Shaded Region Research Articles

Characterization of SOL profiles and turbulence in ICRF-heated plasmas in EAST

Scrape-off layer (SOL) profiles and turbulence in ion cyclotron range of frequency (ICRF)-heated plasmas are investigated by the reciprocating probe diagnostic system (FRPs) and gas puff imaging (GPI) diagnostic in EAST. A radio-frequency (RF) sheath potential reaching up to 100 V is identified proximate to the ICRF antennas. Notably, the amplitude of this RF sheath potential escalates in response to rising ICRF power and inversely with plasma density. When a RF sheath is present in the far SOL, a pronounced density ‘shoulder’ forms in front of the ICRF antennas, while the ‘shoulder’ fade away as the antenna and associated RF sheath shift outwards. A strong E r shear is revealed by measurements from both FRPs and GPI. Analysis of the poloidal wave number-frequency spectrum reveals suppression of high-frequency turbulence in the far SOL due to the RF sheath. This effect is manifested in the reduced autocorrelation time τ c and reduced average blob size δ blob of the SOL plasma. Intriguingly, the poloidal propagation direction of the low-frequency turbulence reverses from the electron to the ion diamagnetic drift direction at the RF sheath location. A surge of tungsten impurity is potentially attributed to the heightened interaction between the SOL plasmas and the wall material. Shifting the ICRF antennas outward, to alleviate heat spots, results in the relocation of the RF sheath to the shaded region of the main limiter. This shift amplifies the radial velocity of blobs in the far SOL and concurrently diminishes the SOL density when compared to conditions without ICRF injection. The properties of ion saturation current fluctuations are consistent with the stochastic model predictions.

Reconstruction of flow field with missing experimental data of a circular cylinder via machine learning algorithm

In this study, artificial neural networks (ANNs) have been implemented to recover missing data from the particle image velocimetry (PIV), providing quantitative measurements of velocity fields. Due to laser reflection or lower intensity of particles in the interrogation area, the reconstruction of erroneous velocity vectors is required. Therefore, the distribution of time-averaged and normalized flow characteristics around a circular cylinder has been demonstrated as streamwise and cross-stream velocities at Re = 8000. These velocity components have been given for different regions at x/D = 0.5, x/D = 1.25, x/D = 2, and y/D = 0. These stations have been chosen to estimate missing data for near-wake, mid-wake, far-wake, and symmetry regions. The missing data ratios (A*) for 0.5 ≤ x/D ≤ 2 are A* = 3.5%, 7%, and 10%. In addition, these values are A* = 4%, 8%, and 12% for y/D = 0, while A* = 7.5% for the shaded region. The increment of area positively affects the estimation results for near-wake and mid-wake regions. Moreover, the errors tend to decrease by moving away from the body. At y/D = 0, increasing the area negatively influences the prediction of the results. The mean velocity profiles of predicted and experimental data have also been compared. The missing data have been predicted with a maximum percentage error of 3.63% for horizontal stations. As a result, the ANN model has been recommended to reconstruct PIV data.

Traditional and hybrid solar photovoltaic array configurations for partial shading conditions: perspectives and challenges

he role of photovoltaic (PV) array in converting solar energy to electrical energy is very much important to get maximum power. Current challenge in solar PV systems is to make them energy efficient. Partial shading conditions (PSCs) is one of the main causes for performance degradation of PV array. It not only effects the shaded region but also effect the overall output of the PV array. Proper selection of configuration is essential to overcome such type of challenges. There exist various types of traditional configurations such as series (S), parallel (P), series parallel (SP), total-cross-tied (TCT), bridge-link (BL), and honeycomb (HC). Hybrid configurations also available such as series-parallel-total-cross-tied (SPTCT), bridge-link-total-cross-tied (BL-TCT), honey-comb- total cross-tied (HC-TCT), and bridge-link-honey-comb (BL-HC). This paper presents an overview on various types of configurations available with their merits and demerits under various partial shading situations. This paper also insights recent advancements in PV array configurations with their future trends to benefit the researchers working in this domain.

Temperature Estimation of Partially Shaded Photovoltaic Modules Using a Multiphysics Model

Partial shading is common in both photovoltaic (PV) stations and building integrated PV systems. The temperature increase of partially shaded (PTS) module not only reduces its efficiency but also accelerates its degradation. Therefore, temperature estimation of PTS module is essential for assessment and maintainence of PV systems. In this article, a multiphysics model consisting of an electrical model, an optical model, and a thermal model is developed. Particularly, the parallel circuit is adopted for the PTS cell, making it possible to calculate the electric power and heat generation of shaded region and unshaded region in the PTS cell, respectively. To the best of our knowledge, it is the first attempt to estimate the temperature distribution of PV module with PTS cell. Experiments are conducted on monocrystalline PV modules. One specific cell is partially shaded in various proportions and environmental conditions. The maximum temperature on the front surface of the PTS module is measured with the infrared thermographic camera and also calculated by our method. The root mean square error is 6.14 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C, which verifies the effectiveness of the proposed multiphysics model for temperature estimation of PTS modules.

Modeling of photovoltaic modules under common shading conditions

Common shading conditions will lead to power loss and even result in hotspots, which may influence the reliability of photovoltaic (PV) systems. Therefore, it is necessary to model for PV modules under common shading conditions. Existing methods ignore the change of shunt resistance when the cell is shaded, leading to some errors of the I–V curve and P–V curve. In this paper, a physically explicable parallel circuit based on the single-diode model is proposed for the shaded cell. The parameters of shaded region and unshaded region are estimated respectively based on the shading proportion and transmittance. The shunt resistance of the shaded cell can be accurately estimated by the proposed method. The electrical model of PV module under common shading conditions is developed. Extensive experiments are conducted: PV modules are shaded by area-measurable shade cloth with regular shape to analyze I–V characteristics. PV modules are also shaded by uniformly accumulated dust, and leaf/soil/shadow with arbitrary shape and location to simulate the situation in real PV station. Experimental results verify that the I–V curve and P–V curve simulated by the proposed electrical model are more consistent with the measured results compared with the existing method.

Slow Photon-Enhanced Heterojunction Accelerates Photocatalytic Hydrogen Evolution Reaction to Unprecedented Rates

Slow Photon-Enhanced Heterojunction Accelerates Photocatalytic Hydrogen Evolution Reaction to Unprecedented Rates

Non-Symmetrical (NS) Reconfiguration Techniques to Enhance Power Generation Capability of Solar PV System

At present, primary power generation depends on non-renewable energy resources, which will become extinct. Solar is the best option in renewable energy sources to achieve clean and green power extraction. Solar PV transforms light energy into electrical energy. However, the output power of solar PV changes with solar insolation. It is also affected by environmental factors and the shading effect. One of the key factors that can reduce the PV system output power is partial shading condition (PSC). The reduction in power output not only depends on shaded region but also depends on pattern of shading and physical position of shaded modules in the array. Due to PSCs, mismatch losses are induced between the shaded modules which can cause several peaks in the output power-voltage (P-V) characteristic. This article describes the non-symmetrical reconfiguration technique and compares it with the primary total cross tied connection. The performance of non-symmetrical reconfiguration techniques is evaluated and compared in terms of global maximum power (GMP), voltage and currents at GMP, open and short circuit voltage and currents, mismatch power loss (MPL), fill factor, efficiency, and number of local maximum power peaks (LMPPs) on a 9 × 9 PV array.

Promotion and suppression of single-molecule conductance by quantum interference in macrocyclic circuits

Promotion and suppression of single-molecule conductance by quantum interference in macrocyclic circuits

TWISTER PLOTS FOR TIME-TO-EVENT STUDIES.

Results of randomized trials and observational studies can be difficult to communicate. Results are often presented as risk or survival functions stratified by the treatment or exposure (1, 2). However, a contrast between the stratified risk functions is often of primary interest. Here we propose a “twister” plot to visualize contrasts in risk over the duration of a study. The twister plot is a −90-degree rotation of a typical contrast measure plot (e.g., Figure 3 in Cole et al. (3)), whereby the contrast measure is instead on the abscissa (x-axis) and time on the ordinate (y-axis). Pointwise confidence intervals are similarly added as a shaded region that typically widens as follow-up duration increases, giving twister plots their characteristic shape that resembles their namesake. To ease application, we provide SAS, R, and Python code on GitHub (4). In Figure 1A...

A FULLY AUTOMATED AND FAST APPROACH FOR CANOPY COVER ESTIMATION USING SUPER HIGH-RESOLUTION REMOTE SENSING IMAGERY

Abstract. Canopy cover is a key agronomic variable for understanding plant growth and crop development status. Estimation of canopy cover rapidly and accurately through a fully automated manner is significant with respect to high throughput plant phenotyping. In this work, we propose a simple, robust and fully automated approach, namely a rule-based method, that leverages the unique spectral pattern of green vegetation at visible (VIS) and near-infrared red (NIR) spectra regions to distinguish the green vegetation from background (i.e., soil, plant residue, non-photosynthetic vegetation leaves etc.), and then derive canopy cover. The proposed method was applied to high-resolution hyperspectral and multispectral imagery collected from gantry-based scanner and Unmanned Aerial Vehicle (UAV) platforms to estimate canopy cover. Additionally, machine learning methods, i.e., Support Vector Machine (SVM) and Random Forest (RF) were also employed as bench mark methods. The results show that: the rule-based method demonstrated promising classification accuracies that are comparable to SVM and RF for both hyperspectral and multispectral datasets. Although the rule-based method is more sensitive to mixed pixels and shaded canopy region, which potentially resulted in classification errors and underestimation of canopy cover in some cases; it showed better performance to detect smaller leaves than SVM and RF. Most importantly, the rule-based method substantially outperformed machine learning methods with respect to processing speed, indicating its greater potential for high-throughput plant phenotyping applications.

AIM and ELF bonding analyses of M–O and M–N (Metal= Ba, Y, Zr) in metal–complexes using DFT approach

The molecular interaction between the chelating agents of citric acid (CA), ethylenediaminetetraacetic acid (EDTA), and triethylenetetraamine (TETA) with metals (M = Ba, Y, and Zr) were studied using Density Functional Theory (DFT) method. This study aims to determine the type of bonding between M–O/N bonds in the CA/EDTA/TETA– complexes. In this study, each metal was attached at strategic positions of chelating agents and was optimized at B3LYP/6-31G* and UGBS level of theory. The M–O bonds were characterized based on Atoms–in–molecules (AIM) and Electron Localization Function (ELF) in the topological analysis. In AIM analysis, the total electron energy density at the bond critical point (BCP) of the M–O/N bonds are used to estimate the interaction involved. The low values of ρ(r) and positive values of ∇2ρ(r) indicates that ionic character exists in the M–O/N bonds. In ELF color-filled map, the blue shaded region between M–O/N atom acts as an indicator for the existence of the ionic interaction. Both AIM and ELF results confirm the existence of ionic bonding between M–O/N bonds, with values of ρ(r) and ∇2ρ(r) ranging from 0.02 to 0.12 au and 0.09 to 0.5 au respectively. Further analysis on charge distribution at M–O/N bonds show that the opposite charge between Ba, Y, and Zr with O/N assured the M– O/N ionic bonding interactions.&#x0D; Keywords: Density functional theory, metals, bonding, atom–in–molecules, bond critical point, electron localization functions

Modeling of Photovoltaic Modules Under Common Shading Conditions

Common shading conditions will leads to power loss and even result in hotspots, which influence the reliability of PV systems. Therefore, it is necessary to model for PV modules under common shading conditions in the PV station. Modeling of the shaded module relies on the appropriate model for the (partial) shaded cell. We observe that shaded region and unshaded region in a PV cell work quite differently. In the shaded region, the photoinduced current will decrease, and the shunt resistance will increase. In the unshaded region, the temperature rise can be even higher than 100 ℃. Consequently, it is essential to model for the shaded region and unshaded region respectively. In this paper, a physically explicable parallel model is proposed for the shaded cell and modeling of PV modules under common shading conditions are studied. We conduct extensive experiments, shading PV modules by area-measurable shade cloth with regular shape to analyze their I-V characteristics. PV modules are also shaded by uniformly accumulated dust, and leaf / soil / shadow with arbitrary shape and location to simulate the situation in real PV station. Experimental results verify the effectiveness of our method.

Amorphous NaVOPO 4 as a High-Rate and Ultrastable Cathode Material for Sodium-Ion Batteries

The low cost and profusion of sodium resources make sodium-ion batteries (SIBs) a potential alternative to lithium-ion batteries for grid-scale energy storage applications. However, the use of conv...

Real-Time Under-Load Electrochemical Impedance Spectroscopy (EIS) Analysis and Modeling

All batteries degrade, but the challenge comes in quantifying that degradation and ultimately predicting a battery's failure and/or end-of-life. Battery health and monitoring have become more imperative with larger deployment of lithium batteries in electric vehicle (EV) and energy storage system (ESS) applications. Research shows a strong correlation between battery degradation and AC impedance measured using electrochemical impedance spectroscopy (EIS). This indicates that AC impedance can be used as a proxy for battery health. Additional information, like a battery's internal temperature can also be extracted from EIS measurements. As such, there is a strong push to measure AC impedance of a battery in field diagnostic applications. However, EIS is typically performed at rest under very stable environmental conditions. This traditional method of interpreting EIS must be modified to account for changing environmental conditions and changing current loads like those seen in EV and ESS applications. This paper explores the prospect of using EIS in a real-time battery management system (BMS) with the primary focus on determining the limits for interpreting EIS under loaded current conditions. An experiment is conducted to evaluate using EIS measurements taken on a loaded battery for the purpose of temperature estimation.A set of experiments were conducted where EIS was performed on Samsung 18650 Nickel Manganese Cobalt (NMC) cells while the cell was subject to loaded conditions. These experiments consisted of load currents ranging from charging rates (C-rate) between C/5 to 2C, and discharging rates (D-rate) between D/5 to 2D. Test were conducted at temperatures in the range of 5°C to 35°C. Closer inspection of Figure 1 shows EIS spectra diverging for charging conditions at lower frequencies. This is believed to be caused by a drift in the battery’s SOC. During charging, lower frequencies in AC impedance tend to have lower magnitude. Conversely, higher AC impedance magnitude is observed during discharging. The EIS frequency at which the loaded impedance deviates from the unloaded impedance by >10% is determined. The curve in Figure 2 represents the lowest EIS frequency at which under load EIS spectra is deemed usable, meaning that the shaded region below the curve represents the unusable portion of the EIS spectra. Moreover, this relationship serves as groundwork upon which to correct for EIS under loaded conditions. It is believed that the relationship of frequency limit as a function of load current shown in Figure 2 is slightly skewed by battery heating as an artifact of the test procedure. As a result, this experiment will be repeated prior to the final paper to gather data that accounts for these heating effects. A method to correct for shifts in an under-load EIS spectra will also be presented in the final paper.The prospect of using an under-load EIS spectra for internal temperature prediction is also demonstrated on a lab scale. In this experiment, the Samsung cell was soaked in a thermal chamber at constant temperature for several hours. A series of 3D discharge pulses are then applied to the battery for various durations. EIS is performed back-to-back during the current pulses (i.e., under load) and during rest times. The EIS spectra are fed into a cell temperature estimation model based on a non-zero interrupt frequency (NZIF) method. Figure 3 shows how EIS spectra changes with temperature for both loaded and unloaded conditions. The details of the NZIF model are beyond the scope of this paper. Thermistors are placed on the surface of the battery to measure a reference temperature. The results of the NZIF-predicted internal temperature are contrasted with measured thermistor battery surface temperatures, and those results are shown in Figure 4. These results indicate that NZIF-predicted internal temperature rises and falls during discharge and rest events, consistent with expected temperature rise and thermistor-measured battery surface temperature.Preliminary analysis suggests that constant current loads only slightly skew no-load EIS measurements, and that most of the EIS spectra taken under load is still usable. Furthermore, the usable portion of an EIS spectra can be determined by an EIS frequency vs load current relationship. This paper demonstrated that EIS can be used for internal temperature prediction while the battery is subject to a loaded condition, which is potentially useful to improve safety and performance of battery packs in field applications. In future work, more EIS measurements will be taken under different loaded conditions to improve NZIF predictions of internal temperature. Nevertheless, these early results are extremely promising for the use of EIS in real-time BMS applications. Figure 1

Robust circular marker localization under non-uniform illuminations based on homomorphic filtering

Circular markers are widely used in image-based measurement fields, e.g. vision system calibration, displacement measurement, and vibration monitoring. Generally, the marker positioning error inevitably leads to inaccurate results. As one of the key factors, the non-uniform illumination seriously affects the localization precision of circular markers. In order to reduce the influences of uneven lighting, a homomorphic filtering-gray weighted centroid method (HF-GWCM) is presented in this work. Firstly, the basic principles of both HF and its combination with GWCM are introduced. Subsequently, some simulation examples are conducted to analyze the localization accuracy of concentric circle markers under non-uniform illumination situations, which comprise the influences of HF parameters and different localization methods. Finally, a single camera imaging system with multiple light sources is employed to perform some tests for the effectiveness validation of HF-GWCM. Both positioning accuracy and stability of HF-GWCM are analyzed under different uneven illumination situations, including lighting movement, multiple light sources, and shaded region. Results demonstrate that HF-GWCM owns the ability to resist the interference of non-uniform illuminations, and it is also an effective way to improve the localization accuracy of circular markers.

The Impact of Different Ethical Allocation Strategies on Survival during Vincristine Shortages

INTRODUCTION: Since 2015, there have been between 10-20 unique chemotherapeutic shortages per year in the United States. Published ethical frameworks consider the following principles as potentially just strategies to allocate chemotherapy during shortages: prioritizing the youngest, those whose disease is most responsive to the scarce medication by volume of drug, those with worse alternatives, or those who have waited longest (Persad, Lancet 2009). To evaluate the impact of these allocation strategies on patient survival during a chemotherapy shortage, we developed a simulation model through the use-case of vincristine, a widely prescribed blood cancer chemotherapeutic recently in shortage. METHODS: We developed a model to recapitulate scarce chemotherapy allocation at the hospital level. Simulated patients enter the model when they require treatment and are ordered in a queue to receive the scarce chemotherapy-or their best alternative regimen-according to ethically-accepted strategies that prioritize by (1) youngest age, (2) greater efficacy per volume, (3) worse alternatives, or (4) first-come, first-served (the default strategy). For the vincristine use-case, demographic, disease, and treatment data were abstracted from 1689 patients treated at Dana-Farber Cancer Institute from 2015-2019; 3-year treatment regimen survival probabilities and disease risk-adjustments were abstracted from publications cited in the National Comprehensive Cancer Network guidelines. Modeled survival outcomes were validated against Surveillance, Epidemiology, and End-Results Program (SEER) data. Based on the length of the recent vincristine shortage, mean survival rates for a 9-month scenario were modeled according to individual and combination allocation strategies across varying supply levels. RESULTS: Model functions and risk-adjusted survival probabilities demonstrated no significant differences between the cohort and SEER data, respectively. During the 9-month shortage scenario, a strategy that prioritized patients by greater efficacy per volume significantly increased the mean number of patients surviving at 3-years by &amp;gt;5% across 34.8% of possible vincristine supply levels (grey line and shaded region in Figure) compared to the default of first-come, first-served (red line; all p&amp;lt;0.01). The mean difference in survival over this range was 6.6%. Though a strategy that prioritized drug for those with worse alternatives did not produce improvements over the default by itself, a combination strategy that prioritized by both greater efficacy and worse alternatives produced significant and &amp;gt;5% differences in the mean number of patients surviving across 56.7% of possible supply levels (all p&amp;lt;0.01; blue line and shaded region). The mean survival difference over this range was 7.2%. As compared to the number of patients surviving without any shortage, this combination strategy and the efficacy-only strategy kept statistically similar mean numbers of patients alive for supply reductions 16.7% greater than the default of first-come, first-served (72.2% versus 88.9% of adequate supply, respectively; arrows in Figure). The combination strategy also resulted in a &amp;lt;2.3-year difference in the mean age of surviving patients compared to the youngest age strategy and no increase in mean times to treatment compared to the first-come, first served strategy. CONCLUSIONS: During a simulated vincristine shortage, a strategy that allocated by both greater efficacy per volume and worse alternatives improved survival compared to either alone, younger age, or the default of first-come, first-served. Moreover, this combined strategy ameliorated reductions in survival across a larger range of drug scarcity than the default. Such a model can be adapted for use for future chemotherapy shortages when multiple ethical allocation strategies exist. Figure Disclosures No relevant conflicts of interest to declare.

Population Pharmacokinetics of Eryaspase in Patients with Acute Lymphoblastic Leukemia or Pancreatic Adenocarcinoma

L-asparaginase (ASNase) is a microbial enzyme and a chemotherapeutic agent that has been a standard component of multi-agent chemotherapy for the treatment of acute lymphoblastic leukemia (ALL). Eryaspase, ASNase encapsulated in red blood cells, is being developed with an improved pharmacokinetic profile compared to some other ASNase products. The purpose of the present analysis was to describe the population pharmacokinetics (Pop PK) of eryaspase and sources of variability in two patient populations - ALL or pancreatic adenocarcinoma (PAC). Eryaspase was administered intravenously at doses of 50, 100, and 150 U/kg to patients enrolled in Phase 1-3 clinical trials in combination with chemotherapy. Either serial or sparse pharmacokinetic sampling was performed in each study. A Pop PK model was fit to the data using Nonlinear Mixed Effects Modeling (NONMEM®) software, and included an assessment of covariates, e.g., demography, disease type, formulation, and immunogenicity. The adequacy of the final Pop PK model and parameter estimates was investigated with a visual predictive check (VPC) and non-parametric bootstrap analysis. Using the final Pop PK model, a simulation was performed for eryaspase 100 U/kg every 2 weeks and included a target trough reference ASNase level of 100 U/L. The Pop PK analysis included 162 patients (94 ALL and 68 PAC) with median age of 56.5 years (range of 2-84 years). Eryaspase concentration-time data were best described by a one compartment model with first order elimination. Population clearance and volume of distribution were 0.29 L/day and 6.12 L, respectively. That equates to a terminal half-life of approximately 15 days. Both clearance and volume of distribution were found to increase with increasing body weight. No other covariate tested was found to influence eryaspase pharmacokinetics, including patient age and gender, patient population (ALL vs PAC), and formulation (native vs recombinant ASNase). VPC showed the final model well captured the data; furthermore, the final model parameters and bootstrap results were in accordance. The effect of positive presence of neutralizing antibodies on eryaspase clearance was inconclusive because of variability within and across studies. The figure below displays the median (solid line) and 95% prediction interval (blue shaded region) of simulated ASNase concentrations with a reference line of 100 U/L. The simulation shows that approximately 95% of patients would exceed the target trough level of 100 U/L following the first and subsequent infusions following administration of 100 U/kg every 2 weeks. In conclusion, the Pop PK analysis provided valuable information in the characterization of eryaspase and factors that influence its variability. As expected for an RBC-type product, the clearance was low, and the volume of distribution was consistent with blood volume. Terminal phase t1/2 was approximately 15 days, and body weight was a significant covariate for both clearance and volume of distribution. Based on simulation, an eryaspase dosing regimen of 100 U/kg every 2 weeks would provide trough ASNase activity levels above 100 U/L for approximately 95% of patients. Eryaspase is currently being investigated in ALL patients with hypersensitivity reactions, as well as a phase 3 clinical study in PAC (Trybeca-1) and a phase 2 study in Triple Negative Breast Cancer (Trybeca-2). Figure Disclosures Hoke: Erytech: Current Employment. Lorenzi:Precision Pathways: Consultancy. El-Hariry:Erytech: Current Employment.

Internal resonances among the first three modes of a hinged–hinged beam with cubic and quintic nonlinearities

This paper presents a derivation of a hinged–hinged Euler–Bernoulli beam including cubic and quintic nonlinearities. Then, a three-mode Galerkin discretization technique has been utilized to generate a system of ordinary differential equations governing the temporal deflections of the first three modes of the studied beam. The pioneering work of Nayfeh and Mook (1995) has shown the absence of internal resonances among the modes of a hinged–hinged beam with cubic nonlinearities despite there are commensurable linear natural frequencies. In this work, extra quintic nonlinearities are involved to show the presence of internal resonances among such modes. Approximate solutions of the resulted system have been approached by the method multiple scales to get the modulations governing the amplitudes and phases of the first three modal temporal deflections. Their stability is investigated via Routh–Hurwitz criterion and a shaded region of unstable solutions has been plotted to conclude picture where the stable solutions are. Different response curves are plotted to explore the effects of beam parameters on the nonlinear dynamical behavior of such beam. Finally, a simulated response of the modal temporal deflections and the overall spatial–temporal deflection are portrayed to show the accurate behavior of the beam at different initial conditions.

Simulation and Data Analysis of the Temperature Distribution and Variation in the Permanent Shaded Region of the Moon

The permanent shaded regions (PSRs) at the lunar poles receive no direct solar illumination throughout the year, so their temperatures are extremely low. The PSR is mainly heated by the radiation heat flow and the scattered solar radiation from the sunlit crater wall. The temperature distribution in the PSR and its diurnal and seasonal variations have been calculated using the ray-tracing method, which determines the radiation heat flow and the scattered solar radiation. In this article, the radiation heat flows were calculated by anisotropic emissivity of the PSR, and the scattered solar radiation was calculated using the lunar Lambert model. To conform to the Diviner IR temperature data, the 1-D heat conduction equation was solved with modified heat conductivity (an important parameter of the regolith media). As an example, the daytime and nighttime temperatures in the Hermite-A crater at the North Pole during summer and winter were numerically simulated and were compared with the Diviner IR data. In addition, rocks near the central peak of the crater in the PSR may enhance the nighttime temperature. This was validated by the PSR images captured by the Lunar Reconnaissance Orbiter Camera (LROC), the Miniature Radio Frequency instrument data on the LRO, and the numerical simulations.

Performance investigation of hybrid and conventional PV array configurations for grid-connected/standalone PV systems

Now a days, the critical challenge in solar photovoltaic (PV) system is to make them energy efficient. One of the key factors that can reduce the PV system power output is partial shading condition (PSC). The reduction in power output not only depends on shaded region but also depends on pattern of shading and physical position of shaded modules in the array. Due to PSCs, mismatch losses are induced between the shaded modules which can cause several peaks in the output power-voltage (P-V) characteristic. The series-parallel (SP), total-cross-tied (TCT), bridge-link (BL), honey-comb (HC), and triple-tied (TT) configurations are considered as conventional configurations, which are severely affected by PSCs and generate more mismatch power loss along with a greater number of local peaks. To reduce the effect of PSCs, hybrid PV array configurations such as series-parallel : total-cross-tied (SP-TCT), bridge-link : total-cross-tied (BL-TCT), honey-comb : total-cross-tied (HC-TCT) and bridge-link : honeycomb (BL-HC) are proposed in this paper. This paper briefly discusses the modeling, simulation and performance evaluation of hybrid and conventional 7∗7 PV array configurations during different PSCs in Matlab/Simulink environment. The performance of hybrid and conventional PV configurations are evaluated and compared in terms of global maximum power (GMP), voltage and currents at GMP, open and short circuit voltage and currents, mismatch power loss (MPL), fill factor, efficiency, and number of local maximum power peaks (LMPPs).