Percentage Of Total Power Research Articles

Analysis and Optimizations of Power Grid Network Accuracy and Efficiency

We propose a method to power specific areas of a large-scale integrated circuit, such as the core of a system-on-chip (SoC), at a voltage higher than VDD. The voltage drops with the current flowing through the power grid, resulting in I2R losses in the on-chip power circulation. This new concept for VLSI devices is based on the commercial distribution system of long-distance power transmission companies. Our design reduces the voltage to VDD levels with an integrated DC-DC converter located near the core, like how electrical systems rely on transformers. The efficiency of a distribution matrix is the percentage of total power taken from the power source and delivered to the loads (cores). We obtained the grid from data for a commercial DC/DC converter. This paper also discusses the need for highly efficient DC/DC converters that can be integrated on chip. As state-of-the-art semiconductors become smaller and smaller, silicon process variations continue to occur and affect the performance of the chip. One of the most critical steps is worst-case voltage variations that cause inductive fluctuations. Therefore, pinpointing hotspots across the power matrix network is critical to effectively utilize the right computing environment for design verification and appropriate strategies.

Capacitive resistive electric transfer modifies gait pattern in horses exercised on a treadmill

BackgroundCapacitive resistive electric transfer (CRET), a radiofrequency at 448 kHz, resulted in increased superficial and deep temperature and hemoglobin saturation, faster elimination of metabolic and inflammatory products and enhanced sport performance in humans. This research aims to investigate whether the application of CRET affects the locomotor pattern in horses and to assess whether an accumulative effect appears when two CRET sessions are applied two consecutive days.MethodsNine horses were subjected to two CRET sessions applied in both right and left sides of neck, shoulder, back and croup. The horses were exercised on a treadmill, at walk and at trot, before CRET application and at 2, 6 and 12 h after. A second CRET session was applied next day, and the animals were evaluated again at the same times (i.e. at 26, 30 and 36 h after the first session). Between 5 and 7 days later, the same horses were subjected to a sham procedure and they were evaluated in the same times as in the CRET experiment. During treadmill exercise, locomotor parameters were measured with a triaxial accelerometer fixed in the pectoral region and in the sacrum midline.ResultsThe sham procedure did not affect any of the accelerometric variables studied. CRET applications resulted in greater total powers, which resulted in absolute increased dorsoventral, mediolateral and longitudinal powers. However, a reduction in dorsoventral power expressed as a percentage of total power was found. Stride regularity increased. The greater total power resulted in longer stride length and because the velocity was kept fixed on the treadmill, stride frequency decreased. An accumulative effect of CRET application was only found in stride length and frequency.ConclusionsIt appears that CRET is a useful technique to enhance power and to elongate the stride at defined walk and trot velocities. The effect of these changes on performance should be studied for horses competing in different sport disciplines.

The Impact of Process Scaling on Scratchpad Memory Energy Savings

Scratchpad memories have been shown to reduce power consumption, but the different characteristics of nanometer scale processes, such as increased leakage power, motivate an examination of how the benefits of these memories change with process scaling. Process and application characteristics affect the amount of energy saved by a scratchpad memory. Increases in leakage as a percentage of total power particularly impact applications that rarely access memory. This study examines how the benefits of scratchpad memories have changed in newer processes, based on the measured performance of the WIMS (Wireless Integrated MicroSystems) microcontroller implemented in 180- and 65-nm processes and upon simulations of this microcontroller implemented in a 32-nm process. The results demonstrate that scratchpad memories will continue to improve the power dissipation of many applications, given the leakage anticipated in the foreseeable future.

Relationship of Heart Rate Variability to Sleepiness in Patients with Obstructive Sleep Apnea with and without Heart Failure

Many patients with severe obstructive sleep apnea (OSA) do not complain of excessive daytime sleepiness (EDS), possibly due to increased sympathetic nervous activity (SNA) and accompanying heightened alertness. We hypothesized that in patients with OSA, those without subjective EDS (Epworth Sleepiness Scale, ESS score < 11) would have higher very low frequency (VLF) heart rate variability (HRV) during sleep, reflecting greater sympathetic heart rate modulation than patients with an ESS score ≥ 11. Patients with severe OSA (AHI ≥ 30: 26 with and 65 without heart failure) were divided into those with and without EDS. Heart rate (HR) signals were acquired in stage 2 sleep during periods of recurrent apneas and hypopneas and submitted to coarse graining spectral analysis, which extracts harmonic, neurally mediated contributions to HRV from total spectral power. Because the apnea-hyperpnea cycle entrains muscle SNA at VLF (0 to 0.04 Hz), VLF power was our principal between-group comparison. Subjects without EDS had higher harmonic VLF power (944 ± 839 vs 447 ± 461 msec(2), p = 0.003) than those with EDS, irrespective of the presence or absence of heart failure (1218 ± 944 vs 426 ± 299 msec(2), p = 0.043, and 1029 ± 873 vs 503 ± 533 msec(2), p = 0.003, respectively). ESS scores correlated inversely with VLF power in all (r = -0.294, p = 0.005) and in heart failure subjects (r = -0.468, p = 0.016). Patients with severe OSA but without EDS have higher VLF-HRV than those with EDS. This finding suggests that patients with severe OSA but without EDS have greater sympathetic modulation of HRV than those with EDS that may reflect elevated adrenergically mediated alertness. Taranto Montemurro L; Floras JS; Picton P; Kasai T; Alshaer H; Gabriel JM; Bradley TD. Relationship of heart rate variability to sleepiness in patients with obstructive sleep apnea with and without heart failure.

Frequency analysis of lower extremity electromyography signals for the quantitative diagnosis of dystonia

The purpose of this study was to develop an objective, quantitative tool for the diagnosis of lower extremity dystonia. Frequency domain analysis was performed on surface and fine-wire electromyography (EMG) signals collected from the lower extremity musculature of ten patients with suspected dystonia while performing walking trials at self-selected speeds. The median power frequency (MdPF) and percentage of total power contained in the low frequency range (%AUCTotal) were determined for each muscle studied. Muscles exhibiting clinical signs of dystonia were found to have a shift of the MdPF to lower frequencies and a simultaneous increase in the %AUCTotal. A threshold frequency of 70Hz identified dystonic muscles with 73% sensitivity and 63% specificity. These results indicate that frequency analysis can accurately distinguish dystonic from non-dystonic muscles.

Respiratory-related heart rate variability in progressive experimental heart failure

Heart failure is associated with autonomic imbalance, and this can be evaluated by a spectral analysis of heart rate variability. However, the time course of low-frequency (LF) and high-frequency (HF) heart rate variability changes, and their functional correlates during progression of the disease are not exactly known. Progressive heart failure was induced in 16 beagle dogs over a 7-wk period by rapid ventricular pacing. Spectral analysis of heart rate variability and respiration, echocardiography, hemodynamic measurements, plasma atrial natriuretic factor, and norepinephrine was obtained at baseline and every week, 30 min after pacing interruption. Progressive heart failure increased heart rate (from 91 +/- 4 to 136 +/- 5 beats/min; P < 0.001) and decreased absolute and normalized (percentage of total power) HF variability from week 1 and 2, respectively (P < 0.01). Absolute LF variability did not change during the study until it disappeared in two dogs at week 7 (P < 0.05). Normalized LF variability increased in moderate heart failure (P < 0.01), leading to an increased LF-to-HF ratio (P < 0.05), but decreased in severe heart failure (P < 0.044; week 7 vs. week 5). Stepwise regression analysis revealed that among heart rate variables, absolute HF variability was closely associated with wedge pressure, right atrial and pulmonary arterial pressure, left ventricular ejection fraction and volume, ratio of maximal velocity of early (E) and atrial (A) mitral flow waves, left atrial diameter, plasma norepinephrine, and atrial natriuretic peptide (0.45 < r < 0.65, all P < 0.001). In tachycardia-induced heart failure, absolute HF heart rate variability is a more reliable indicator of cardiac dysfunction and neurohumoral activation than LF heart rate variability.

Effect of physical training on heart-period variability in obese children

Objective: The beat-to-beat variability in electrocardiogram intervals (RR, i.e., heart-period variability) provides information on cardiac autonomic activity that predicts arrhythmias and mortality rate in animals and adults. We determined the effect of physical training on heart-period variability in obese children. Methods: Thirty-five subjects were randomly assigned to physical training and control groups. The training involved 4 months of exercise, 5 days per week, 40 minutes per day. Cardiovascular fitness was measured with submaximal heart rate during supine cycling; percentage of body fat was measured with dual-energy absorptiometry; and resting heart-period variability parameters were measured in a supine position. A pretraining to posttraining change score was computed for each variable. The effect of the training was determined by comparing the changes of the training and control groups. Results: Compared with the control group, the trained group (1) reduced submaximal heart rate and percentage of body fat ( p <0.01); (2) increased in the root mean square of successive differences, a time-domain parameter reflective of vagal tone ( p <0.05); (3) decreased in low-frequency power expressed as a percentage of total power, a frequency-domain index of combined sympathetic and vagal activity ( p <0.03); and (4) decreased in the ratio of low- to high-frequency power, an index of sympathetic-parasympathetic balance ( p <0.01). Conclusions: In obese children, physical training alters cardiac autonomic function favorably by reducing the ratio of sympathetic to parasympathetic activity. (J Pediatr 1997;130:938-43)

Elucidating the mechanisms of atrial flutter cycle length variability using power spectral analysis techniques.

The mechanism of the small beat-to-beat variations in cycle length of atrial flutter in humans has not been fully explained. We investigated the beat-to-beat control of atrial flutter cycle length using time and frequency analysis techniques. Mean, SD, and power spectra of atrial cycle lengths were calculated from atrial recordings in 28 patients with type I atrial flutter. In control patients, mean and SD values of atrial cycle length were 265 +/- 37 and 4.9 +/- 1.7 ms. Power spectra contained two or three major peaks with 10.6 +/- 9.2% in band 1 (0.0 to 0.18 Hz), 26.7 +/- 15.9% in band 2 (0.18 to 0.6 Hz), and 63.1 +/- 17.7% in band 3 (0.6 to 2.2 Hz). Isoproterenol infusion (n = 8) increased percentage of total power in band 1 (7.1 +/- 5.6% to 25.7 +/- 18.9%, P < .001). Percentage of total power in band 1 was less in patients receiving (n = 5) versus not receiving (n = 18) oral beta-blockers (2.2 +/- 1.9% versus 10.6 +/- 9.2%, P = .003). Standard deviation (2.5 +/- 1.3 versus 4.9 +/- 1.7 ms, P = .009) and total power (2025 +/- 1350 versus 9768 +/- 8874 ms2, P = .005) were less in heart transplant recipients (n = 5) than control patients. Increases in respiratory rate (n = 6) shifted band 2 frequency peak to higher frequencies (0.26 +/- 0.13 to 0.38 +/- 0.18 Hz, P < .05). Atrial cycle length was longer and monophasic action potential duration was shorter during inspiration than during expiration. Band 3 frequency peak was correlated with heart rate (r = .797, P < .0001). Atrial flutter cycle length variability has an underlying periodic pattern that is detected by spectral analysis. Atrial flutter is modulated on a beat-to-beat basis by an interplay between the autonomic nervous and respiratory systems and the ventricular rate.

Waking electroencephalogram activity as a consequence of sleep and total sleep deprivation in the rat.

Effects of 6 hours of total sleep deprivation (TSD) by gentle handling and 6 hours of sleep on the waking electroencephalogram (EEG) activity of 14 Wistar rats were studied during the lights-on portion of the light-dark cycle under two TSD schedules: a) TSD 0800-1400 hours and sleep 1400-2000 hours, and b) sleep 0800-1400 hours and TSD 1400-2000 hours. EEG was recorded monopolarly from left and right parietals referred to ipsilateral reference electrodes. Spectral analysis was performed on samples of waking EEG during TSD (each 30 minutes) and during sleep (each 60 minutes after enforced awakening). The following significant changes were observed: TSD induced a linear increase in the absolute power of delta (1.46-3.42 Hz) and the full band (1.6-24.9 Hz) and produced a decrease in the interparietal correlation of theta. Sleep induced the opposite results. Theta relative power (power in a band expressed as a percentage of total power between 1.46 and 24.9 Hz) showed a circadian effect. It was higher at 1400 hours than at 0800 and 2000 hours after both sleep and TSD conditions. Six hours of TSD were enough to induce significant changes in the waking EEG regardless of position of TSD in the lights-on period of the light-dark cycle.

Effects of three anesthetic induction techniques on heart rate variability

Study Objective: To investigate the effects of different clinical induction techniques on heart rate variability (HRV). Design: Two studies are reported. Study 1 prospectively compared the effects of two induction techniques (tetomidate vs. thiopental sodium) known to have widely disparate effects on cardiovascular reflexes. Study 2 specifically investigated whether the vagotonic effects of sufentanil cause an increase in vagally mediated HRV. Setting: Elective surgery in a university-affiliated hospital. Patients: Study 1 : 18 ASA physical status I patients having minor surgery; Study 2: 10 ASA physical status III and IV patients having cardiac surgery. Interventions: In Study I, anesthesia was induced with either etomidate 0.3 mg/kg or thiopental sodium 4 mg/kg with 60% nitrous oxide in oxygen. In Study 2, anesthesia was induced with a sufentanil infusion (total dose 2.9 ± 0.2 μg/kg). Measurements and Main Results: The electrocardiogram-derived heart rate signal was subjected to power spectral analysis (similar to electroencephalographic analysis) to obtain measurements of (1) absolute HRV power [units of (beats per minute) 2] within defined frequency ranges (HRV LO = power between 0 and 0.125 Hz; HRV HI = power between 0.126 and 0.5 Hz; HRV TOT = HRV TOT = HRV LO + HRV HI) and (2) normalized HRV power (the percentage of total power) within these same frequency ranges [ e.g., %HRV HI = (HRV HI/HRV TOT × 100%]. In Study 1, both techniques caused large reductions in HRV TOT . The reduction caused by the thiopental sodium technique (−89% ± 2%) significantly exceeded that caused by the etomidate technique (−58% ± 13%, p < 0.02). In Study 2, sufentanil decreased absolute power measurements of vagally mediated HRV (−69 ± 12 change in HRV HI) but increased corresponding normalized measurements of vagally mediated HRV (90% ± 30% increase in %HRV HI). Conclusions: In Study 1, the greater reduction in HRV with the thiopental sodium technique provides evidence that the depressant effects of anesthetics on HRV are related in part to their effects on cardiovascular reflexes. However, the significant depression in HRV caused by the etomidate technique suggests that mechanisms other than baro-reflex depression (e.g., impaired consciousness) also are important in these depressant effects. In Study 2, the decrease in HRV HI caused by sufentanil documents that absolute power measurements of vagally mediated HRV are not correlated with changes in parasympathic tone during a potent opioid induction. This lack of a correlation may result from the decrease in total HRV observed with loss of consiousness. The increase in %HRV HI suggests that normalized measurements of HRV may still provide an index of changes in sympathetic-parasympathetic balance, even when total HRV is decreased following anesthetic administration.

Comparing Bandwidth Requirements for Binary Baseband Signals

The percentage of total power passed through ideal bandlimited channels with bandwidths equal to various multiples of the bit rate is examined for 14 unique binary baseband signaling schemes. The channel bandwidth required to pass 5 percent of the total power is determined as a measure of the need for near-dc channel response. Conclusions are reached as to which signals would be most suitable for high-rate magnetic tape recording.