This note develops analytical picker blocking models to simply and accurately assess picker blocking in parallel-aisle order picking systems when multiple picks occur at a pick point. The Markov chain-based models characterize the two bounding walking speeds for modeling picker movement: unit walk-time and instantaneous walk-time. The unit-walk time model has a state space transition matrix tha...

Impaired control of mediolateral body motion during walking is an important health concern. Developing treatments to improve mediolateral control is challenging, partly because the mechanisms by which muscles modulate mediolateral ground reaction force (and thereby modulate mediolateral acceleration of the body mass center) during unimpaired walking are poorly understood. To investigate this, w...

Music or sound effects are often used to enhance Virtual Environments, but it is not known how this audio may influence gait speed. This study investigated the influence of audio cue tempo on treadmill walking with and without visual flow. The walking speeds of 11 individuals were recorded during exposure to a range of audio cue rates. There was a significant effect of audio tempo without visua...

If he had not witnessed the induction procedure, the casual observer might well believe a typical hypnotized subject was asleep. It was this sleeplike appear-ance that led Braid to coin the term "hypnosis" from the Greek hypnos (to sleep) and "somnambulist" from the Latin somnus (sleep) and ambulare (to walk), to describe the deeply hypnotized person. There are indeed many phe-nomenological par...

This study compared the kinematic and electromyographic (EMG) gait patterns of able-bodied adults at natural speed in contrast to extremely slow overground and treadmill walking speeds. Kinematic and EMG data were collected at three speeds (self-selected, 0.30 m/s, and 0.20 m/s). Eighteen subjects were evaluated for trunk and lower-limb motion and EMG of five lower-limb muscles. Significant red...

The purpose of this paper was twofold: firstly to measure and partially validate the rates of work done (powers) by the joint reaction forces and moments on the leg segments and secondly to explain the changes in mechanical energy of the segments by the transfer, generation or absorption of energy by the muscles and/or the transfer of energy through the joints. Measurement of the powers require...

Research has shown that individuals have an optimal walking speed-a speed which minimizes energy expenditure for a given distance. Because the optimal walking speed varies with mass and lower limb length, it also varies with sex, with males in any given population tending to have faster optimal walking speeds. This potentially creates an energetic dilemma for mixed-sex walking groups. Here we e...

The authors tested the feasibility and acceptability, and explored the outcomes, of 2 walking interventions based on ecological models among older adults living in retirement communities. An enhanced intervention (EI) was compared with a standard walking intervention (SI) among residents in 4 retirement facilities (N = 87 at baseline; mean age = 84.1 yr). All participants received a walking int...

The constraints to maximum walking speed and the underlying cause of the walk-run transition remains controversial. However, the motions of the body and legs can be reduced to a few mechanical principles, which, if valid, impose simple physics-based limits to walking speed. Bipedal walking may be viewed as a vaulting gait, with the centre of mass (CoM) passing over a stiff stance leg (an 'inver...