Which lower-limb joints compensate for destabilising energy during walking in humans

Maintaining stability during perturbed locomotion requires coordinated responses across multiple levels of organization (e.g., legs, joints, muscle-tendon units). However, current approaches to investigating such responses lack a "common currency" that is both shared across scales and can be directly related to perturbation demands. We used mechanical energetics to investigate the demands imposed on a leg by a transient increase in unilateral treadmill belt speed targeted to either early or late stance. We collected full body kinematics and kinetics from 7 healthy participants during 222 total perturbations. From across-subject means, we found early stance perturbations elicited no change in net work exchanged between the perturbed leg and the treadmill but net positive work at the overall leg level, and late stance perturbations elicited positive work at the leg/treadmill interface but no change in net work at the overall leg level. Across all perturbations, changes in ankle and knee work from steady state best reflected changes in overall leg work on the perturbed and contralateral sides, respectively. Broadening this paradigm to include joint level (vs. leg level) perturbations and including muscle-tendon unit mechanical energetics may reveal neuromechanical responses used in destabilizing environments which could inform design of balance-assisting devices and interventions.

Power Consumption Model of Permanent-Magnet Direct-Drive Belt Conveyor System Based on GACO–BP

Permanent-magnet direct-drive belt conveyors (PMDDBCs) rotate at high speed most of the time, resulting in a large number of invalid energy consumption. To realize the speed regulation of PMDDBC, it is necessary to clarify the relationship between the belt speed, coal quantity of the conveyor and total power of the system. Based on the BP neural network, this paper establishes the power consumption model of PMDDBC, which is related to coal quantity, belt speed and total power. Furthermore, an improved hybrid algorithm (GACO) that combines the advantages of genetic algorithm (GA) and ant colony optimization (ACO) is proposed to optimize the BP power consumption model. The GACO–BP power consumption model is obtained. The original power consumption model is compared with the GACO–BP power consumption model through experiments. Results demonstrate that the GACO–BP power consumption model reduces various prediction errors, while the optimization ability, prediction accuracy and convergence speed are significantly enhanced. It provides a reliable speed regulation basis for the permanent-magnet direct-drive belt conveyor system and also provides a theoretical reference for energy savings and consumption reduction in the coal industry.

Simulation of unloading processes of short dump belt conveyors with speed control belt movement

Short dump belt conveyors are used to create bulk cargo both as an integral part of technological machines in the processing of building materials, and as vehicles in a chain of conveyors for transporting bulk cargo in accordance with the logistics of open warehouses. When implementing mechanization schemes for open warehouses, depending on the degree of variability of the cargo flow in the structures of such conveyors, drives can be used that allow regulating the speed of the belts, thereby controlling the productivity of the entire line. Often, short belt conveyors are not equipped with specialized unloading devices, which requires elaboration of the issues of movement of cargo particles during unloading, especially if the conveyor is operating in a production line. The article simulates the processes of unloading short dump belt conveyors when controlling the speed of the belt. Trajectories of movement of cargo particles for various parameters of conveyors are obtained: belt speed, conveyor tilt angle to the horizon, diameter of the unloading drum. It is shown that it is necessary to simulate unloading processes in all cases with belt speed control and conveyor operation without specialized unloading devices.

Small Directional Treadmill Perturbations Induce Differential Gait Stability Adaptation

Introducing unexpected perturbations to challenge gait stability is an effective approach to investigate balance control strategies. Little is known about the extent to which people can respond to small perturbations during walking. This study aimed to determine how subjects adapted gait stability to multidirectional perturbations with small magnitudes applied on a stride-by-stride basis. Ten healthy young subjects walked on a treadmill that either briefly decelerated belt speed ("stick"), accelerated belt speed ("slip"), or shifted the platform medial-laterally at right leg mid-stance. We quantified gait stability adaptation in both anterior-posterior and medial-lateral directions using margin of stability and its components, base of support and extrapolated center of mass. Gait stability was disrupted upon initially experiencing the small perturbations as margin of stability decreased in the stick, slip, and medial shift perturbations and increased in the lateral shift perturbation. Gait stability metrics were generally disrupted more for perturbations in the coincident direction. Subjects employed both feedback and feedforward strategies in response to the small perturbations, but mostly used feedback strategies during adaptation. Subjects primarily used base of support (foot placement) control in the lateral shift perturbation and extrapolated center of mass control in the slip and medial shift perturbations. These findings provide new knowledge about the extent of gait stability adaptation to small magnitude perturbations applied on a stride-by-stride basis and reveal potential new approaches for balance training interventions to target foot placement and center of mass control.

Modelling Kinetics of Extruded Fish Feeds in a Continuous Belt Dryer

Feed is the major inputs in aquaculture production which affects the development growth of aquaculture in the African continent. Extruded fish feeds are dried to desire moisture content to increase the shelf life. Conventional method of drying fish feeds had gained attention recently in Nigeria in order to reduce high cost of producing fish feeds. However, this method is still grossly underutilized. Extrude floating fish feed was dried using continuous belt dryer at drying air temperature from 60°C to 100°C at an interval of 10°C, velocity of air using for drying from 0.8 m s-1 to 1.0 m s-1 at an interval of 0.1 m s-1 using a constant linear belt speed of 50 m s-1. Various moisture contents gotten at different conditions were changed to ratio of the dried extrudates moisture so as to obtain curves of drying by plotting the ratio of moisture against time. The dried extrudates behaviour was determined by fixing the drying curves with five well known models. Model with high determination coefficient and low reduced chi-square, low standard error, low value of least square and low standard deviation error (SEE) was used as best model. Midilli et al model was found suitable in describing the behaviour of extruded fish feed during drying. The temperature of air used for drying was discovered to have a major influence on the drying kinetics of the extruded fish feeds based on the conditions of this experiment.

Modelling Kinetics of Extruded Fish Feeds in a Continuous Belt Dryer

Feed is the major inputs in aquaculture production which affects the development growth of aquaculture in the African continent. Extruded fish feeds are dried to desire moisture content to increase the shelf life. Conventional method of drying fish feeds had gained attention recently in Nigeria in order to reduce high cost of producing fish feeds. However, this method is still grossly underutilized. Extrude floating fish feed was dried using continuous belt dryer at drying air temperature from 60°C to 100°C at an interval of 10°C, velocity of air using for drying from 0.8 m s-1 to 1.0 m s-1 at an interval of 0.1 m s-1 using a constant linear belt speed of 50 m s-1. Various moisture contents gotten at different conditions were changed to ratio of the dried extrudates moisture so as to obtain curves of drying by plotting the ratio of moisture against time. The dried extrudates behaviour was determined by fixing the drying curves with five well known models. Model with high determination coefficient and low reduced chi-square, low standard error, low value of least square and low standard deviation error (SEE) was used as best model. Midilli et al model was found suitable in describing the behaviour of extruded fish feed during drying. The temperature of air used for drying was discovered to have a major influence on the drying kinetics of the extruded fish feeds based on the conditions of this experiment.

Recovery of Cassiterite and Topaz Minerals from an Old Metallurgical Dump, Eastern Desert of Egypt

Huge amounts of tailing dumps as a result of mines’ blasting operations were impacting both economical and environmental problems. This issue was in serious need to be treated with suitable solutions. Evaluation of one of these tailing dumps in the Eastern Desert of Egypt showed the presence of reasonable amount of cassiterite mineral reaching 0.199%. The mineral was found as finely disseminated particulates within varieties of quartz-feldspar-hornblende-biotite granitic formations. In the present study, the processing regime relied upon the synergy between reaching liberation size, and mineral over grinding due to its extreme brittleness. However, delicate grinding via attrition scrubbing was adopted to produce − 0.51 + 0.074 mm attrition product with fine fractions, reaching 62.31% and 37.59%, respectively. The recovery of cassiterite from the − 0.50 + 0.074 mm size fraction was accomplished by the physical difference between mother granitic formations that shielded the mineral grains. Under these conditions, joint shaking table/dry high intensity magnetic separation techniques were conducted to recover cassiterite mineral. The CCD statistical system was used as a mathematical approach to optimize the effect of the main working parameters of the magnetic separator, i.e., splitter inclination angle, and belt speed, and their interactions on the cassiterite recovery of the final concentrate. The suggested flow sheet succeeded to recover cassiterite mineral with a grade reaching 11.25% SnO2 with 94.08% operational recovery from a feed contained 0.19% SnO2. These results are highly imperative to achieve applicable processing flow-sheet of such kind of minerals’ secondary resources.

DESIGN AND EXPERIMENT OF TRANSPLANTING MACHINE FOR CABBAGE SUBSTRATE BLOCK SEEDLINGS

Aiming at the problems of high specificity and low efficiency of vegetable transplanting machine, a substrate block seedling transplanter was designed. Through theoretical calculation and force analysis, the structural parameters of two key components of automatic seedling separation device and planting device are determined. Taking cabbage seedlings with 40 × 40 × 40mm substrate block size as the experimental object, the effects of forward speed, planting frequency, front conveyor belt speed on lodging rate, missing rate and qualified rate were studied by single factor test and three factor three-level orthogonal test. Based on the analysis of the significance and interaction of the experimental data, the best combination of the forward speed of 1.1km/h, the planting frequency of 55 plants / min and the front conveyor belt speed of 0.5km/h was obtained. The verification test of the best combination showed that the average qualified rate of planting was 93.31%, which met the relevant industry standards.