Performance Evaluation Criteria Research Articles

Nanofluid effect on dual-flow parabolic trough collector performance accompanies with passive technique using experimental data

Purpose Using passive techniques like twisted tapes and corrugated surface is an efficient method of heat transfer improvement, since the referred manners break the boundary layer and improve the heat exchange. This paper aims to present an improved dual-flow parabolic trough collector (PTC). For this purpose, the effect of an absorber roof, a type of turbulator and a grooved absorber tube in the presence of nanofluid is investigated separately and simultaneously. Design/methodology/approach The FLUENT was used for solution of governing equation using control volume scheme. The control volume scheme has been used for solving the governing equations using the finite volume method. The standard k–e turbulence model has been chosen. Findings Fluid flow and heat transfer features, as friction factor, performance evaluation criteria (PEC) and Nusselt number have been calculated and analyzed. It is showed that absorber roof intensifies the heat transfer ratio in PTCs. Also, the combination of inserting the turbulator, outer corrugated and inner grooved absorber tube surface can enhance the PEC of PTCs considerably. Originality/value Results of the current study show that the PTC with two heat transfer fluids, outer and inner surface corrugated absorber tube, inserting the twisted tape and absorber roof have the maximum Nusselt number ratio equal to 5, and PEC higher than 2.5 between all proposed arrangements for investigated Reynolds numbers (from 10,000 to 20,000) and nanoparticles [Boehmite alumina (“λ-AlOOH)”] volume fractions (from 0.005 to 0.03). Maximum Nusselt number and PEC correspond to nanoparticle volume fraction and Reynolds number equal to 0.03 and 20,000, respectively. Besides, it was found that the performance evaluation criteria index values continuously grow by an intensification of nanoparticle volume concentrations.

Analysis of hydrodynamics and thermal–hydraulic performance of twisted angle fins within an annular conduit

AbstractThis paper investigated the influence of various twisted angles of fin inserts integrated on the inner heated pipe wall of a double-pipe heat exchanger by analysing the thermal–hydraulic performance through numerical simulations. Results showed twisted angle fin (TAF) induced turbulent fluid flow phenomena, generating transverse and longitudinal vortices, along with swirling flow. This collaboration between the vortices and swirling flow effectively prevents heat trapping and enhances heat transfer from the inner pipe wall through the intensive fluid mixing. Despite longitudinal swirling vortices and turbulence significantly enhance local and global heat transfer performance, they led to increased pressure drop. However, TAF twisting reduces pressure drop by streamlining flow. The performance evaluation criterion (PEC) value is a dimensionless quantity that facilitates the comprehensive evaluation of optimal configurations by comparing the increment in Nusselt number and the increment in friction factor. PEC values greater than 1 indicate that the increase in Nusselt number exceeded the increase in friction factor. Among tested configurations, the twisted fin angles of 60° (TAF60) exhibited the highest improvement in Nusselt number and friction factor, also achieving the highest PEC of 1.59712 at Reynolds number of 1194.71. TAF40 and TAF50 were identified as optimal configurations for enhancing the thermal–hydraulic efficiency, with average PEC values of 1.26893 and 1.27030, respectively. Overall, the study indicated a consistent enhancement trend with increasing twisted angles and emphasizes the significant thermal performance improvement of TAF configurations compared to the smooth conduit. Furthermore, the results showed a converging tendency across all TAF configurations in the percentage improvement in Nusselt number and friction factor, as well as PEC compared to the baseline No fin configuration with increasing Reynolds number, suggesting that future improvements in thermal–hydraulic performance are more dependent on geometric angles than fluid flow velocity.

Thermal Performance of a Laminar Flow Double Pipe Heat Exchanger with Spiral Airfoil Inserts

Objective: This study evaluates the thermal performance of a double-pipe heat exchanger using a spiral airfoil insert in the inner pipe. Methods: The enhancement technique is classified as a passive method, as it does not require the direct application of external power to improve the heat transfer coefficient. Spiral pitch ratios of P/D=7, 5, and 3 were used, with the Reynolds number (Re) varying within the laminar flow regime (Re ≤ 2,100). Cold water flows inside the inner pipe, while hot water flows counter to it in the annulus. Results: The experimental results show that the Nusselt number increased by 159%, 161%, and 171%, respectively, compared to a smooth pipe alone, for flow rates of 2L/min, 2.5L/min, and 3L/min. Additionally, the highest friction factor reached 142%. Conclusion: The results indicate that the best performance evaluation criterion (PEC) was achieved within the flow range of 2L/min to 3L/min, with a pitch insertion of 3, yielding a PEC of 158% to 152%, respectively.

Investigating Enhanced Convection Heat Transfer in 3D Micro-Ribbed Tubes Using Inverse Problem Techniques

The improved heat dissipation observed in 3D micro-ribbed tubes is primarily influenced by the intricate interplay of multiple structural parameters. Nevertheless, research into the coupling mechanisms of these multi-structural parameters remains constrained by the absence of effective methodology in numerical solutions. In the present work, a new 3D micro-rib structure based on discrete adjoint method is established. Firstly, the research examines the interplay of different parameters (such as arrangement, relative roughness height, angle of attack, and circumferential rows) on the thermo-hydraulic performance. It is noted that the heat transfer efficiency is notably impacted by the relative roughness height. And the arrangement methodology dictates the optimal positioning for heat transfer efficiency. An increase in the number of circumferential rows enhances fluid mixing, while the angle of attack plays a crucial role in the formation of longitudinal vortices. Secondly, the coupling optimization technique is employed to obtain the optimal structure featuring non-uniform relative roughness height by the developed numerical solution. Overall, in comparison to the smooth tube, the optimized ribbed tube exhibits a remarkable 64.9% enhancement in performance evaluation criteria. Finally, a notable enhancement of 10.65–22.78% is observed when comparing with the prevailing micro-rib structures.

Enhanced heat transfer performance in a parabolic trough solar collector: A CFD investigation of silver and copper nanofluids utilizing porous medium

A recent study was being conducted to offer a three-dimensional numerical inspection of the water–Ag/Cu nanofluids’ hydrothermal profitability within a parabolic-trough solar collector incorporating a porous medium. This study aims to improve the thermal efficiency of parabolic-trough solar collectors by integrating nanofluids and porous media into the receiver tube. The focus is on enhancing heat transfer to the working fluid for better performance. In our numerical simulation, the working fluid of water (or nanofluid) at 5 different mass flow rates of 20, 40, 60, 80, and 100 L/h and with a temperature of 20°C enters the receiving pipe of a parabolic-trough solar collector while the non-constant heat flux is set on it. Copper and silver nanoparticles in volume fractions of (0.1 to 0.5%) and Darcy numbers of 0.1, 0.01, and 0.001 are simulated in applied porous media. The results of the simulations revealed that the use of a porous medium with (rp = 1 and Da = 0.1) and also in mass flow rate of 20 L/h, our receiver pipe saw a 2204.8% increase in the Nusselt number and 687.8% pressure drop, and the PEC was equal to the number 11.3. In the following, we examined copper and silver nanoparticles in two cases of applying porosity and without applying porosity in the receiving tube in volume fractions of 0.1 to 0.5%. Due to the creation of a high-pressure drop by the porous medium, nanofluids showed higher numbers for the performance evaluation criterion than unity for the non-porous state. Silver nanoparticles in volume fraction of 0.5% (at rp = 1 and Da = 0.1) showed an increase of 71.3% and 197.8%, respectively, for the Nusselt number and pressure drop. In the case of non-porous copper nanoparticles with a volume fraction of 0.5%, they showcased an uptick in 217.6% and 3.8% respectively for the Nusselt number and pressure drop.

Numerical Study on Heat Transfer Efficiency and Inter-Layer Stress of Microchannel Heat Sinks with Different Geometries

As electronics become more powerful and compact, laminated microchannel heat sinks (MCHSs) are essential for handling high heat flux. This study aims to optimize the MCHS design for improved heat dissipation and structural strength. An orthogonal experiment was established with the average surface temperature of the heat source as the evaluation metric, and the optimal structure was determined through simulation. Finally, cooling uniformity, fluidity, and performance evaluation criterion (PEC) analyses were carried out on the optimal structure. It was determined that the optimal combination was the triangular cavity microchannel (MCTC), with a microchannel width of 0.5 mm, a microchannel distribution density of 60%, and the presence of surface undulation on the microchannels. The result shows that the optimal structure’s peak inter-layer stress is just 34.8% of its longitudinal tensile strength. Compared to the traditional parallel straight microchannel (MCPS), this structure boasts an 8.6 K decrease in the average surface temperature and a temperature variation along specific paths that is only 9.9% of that in traditional designs. Moreover, the optimal design cuts the velocity loss at the microchannel entrance from 75% to 59%. Thus, this research successfully develops an effective optimization strategy for MCHSs.

Optimized design of Helical-Finned Double Pipe heat exchangers via numerical simulation and Artificial Intelligence

Heat exchangers are essential in industrial applications, where optimizing their design offers significant environmental and economic benefits. However, traditional methods of enhancing heat transfer, such as adding fins, often lead to increased friction and pressure drop. This study aims to optimize the design of helical-finned double-pipe heat exchangers to improve heat transfer efficiency while minimizing frictional losses. Numerical simulations, combined with Artificial Neural Networks (ANNs), were used to model the impact of design parameters (Reynolds number, number of fins, fin height, and twist pitch) on performance. The k-ω shear-stress transport turbulence model and finite volume method were used for fluid flow and heat transfer simulations, while Genetic Algorithms (GAs) were employed for optimization. ANN models demonstrated high predictive accuracy (R2≈1), and the optimized designs achieved a relative Nusselt number of 2.01, a relative friction factor of 1.01, and a Performance Evaluation Criterion (PEC) of 1.43. Notably, fins did not always improve thermal efficiency, illustrating the complexity of optimizing heat exchanger designs. This study presents an approach by integrating ANN and GA, providing an effective strategy for improving heat exchanger performance.

Enhanced flow boiling heat transfer with three-section sudden expansion microchannels

In this study, a three-section sudden expansion microchannels (TSE-MCs) heat sink was proposed to stabilize the flow boiling and improve the thermal performance of the heat sink exposed to high-heat-flux scenarios. The structural effect of newly designed TSE-MC and operating conditions on the heat transfer coefficient (HTC), pressure drop penalty, and flow instability were experimentally investigated and contrasted with continuous straight microchannels (CS-MCs). The experiments were performed at a saturation temperature of 35.5 °C, the mass flux ranging from 468–1033 kg/m2 s, and the heat flux up to ∼132 W/cm2. A comparative analysis based on the experimental results was conducted. Compared to CS-MCs, the nucleate boiling in TSE-MCs was initiated in advance with 0.2–1.2 °C reduction of wall superheat. The maximum HTCs at four mass fluxes, which was up to 62784 W/m2 K, were enhanced by 18.9–23.6 %. The uniformity of wall temperature was improved and the average wall temperature was reduced. HTCs and visualized results indicated that the dominant mechanism for heat transfer in TSE-MCs was nucleate boiling. Meanwhile, the pressure drop in TSE-MCs was slightly reduced, and pressure drop oscillations were greatly suppressed. The flow reversal in the inlet plenum was completely eradicated, and the performance evaluation criterion (PEC) of TSE-MC outperformed that of CS-MCs and was improved by 79.81 %–86.25 %. Overall, the present work demonstrates the great advantages of the newly proposed TSE-MCs, it offers a reference for the design of microchannel heat sinks for the real high heat flux dissipation applications.

Evaluation of heat transfer enhancement effect at the hot/cold end of a Stirling engine using performance improvement factor

The driving force of a Stirling engine comes from the heating expansion and cooling compression of working medium. The enhancement of heat transfer capacity of the hot/cold end is the key to improve the Stirling engine performance, while how to objectively evaluate the heat transfer enhancement effect is a precondition. Herein, a polytropic model of a Stirling engine thermal cycle process was firstly established. A method for evaluating the heat transfer enhancement performance under oscillating flow was proposed based on the efficiency and power improvement of a Stirling engine. This method was further used to evaluate the heat transfer enhancement effect of a novel four-leaf helical heating tube under oscillating flow, the efficiency and power improvement factor of which was reached 13.5 % and 6.1 %, respectively. The results show that the efficiency and power improvement evaluation criterion was more comprehensive and intuitive in evaluating the heat transfer enhancement performance under oscillating flow compared with the conventional evaluation indictor like performance evaluation criterion and equivalent tube length and tube number criterion.

Numerical analysis of mono and hybrid nanofluids-cooled micro finned heat sink for electronics cooling-(Part-II)

This study investigates the thermal and hydraulic performance of heat sinks with micro pin-fins in circular and rectangular configurations using mono and hybrid nanofluids. Motivated by the need for efficient cooling solutions in high-performance electronic devices, the research explores novel combinations of metallic oxide (Ag, MgO) and carbon-based nanoparticles (GNP, MWCNT) in nanofluids. A constant volume fraction of micro pin-fins and nanoparticles was maintained to assess their effects on thermohydraulic performance. The method involved experiments with aqueous nanofluids as coolants, measuring pressure drops (Δp) at the inlet and outlet. Thermal performance was evaluated using metrics like thermal resistance (Rth), Nusselt number (Nuavg), pumping power (PP), volumetric flow rate (Q), overall performance (OP), and performance evaluation criterion (PEC). Results showed that GNP-based mono nanofluids significantly reduced Rth by 46.41 % and increased Nuavg by 60.54 % and PEC by 62 % in rectangular heat sinks compared to conventional water cooling. Comparisons between rectangular and circular configurations revealed minimal Rth differences of 2.54 % and 3.57 %. GNP-dispersed nanofluids outperformed other coolants, with the rectangular configuration achieving a higher PEC of 1.62 versus 1.52 for the circular configuration at 820 Pa. The conclusions suggest that rectangular pin-fins with GNP-based nanofluids offer superior thermohydraulic performance. The key outcomes from current study have significant contribution in enhancing the cooling efficiency of advanced electronic systems.

A comparative study on thermal behavior of PEG 400 and two oxide nanocolloids

Fluids plays a significant role in all heating and cooling processes, while their thermal conductivity is extremely relevant for a large number of heat exchange applications. This paper mainly discusses the results of an experimental study on thermal conductivity of PEG 400 and two oxide nanocolloids with MgO and TiO2, together with an analysis on Prandtl number, thermal diffusivity and performance evaluation criteria. Several samples (i.e. 11), with different nanoparticle concentration, were manufactured, analyzed and all the experimental data were discussed and further compared with current findings on new heat transfer fluids. Collected experimental data outlined that the thermal conductivity increases with nanoparticle addition and highly depends on the nanoparticle type. Plus, temperature variation does not affect the thermal conductivity of studied samples, while Pr number for all samples follows the behavior of fluids viscosity. For example, Pr number is decreasing with MgO concentration, while the diffusivity increases by 33.86 % for PEG + 2.50 MgO. Concluding, the combined analysis on Prandtl number and thermal diffusivity revealed that the suspensions with MgO have a better behavior at heat transfer if compared with nanocolloids with TiO2.

Numerical study on heat transfer and flow characteristics of symmetric Tesla-type microchannel heat sinks

This study numerically investigates the thermal performance of multi-stage Tesla valve microchannels (TVM) and a symmetric variant (SYMTVM) using single-phase deionized water, with mass flow rates ranging from 0.5459 to 1.6377 g/s. Both designs, particularly under reverse flow, exhibit lower peak temperatures and reduced temperature gradients compared to forward flow. The SYMTVM, characterized by its increased vortices and bifurcations, periodically disrupts and redevelops the thermal boundary layer, enhancing heat transfer efficiency. The TVM exhibits a significantly higher pressure drop than the SYMTVM across all flow conditions, with the reverse flow in TVM reaching up to 2.48 times that of forward flow and exceeding SYMTVM, especially at a peak flow rate of 1.6377 g/s. The performance evaluation criteria (PEC) and thermal resistance criteria (PECTR) demonstrate the superior performance of SYMTVM, with a reduced connection angle between the trunk and helix regions enhancing thermal efficiency. Furthermore, the SYMTVM-Reverse structure with a 30° interconnection angle demonstrates superior performance compared to the conventional rectangular microchannel (RM), achieving a Nusselt number (Nu) that is five times higher than that of the RM and an overall performance up to 2.59 times greater. These results indicate the SYMTVM-Reverse’s high heat transfer efficiency and its capacity to effectively balance thermo-hydraulic performance, even with increased power dissipation.

Optimization and mechanistic analysis of the configurational parameters of a serrated trench for improving film cooling performance

Combinations of trench and holes in film cooling design for turbine blades have been suggested recently. In this work, structural optimization is performed for one of our previously proposed serrated trenches. Geometric parameters including serrated angle, width, and height of the trench, which are the key factors affecting the flow and cooling characteristics, are optimized. The relative area-averaged cooling effectiveness, the relative pressure drop coefficient, and the performance evaluation criterion (PEC) are the optimizing objectives. The multi-objective genetic algorithm is employed as the search strategy to achieve PEC maximization at blowing ratios in the range of 0.5–2.0. The individual variations of each parameter are studied by controlling the variables using the response surface method. It shows that the trench height is the most influential factor on flow and heat transfer; while the trench serrated angle mainly affects the heat transfer; and the trench width has a weak effect on both, depending on the blowing ratio. To achieve maximum PEC, the trench height needs to enlarge with the increase in blowing ratio, while contrary to this, the trench width needs to increase under low blowing ratios and decrease under high blowing ratios, and the optimum trench serrated angle is within the range of 80°–85° at all blowing ratios. The optimum geometry reduces the pressure loss while improves the cooling effectiveness by 8.43 %–17.97 % compared to the baseline trench. This work is instructive for the design and application of practical structures for blade cooling.

A ridge estimation method for the Waring regression model: simulation and application

This study focuses on parameter estimation in the presence of multicollinearity for the count response that follows the Waring distribution. The Waring regression model deals with over-dispersion. So, this study proposed the Waring ridge regression (WRR) model as a solution for multicollinearity with over-dispersion. We conducted a theoretical comparison between the ridge estimator and the maximum likelihood estimators using matrix and scalar mean squared error as a performance evaluation criterion. Several ridge parameters are considered for the WRR estimator. The performance of these parameters is numerically evaluated using a Monte Carlo simulation study and a real application. The results of the simulation and application demonstrate the superiority of the WRR model with different ridge parameters over the maximum likelihood estimator.

Experimental analysis and optimization of a concentrated thermo-photovoltaic collector with bi-facial receiver

In this study, a concentrated thermo-photovoltaic collector is examined experimentally and numerically, while it was geometrically optimized. The main objective is the collector's thermal performance evaluation and optical optimization for operation in Greece. Experiments were conducted in Athens, Greece, from July 10th to 17th, 2023, investigating the thermal operation of the collector in a temperature range of approximately 40–80 °C. The collector's slope was set to 12.3° for maximum solar irradiance utilization during the specified dates, considering south orientation. A numerical model was created using SolidWorks Flow Simulation and COMSOL Multiphysics, The model was validated with the experimental data, achieving mean deviation less than 6.5 % and a maximum deviation of 9.6 %. Various geometries were optically examined using Tonatiuh software. By applying a performance evaluation criterion, a new design is proposed and compared to the initial design across four different months, considering constant tilt angle. A maximum thermal efficiency of 49.19 % at the lower inlet temperature was found experimentally. The temperature of the PV cells was found to be highest where the solar rays are concentrated. Shape optimization revealed significant enhancements in optical efficiency, particularly at negative incident angles. The new geometry showed substantial improvement, with enhancements exceeding 20 % considering daily operation.

Traffic Light Control in Vehicular Network Systems using Fuzzy Logic

Vehicular concentration is getting worse in big and developed cities as we approach the year 2020, creating a challenge. Accurate traffic signal management is a key to efficient free traffic movement and increasing transport security levels. It is thus important to have traffic lights that change with the traffic intensity information that is collected in real-time. Thus, the objective of this study is to design a viable traffic signal control algorithm that would cause minimal delay to drivers. Building on the basis of fuzzy logic, the approach sets input attributes like the volume of the street and the queue of vehicles to identify the right traffic light settings. Performance criteria for evaluation include the average waiting time of the vehicles, and the findings of simulations in this regard show 21.7 seconds, which is faster than the benchmark formula of 25 seconds. This improvement is attributed to the fact that the fuzzy control system is adjustable.

An Empirical Investigation of Organizational Readiness towards Hospital Autonomy.

We aimed to investigate Tehran's University of Medical Sciences (TUMS) affiliated hospitals organizational readiness toward implementing the 'Autonomous Hospitals' program as a change initiative from a managerial perspective in 2020. A census covering all eligible managers working in TUMS affiliated hospitals, Tehran, Iran (350 individuals) was carried out. Overall, 281 questionnaires were returned (a 30% non-responsiveness rate). A standard construct was adopted for data collection which was validated through a process of translation- back translation, face validity, and content validity (CVI=0.86, CVR=0.76). The reliability was acquired using Cronbach's alpha coefficient (0.87 and over 0.7). Both descriptive and inferential statistics were employed to draw conclusions .SPSS 26 was used for data analysis. Total organizational readiness for change (TORC) in hospitals was 60.75%±10.11 showing a state of medium to upper-medium readiness status. Also, the 'Clear mandate and centralized leadership' theme scored the lowest mean (53.02%±15.78) for ORC. 'Hospital accreditation level' (r=-0.14, P≤0.05), 'bed occupancy rate' (r=-0.19, P ≤0.05), and 'leadership status' (r=0.26, P≤0.001), also showed significant association with TORC. In addition, 'standardized bed occuPancy rate' (P≤0.05, B=-2.41), a 'male' leader (P ≤0.05, B=3.42), and 'academic affiliation' (P≤0. 1, B=-9.52), were good Predictors of TORC based on 'Backward Multiple Linear Regression' analysis. Full support from hospital and headquarters executives, delegation of sufficient decision-making authority to hospital managers, and implementation of comprehensive performance evaluation criteria were prerequisites for robust hospital autonomy in TUMS-affiliated hospitals.

Genetic parameters and genotype-by-environment interaction estimates for growth and feed efficiency related traits in Chinook salmon, Oncorhynchus tshawytscha, reared under low and moderate flow regimes

BackgroundA genotype-by-environment (G × E) interaction is defined as genotypes responding differently to different environments. In salmonids, G × E interactions can occur in different rearing conditions, including changes in salinity or temperature. However, water flow, an important variable that can influence metabolism, has yet to be considered for potential G × E interactions, although water flows differ across production stages. The salmonid industry is now manipulating flow in tanks to improve welfare and production performance, and expanding sea pen farming offshore, where flow dynamics are substantially greater. Therefore, there is a need to test whether G × E interactions occur under low and higher flow regimes to determine if industry should consider modifying their performance evaluation and selection criteria to account for different flow environments. Here, we used genotype-by-sequencing to create a genomic-relationship matrix of 37 Chinook salmon, Oncorhynchus tshawytscha, families to assess possible G × E interactions for production performance under two flow environments: a low flow regime (0.3 body lengths per second; bl s−1) and a moderate flow regime (0.8 bl s−1).ResultsGenetic correlations for the same production performance trait between flow regimes suggest there is minimal evidence of a G × E interaction between the low and moderate flow regimes tested in this study, for Chinook salmon reared from 82.9 ± 16.8 g (x¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\overline{\ ext{x}}}$$\\end{document} ± s.d.) to 583.2 ± 117.1 g (x¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\overline{\ ext{x}}}$$\\end{document} ± s.d.). Estimates of genetic and phenotypic correlations between traits did not reveal any unfavorable trait correlations for size- (weight and condition factor) and growth-related traits, regardless of the flow regime, but did suggest measuring feed intake would be the preferred approach to improve feed efficiency because of the strong correlations between feed intake and feed efficiency, consistent with previous studies.ConclusionThis new information suggests that Chinook salmon families do not need to be selected separately for performance across different flow regimes. However, further studies are needed to confirm this across a wider range of fish sizes and flows. This information is key for breeding programs to determine if separate evaluation groups are required for different flow regimes that are used for production (e.g., hatchery, post smolt recirculating aquaculture system, or offshore).

Comparison and development of cross-study normalization methods for inter-species transcriptional analysis.

Performing joint analysis of gene expression datasets from different experiments can present challenges brought on by multiple factors-differences in equipment, protocols, climate etc. "Cross-study normalization" is a general term for transformations aimed at eliminating such effects, thus making datasets more comparable. However, joint analysis of datasets from different species is rarely done, and there are no dedicated normalization methods for such inter-species analysis. In order to test the usefulness of cross-studies normalization methods for inter-species analysis, we first applied three cross-study normalization methods, EB, DWD and XPN, to RNA sequencing datasets from different species. We then developed a new approach to evaluate the performance of cross-study normalization in eliminating experimental effects, while also maintaining the biologically significant differences between species and conditions. Our results indicate that all normalization methods performed relatively well in the cross-species setting. We found XPN to be better at reducing experimental differences, and found EB to be better at preserving biological differences. Still, according to our in-silico experiments, in all methods it is not possible to enforce the preservation of the biological differences in the normalization process. In addition to the study above, in this work we propose a new dedicated cross-studies and cross-species normalization method. Our aim is to address the shortcoming mentioned above: in the normalization process, we wish to reduce the experimental differences while preserving the biological differences. We term our method as CSN, and base it on the performance evaluation criteria mentioned above. Repeating the same experiments, the CSN method obtained a better and more balanced conservation of biological differences within the datasets compared to existing methods. To summarize, we demonstrate the usefulness of cross-study normalization methods in the inter-species settings, and suggest a dedicated cross-study cross-species normalization method that will hopefully open the way to the development of improved normalization methods for the inter-species settings.

Prediction of groundwater level using artificial neural network as an alternative approach: a comparison assessment with numerical groundwater flow model

ABSTRACT Over-exploitation of groundwater in arid and semi-arid regions requires an understanding of dynamics for effective management strategies. This study uses an artificial neural network (ANN) to predict groundwater levels using initial water level, pumping, and hydrological and meteorological input variables. A sensitivity analysis assessed predictors’ impact on accurate groundwater level prediction. The accuracy of predictions by the ANN model was examined through different performance evaluation criteria and the result achieved is satisfactory as compared to reasonable statistical indicator values. A comparison of results simulated by the ANN model and numerical groundwater flow model (MODFLOW) was carried out and it was found that the prediction of the ANN model was consistently superior to that of the numerical model. Therefore, data-driven models such as ANN can provide better predictions of groundwater level that will aid in groundwater resource management.