Dynamic weight parameter for the Random Early Detection (RED) in TCP networks

This paper presents the Weighted Random Early Detection (WTRED) strategy for congestion handling in TCP networks. WTRED provides an adjustable weight parameter to increase the sensitivity of the average queue size in RED gateways to the changes in the actual queue size. This modification, over the original RED proposal, helps gateways minimize the mismatch between average and actual queue sizes in router buffers. WTRED is compared with RED and FRED strategies using the NS-2 simulator. The results suggest that WTRED outperforms RED and FRED. Network performance has been measured using throughput, link utilization, packet loss and delay

Beyond capitalism and liberal democracy: on the relevance of GDH Cole’s sociological critique and alternative

This article argues for a return to the social thought of the often ignored early 20th-century English thinker GDH Cole. The authors contend that Cole combined a sociological critique of capitalism and liberal democracy with a well-developed alternative in his work on guild socialism bearing particular relevance to advanced capitalist societies. Both of these, with their focus on the limitations on ‘free communal service’ in associations and the inability of capitalism to yield emancipation in either production or consumption, are relevant to social theorists looking to understand, critique and contribute to the subversion of neoliberalism. Therefore, the authors suggest that Cole’s associational sociology, and the invitation it provides to think of formations beyond capitalism and liberal democracy, is a timely and valuable resource which should be returned to

Overview of SERI's high efficiency solar cell research

The bulk of the research efforts supported by the Solar Energy Research Institute (SERI) High Efficiency Concepts area has been directed towards establishing the feasibility of achieving very high efficiencies, 30% for concentrator and more than 20% for thin film flat plate, in solar cell designs which could possibly be produced competitively. The research has accomplished a great deal during the past two years. Even though the desired performance levels have not yet been demonstrated, based on the recent progress, a greater portion of the terrestrial photovoltaics community believes that these efficiencies are attainable. The program will now allocate a larger portion of resources to low cost, large area deposition technology. The program is currently shifting greater emphasis on to the study of crystal growth in order to provide the understanding and tools needed to design a large area process

Exponential Mixing for a Stochastic PDE Driven by Degenerate Noise

We study stochastic partial differential equations of the reaction-diffusion type. We show that, even if the forcing is very degenerate (i.e. has not full rank), one has exponential convergence towards the invariant measure. The convergence takes place in the topology induced by a weighted variation norm and uses a kind of (uniform) Doeblin condition.Comment: 10 pages, 1 figur

TRUNK KINEMATICS DURING THE TEE-SHOT OF MALE AND FEMALE GOLFERS

While females comprise 20% of the golfing population in some Western countries (e.g. Australian Bureau of Statistics, 2007), previous research has typically assessed populations that are exclusively comprised of male golfers (e.g. Cheetham et al., 2008). However, the overall prevalence of golf-related injuries is reported to be similar for males and females (McHardy et al., 2006) and thus, it is of interest to assess whether the kinematics of the female golf swing are similar to those demonstrated by male players. This is important, as this knowledge will ensure that any changes that are made by coaches to improve performance and/or reduce the risk of injury in these golfers are appropriate

Direct Numerical Simulation of Acoustic Disturbances in the Rectangular Test Section of a Hypersonic Wind Tunnel

Direct numerical simulations (DNS) of the full-scale rectangular nozzle of a hypersonic wind tunnel are conducted to study the acoustic freestream fluctuations radiating from turbulent boundary layers (TBLs) along the nozzle walls. The nozzle geometry and the flow conditions of the DNS match those of the NASA 20-Inch Mach 6 Tunnel, and the DNS has been completed for a domain without spanwise sidewall boundary conditions. The turbulent boundary layer parameters based on the DNS compare well with those derived from Reynolds Averaged Navier-Stokes (RANS) calculations as well as with the predictions based on Pates correlation. A similarly good comparison is observed for both the Mach number distribution and the Reynolds stresses obtained from the DNS and RANS calculations, respectively. Various characteristics of the acoustic pressure fluctuations within the inviscid core of the nozzle flow are compared with those associated with a single flat plate at a similar freestream Mach number. The frequency spectrum and bulk propagation speeds match well between the nozzle and the flat plate, but the rms pressure fluctuation is higher for the nozzle configuration, likely due to the combined effect of acoustic radiation from the top and bottom walls. Spatial contours of the two-point correlation coefficient display elliptical tails with approximately equal but opposite angles corresponding to the preferred directionality of acoustic structures radiated from both walls. Future work will focus on DNS of the full nozzle configuration, including the effects of the nozzle side walls

LOW BACK PAIN IN GOLF: DOES THE CRUNCH FACTOR CONTRIBUTE TO LOW BACK INJURIES IN GOLFERS?

INTRODUCTION: Nearly 41% of low back injuries in golf occur around impact or during early follow-through (McHardy et al., 2007). In view of these recent statistics, it is important consider the significance of the crunch factor as a possible contributor to golf-related back injuries. The crunch factor was described by Sugaya et al. (1997) as the instantaneous product of lateral trunk flexion (LFA) and axial trunk rotational velocity (ARV) and was based on the knowledge that both of these measures reach their peak close to impact. The authors reported that these factors would contribute to spinal degeneration and stated that the crunch factor could be useful to compare trunk mechanics in injured and healthy golfers. However, as only one earlier study (Lindsay & Horton, 2002) has examined the crunch factor in injured golfers, this work further considered the importance of this measure in low back pain golfers. METHODS: Fifteen healthy golfers (NLBP) and twelve golfers with a mild or greater level low back pain (LBP) were recruited. Each golfer performed 20 drives, whilst being filmed three genlocked video cameras (50 Hz). Three-dimensional kinematics were derived for best three swings using Peak Motus. The crunch factor was calculated as the instantaneous product of LFA and ARV, where LFA was the angle between the segments joining the mid-hip and mid-shoulder markers and the right and left hip markers minus ninety degrees ARV was the first derivative of the hip to mid-trunk differential angle with respect to time. ANCOVA controlling for age was used to assess for inter-group differences. RESULTS: The crunch factor for both groups increased rapidly from the mid-point of downswing through impact and into the follow-through, but the statistical results showed significant difference between the groups with respect to the peak value. Similarly, peak lateral flexion and axial trunk rotational velocity did not differ between the golfers (Table 1). Table 1: Peak crunch factor, lateral flexion and axial trunk rotational velocities. LBP NLBP Mean SD Mean SD p Cohen’s Peak Crunch (deg2/s) 4879.7 2194.9 4920.2 2273.4 0.44 0.24 Peak Lateral Flexion (deg) -19.1 5.6 -19.1 5.7 0.36 0.28 Peak Axial Trunk Rotational Velocity (deg/s) -271.0 76.8 -260.4 50.3 0.36 0.33 DISCUSSION: This research showed no significant difference between the LBP and NLBP groups for peak LFA, ARV or the resulting crunch factor. These data were comparable to peak crunch factors reported previously for six injured and uninjured golfers (Lindsay Horton, 2002), but were greater than those presented for healthy golfers (Morgan al.,1999). The non-significant findings together with small effect sizes suggest that the crunch factor is not a contributory factor in the development of low back pain in golfers. REFERENCES: Lindsay, D. M., & Horton, J. F. (2002). Journal of Sports Sciences, 20(8), 599-605. McHardy, A., et al. (2007). Journal of Chiropractic Medicine, 6(1), 20-26. Morgan, D. et al. (1999). Science and Golf III, pp.120-126. Champaign, IL: Human Kinetics. Sugaya, H., et al. (1997). 22nd Annual Meeting of the AOSSM, Sun Valley, ID

Remote sensing study of soil hazards for Odendaalsrus in the Free State Province

Expansive soils are some of the most widely distributed and costly of geological hazards. This study examined ASTER satellite data, combined with standard remote sensing techniques, namely band ratios, in identifying these soils. Ratios designed to detect various clay minerals were calculated and possible expansive soils were detected, especially in the pans. It was also possible to delineate the mudrock that may act as a source for expansive soils. Moisture content clearly affected the ratios and it shows that remote sensing can detect where wetness leads to the development of problem soils. The fact that the area has relatively dry climatic conditions may explain why large areas of the mudrock have not yet weathered to clays. Because the ratios are not unique, results can be ambiguous, so care must be taken in the interpretation phase

ARGO CMB Anisotropy Measurement Constraints on Open and Flat-Lambda CDM Cosmogonies

We use data from the ARGO cosmic microwave background (CMB) anisotropy experiment to constrain cosmogonies. We account for the ARGO beamwidth and calibration uncertainties, and marginalize over the offset removed from the data. Our derived amplitudes of the CMB anisotropy detected by the ARGO experiment are smaller than those derived previously. We consider open and spatially-flat-Lambda cold dark matter cosmogonies, with clustered-mass density parameter Omega_0 in the range 0.1-1, baryonic-mass density parameter Omega_B in the range (0.005-0.029)h^{-2}, and age of the universe t_0 in the range (10--20) Gyr. Marginalizing over all parameters but Omega_0, the ARGO data favors an open (spatially-flat-Lambda) model with Omega_0= 0.23 (0.1). However, these numerical values are model dependent. At the 2 sigma confidence level model normalizations deduced from the ARGO data are consistent with those drawn from the UCSB South Pole 1994, MAX 4+5, White Dish, and SuZIE data sets. The ARGO open model normalizations are also consistent with those deduced from the DMR data. However, for most spatially-flat-Lambda models the DMR normalizations are more than 2 sigma above the ARGO ones.Comment: 21 pages of latex. Uses aaspp4.sty. 8 figures included. ApJ in pres