Single-slope Model Research Articles

Experiments’ feasibility study of solar stills in Indonesia, using evaporator covers and cornerless solar collectors

Desalination is a pivotal method for purifying water, offering a reliable means to obtain clean, potable water. Its operational simplicity and utilization of solar energy render desalination a promising technology. In desalination, condensation is the final stage for collecting purified water. However, the persistent challenge of high evaporator glass temperatures significantly impacts the nucleation rate and subsequent condensate release. This research aims to enhance the efficiency of the desalination system by focusing on increasing the rate of condensate water collection. The methodology involves a seven-day direct testing period using a single slope model desalination device featuring dimensions of 1 m2 and an evaporator glass tilt angle of 35°. Solar energy is the primary energy source, absorbed by a collector comprising 3/4-inch diameter copper pipes (14 pipes, 1 m in length) designed without slope. The glass cover is insulated with Styrofoam covered by aluminum foil to mitigate heat ingress from the sun, thereby reducing the temperature of the inner glass surface and accelerating nucleation rates. The maximum water temperature in the evaporator reached 68.7 °C, with the system absorbing energy at a rate ranging from 1048.40 W/m2 to 289.19 W/m2. The energy efficiency of the desalination system was measured at 39.82 %. The highest freshwater production during testing reached 2.33 L/day, with a daily average of 1.52 L/day. Overall, the solar test results still have the potential to be utilized and continue to be developed due to low-cost materials that can overcome the clean water crisis, especially in remote areas.

Clinical trial designs to assess treatment effects on glomerular filtration rate decline

Glomerular filtration rate (GFR) decline is used as surrogate endpoint for kidney failure. Interventions that reduce chronic kidney disease (CKD) progression often exert acute GFR reductions which differ from their long-term benefits and complicate the estimation of long-term benefit. Here, we assessed the utility of two alternative trial designs (wash-out design and active run-in randomized withdrawal design) that attempt to exclude the impact of acute effects. Post-hoc analyses of two clinical trials that characterized the effect of an intervention with acute reductions in GFR were conducted. The two trials included a wash-out period (EMPAREG-Outcome testing empagliflozin vs placebo) or an active run-in period with a randomized withdrawal (SONAR testing atrasentan vs placebo). We compared the drug effect on GFR decline calculated from the first on-treatment visit to the end-of-treatment (chronic effect in a standard randomized trial design) with GFR change calculated from randomization to end-of-wash-out, or GFR change from treatment specific baseline GFR values (GFR at start-of-run-in for placebo and end-of-run-in for atrasentan) until end-of-treatment. The effect of empagliflozin versus placebo on chronic GFR slope was 1.72 (95% confidence interval 1.49-1.94) mL/min/1.73m2 /year, similar to total GFR decline from baseline to the end of wash-out period using a linear mixed model 1.64 (1.44-1.85) mL/min/1.73m2 /year). The effect of atrasentan versus placebo on chronic GFR slope was 0.72 (0.32-1.11) mL/min/1.73m2 /year, similar to total slope from a single slope model when estimated from treatment specific baseline GFR values 0.77 (0.39-1.14) mL/min/1.73m2 /year). Statistical power of the two designs outperformed the standard randomized design. Thus, wash-out and active-run-in randomized-withdrawal trial designs are appropriate models to compute treatment effects on GFR decline.

Performance of Indoor 5G 3GPP Systems

Background: The 5G cellular networks are expected to provide high data rates for indoor environments by utilizing the mmWave bands. Due to a lack of general path loss models of these bands, various works have been carried out to find the most appropriate model that can provide accurate values of path loss over distance for different indoor scenarios. This paper focuses on some well-known path loss models, e.g., mixed and OpenOffice models introduced by 3GPP; the dualstripe model was presented by Alcatel-Lucent, picoChip Designs, and Vodafone at the 3GPP meeting; single and dual ABG models were designed by leading academic and industrial labs. Methods: Two network scenarios, e.g., single-cell and 3-cell networks, are utilized in simulation to analyze the effects of path loss models on network performance. Results: The simulation results indicate that the single-slop and dual-slop models can derive a similar performance when only a cell is deployed. However, in a 3-cell network system with intercell interference, the achieved performance in these systems is significantly different. Conclusion: The dual-slop model is better than the single–slope model in terms of path loss modeling since it can capture more characteristics of wireless transmission links, particularly the Light-of- Sight (LoS) and Non-LoS (NLoS) effects.

Analisa Energi pada Alat Desalinasi Air Laut Tenaga Surya Model Lereng Tunggal

<p class="Abstract">The use of solar energy every day is increasing due to the greater human need for energy. the application of solar desalination equipment is classified as a renewable technology that is very profitable because the energy used is obtained for free and does not cause damage to the environment. This study examines the performance of the solar desalination device with a single slope model with a passive system. It is hoped that greater energy absorption is expected to accelerate the process of evaporation of seawater in the evaporator so as to produce lots of clean water. The desalination tool on the surface of the wall is insulated using aluminum foil with a thickness of 20 mm. The highest solar intensity was obtained on the fifth day of testing, namely 420.85 W/m<sup>2</sup> with the radiation heat transfer coefficient of 18.44 W/m<sup>2 o</sup>C, and the lowest solar intensity on the second day, namely 96.89 W/m<sup>2</sup> with the lowest total outside heat transfer coefficient of 25.57 W/m<sup>2 o</sup>C. The highest evaporative heat transfer coefficient is 10.54 W/m<sup>2 o</sup>C and the lowest is 4.42 W/m<sup>2</sup> <sup>o</sup>C. the lowest energy absorbed by the evaporator on the second day was 1.37 kWh. And the highest efficiency on the fifth day reached 58.89% and the lowest energy efficiency on the second day, namely 34.05%.</p>

Accelerated Testing of Vanadium Catholyte Stability

Using our standard methodology, we have examined the stability of electrolytes with compositions close to those used in actual flow batteries over a range of temperature from 70 to 30°C. Measurements at higher temperatures (45–70°C) showed excellent reproducibility but measurements at lower temperatures (30–45°C) showed some scatter. Furthermore, the measurements at higher temperatures are in good agreement with our (single-slope) model which is based on earlier data but there is some divergence from the model at lower temperatures. Arrhenius plots of the data show two linear regimes: one in the range 45–70°C and another in the range 30–45°C, the latter having a higher Arrhenius slope. Based on linear least-squares best fits in these two regimes, we have formulated an improved stability model (two-slope model). For each of the two models, we derive expressions for acceleration factors for temperature testing of catholyte stability and estimate values over a range of test and use temperatures. Acceleration factors based on the two-slope model are higher than those for the single slope model by a factor of 3–6 depending on the temperatures. Thus, predictions based on the single-slope model are more conservative.

Psychopathic personality development from ages 9 to 18: Genes and environment.

The genetic and environmental etiology of individual differences was examined in initial level and change in psychopathic personality from ages 9 to 18 years. A piecewise growth curve model, in which the first change score (G1) influenced all ages (9-10, 11-13, 14-15, and 16-18 years) and the second change score (G2) only influenced ages 14-15 and 16-18 years, fit the data better did than the standard single slope model, suggesting a turning point from childhood to adolescence. The results indicated that variations in levels and both change scores were mainly due to genetic (A) and nonshared environmental (E) influences (i.e., AE structure for G0, G1, and G2). No sex differences were found except on the mean values of level and change scores. Based on caregiver ratings, about 81% of variance in G0, 89% of variance in G1, and 94% of variance in G2 were explained by genetic factors, whereas for youth self-reports, these three proportions were 94%, 71%, and 66%, respectively. The larger contribution of genetic variance and covariance in caregiver ratings than in youth self-reports may suggest that caregivers considered the changes in their children to be more similar as compared to how the children viewed themselves.

Meteorological and functional response partitioning to explain interannual variability of CO2 exchange at an Irish Atlantic blanket bog

This study aims to develop models to describe CO2 fluxes in terms of environmental and meteorological variables and their variation over an Atlantic blanket bog in Glencar, southwest Ireland. Ten full years (September 2002–August 2012) of data were included in the assessment of CO2 flux and micro-meteorological data. Models were based on non-gapfilled growing season data, using complete calendar years for annual models, and the entire time-series for weekly models, whilst taking interaction between variables into account for increased model accuracy. This was to determine which environmental variables were most influential in directly controlling CO2 exchange on a long- and short-term basis. A homogeneity of slopes (HOS) model was used to determine if there was any ecosystem response to indirect effects (functional response) of environmental or meteorological interannual variation. This model uses multiple regression analysis to determine if the ecosystem response can be better predicted as a linear function of the variables using a single slope model for all years, or a separate slopes model for each year. The separate slopes model gave a different (and improved) outcome for both daytime and night-time CO2 fluxes, and so functional responses were deemed to have occurred. The contribution to variation of day and night-time net ecosystem exchange (NEEday and NEEnight respectively) was then separated into four components: indirect functional responses, direct interannual meteorological variability, direct week to week meteorological variability, and random error, which identified 13.8%, 36.6%, 28.2% and 21.4% respectively of the variation in NEEday, as well as 23.4%, 24.4%, 22.2% and 30% respectively of the variation in NEEnight. Water table level (WTL) had the greatest influence upon functional variation of NEE at the Glencar blanket peatland, and comparisons of modelled NEEday with leaf area index (LAI) measurements verified the estimate of functional contribution using the separate slopes model. The significance of interannual variation (IAV) and functional responses on NEE at Glencar suggests that it is a resilient ecosystem which might be able to adapt to environmental or climatic changes, although given current climate change predictions, it is likely to have a reduced carbon dioxide sink status in the future.

Efficient CDMA System Design for Highway Microcells Based on Accurate Modeling of Path Loss

Out-of-cell interference is an important factorin determining the system capacity of CDMA systems.Out-of-cell interference is influenced by propagationparameters such as slope index s of the path loss model, the standard deviation sigma of shadowloss, and the correlation coefficients of shadow lossfor propagation from the desired base station and fromthe interfering base station. For line-of-sight (LOS) cells along streets or roadways,propagation may be described by a two-slope model thathas smaller slow-fading loss sigma and a larger slopeindex past the breakpoint Rb than thesingle-slope model. As a result, smaller out-of-cellinterference is obtained with the two-slope model,leading to system designs having less infrastructurethan are obtained using the single-slope model. In thispaper we examine how a more realistic prediction ofquality of service (QOS) made with the two-slope modelleads to cost-effective system designs.