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The conditions under which time–energy uncertainty relations derived by Deffner and Lutz [10] for time-dependent quantum systems minimize the time necessary to excite such systems from their ground state to excited states are examined. The generalized Margolus–Levitin and Mandelstam–Tamm inequalities are worked out for specific fermionic and bosonic systems.

We implement an algorithm which is aimed to reduce the dimensions of the Hilbert space of quantum many-body systems by means of a renormalization procedure. We test the role and importance of different representations on the reduction process by working out and analyzing the spectral properties of strongly interacting frustrated quantum spin systems., to be published in Physica B

We propose and test a renormalization procedure which acts in Hilbert space. We test its efficiency on strongly correlated quantum spin systems by working out and analyzing the low-energy spectral properties of frustrated quantum spin systems in different parts of the phase diagram and in the neighbourhood of quantum critical points., Comment: 13 pages, 3 figures, to appear in PLA

The main objective of this study was to investigate the effects of window size on estimated surface myoelectric signal (MES) parameters in frequency domain. Seven healthy male subjects participated in this study. All subjects were required to perform a sustained isometric muscle contraction corresponding to 25, 50 and 100% of the Maximum Voluntary Contraction (MVC). MES was recorded by surface electrodes for a period of 6 s. Seven different window sizes (64, 128, 256, 512, 1024, 2048, and 4096 ms) were used to estimate the power spectrum. The results obtained showed that the window size has a significant effect on the estimated characteristic frequencies of the power spectrum. The minimum window size that can be used to estimate the power spectrum was found to be 0.5 seconds. The loading level was found to have a significant effect on the frequency domain characteristics. It was observed that the frequencies below the 75th fractile tend to shift upward as the load increases. The upward shift in higher frequencies (≥ 75th fractile) was reversed as the load reached MVC, which indicates that during a constant isometric contraction the shape of the spectrum changes as the force level is increased. The results obtained in this study show that the use of a single spectral variable such as the median frequency may not be sufficient for capturing all the spectral modifications of the MES.

Electromyography (EMG) provides an in vivo quantitative measure of the musculoskeletal system. The main objective of this study was to investigate the effects of epoch duration on the estimated EMG parameters in both time and frequency domains. The results obtained showed that the window size has no significant effect on the EMG estimated parameters in the time domain. On the other hand, window size has a significant effect on the estimated characteristic frequencies of the power spectrum. The load was found to have significant effects on all EMG parameters used in this study.

This paper demonstrates the use of personal micro-computers to individualize the design of the sitting workplace. Engineering static and functional anthropometry as well as ergonomic design principles are implemented. Computer outputs and a case study are presented.

This study investigates the utility of several computerized digital signal processing techniques in the quantitative analysis of surface electromyograms (EMG). Experiments were conducted to test the sensitivity of each of the developed techniques to changes in the EMG pattern due to small changes in isometric muscle loading. Results indicated that several indices are quite useful in quantifying EMG signals.

The main objective of the present study is to develop a low cost microcomputer-based respiratory system that is capable of computing the oxygen consumption and minute ventilation of individuals engaged in manual materials handling on an on-line basis. The design, specifications, and merits of the system are given. The software package developed was written in assembly language for the IBM AT personal computer.

The main objective of the present study is to develop and test a relatively low cost microcomputer-based metabolic monitoring system that is capable of computing the oxygen consumption and minute ventilation of individuals, while at rest or at work, on an on-line basis. The design, specifications, and merits of the system are given. The software package developed was written in assembly language for the IBM AT personal computer. The experimental evaluation of the microcomputer-based metabolic monitoring system showed that there is a high degree of correlation between computer and manual calculations. The correlation coefficients between manual and computer calculations were 0.9986 and 0.9966 for minute ventilation and oxygen consumption respectively which indicate that the system developed is highly accurate.

This paper discusses a static and dynamic biomechanical evaluation of sagittal lifting activities via a microcomputer model. The input to the developed model includes operator's anthropometric data, and sex. The model provides the reactive forces and torques at the various joints of the body expressed in both British and metric systems. Also, the model shows the calculated compressive force on the spine at the fifth lumber/first sacral joint (L5/S1), and both kinematic and kinetic informations are displayed. The model has a menu of five options: (1) to analyze stress imposed on the L5/S1 during a dynamic activity; (2) to determine maximum weight to be allowed during a dynamic motion; (3) to check stress on the spine (L5/S1) for specified static postures; (4) to determine maximum weight to be allowed for a static posture; or (5) to stimulate the lifting action and determine critical postures while performing lifting tasks based on static biochemical analysis.