Peak to average power ratio analysis for LTE systems

The 3rd generation partnership project (3GPP) long term evolution (LTE) standard uses single carrier frequency division multiple access (SCFDMA) scheme for the uplink transmissions and orthogonal frequency division multiplexing access (OFDMA) in downlink. SCFDMA uses DFT spreading prior to OFDMA modulation to map the signal from each user to a subset of the available subcarriers i.e., single carrier modulation. The efficiency of a power amplifier is determined by the peak to average power ratio (PAPR) of the modulated signal. In this paper, we analyze the PAPR in 3GPP LTE systems using root raised cosine based filter. Simulation results show that the SCFDMA subcarrier mapping has a significantly lower PAPR compared to OFDMA. Also comparing the three forms of SCFDMA subcarrier mapping, results show that interleave FDMA (IFDMA) subcarrier mapping with proposed root raised cosine filter reduced PAPR significantly than localized FDMA (LFDMA) and distributed (DFDMA) mapping. This improves its radio frequency (RF) power amplifier efficiency and also the mean power output from a battery driven mobile terminal.

Effect of body tilt angle on fatigue and EMG activities in lower limbs during cycling

This study compared the rate of fatigue and lower limb EMG activities during high-intensity constantload cycling in upright and supine postures. Eleven active males performed seven cycling exercise tests: one upright graded test, four fatigue tests (two upright, two supine) and two EMG tests (one upright, one supine). During the fatigue tests participants initially performed a 10 s all-out effort followed by a constant-load test with 10 s all-out bouts interspersed every minute. The load for the initial two fatigue tests was 80% of the peak power (PP) achieved during the graded test and these continued until failure. The remaining two fatigue tests were performed at 20% PP and were limited to the times achieved during the 80% PP tests. During the EMG tests subjects performed a 10 s all-out effort followed by a constant-load test to failure at 80% PP. Normalised EMG activities (% maximum, NEMG) were assessed in five lower limb muscles. Maximum power and maximum EMG activity prior to each fatigue and EMG test were unaffected by posture. The rate of fatigue at 80% PP was significantly higher during supine compared with upright posture (-68 ± 14 vs. -26 ± 6 W min-1, respectively, P\0.05) and the divergence of the fatigue responses occurred by the second minute of exercise. NEMG responses were significantly higher in the supine posture by 1–4 min of exercise. Results show that fatigue is significantly greater during supine compared with upright high-intensity cycling and this effect is accompanied by a reduced activation of musculature that is active during cycling.

Exercise performance and V0₂ kinetics during upright and recumbent high-intensity cycling exercise

This study investigated cycling performance and oxygen uptake (VO₂) kinetics between upright and two commonly used recumbent (R) postures, 65ºR and 30ºR. On three occasions, ten young active males performed three bouts of high-intensity constant-load (85% peak workload achieved during a graded test) cycling in one of the three randomly assigned postures (upright, 65ºR or 30ºR). The first bout was performed to fatigue and second and third bouts were limited to 7 min. A subset of seven subjects performed a final constant-load test to failure in the supine posture. Exercise time to failure was not altered when the body inclination was lowered from the upright (13.1 ± 4.5 min) to 65ºR (10.5 ± 2.7 min) and 30ºR (11.5 ± 4.6 min) postures; but it was significantly shorter in the supine posture (5.8 ± 2.1 min) when compared with the three inclined postures. Resulting kinetic parameters from a tri-exponential analysis of breath-by-breath VO₂ data during the first 7 min of exercise were also not different between the three inclined postures. However, inert gas rebreathing analysis of cardiac output revealed a greater cardiac output and stroke volume in both recumbent postures compared with the upright posture at 30 s into the exercise. These data suggest that increased cardiac function may counteract the reduction of hydrostatic pressure from upright ~25 mmHg; to 65ºR ~22 mmHg; and 30ºR ~18 mmHg such that perfusion of active muscle presumably remains largely unchanged, and also therefore, VO₂ kinetics and performance during high-intensity cycling.

Construction of optimal prediction intervals for load forecasting problems

Short-term load forecasting is fundamental for the reliable and efficient operation of power systems. Despite its importance, accurate prediction of loads is problematic and far remote. Often uncertainties significantly degrade performance of load forecasting models. Besides, there is no index available indicating reliability of predicted values. The objective of this study is to construct prediction intervals for future loads instead of forecasting their exact values. The delta technique is applied for constructing prediction intervals for outcomes of neural network models. Some statistical measures are developed for quantitative and comprehensive evaluation of prediction intervals. According to these measures, a new cost function is designed for shortening length of prediction intervals without compromising their coverage probability. Simulated annealing is used for minimization of this cost function and adjustment of neural network parameters. Demonstrated results clearly show that the proposed methods for constructing prediction interval outperforms the traditional delta technique. Besides, it yields prediction intervals that are practically more reliable and useful than exact point predictions.

Transition in wear performance for ionic liquid lubricants under increasing load

The effect of ionic liquid (IL) lubrication for aluminium/steel systems is highly dependant on the applied load and the IL structure. This study illustrates that a change in anion of an IL lubricant results in different physicochemical properties that will alter its performance at a given load. As the load is increased there is a shift in lubricant performance and mechanism of the IL. Up to a load of 30 N the lowest wear coefficient was achieved by a phosphonium diphenylphosphate IL, whilst above 30 N a phosphonium bis(trifluoromethanesulfonyl)amide IL was able to form a more tenacious tribolayer that resulted in the lowest wear.

Neurophysiological responses after short-term strength training of the biceps brachii muscle

The neural adaptations that mediate the increase in strength in the early phase of a strength training program are not well understood; however, changes in neural drive and corticospinal excitability have been hypothesized. To determine the neural adaptations to strength training, we used transcranial magnetic stimulation (TMS) to compare the effect of strength training of the right elbow flexor muscles on the functional properties of the corticospinal pathway. Motorevoked potentials (MEPs) were recorded from the right biceps brachii (BB) muscle from 23 individuals (training group; n = 13 and control group; n = 10) before and after 4 weeks of progressive overload strength training at 80% of 1-repetition maximum (1 RM). The TMS was delivered at 10% of the root mean square electromyographic signal (rmsEMG) obtained from a maximal voluntary contraction (MVC) at intensities of 5% of stimulator output below active motor threshold (AMT) until saturation of the MEP (MEP maxl. Strength training resulted in a 28% (p = 0.0001) increase in 1 RM strength, and this was accompanied by a 53% increase (p = 0.05) in the amplitude of the MEP at AMT; 33% (p = 0.05) increase in MEP at 20% above AMT, and a 38% increase at MEPmax (p = 0.04). There were no significant differences in the estimated slope (p = 0.4 7) or peak slope of the stimulus-response curve for the left primary motor cortex (M1) after strength training (p = 0.61). These results demonstrate that heavy-load isotonic strength training alters neural transmission via the corticospinal pathway projecting to the motoneurons controlling BB and in part underpin the strength changes observed in this study.

Load forecasting and neural networks : a prediction interval-based perspective

Successfully determining competitive optimal schedules for electricity generation intimately hinges on the forecasts of loads. The nonstationarity and high volatility of loads make their accurate prediction somewhat problematic. Presence of uncertainty in data also significantly degrades accuracy of point predictions produced by deterministic load forecasting models. Therefore, operation planning utilizing these predictions will be unreliable. This paper aims at developing prediction intervals rather than producing exact point prediction. Prediction intervals are theatrically more reliable and practical than predicted values. The delta and Bayesian techniques for constructing prediction intervals for forecasted loads are implemented here. To objectively and comprehensively assess quality of constructed prediction intervals, a new index based on length and coverage probability of prediction intervals is developed. In experiments with real data, and through calculation of global statistics, it is shown that neural network point prediction performance is unreliable. In contrast, prediction intervals developed using the delta and Bayesian techniques are satisfactorily narrow, with a high coverage probability.

Oxygen (O2) kinetics during early recovery from peak exercise in patients with type 2 diabetes

Aims To examine the oxygen (O₂) kinetics during early recovery from peak exercise in patients with Type 2 diabetes and to examine whether oxygen O₂ recovery is associated with fasting glucose and HbA_1c in this population.

Methods Eighty-nine participants (52 men) aged 51.8 ± 7.1 years (mean ± sd) were divided into three groups: normal weight (BMI ≤ 25.0 kg/m²), overweight/obese without diabetes (BMI ≥ 26 kg/m²) and overweight/obese with Type 2 diabetes. Participants were assessed for their aerobic power (VO_2peak) on a cycle ergometer, provided a fasting blood sample and underwent a series of anthropometric measurements. Early recovery period was measured for 60 s from cessation of exercise and expressed as percentage of VO_2peak (higher percentage represents slower recovery).

Results No significant differences were observed for age between the three study groups. Both the overweight/obese groups without diabetes and with Type 2 diabetes had higher BMI than the normal weight group, with no significant differences between overweight/obese participants without diabetes and those with diabetes. Participants with Type 2 diabetes had lower VO_2peak than overweight/obese participants without diabetes and normal weight individuals (19.6 ± 4.8, 22.6 ± 5.4 and 25.7 ± 5.3 ml kg⁻¹ min⁻¹, respectively, P < 0.004 for overall trends). Participants with Type 2 diabetes also had slower recovery in oxygen O₂ kinetics after exercise, compared with both normal weight and overweight/obese individuals without diabetes (56.5 ± 7.7, 49.2 ± 7.2, 47.7 ± 7.4%, P < 0.004 for overall trends). Multiple regression analysis revealed that percentage of oxygen O₂ recovery was a stronger predictor than VO_2peak, BMI or age for fasting glucose and HbA_1c.

Conclusions Patients with Type 2 diabetes have lower VO_2peak and prolonged oxygen O₂ recovery from peak exercise. However, only prolonged oxygen O₂ recovery was associated with fasting glucose and HbA_1c.

Peak modeling approach to accurate assignment of first-dimension retention times in comprehensive two-dimensional chromatography

Modeling of first-dimension retention of peaks based on modulation phase and period allows reliable prediction of the modulated peak distributions generated in the comprehensive two-dimensional chromatography experiment. By application of the inverse process, it is also possible to use the profile of the modulated peaks (their heights or areas) to predict the shape and parameters of the original input chromatographic band (retention time, standard deviation, area) for the primary column dimension. This allows an accurate derivation of the firstdimension retention time (RSD 0.02%) which is equal to that for the non-modulated experiment, rather than relying upon the retention time of the major modulated peak generated by the modulation process (RSD 0.16%). The latter metric can produce a retention time that differs by at least the modulation period employed in the experiment, which displays a discontinuity in the retention time vs modulation phase plot at the point of the 180° out-ofphase modulation. In contrast, the new procedure proposed here gives a result that is essentially independent of modulation phase and period. This permits an accurate value to be assigned to the first-dimension retention. The proposed metric accounts for the time on the seconddimension, the phase of the distribution, and the holdup time that the sampled solute is retained in the modulating interface. The approach may also be based on the largest three modulated peaks, rather than all modulated peaks. This simplifies the task of assigning the retention time with little loss of precision in band standard deviation or retention time, provided that these peaks are not all overloaded in the first or second dimension.

Meteorological influences on respirable fragment release from Chinese elm pollen

Exposure to airborne pollen from certain plants can cause allergic disease, leading to acute respiratory symptoms. Whole pollen grains, 15–90 μ m-sized particles, provoke the upper respiratory symptoms of rhinitis (hay fever), while smaller pollen fragments capable of depositing in the lower respiratory tract have been proposed as the trigger for asthma. In order to understand factors leading to pollen release and fragmentation we have examined the rupture of Chinese elm pollen under controlled laboratory conditions and in the outdoor atmosphere. Within 30 minutes after immersion in water, 70% of fresh Chinese pollen ruptures, rapidly expelling cytoplasm. Chinese elm flowers, placed in a controlled atmosphere chamber, emitted pollen and pollen debris after a sequential treatment of 98% relative humidity followed by drying and a gentle disturbance. Immunologic assays of antigenic proteins specific to elm pollens revealed that fine particulate material (D p < 2 μ m) collected from the chamber contained elm pollen antigens. In a temporal study of the outdoor urban atmosphere during the Chinese elm bloom season of 2004, peak concentrations of pollen and fine pollen fragments occurred at the beginning of the season when nocturnal relative humidity (RH) exceeded 90%. Following later periods of hot dry weather, pollen counts decreased to zero. The Chinese elm pollen fragments also decreased during the hot weather, but later displayed additional peaks following periods of more moderate RH and temperature, indicating that pollen counts underestimate total atmospheric pollen allergen concentrations. Pollen fragments thus increase the biogenic load in the atmosphere in a form that is no longer recognizable as pollen and, therefore, is not amenable to microscopic analysis. This raises the possibility of exposure of sensitive individuals to pollen allergens in the form of fine particles that can penetrate into the lower airways and pose potentially severe health risks.

Short term load forecasting using interval type-2 fuzzy logic systems

Accurate Short Term Load Forecasting (STLF) is essential for a variety of decision making processes. However, forecasting accuracy may drop due to presence of uncertainty in the operation of energy systems or unexpected behavior of exogenous variables. This paper proposes the application of Interval Type-2 Fuzzy Logic Systems (IT2 FLSs) for the problem of STLF. IT2 FLSs, with extra degrees of freedom, are an excellent tool for handling prevailing uncertainties and improving the prediction accuracy. Experiments conducted with real datasets show that IT2 FLS models appropriately approximate future load demands with an acceptable accuracy. Furthermore, they demonstrate an encouraging degree of accuracy superior to feedforward neural networks used in this study.

Effect of speculative prefetching on network load in distributed systems

Previous studies in speculative prefetching focus on building and evaluating access models for the purpose of access prediction. This paper on the other hand investigates the performance of speculative prefetching. When prefetching is performed speculatively, there is bound to be an increase in the network load. Furthermore, the prefetched items must compete for space with existing cache occupants. These two factors-increased load and eviction of potentially useful cache entries-are considered in the analysis. We obtain the following conclusion: to maximise the improvement in access time, prefetch exclusively all items with access probabilities exceeding a certain threshold.