.8–6.4µg/mL). Umbilical cord blood levels reached a peak approximately 30 min after IAP and then declined significantly (p<0.001). Peripheral blood levels did not differ among study groups. Neonates exposed to a full loading dose (n=115) had peripheral blood levels 2.5–70 times higher than the minimal inhibitory concentration for group B streptococcus. There was no relationship between neonatal ampicillin concentrations and the duration of IAP prior to delivery (β=−0.0003, 95% CI −0.02 to 0.001, p=0.680).ConclusionsAmpicillin levels reach a peak in the umbilical cord blood within 30 min of intrapartum administration. After a full loading dose, bactericidal levels persist for at least 4 hours after birth and seem independent of the duration of IAP prior to delivery.