Cp Values Research Articles

Novel sampling procedure and statistical analysis for the thermal characterization of ionic nanofluids

An efficient storage system is crucial for the effective implementation of renewable energies in the energy ecosystem, required to mitigate the climate change and to reach the European Green Deal. Nanofluids features improved thermal properties, being able to store unexpected amount of energy by adding around 1 wt% nanoparticles at the base fluid. Therefore, nanofluids become more attractive for their implementation as Thermal Energy Storage (TES) medium or Heat Transfer Fluid (HTF). However, the main drawbacks of nanofluids are the lack of consensus on a theoretical explanation of this behaviour, and the controversial lack of uniformity of the thermophysical experimental results in the literature. The goal of this work is to develop and perform a study of the thermophysical properties of several nanofluid samples and the subsequent statistical analysis. To achieve this objective, three batches of 24-samples were analysed: NaNO3 based nanofluids with three types of nanoparticles (1% wt.): SiO2, Al2O3 and clay. The statistical analysis indicates that nanoparticles have a low impact in the melting enthalpy and melting temperature and a strong impact in the specific heat capacity (Cp). The most remarkable result is the high dispersion of Cp values despite considering the sampling procedure. This fact agrees with the high variability of results found in the literature. Finally, the methodology proposed in this work may facilitate the comparison among measured results and literature results.

Identification of critical watershed at risk of soil erosion using morphometric and geographic information system analysis

Morphometric analysis is a pertinent scientific approach in any hydrological analysis, and it is necessary in the progress and management of drainage basin. Identification of areas at risk of erosion, and the prioritization of 48 sub-watersheds of Inaouene basin, was done by using linear, relief and areal aspects of watershed. The research carried out the use of geographic information system spatial data. The linear aspects include stream number, stream sequence, stream length, and bifurcation ratio, mean length of stream order, stream length ratio, mean stream length ratio, and form factor. The areal aspect includes frequency of stream, drainage density, texture ratio, channel length constant, and overland flow maintenance length. Ultimately, the relief dimensions included relief proportion, relief and ruggedness number. The array of compound (Cp) values computed allow us to set the priority ranks and classify the sub-watershed into three priority ranks groups: low, moderate, and high priority. Such morphometric analyses can be used therefore as a watershed erosion status estimator to prioritize land and water conservation initiatives and natural resources management.

Molecular and Serological Characterization of the SARS-CoV-2 Delta Variant in Bangladesh in 2021.

Novel SARS-CoV-2 variants are emerging at an alarming rate. The delta variant and other variants of concern (VoC) carry spike (S)-protein mutations, which have the potential to evade protective immunity, to trigger break-through infections after COVID-19 vaccination, and to propagate future waves of COVID-19 pandemic. To identify SARS CoV-2 variants in Bangladesh, patients who are RT-PCR-positive for COVID-19 infections in Dhaka were screened by a RT-PCR melting curve analysis for spike protein mutations. To assess the anti-SARS CoV-2 antibody responses, the levels of the anti-S -proteins IgA and IgG and the anti-N-protein IgG were measured by ELISA. Of a total of 36 RT-PCR positive samples (75%), 27 were identified as delta variants, with one carrying an additional Q677H mutation and two with single nucleotide substitutions at position 23029 (compared to Wuhan-Hu-1 reference NC 045512) in the genome sequence. Three (8.3%) were identified as beta variants, two (5.5%) were identified as alpha variants, three (8.3%) were identified as having a B.1.1.318 lineage, and one sample was identified as an eta variant (B.1.525) carrying an additional V687L mutation. The trend of higher viral load (lower Cp values) among delta variants than in the alpha and beta variants was of borderline statistical significance (p = 0.045). Prospective studies with larger Bangladeshi cohorts are warranted to confirm the emergence of S-protein mutations and their association with antibody response in natural infection and potential breakthrough in vaccinated subjects.

Keragaman genotipik entok (Cairina moschata) berdasarkan polimorfisme protein darah

<p class="MDPI17abstract"><strong>Objective: </strong>The aim of this study was to identified genetic diversity of muscovy duck in Central Java through blood protein polymorphisms by using electrophoresis method.</p><p class="MDPI17abstract"><strong>Methods: </strong>Blood sample was collected from a total of 60 muscovy ducks from the districts of Demak, Magelang and Pekalongan, 20 samples each. The Electrophoresis Polyacrylamide Gel of Electrophoresis–Thin Layer Electrophoresis (PAGE-TLE) was used in this study. Parameters observed were protein of albumin (Alb), ceruloplasmin (Cp), transferrin (Tf) and amylase-I (Am-I). Gene frequency, heterozygosity (Ho) and genetic distance were analyzed by using DISPAN program.<strong></strong></p><p class="MDPI17abstract"><strong>Results</strong><strong>: </strong>The results showed that the Alb, Cp, Tf and Am-I of muscovy duck showing polymorphic characters. Gene frequency of Alb<sup>B</sup> (0.61) was higher compared to Alb<sup>A</sup> (0.39). Gene frequency of Cp<sup>A</sup> (0.62) was higher than the Cp<sup>B</sup> (0.38). Furthermore, gene frequency of Tf<sup>A</sup> and Tf<sup>B</sup> were 0.32 and 0.68, respectively as well as gene frequency of Am-I<sup>A</sup> (0.82) was higher than Am-I<sup>B</sup> (0.18). Muscovy duck population of Demak showed higher Ho value for Alb and Am-I, whereas Magelang showed higher value for Cp and Tf. Population of muscovy duck of Demak showed closer genetic distance to Pekalongan than Magelang.<strong></strong></p><strong>Conclusions: </strong>The protein blood locus of three population of muscovy duck in Central Jawa showed polymorphic characters.

Nutrient requirement equations for Indian goat by multiple regression analysis and least cost ration formulation using a linear and non-linear stochastic model.

An elaborate multiple regression analysis was done to arrive a nutrient requirement equation for goat including dry matter intake, DMI (kg/day), total digestible nutrient, TDN (g/day) and crude protein, CP (g/day) based on animal body weight (BW) (kg) and average daily gain (ADG)(g/day). The derived equations were highly significant (p<0.001) and had high R2 (0.99) values. The estimated values of TDN, CP and DMI are compared with NRC (1981), Kearl (Nutrient Requirements of Ruminants in Developing Countries, All Graduate Theses and Dissertations, 1982), as well as ICAR (Livestock Management, 2013). The estimated total TDN and CP requirements at different body weights and ADG are close to the values of recommended feeding standards of Mandal et al. (Small Ruminant Res., 58, 2005, 201). The estimated DMI values are close to the values of ICAR (Livestock Management, 2013) but lower (26.5%-43.8%) as compared to NRC (1981). Regressed values are used to develop a linear programming (LP) model and a stochastic model (SM) for least-cost ration formulation for the Indian goat breed, whose average BW is about 45kg and ADG is 130 (g/day), and which is solved using LP simplex and Generalised Reduced Gradient (GRG) nonlinear of Microsoft Excel. The models satisfy the nutrient requirement calculated by regression equations with minimum specified level of variation (usually 5%-10%) in CP and TDN. Both methods adequately meet the nutritional requirements. Therefore, an electronic sheet is developed in Excel to calculate DMI, TDN and CP for different body weights, ADG and formulate the ration by LP and stochastic model.

The advantage of flow disturbance for vertical-axis turbine in low current velocity

Some findings start with inadvertent. One lack of a vertical-axis turbine is its low self-starting capability. This study aimed to improve the performance in low current velocities by adding a flow disturbance in front of the turbine. The idea has been inspired by the previous experimental study that was not specifically focused on this problem. The study was conducted using a numerical simulation method with Computational Fluid Dynamics (CFD). Firstly, the simulation results of the original turbine were validated with experimental data. Secondly, the turbine was modified by adding a flow disturbance in front of it. There were two foil types of flow disturbance modelled. The results showed that the flow disturbance with DU 06-W-200 had a slightly higher performance than NACA 63(4)021, with a coefficient of power (Cp) value of 0.52 at a current velocity of 0.54 m/s. At tip speed ratio (TSR) > 1, the turbine performance tended to decrease when using a higher angle of attack (AoA). Therefore, the recommended AoA for the flow disturbance is 0°. The flow disturbance has been proven to increase the performance of the vertical-axis turbine at a low current velocity.

Optimization of a Draft Tube using Statistical Techniques- DOE and 2D Computational Fluid Dynamic Analysis

The draft tube is one of the main components that integrate a turbine, since it has the function of recovering the residual kinetic energy after the runner by the pressure energy. The search for a draft tube design that increases the efficiency of the turbine is always an engineering challenge. The hydromechanics components geometry optimization can be accomplished through the integration of optimization methods and CFD tools. In this work, the geometric optimization of a double diffuser draft tube of a Bulb turbine applied to ultra-low heads is presented, with the objectives of maximizing the pressure recovery coefficient, Cp, and increasing the hydraulic efficiency of the turbine, ηh. These improvements would make it possible to reduce the longitudinal length of the draft tube, thereby, making an easier insertion of this kind of turbines in water transport systems, with pressures around 3 [mH2O]. The optimization methodology was performed in the meridional plane, using twelve geometric variables in the draft tube through the integration of optimization methods and computational fluid dynamics. The optimized geometry obtained showed an increase in the Cp value of 0.71516, from the original geometry, to 0.83080. The results were extended to the 3D flow analysis, where the optimized turbine showed efficiency gains of 82% to 84%, when compared to the original turbine considering that its total length was reduced and its geometry simplified, resulting in a more compact and versatile equipment. The study also concluded that the applied methodology can be extended to other similar optimization problems in the design of hydraulic machines‎.

Low-temperature anomalies of thermodynamic properties of lanthanum trifluoride LaF3 and (SrF2)0.5 (LaF3)0.5 multivalent solid solution

Temperature dependences of the heat capacity Cp(T) (2–300 K) and lattice parameter a(T) (5–300 K) of LaF3 and (SrF2)0.5(LaF3)0.5, in addition to the earlier studied SrF2, are experimentally investigated for the first time. The experimental dependences of Cp(T) and the unit cell volume V(T) of the studied fluorides are analysed using the Debye–Einstein model considering the influence of the disorder of their crystal structures. The parameters of the model are determined. An anomalous arrangement of the Cp(T) and V(T) curves of the solution with respect to the corresponding curves of the components is revealed. At low temperatures (T < 150 K), the values of Cp(T) and V(T) of the solution exceed the values calculated by the additivity rule. At higher temperatures (T > 150 K), deviations towards smaller values are observed. We have established that the disorder in solid-solution crystal structure is the common reason of anomalies revealed. It is found that at low temperatures, the cause of these anomalies is a decrease in the vibrational frequencies in the solid-solution metal sublattice upon the replacement of Sr with La, which has a large size and mass. Such a replacement leads to distortions of the original structure and an increase in its disorder. At elevated temperatures, the deviations are caused by an increase in the vibrational frequencies in the F- sublattice due to distortion of the crystal structure, as well as the increased influence of the anharmonicity of the disordered crystal lattice vibration.

Citrus pulp and orange fiber as dietary fiber sources for dogs

Citrus pulp pellets (CPP) and orange fiber (OF) are coproducts of the citrus juice industry. OF is a novel fiber source that contains elevated amounts of soluble fiber and has not yet been studied in dog nutrition. The objectives of this study were to evaluate the inclusion of CPP and OF in dog foods and their effects on the extrusion parameters, the coefficient of total tract apparent digestibility (CTTAD) of nutrients, fermentation end products, and palatability. A control diet (CO) without an added fiber source tested was formulated, and the experimental diets were composed of 30 g/kg, 60 g/kg and 120 g/kg CPP or 60 g/kg OF inclusion (as-fed basis). Extrusion parameters were recorded to determine extruder energy balance and kibble macrostructure. Thirty beagle dogs (3.2 ± 0.7 years; 12.4 ± 1.5 kg body weight) were distributed in a randomized block design with 6 dogs per group to evaluate the CTTAD of nutrients and the fermentation products in feces. The results were analyzed by analysis of variance, and means were compared by polynomial and orthogonal contrasts. The inclusion of CPP and OF reduced motor amperage (P < 0.001), mass pressure (P = 0.002), and specific mechanical energy transference (P < 0.001). Kibble macrostructure was affected by a decrease in expansion and an increase in hardness by CPP and OF inclusions (P < 0.001). Starch gelatinization was reduced by CPP (P < 0.001) but not by OF inclusion (P > 0.05). Total dietary fiber (TDF) intake increased (P < 0.001) with the addition of CPP, with a linear reduction in CTTAD of nutrients and energy (P < 0.05). The OF treatment, however, presented similar CTTAD values of DM and CP to those of the CO diet (P > 0.05). The TDF CTTAD was higher for 60 g/kg OF than for 60 g/kg CPP (P = 0.028). The fecal pH decreased, and total short-chain fatty acids (SCFA), acetic acid, butyric acid, and lactate concentrations increased with CPP and OF inclusion (P < 0.05). However, the diet supplemented with OF induced the production of feces with a lower pH and higher total SCFA concentrations than those of feces produced from CPP inclusion (P < 0.001). The OF diet presented a higher preference (65%) than the CO diet (35%) by dogs (P < 0.05). The CPP and OF were fermentable fiber sources, increasing SCFA and butyric acid concentrations in feces. The OF was more fermentable than CPP, with a limited impact on kibble formation, starch cooking, and CTTAD of nutrients and showing good acceptance on diets by dogs.

Performance Comparison of Multiplexed Fluorescent Resonance Emission Transfer Hybridization Probes Across Roche LightCycler® Real-Time PCR Systems for the Detection of Bartonella species

Abstract Introduction/Objective Molecular assays for Bartonella species are important in diagnosing infection and expediting patient treatment. Real time polymerase chain reaction (RT-PCR) using fluorescent resonance energy transfer (FRET) hybridization probes can be used to detect Bartonella species in blood and fresh/fixed tissue biopsies in RT-PCR instruments. Over time, new technologies and reagents are introduced and existing PCR primers and FRET probes must be re-validated on new platforms. This study aimed to compare the performance of a Bartonella RT-PCR assay using the sunsetting Roche LightCycler® 2.0 (Roche Diagnostics, Indianapolis, IN) and newer LightCycler® 480 RT- PCR instruments. Methods/Case Report DNA was extracted from 132 historically positive, whole organism spiked, and historically negative whole blood and formalin fixed paraffin embedded (FFPE) samples. Samples were run on the LightCycler® 2.0 using instrument specific LightCycler® FastStart DNA Master HybProbe enzyme and compared to results generated using the LightCycler® 480 and its instrument specific LightCycler® 480 Genotyping Master enzyme. During optimization, MgCl2 concentrations and thermocycling profiles were adjusted. Accuracy, specificity, inclusivity, and limit of detection studies were performed. Crossing point (Cp), melting temperature (Tm), fluorescent peak and fluorescent background values were compared between the two instruments. Results (if a Case Study enter NA) The agreement in accuracy between the LightCycler® 2.0 and the LightCycler® 480 was 100% for whole blood samples. For historically positive FFPE samples, LightCycler® 2.0 sensitivity and LightCycler® 480 sensitivity were 86% and 100%, respectively. Specificity and inclusivity of the assay were identical between the two instruments. The limit of detection in whole blood was 5-fold lower on the LightCycler® 480 (50 copies/µL) compared to the LightCycler® 2.0 (250 copies/µL). Mean Cp and fluorescent peak intensity values increased by 5.1% and 65-fold, respectively. Conclusion The study demonstrates similar performance and improved limit of detection for the Bartonella FRET hybridization probe RT-PCR assay on the LightCycler® 480 compared to the LightCycler® 2.0.

Edge clique partition in [formula omitted]-graphs

An edge clique partition of G is a set of edge-disjoint cliques of G which together contain every edge of G. In this work we investigate the computational complexity of determining the minimum size of an edge clique partition of G, denoted by cp(G). This problem is NP-hard for split graphs and K4-free graphs. We establish a complete complexity classification of this problem on the hierarchy of (k,ℓ)-graphs, graphs that can be partitioned into k independent sets and ℓ complete sets. In addition, we determine in polynomial time the value of cp(G) for interesting subclasses of (k,ℓ)-graphs: split-indifference graphs, partial 2-trees, and triangular grids.

Topological features of limbic dysfunction in chronicity of tinnitus with intact hearing: New hypothesis for ‘noise-cancellation’ mechanism

PurposeThe reorganization of the limbic regions extend to general cognitive network is believed to exist in the chronicity of tinnitus with particular ‘hubs’ contributing to a ‘noise-cancellation’ mechanism. To test this hypothesis, we investigated the topological brain network of tinnitus in different periods. MethodsResting-state functional magnetic resonance imaging were obtained from 32 patients with acute tinnitus, 41 patients with chronic tinnitus and 60 age- and gender- matched healthy controls (HC). The topological features of their brain networks were explored using graph theory analysis. ResultsCommon small-world attributes were compared between the three groups, all showed a significantly increased values in Cp, Lp, λ (all p < 0.05). Significantly increased nodal centralities in the left superior frontal gyrus and the right precuneus, significantly decreased nodal centralities in the right inferior temporal gyrus were observed for acute tinnitus patients compared to HC. While for chronic tinnitus patients, there were significant increased nodal centralities in the left hippocampus, amygdala, and temporal pole, but decreased nodal centralities in the right inferior temporal gyrus. Additionally, significant higher nodal centralities were found in bilateral medial superior frontal gyrus for acute tinnitus patients compared to chronic tinnitus patients. Besides, alterations in rich-club organization were found in acute tinnitus patients and chronic tinnitus patients compared with HC, with increased functional connections among rich-club nodes and peripheral nodes in patients with tinnitus. ConclusionsBrain network topological properties altered across prefrontal-limbic-subcortical regions in tinnitus. The existed hubs in tinnitus might indicate an emotional and cognitive burden in ‘noise-cancellation’ mechanism.

“2 1/2[formula omitted]” generation Calphad databases: Extrapolating heat capacities of elements and compounds to 0K

The extrapolation of thermodynamic properties below the room temperature is still, in practical terms, an unsolved issue. The majority of the already established Calphad databases are based on the 2nd generation Calphad models, which are available only at (T>298.15K), there exist a few assessments relying on 3rd generation Calphad models that include more physical descriptions of heat capacity and extend the range of applicability down to 0K. To combine these slowly developing assessments with huge number of existing assessments, a compatible solution that can bridge the gap between 0K and 298.15K in an efficient and fully automated process is needed.Here, an automated modelling approach is proposed, that can be used to produce a reliable thermodynamic descriptions for a wide range of pure elements and compounds. The heat capacity and entropy values at room temperature are the only inputs required. Two fitting parameters are derived, which are, depending on the values of CP and S at 298.15K, either the Debye temperature and its low-temperature dependence or the Debye temperature and a CP contribution changing linearly with temperature. The results are produced as a simple polynomial expression that can be universally utilized in different computational thermodynamic software. Moreover, they are more accurate when compared with experimental or ab-initio results than solutions that rely on pure Einstein or pure Debye models. The applicability is shown on a huge dataset of solid compounds from the material classes of elements, metallic compounds, oxides, semiconductors and salts, thus covering all material classes relevant in Calphad assessments.

Performance improvement of Darrieus wind turbine using different cavity layouts

The Darrieus wind turbine has a low starting torque, which is one of its main disadvantages. The main objective of the present study is to design an advanced Darrieus wind turbine capable of self-starting at low wind speeds without extra components. This will allow us to utilize this sort of wind turbine in less windy regions, such as urban areas. The new design relied solely on the blade profile for exploiting the drag force caused by the wind on the blades. The profile modifications under consideration included a variety of cavity shapes, numbers, sizes, and positions on the blade surface. The Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations were numerically solved in combination with the SST k-ω turbulence model. The characteristics of power and torque, as well as their flow fields, were studied. The results demonstrated that the maximum enhancements of power and torque coefficients were achieved using a single cavity located on the upper surface of the trailing edge of the airfoil, namely UST airfoil. A maximum improvement of 18% for power coefficient was obtained using a UST airfoil with a Tip Speed Ratio (TSR) of 3.5. The UST airfoil has a circular shape with a diameter equal to 0.08 of airfoil chord length. The airfoil with a single cavity performed noticeably better than the airfoil with a dual cavity. However, the ULST airfoil which consisted of two cavities located on upper and lower surfaces of the airfoil trailing edge generated the maximum power coefficient among other airfoils. The ULST airfoil generated a CP value of 0.27 at TSR = 3.5, representing a maximum improvement of 17% over an airfoil without a cavity.

The influence of hydrogen addition on the combustion characteristics of a common-rail CI engine fueled with waste cooking oil biodiesel/diesel blends

In this study, the effect of hydrogen assisted intake air on combustion characteristics of a diesel fuel-waste cooking oil biodiesel (WCOB) blend fueled CI engine has been extensively studied. While the diesel and B25 (75% diesel fuel+25% WCOB) fuels used as the main fuel were sprayed directly into the cylinder, the hydrogen, the secondary fuel was mixed with the intake air at 10, 20, 30 and 40 lpm flow rates and taken into the cylinder. The maximum in-cylinder pressure (CP) values decreased with B25 fuel compared to diesel fuel. But B25‑hydrogen dual-fuel mode operation exhibited higher maxium CP and RoPR value according to diesel fuel. It was seen that hydrogen has a more significant effect on premixed pilot fuel combustion phase compared to the diffusion combustion phase. It was observed that the combustion duration (CD) of neat B25 fuel lower than that of diesel fuel, generally. In case of B25‑hydrogen dual-fuel mode operation, CD increased depending on increasing hydrogen addition rate. It was seen that hydrogen enrichment has no adverse effect on ringing intensity (RI).

Biomass-derived activated carbons with extremely narrow pore size distribution via eco-friendly synthesis for supercapacitor application

Activated carbons (ACs) are promising materials for supercapacitor application. The production process is however still considered expensive and environmentally harmful due to using harsh chemicals under aggressive conditions. In this research, ACs have been prepared from rubber seed shell (RSS), durian shell (DS) and palm petiole (PP) via an eco-friendly self-activation method with KOH activating agent. The chemical, morphological and textural properties of the carbonaceous materials were studied using various characterization techniques: FTIR, XRD, Raman spectroscopy, FESEM-EDS and BET. The electrochemical behaviors of the AC-based supercapacitor electrodes were examined by CV, GCD and EIS. The highest specific surface area (436 m2 g−1) and specific capacitance (178 F g−1) were obtained from PP and DS activated carbons, respectively. The high specific capacitance (Cp) of the DS activated carbon was attributed to its extremely narrow pore size distribution and the presence of excellent charge storage and charge transfer balance. The Cp values obtained are comparable to those reported in the literature; therefore, this study successfully demonstrated a better route to produce an AC-based supercapacitor electrode.

Risk of aortic aneurysm and dissection following exposure to fluoroquinolones, common antibiotics, and febrile illness using a self-controlled case series study design: Retrospective analyses of three large healthcare databases in the US.

Recent observational studies suggest increased aortic aneurysm or dissection (AAD) risk following fluoroquinolone (FQ) exposure but acknowledge potential for residual bias from unreported patient characteristics. The objective of our study is to evaluate the potential association between FQ, other common antibiotics and febrile illness with risk of AAD using a self-controlled case series (SCCS) study design. Retrospective database analysis-SCCS. Primary and Secondary Care. 51,898 patients across 3 US claims databases (IBM® MarketScan® commercial and Medicare databases, Optum Clinformatics). FQ or other common antibiotics or febrile illness. AAD. We studied patients with exposures and AAD between 2012 and 2017 in 3 databases. Risk windows were defined as exposure period plus 30 days. Diagnostic analyses included p-value calibration to account for residual error using negative control exposures (NCE), and pre-exposure outcome analyses to evaluate exposure-outcome timing. The measure of association was the incidence rate ratio (IRR) comparing exposed and unexposed time. Most NCEs produced effect estimates greater than the hypothetical null, indicating positive residual error; calibrated p (Cp) values were therefore used. The IRR following FQ exposure ranged from 1.13 (95% CI: 1.04-1.22 -Cp: 0.503) to 1.63 (95% CI: 1.45-1.84 -Cp: 0.329). An AAD event peak was identified 60 days before first FQ exposure, with IRR increasing between the 60- to 30- and 29- to 1-day pre-exposure periods. It is uncertain how much this pre-exposure AAD event peak reflects confounding versus increased antibiotic use after a surgical correction of AADs. This study does not confirm prior studies. Using Cp values to account for residual error, the observed FQ-AAD association cannot be interpreted as significant. Additionally, an AAD event surge in the 60 days before FQ exposure is consistent with confounding by indication, or increased use of antibiotics post-surgery. NCT03479736.

Experimental and Numerical Evaluation of Performance of a Variable Pitch Vertical-Axis Wind Turbine

Abstract The research work depicts the study of the comparison of a 1 kW fixed pitch vertical-axis wind turbine (VAWT) and a variable pitch VAWT via analytical, numerical, and experimental results. Being an emerging technology, wind turbine is becoming a source of attraction for the researchers. The VAWT in comparison to the horizontal-axis wind turbine (HAWT) has shown numerous benefits. The fundamental purpose of this study is to maximize the output power and output torque of the wind turbine. For achieving an improved output, a novel and unique mechanism, termed as pitching mechanism, is employed that follows the variable pitch concept. The mathematical modeling was performed for the straight blade variable pitch VAWT and for the fixed rotor. The four-bar mechanism was developed to execute the variable pitch mechanism and implemented in the form of the computer-aided design, model. A scaled down three-dimensional (3D) model of the rotor was manufactured using the 3D printing technique. The aerodynamic forces such as lift and drag were measured upon the rotor as per the testing on the rotor in the wind tunnel. Computational fluid dynamics (CFD) simulations were run for the fixed pitch and the variable pitch rotor. The transient analysis was performed for the azimuthal angle ranging from 0 to 360 deg and for a pitch angle varying from +25 to −25 deg in ansys software. The comparative study was undertaken, keeping in view the analytical, simulation, and experimental results. A worthy agreement was observed among analytical, software, and experimental results, and a promising increase in power and torque was observed due to the introduction of the variable pitch mechanism. The power produced by the variable pitch design showed a significant increase in the power production compared to the fixed pitch design. The numerical and experimental values of cp for the variable pitch design were quite comparable.

Carbon Clusters: Thermochemistry and Electronic Structure at High Temperatures.

This paper studies the thermochemistry and electronic structure of small carbon clusters and hydrocarbons, which are major constituents of pyrolysis gases released into the boundary layer of ablating heat shields. Our focus lies on clusters of up to four carbon atoms. Among other molecules, thermochemistry data for molecules such as C3H and C4H have been determined using the Weizmann-1 (W1) method. These molecules have very limited thermochemistry data recorded in the literature, thereby necessitating new and accurate computations of required properties such as electronic energies of low-lying states, heats of formation, harmonic frequencies, and rotational constants. A study of electronically excited states of these molecules computed using the equations of motion coupled cluster singles doubles method revealed C4 and C4H to be potential sources of radiation absorption in the boundary layer. The excited electronic states of interest are studied further to obtain their optimum geometries, rotational constants, and vibrational frequencies. Moreover, we also study the effect of low-lying excited electronic states on the partition function to assess their effect on the thermodynamics of these pyrolysis gases in the high-temperature regime. Neglecting the excited electronic states records a maximum difference of 12% in the computed specific heat capacity values, Cp values. Finally, comparisons of the equilibrium mole fractions obtained using the thermodynamics computed in this paper with the existing state-of-the-art tables used for hypersonic applications (e.g., JANAF and Gurvich Tables) show an order of magnitude difference in the mixture compositions. It is shown that the rhombic isomer of C4 (1Ag), which is energetically close to the ground state (3Σg-) and usually neglected in composition calculations, contributes to a 28% increase in the equilibrium mole fraction of the C4 molecule.

Role of regional diffusion tensor imaging (DTI)-derived tensor metrics in the evaluation of intracranial gliomas and its histopathological correlation

BackgroundThe imaging of brain tumours has significantly improved with the use of advanced magnetic resonance (MR) techniques like diffusion tensor imaging (DTI). This study was conducted to analyse the utility of DTI-derived tensor metrics in the evaluation of intracranial gliomas with histopathological correlation and further adoption of these image-data analyses in clinical setting. MethodsA total of 50 patients with suspected diagnosis of intracranial gliomas underwent DTI along with conventional MR examination. The study correlated various DTI parameters in the enhancing part of the tumour and the peritumoral region with the histopathological grades of the intracranial gliomas. ResultsThe study revealed higher values of Cl (linear anisotropy), Cp (planar anisotropy), AD (axial diffusivity), FA (fractional anisotropy) and RA (relative anisotropy) and lower values of Cs (spherical anisotropy), MD (mean diffusivity) and RD (radial diffusivity) in the enhancing part of the tumour in case of high-grade gliomas. However, in the peritumoral region, the values of Cl, Cp, AD, FA and RA were less whereas values of Cs, MD and RD were more in high-grade gliomas than in the low-grade gliomas. The various cutoff values of these DTI-derived tensor metrics were found to be statistically significant. ConclusionDTI-derived tensor metrics can be a valuable tool in differentiation between high-grade and low-grade gliomas which might be accepted in clinical practice in near future.