Increasing Tilt Angle Research Articles

Collision-adhesion mechanism of particles and dust deposition simulation on solar PV modules

Dust accumulation has a significant influence on the performance of solar photovoltaic (PV) modules. Investigating the particle collision-adhesion mechanism helps to understand dust accumulation characteristics of PV modules and provide theoretical support for dust removal work, and hence, improve PV efficiency. This study established a collision-adhesion model between particles and PV modules. Then, the mechanical equilibrium-based and energy-based particle adhesion mechanisms were explored and particle deposition condition was proposed. Furthermore, a dust accumulation experiment was created to verify the rationality of simulation model, which was constructed using energy-based particle adhesion mechanism. Based on this, a simulation was performed on the impact of various factors on particle deposition. The results showed the particle kinetic energy loss with a magnitude of 10 −13 J in the collision was positively correlated with humidity and particle size, while negatively correlated with wind speed and tilt angle. The particle deposition amount first decreases and then increases with increasing wind speed and particle size. However, it increases with increasing humidity and decreases with increasing tilt angle. Additionally, when the tilt angle increases from 15° to 60°, the particle deposition amount reduced from 4.28 g/m 2 to 1.81 g/m 2 under 7 m/s. In the future construction of PV power plants, for the area where particle size and average annual wind speed are less than 30 μm and 7 m/s, increasing the tilt angle appropriately can reduce dust accumulation. Understanding the movement process and the force behavior of particles is the premise to investigate the particle adhesion mechanism and deposition conditions. Besides, the collision between the particle and PV panel is an essential precondition for the deposition of particles on the panel surface. Therefore, the collision-adhesion physical model between the particle and PV panel surface is established. In a humid environment, the panel surface will absorb a water film of certain thickness, and increasing humidity will increase the water film thickness. To facilitate the analysis, it can be equivalent to a water film with uniform thickness. When the particles integrated with the wind move to the PV panel surface and collide with it, they usually go through four stages: incident, collision deformation, deformation recovery, and reflection stage, as shown in Fig. A above. The unbalanced force is the main reason for the particle deposition on the PV module surface . Therefore, according to collision-adhesion physical model between the particle and PV panel surface, the particle force behavior in the collision-adhesion process is analyzed, as shown in Fig. B above. This lays a foundation for the investigation of particle adhesion mechanism and the proposal of deposition conditions in this paper. • Particle deposition criterion condition is proposed. • A collision-adhesion model between the particle and PV module is built. • Particle adhesion mechanism based on mechanical equilibrium and energy is explored. • A dust accumulation experiment is done to verify the simulation model rationality. • Effect of various factors on particle deposition in humid condition is simulated.

Effects of vibrations on tilted silo discharge

• A three-dimensional tilted silo submitted to vibration was established. • Discharge rate did not depend on depth but decreased with the increase of tilt angle. • That the discharge was promoted or suppressed was affected by vibration parameters. • Effect of angle on discharge rate was higher than that of frequency and amplitude. Introducing vibrations is a common way to improve the granular flow in silos to avoid clogging. In this study, a three-dimensional silo submitted to vertical vibration was built. The effect of vibration on the discharge of tilted silo was studied. The results showed that, the discharge rate did not depend on the particle depth but decreased with the increase of the outlet tilt angle, regardless if the silo was vibrated or not. Discharge rate showed non-monotonic relationship with vibration frequency at high amplitude, while increased with increasing frequency at low amplitude. The contour plots of the influence of vibration and tilt angle on the discharge were given. Based on the analysis of variance (ANOVA), the effect of the tilt angle on the discharge was higher than the vibration amplitude and frequency.

How to Select the Lower Instrumented Vertebra in Traditional Growing Rods Index Surgery.

There are still no consensus criteria on how to select the lower instrumented vertebra (LIV) for traditional growing rods (TGRs) at index surgery. The aim was to evaluate whether the criteria used for adolescent idiopathic scoliosis fusion adapts to early onset scoliosis (EOS). Retrospective analysis of prospectively longitudinal collected data in a consecutive cohort of patients with EOS treated with TGR, expanding from index surgery to 2 years after graduation. The LIV was analyzed regarding its relation to the stable vertebra (SV), substantially touched vertebra (STV), and not STV (NSTV). Failure of LIV selection was considered when revision surgery with distal extension was needed during follow up, due to adding on (ΔLIV tilt > 10°). A total of 25 patients met inclusion criteria. Mean age was 8.6 ± 3 (at index surgery), 15.1 ± 1.8 (at graduation), and 17.8 ± 1.6 (at final follow up). The most frequent LIV at index surgery was L3 (13/25); in 13 cases, STV was selected as LIV; in 7, it was NSTV; and in 5, SV on the standard postero-anterior radiographs. During follow up, a significant increase in the mean LIV tilt (P = .049) and distal junctional angle (P = .017) was found. Nine of the 25 patients (36%) developed adding on: 20% (1/5) of those with LIV at SV, 38.5% (5/13) at STV, and 42.8% (3/7) at NSTV. Of those 9 cases of adding on, only four needed distal extension (mean LIV tilt = 17.6°): 2 STV patients (15.4%), and 2 NSTV patients (28.6%). None of the patients with the LIV chosen at SV needed distal extension due to adding on. The more cranial the selection of the LIV above the SV, the higher the risk of adding on and of revision surgery with distal extension during follow up. Saving motion segments could be justified by choosing STV as LIV because the need for distal extension is not high, and it can be scheduled during lengthening procedures or at graduation surgery. 4. Choosing the correct LIV in TGR index surgery is crucial to have a secure distal foundation, control and correct the deformity during growth, and save distal segments to allow growth and mobility.

Energy, exergy, and environmental (3E) analyses of reverse and cross-corrugated trapezoidal solar air collectors: An experimental study

Reported here is an experimental investigation of the thermal performances of two solar air collectors (SACs) with modified absorber plates, one reverse trapezoidal (type-I SAC) and the other cross-corrugated trapezoidal (type-II SAC). Tests are performed with air mass flow rates of 0.0039–0.0156 kg/s and tilt angles of 15°, 30°, and 45°, and the energy efficiency, exergy efficiency, temperature rise, sustainability index, and environmental impact factor are evaluated. The results indicate that because of its better heat transfer, the type-II SAC produces up to 7.72% more energy than does the type-I SAC. The energy efficiency increases with increasing tilt angle and is greatest at 45°. Furthermore, with a threefold increase in air mass flow rate, the energy and exergy efficiencies increase by as much as 100–105%. The maximum energy efficiency for the type-I and type-II SACs is found to be 30.3% and 39.4%, respectively. The sustainability index of the type-II SAC is 13.86% higher than that of the type-I SAC, whereas the environmental impact factor of the type-II SAC is almost 40.90% lower than that of the type-I SAC.

Interactions of Linear Analogues of Battacin with Negatively Charged Lipid Membranes

The increasing resistance of bacteria to available antibiotics has stimulated the search for new antimicrobial compounds with less specific mechanisms of action. These include the ability to disrupt the structure of the cell membrane, which in turn leads to its damage. In this context, amphiphilic lipopeptides belong to the class of the compounds which may fulfill this requirement. In this paper, we describe two linear analogues of battacin with modified acyl chains to tune the balance between the hydrophilic and hydrophobic portion of lipopeptides. We demonstrate that both compounds display antimicrobial activity with the lowest values of minimum inhibitory concentrations found for Gram-positive pathogens. Therefore, their mechanism of action was evaluated on a molecular level using model lipid films mimicking the membrane of Gram-positive bacteria. The surface pressure measurements revealed that both lipopeptides show ability to bind and incorporate into the lipid monolayers, resulting in decreased ordering of lipids and membrane fluidization. Atomic force microscopy (AFM) imaging demonstrated that the exposure of the model bilayers to lipopeptides leads to a transition from the ordered gel phase to disordered liquid crystalline phase. This observation was confirmed by attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) results, which revealed that lipopeptide action causes a substantial increase in the average tilt angle of lipid acyl chains with respect to the surface normal to compensate for lipopeptide insertion into the membrane. Moreover, the peptide moieties in both molecules do not adopt any well-defined secondary structure upon binding with the lipid membrane. It was also observed that a small difference in the structure of a lipophilic chain, altering the balance between hydrophobic and hydrophilic portion of the molecules, results in different insertion depth of the active compounds.

Simulations of 1-MeV proton transmission through an insulating conical macrocapillary: Further insight into transmission mechanisms

Transmission of 1-MeV protons through a conical borosilicate macrocapillary was simulated. In present simulations we included atomic scatterings and patch deflections, different from pioneer work where only the former was considered. The simulated results provide deep insight into the transmission mechanisms of MeV ions through a conical macrocapillary: for tilt angles smaller than the taper angle, the enhanced transmission is fully governed by atomic scatterings, whereas beyond the taper angle the patch deflections are of some importance. Moreover, the strength of patch deflections was found to first increase to a maximum and then drop to zero as the tilt angle increases. This is different from those of the atomic scatterings and geometric laws, which both monotonously decrease with the tilt angle. The core and halo structure in the transmission profile unique to the MeV ions through the conical capillary can be formed only for smaller beam divergence.

Draft force prediction for a high-speed disc implement using discrete element modelling

Draft force is an important dynamic parameter for agricultural soil-engaging tools and implements. Soil-disc interaction dynamics has changed enormously in modern tillage practice because of the use of larger machines, faster speeds, and different tool arrangements. Most existing studies on draft force prediction are for conventional tillage. In this study, a discrete element model (DEM) was developed to predict draft forces for high-speed (12 km h−1 or higher) tillage. Draft forces were measured for an individually mounted disc using soil bin tests at low speeds in a sandy loam soil. Results were compared for the accuracy with the predicted values from the ASABE standard equation. Results showed that relative error ranged from 8% to 14%. Due to the limitations of the testing facility, the DEM model was calibrated using 6 km h−1 tillage speed and verified with other test speed measurement. The calibrated model was able to predict draft force with a minimum relative error of 1%. The calibrated particle stiffness, was found to be 20 kN m−1. The calibrated model was then used to examine the effects of operating parameters including gang angle, tilt angle, operating speed, disc diameter and tillage depth on draft forces at 16 km h−1. From these simulations, it was shown that draft increased with an increase in gang angle, tillage depth, and speed. The draft force was reduced with an increase in tilt angle and remained relatively constant with the change of disc diameter. Finally, the simulated data were used to develop a multivariate regression equation to predict the draft for a high-speed tillage operation. This equation is suitable for the soil conditions studied and further validation is required to verify this equation.

Base Cutting Energy Consumption for Sugarcane Stools Using Contra-Rotating Basecutters

HighlightsThis study focused on the base cutting energy consumption for sugarcane stools instead of single stalks, thus being more consistent with actual field harvesting.The energy consumption increased with increasing rotational speed (RS) and stool diameter (SD), while it decreased with increasing tilt angle (TA) and feed rate (FR).Each pair of levels of each factor was compared using Duncan’s multiple range test. Three factors (RS, SD, and FR) had significant effects on energy consumption at 95% confidence level, while one factor (TA) had no significant effect.The order of influence and the optimal combination of the four factors to minimize the energy consumed during base cutting were determined.Abstract. Previous studies on contra-rotating basecutter designs based on supported cutting have mainly focused on the base cutting energy consumption for single sugarcane stalks instead of sugarcane stools. However, in the actual base cutting process, a basecutter typically cuts multiple sugarcane stalks (in one sugarcane stool) simultaneously. Therefore, this study investigated how the rotational speed (RS) and tilt angle (TA) of the cutting discs, the sugarcane stool diameter (SD), and the feed rate (FR) affected the energy consumed when cutting cane stools using a contra-rotating cutting platform. Four single-factor experiments and an orthogonal experiment were performed using a Taguchi orthogonal experimental design, and each group was replicated five times. The results of the single-factor experiments showed that the energy consumption was proportional to RS and SD, while it was negatively correlated with TA and FR. The significance of the difference between each pair of levels of each factor was investigated using Duncan’s multiple range test. According to the results of the orthogonal experiment, RS, SD, and FR had significant influences on the base cutting energy consumption at the 95% confidence level; however, TA had no significant influence. The order of influence of the four factors was SD > FR > RS > TA (18.45 > 18.39 > 12.91 > 9.06), and the optimal factor-level combination for minimizing the cutting energy was RS2, TA4, SD1, and FR3 (200 rpm disc RS, 20° disc TA, 60 mm SD, and 1.0 m s-1 FR). An understanding of the relationships between energy consumption and its influencing factors can serve as a valuable reference for researchers seeking to optimize the design of contra-rotating basecutters, which could lead to increased energy efficiency and a reduction in energy consumption during sugarcane harvesting. Keywords: Contra-rotating basecutter, Energy consumption, Orthogonal experiment, Single-factor experiment, Sugarcane stools, Supported cutting.

Effects of tilt angle on droplets condensation on hydrophobic surface

Condensation surface modification was an important research direction to realize droprise condensation and erhance heat transfer. In order to explore the condensation process and mechanism of droplets on the hydrophobic surface, the condensation process of droplets on the natural Donghu lotus leaves with tilt angle of 30°,60° and 90° were studied. The results show that the tilt angle had a significant effect on the droplets condensation behavior on Donghu lotus leaves hydrophobic surface. Increasing the tilt angle would short the detachment time of condensate droplets. The growth rate of droplets increased with the increase of hydrophobic surface tilt angle. And the condensation droplets diameter also decreased with the increase of incl ination angle.

Experimental study on droplets evaporation on hydrophobic surface at different tilt angles

Droplets evaporation exists widely in industrial manufacturing and engineering applications. Optical visualization system was used to investigate the evaporation process of deionized water droplets on fresh taro leaves with different tilt angles. The evaporation time and mode of droplets were experimental studied at different tilt angles. The results show that the time for the droplet to completely evaporate decreased as the surface tilt angle increases. During the first half of droplet evaporation process on the slant hydrophobic surface, the evaporation modes were different between the two sides of the droplet. When the droplet on an inclined hydrophobic surface evaporated to a certain volume or a certain contact angle, its subsequent evaporation behavior was similar to that of a droplet on a non-tilted hydrophobic surface.

A Multi-Level World Comprehensive Neural Network Model for Maximum Annual Solar Irradiation on a Flat Surface

With the growing demand for clean and economically feasible renewable energy, solar photovoltaic (PV) system usage has increased. Among many factors, the tilt and azimuth angles are of great importance and influence in determining the photovoltaic panel’s efficiency to generate electricity. Although much research was conducted related to solar PV panels’ performance, this work critically determined the tilt and azimuth angles for PV panels in all countries worldwide. The optimum tilt and azimuth angles are estimated worldwide by the photovoltaic geographic information system (PVGIS). Also, annual and average daily solar irradiation incident on the tilted and oriented plate optimally (AR1 and DR1) are calculated. Besides, annual and average daily solar irradiation incident on plate tilt optimally and oriented because of the south in the northern hemisphere and because of the north in the southern hemisphere (AR2 and DR2) are estimated. PVGIS is also used to calculate the annual and average daily solar irradiation incident on the horizontal plate (AR3 and DR3). The data collected from PVGIS are used to develop an efficient and accurate artificial neural network model based on feed-forward neural network approach. This model is an essential subpart that can be used in an embedded system or an online system for further PV system analysis and optimization. The developed neural model reflected very high accuracy in predicting the PV panels’ optimal tilt and azimuth angles worldwide. The benefit of tilting is generally increased by increasing the latitude. As the latitude increases, the tilt factor (F) increases because of the increase in the optimum tilt angle by increasing the latitude. The optimal orientation is due to the north in the southern hemisphere and due to the south in the northern hemisphere for most cities worldwide. In sum, it can be concluded that the optimum tilt angle is equal to or greater than the latitude until the latitude 30°. The optimum tilt angle becomes less than the latitude, and the difference is increased until it reaches more than 20°. Hence in this study the aim is to develop a simple neural network model which can accurately predict the annual radiation and optimum tilt and azimuth angle in any region of the world and can be easily implemented in a low-cost microcontroller.

A novel plant growth regulator improves the grain yield of high-density maize crops by reducing stalk lodging and promoting a compact plant type

• DHEAP is a novel plant growth regulator. • DHEAP improved maize lodging resistance. • DHEAP shaped a compact maize plant type. • DHEAP is helpful to increases summer maize planting density in NCP. Increasing the planting density (PD) of maize ( Zea mays L.) crops is the most efficient method for enhancing maize grain yield, but supra-optimum PD leads to an increase in lodged maize, which alters the maize canopy structure. In this study, N, N-Diethyl-2-hexanoyl oxygen radicals-ethyl amine (2-ethyl chloride) phosphonic acid salt (DHEAP, a single compound), a novel plant growth regulator, was sprayed at the seven-expanded-leaf stage under two different PDs (75,000, and 90,000 plants ha -1 ) using two maize hybrids, ZD958 (lodging-resistance) and XY335 (lodging-susceptible), to reduce maize lodging rates and improve the maize canopy structure under high PD. After DHEAP treatment, the maize lodging rate of ZD958 and XY335 decreased by 70.87% and 75.22%, respectively, through a change in the morphological structure (i.e., reduced plant and ear heights and increased mean tilt angle) and an improvement in the basal internode quality (i.e., increased diameter, dry weight per unit length, crushing strength, cellulose content, lignin content, and vascular area, and reduced length). In addition, DHEAP treatment significantly reduced gibberellin (GA 3 ) contents in maize basal internodes. Moreover, the increase in the mean tilt angle (MTA) above the maize ear leaf after DHEAP treatment improved the light penetration in the middle leaf strata, which increased the chlorophyll content (SPAD), net photosynthetic rate (P n ), and Rubisco enzyme activities. Finally, DHEAP treatment increased the grain yield of ZD958 and XY335 under 90,000 PD by 22.28% and 43.14%, respectively. Thus, it was concluded that the spraying of DHEAP effectively reduced maize lodging rates and improved the photosynthetic performance of the maize ear leaf, which increased maize grain yield under high PDs.

Aspects of arbitrarily oriented dipoles scattering in a plane: Short-range interaction influence

The impact of the short-range interaction on the resonances occurrence in the anisotropic dipolar scattering in a plane was numerically investigated for the arbitrarily oriented dipoles and for a wide range of collision energies. We revealed the strong dependence of the cross section of the 2D dipolar scattering on the radius of short-range interaction, which is modeled by a hard wall potential and by the more realistic Lennard-Jones potential, and on the mutual orientations of the dipoles. We defined the critical (magic) tilt angle of one of the dipoles, depending on the direction of the second dipole for arbitrarily oriented dipoles. It was found that resonances arise only when this angle is exceeded. In contrast to the 3D case, the energy dependencies of the boson (fermion) 2D scattering cross section grows (is reduced) with an energy decrease in the absence of the resonances. We showed that the mutual orientation of dipoles strongly impacts the form of the energy dependencies, which begin to oscillate with the tilt angle increase, unlike the 3D dipolar scattering. The angular distributions of the differential cross section in the 2D dipolar scattering of both bosons and fermions are highly anisotropic at non-resonant points. The results of the accurate numerical calculations of the cross section agree well with the results obtained within the Born and eikonal approximations.

Experiments of keV negative ions transmitted through straight and tapered glass capillaries: tilt angle dependence

In this study, experiments are performed to study the transmission of 15 keV C− ions through straight and tapered borosilicate glass capillaries. The tilt angle is varied from 0° to 0.8°. In a straight capillary, the transmitted ions produced only one spot on the detector, and its intensity declined with increasing tilt angle. In this case, almost 98% of the transmitted particles maintained their initial charge. However, in the tapered capillary, the transmitted particles formed a different pattern composed of a core and a halo. The negative ion fractions of the core and the halo were 97.5% and 42.5% at a 0° tilt angle, respectively. Therefore, the particles formed the halo by scattering after colliding with the inner surface of the capillary, and most of them were neutralized. As the tilt angle increased, the intensity and negative ion fraction of the transmitted particles declined, and the halo gradually became quite asymmetric. These results indicate that the scattering process plays a role in the transmission.

Extracting grain boundary motion in Cu–Al alloy from atomistic simulations

Abstract

Average motion of emerging solar active region polarities: II. Joy's law.

Context.The tilt of solar active regions described by Joy’s law is essential for converting a toroidal field to a poloidal field in Babcock-Leighton dynamo models. In thin flux tube models the Coriolis force causes what we observe as Joy’s law, acting on east-west flows as they rise towards the surface.Aims.Our goal is to measure the evolution of the average tilt angle of hundreds of active regions as they emerge, so that we can constrain the origins of Joy’s law.Methods.We measured the tilt angle of the primary bipoles in 153 emerging active regions (EARs) in the Solar Dynamics Observatory Helioseismic Emerging Active Region survey. We used line-of-sight magnetic field measurements averaged over 6 h to define the polarities and measure the tilt angle up to four days after emergence.Results.We find that at the time of emergence the polarities are on average aligned east-west, and that neither the separation nor the tilt depends on latitude. We do find, however, that EARs at higher latitudes have a faster north-south separation speed than those closer to the equator at the emergence time. After emergence, the tilt angle increases and Joy’s law is evident about two days later. The scatter in the tilt angle is independent of flux until about one day after emergence, when we find that higher-flux regions have a smaller scatter in tilt angle than lower-flux regions.Conclusions.Our finding that active regions emerge with an east-west alignment is consistent with earlier observations, but is still surprising since thin flux tube models predict that tilt angles of rising flux tubes are generated below the surface. Previously reported tilt angle relaxation of deeply anchored flux tubes can be largely explained by the change in east-west separation. We conclude that Joy’s law is caused by an inherent north-south separation speed present when the flux first reaches the surface, and that the scatter in the tilt angle is consistent with buffeting of the polarities by supergranulation.

Dipole Tilt Effect on Magnetopause Reconnection and the Steady‐State Magnetosphere‐Ionosphere System: Global MHD Simulations

AbstractThe Earth's dipole tilt angle changes both diurnally and seasonally and introduces numerous variabilities in the coupled magnetosphere‐ionosphere system. By altering the location and intensity of magnetic reconnection, the dipole tilt influences convection on a global scale. However, due to the nonlinear nature of the system, various other effects like dipole rotation, varying interplanetary magnetic field (IMF) orientation, and nonuniform ionospheric conductance can smear tilt effects arising purely from changes in coupling with the solar wind. To elucidate the underlying tilt angle dependence, we perform magnetohydrodynamic (MHD) simulations of the steady‐state magnetosphere‐ionosphere system under purely southward IMF conditions for tilt angles from 0–90°. We identify the location of the magnetic separator in each case and find that an increasing tilt angle shifts the 3‐D X line southward on the magnetopause due to changes in magnetic shear angle. The separator is highly unsteady above 50° tilt angle, characteristic of regular flux transfer event (FTE) generation on the magnetopause. The reconnection rate drops as the tilt angle becomes large, but remains continuous across the dayside such that the magnetosphere is open even for 90°. These trends map down to the ionosphere, with the polar cap contracting as the tilt angle increases, and region I field‐aligned current (FAC) migrating to higher latitudes with changing morphology. The tilt introduces a north‐south asymmetry in magnetospheric convection, thus driving more FAC in the Northern (sunward facing) hemisphere for large tilt angles than in the Southern independent of conductance. These results highlight the strong sensitivity to onset time in the potential impact of a severe space weather event.

A Novel Flat Friction Stir Spot Welding of Triple Sheet Dissimilar Aluminium Alloys: Analyzing Mechanical Properties and Residual Stresses at Weld Region

In present research work, a novel flat friction stir spot welding was performed on three dissimilar Aluminum alloy sheets (two sheets of AA6082-T6 and one sheet of AA6061-T6). The microstructural features and mechanical properties of joints were investigated at various parameters like tool tilt angle, tool rotational speed, dwell time and tool plunge depth. The optimized value of the response parameter was obtained using Taguchi orthogonal array L27. An increase in tool tilt angle, tool rotational speed and dwell time had improved the microhardness. Optical microscopy, scanning electron microscopy, microhardness tests, lap shear strength test and X-ray diffraction were employed to study the characterization of joints. The present investigations were carried out to correlate the microhardness with microstructural characterization of joints at different welding conditions. It was observed from the XRD analysis that the compressive residual stresses were developed due to reaction for forces exerted by the tool shoulder. Fractograph of joints exhibited mixed mode of fracture with the presence of dimples, transgranular texture and cleavage facets. The comparision of joint efficiency of FFSSW weldment with other variants was done.

Cognitive Function Declines Following Orthostatic Stress in Adults With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).

IntroductionOrthostatic intolerance (OI) is common among individuals with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Cognitive dysfunction has been demonstrated during head-up tilt testing (HUT) in those with ME/CFS: worse scores on cognitive tests occur with increasing tilt angles and increasing complexity of the cognitive challenge. The aim of our study was to determine whether cognitive impairment persists after completion of HUT.Methods and ResultsEligible participants were consecutive individuals satisfying criteria for ME/CFS who underwent HUT because of OI. The 2- and 3-back tests were performed before the start of HUT and within 5 min after completion of HUT. We measured the percentage of correct responses and raw reaction times before and after HUT for both the 2- and 3-back tests. We studied 128 ME/CFS patients who underwent HUT and had a complete set of N-back data before and after HUT. Compared to pre-tilt responses, the percentage of correct responses on the 2-back test decreased post-HUT from 77(18) to 62(21) and of the 3-back test from 57(17) to 41(17) (both p < 0.0001). The raw reaction time of the 2-back test increased post-HUT from 783(190) to 941(234) m/s and of the 3-back test from 950(170) to 1102(176) (both p < 0.0001). There was no difference in the N-back test data for subgroups dichotomized based on disease severity, the presence of co-morbid fibromyalgia, or the presence of postural orthostatic tachycardia syndrome.ConclusionAs measured by the N-back test, working memory remains impaired in adults with ME/CFS following a 30-min head-up tilt test.

Soiling Losses: A Barrier for India’s Energy Security Dependency from Photovoltaic Power

Worldwide photovoltaic power generation is affected by deposited dust on photovoltaic (PV) systems, which creates soiling losses. In this work, factors that have a detrimental influence on dust deposition and an impact on PV systems performance were reviewed. The different ways that dust deposition can be a barrier for India’s energy security plan involving PV were also discussed. Different available cleaning techniques were also introduced. The nature, size, and morphology of dust particles vary with geographical location. Any increase of the PV tilt angle, or high wind speed and heavy rain showers reduce dust deposition. Deposited dust reduces the incident transmitted light on the PV, which has an adverse impact on the reduction of short circuit current. However, the open-circuit voltage has a reduced effect due to dust deposition. The enhancement of temperature caused by dust-covered PVs is still a debatable area. A universal cleaning technique is required to eliminate the soiling losses from PV. India has a solar mission to generate 100 GW of PV power by 2022. However, India’s poor air quality can undermine efforts to achieve this target.