Study on the Motion Stability of the Autonomous Underwater Helicopter

The hydrodynamic performance of a novel hovering autonomous underwater vehicle, the autonomous underwater helicopter (AUH), with an original disk-shaped hull (HG1) and an improved fore–aft asymmetric hull (HG3), is investigated by means of computational fluid dynamics with the adoption of overlapping mesh method. The hydrodynamic performance of the two hull shapes in surge motion with variation of the angle of attack is compared. The results show that HG3 has less resistance and higher motion stability compared to HG1. With the angle of attack reaching 10 degrees, both HG1 and HG3 achieve the maximum lift-to-drag ratio, which is higher for HG3 compared to HG1. Furthermore, based on the numerical simulation of the plane motion mechanism test (PMM) and according to Routh’s stability criterion, the horizontal movement and vertical movement stability indexes of HG1 and HG3 (GHHG1=1.0, GVHG1=49.7, GHHG2=1.0, GVHG3=2.1) are obtained, which further show that the AUH has better vertical movement stability than the torpedo-shaped AUV. Furthermore, the scale model tail velocity experiment indirectly shows that HG3 has better hydrodynamic performance than HG1.

Data Mining-Based Stability and Prescription Analysis of Neonatal Parenteral Nutrition Solution

In order to evaluate the stability of neonatal parenteral nutrition solution, in this paper, the prescription of neonatal parenteral nutrition solution was investigated and analyzed. The formula of neonatal parenteral nutrition solution used, particularly the one utilized in this study, is commonly used in clinical practice. All the neonatal parenteral nutrition solution required for the test was prepared on the purification workbench in a sterile environment. The time points of stability of parenteral nutrient solution were 0, 12, and 24 hours, respectively, and three parallel samples were taken at each time point. Likewise, to investigate the stability of two kinds of fat milk injection in parenteral nutrition solution of neonates and provide a reference for subsequent experiments and to investigate the influence of electrolyte, amino acid, temperature, pH value, mixing sequence, and the final concentration of glucose on the stability of neonatal parenteral nutrition solution, the stability indexes of neonatal parenteral nutrition liquid mainly include appearance, pH, insoluble particles, fat milk particle size, and particle size distribution. Neonatal parenteral nutrition solution prescriptions from the First Affiliated Hospital of Jinan University, specifically from January to June 2019, were collected and statistically processed. The experimental data were processed by SPSS 19.0 software and data mining technology. The results were expressed as mean ± standard deviation and statistically processed by ANOVA. P < 0.05 was considered statistically significant. The results showed that the stability of neonatal parenteral nutrient solution was influenced by many factors. The formula of neonatal parenteral nutrition solution is generally reasonable, but there are unreasonable phenomena which are needed to be improved further if feasible.

Stability on the GMAW Process

The gas metal arc welding (GMAW) process is highly used in industrial production; therefore great efforts are made to select the appropriate procedure to ensure the highest quality. An area of study directly correlated to the quality of GMAW and widely studied is the control of process stability. The objective of this chapter is to present a bibliographical review of the scientific literature related to qualitative and quantitative indexes to evaluate the stability of the GMAW process. The documents present a compilation of the factors that affect stability, stability indexes, and, finally, a synthesis of the study. With a review of the literature, it was concluded that the highest percentage of investigation was aimed at the study of metal transfer stability, specifically with the short-circuit transfer mode. It is also evident that the main processing techniques to develop the indexes were the mathematical formulation; the statistical analysis; image processing; and monitoring of acoustic signals. In this text, the discussion surrounds the papers, the thesis, and other documents found on the theme.

Spray-Air Contact in Tall and Short-Type Spray Dryers Affects Important Physicochemical Properties of Microencapsulated Chia Seed Oil

The aim of this work was to determine the influence of the spray dryer’s aspect ratio (height/diameter) on the physico-chemical properties of microencapsulated chia oil (CSO). Two different dryers were analyzed: a tall-type dryer [H/D = 5/1], and a short-type dryer [H/D = 1.65/1]. The former corresponded to a co-current flow, while the latter had a central air disperser in the chamber, and a rotary air flow. Emulsions were prepared by homogenization of CSO, and a mixture of soy protein isolate (SPI) and gum arabic (GA). The co-current contact in the tall-type dryer yielded greater oxidative stability indexes (OSI) (three times higher than CSO), which was possibly associated the reduced thermal degradation. It can be concluded that a co-current contact constitutes a better alternative for the protection of CSO.

FINAL QUALITY OF A SUSTAINABLE LANDFILL AND POST-CLOSURE MANAGEMENT

Landfill should be designed and constructed in line with the principle of environmental sustainability, guaranteeing over a period of less than one generation (typically considered 30 years) the environmental equilibrium of Final Storage Quality, when waste stability and immobilisation of contaminants is achieved and all active measures of control may be removed without posing any further risk to the environment. The practical definition of FSQ, when a landfill can be released from aftercare, and a procedure for the technical and administrative termination of the post-closure management phase are an evident regulatory strategic need to assure the design of sustainable landfill. The aim of this paper is to provide a criterion to define the FSQ of landfill, based on the control of the analytical emission parameters and of stability indexes related to the residual emission potential. These should concur with the law’s acceptance criteria for the landfilling of wastes (LAC), and with the legal limit values (LLV) established for the emission of contaminants into the environment. The interrelationship between, stability indexes (emission potential), analytical emission parameters, LAC and LLV is discussed and reference values are provided. Finally, the paper proposes a procedure for the termination of technical and administrative aspects following the post-closure management in accordance with FSQ.

Postural Control during Progressively Increased Balance-Task Difficulty in Athletes with Unilateral Transfemoral Amputation: Effect of Ocular Mobility and Visuomotor Processing

This study examined postural control during single leg stance test with progressively increased balance-task difficulty in soccer players with unilateral transfemoral amputation (n = 11) compared to able-bodied soccer players (n = 11). The overall stability index (OSI), the anterior/posterior stability index, and the medial/lateral stability index during three balance tasks with increasing surface instability were estimated. The oculomotor and visuomotor contribution to postural control in disabled athletes was analyzed. Oculomotor function, simple and choice reaction times, and peripheral perception were assessed in a series of visuomotor tests. The variation in OSI demonstrated significantly greater increases during postural tests with increased balance-task difficulty in the able-bodied soccer players compared to amputees (F(2,40) = 3.336, p < 0.05). Ocular mobility index correlated (p < 0.05) with OSI in conditions of increasing balance-task difficulty. Moreover, speed of eye-foot reaction has positive influence (p < 0.05) on stability indexes in tasks with an unstable surface. Amputee soccer players displayed comparable postural stability to able-bodied soccer players. Disabled athletes had better adaptability in restoring a state of balance in conditions of increased balance-task difficulty than the controls. The speed of visuomotor processing, characterized mainly by speed of eye-foot reaction, significantly contributed to these results.

EFFECT OF COMPRESSION SOCKS ON POSTURAL BALANCE AMONG UNIVERSITY NETBALL PLAYERS

The purpose of this study was to observe the effects of wearing compression socks on postural balance in university netball players. Fourteen advanced learners' netball players performed three trials (20 seconds for each trial) of dynamic postural balance test on Biodex Stability System, in two socks conditions, (a) Normal Socks and (b) Compression Socks. Data on overall, anterior/posterior and medial/lateral stability indexes were analyzed using Paired Sample T-tests. Results revealed that wearing compression materials significantly enhanced static and dynamic postural balance among the university netball players. The improvement in the key variables is likely to have occurred through enhanced somatosensory feedback information that was received the lower limbs to regulate better postural stability. It is suggested that compression socks can be used by netball players to improve their postural stability possibly during shooting performance.

STUDY OF NORMAL VALUES OF PROPRIOCEPTION BASED ON AGE

Background: Proprioception is an important function which allows the brain to perceive the body’s position. It is a safety mechanism aiding the generation of movements to correct and maintain balance. During a return to sports for adults, it is essential to have a good postural control. However, this requirement is applied subjectively in a pediatric setting. The Biodex Stability System (BSS) is a validated instrument capable of evaluating proprioception by producing stability indexes. Unfortunately, the stability indexes for a healthy pediatric population and the associated characteristics have not yet been determined. Purpose: The primary objective was to establish normal pediatric values of proprioception using the BSS. The secondary objectives were to find correlations between various subgroups (sex, physical activity participation and joint laxity, etc) and the stability indexes. Methods: An observational cohort study was done. Patients from July 2018 to September 2018 were included from the facture clinic. Inclusion/exclusion criteria were: (1) a consolidated upper limb fracture, (2) no previous history of lower limb injury, (3) no congenital anomalies of the lower limb or neuromuscular disease. Included subjects underwent 3 test trials of 20 seconds each of single-leg shoeless postural control with eyes open and at a stability level of 4. The overall stability index (OSI), anteroposterior stability index (APSI) and mediolateral stability index (MLSI) were noted. The protocol was conducted on both legs. Kolmogorov-Smirnov test will be used for the primary objective and, Pearson correlation for secondary objective. Results: Seventy-one participants (29 girls and 42 boys) with a mean age of 12.75±2.2 years old and a mean Beighton laxity score of 2.5±2.5 were recruited. The mean left OSI is 4.4±3.1 and the mean right OSI is 4.5±3.3. When comparing the subgroups, we were able to find correlations between the body mass index (BMI) and the OSI for both legs (left: r= 0.312, p = 0.008; right: r= 0.437, p = 0.001). We did not find any other correlations for any other groups (sex, age and Beighton score). Conclusion: A larger sample size will be needed to establish normal values based on sex and skeletal maturity but a mean value for OSI for a normal pediatric population was established. This study illustrates that, in our pediatric population, an increase in BMI is associated with an increase in OSI. Therefore, children with a higher BMI could potentially benefit from a proprioception training program in order to prevent the occurrence of injuries.

Truck Handling Stability Simulation and Comparison of Taper-Leaf and Multi-Leaf Spring Suspensions with the Same Vertical Stiffness

The lightweight design of trucks is of great importance to enhance the load capacity and reduce the production cost. As a result, the taper-leaf spring will gradually replace the multi-leaf spring to become the main elastic element of the suspension for trucks. To reveal the changes of the handling stability after the replacement, the simulations and comparison of the taper-leaf and the multi-leaf spring suspensions with the same vertical stiffness for trucks were conducted. Firstly, to ensure the same comfort of the truck before and after the replacement, an analytical method of replacing the multi-leaf spring with the taper-leaf spring was proposed. Secondly, the effectiveness of the method was verified by the stiffness tests based on a case study. Thirdly, the dynamic models of the taper-leaf spring and the multi-leaf spring with the same vertical stiffness are established and validated, respectively. Based on this, the dynamic models of the truck before and after the replacement were established and verified by the steady static circular test, respectively. Lastly, the handling stability indexes for the truck were compared by the simulations of the drift test, the ramp steer test, and the step steer test. The results show that the yaw rate of the truck almost does not change, the steering wheel moment decreases, the vehicle roll angle obviously increases, and the vehicle side slip angle slightly increases after the replacement. Thus, the truck with the taper-leaf spring suspension has better steering portability, however, its handling stability performs worse.