Analysis of the Single-Crystalline Silicon Photovoltaic (PV) Module Performances Under Low γ - Radiation from Radioactive Source

The present paper is about an experimental evaluation of the terrestrial silicon single-crystalline solar PV module behavior under low gamma radiation. The     

In Situ Management of Ions Migration to Control Hysteresis Effect for Planar Heterojunction Perovskite Solar Cells

As one of the most promising photovoltaic materials, the efficiency of inorganic–organic hybrid halide perovskite solar cells (PSCs) has reached 25.5% in 2020. However, the stability and hysteresis remain primary challenges before it can become a commercial photovoltaic technology. Therefore, those issues have drawn significant attention for photovoltaic applications. In this work, a study of the PSCs hysteresis improvement is presented based on a combination of first-principles simulations, scanning electron microscopy images, and time-dependent photocurrent measurements. It indicates the hysteresis led by the ion migration and accumulation is mainly localized at the two interfaces: one is between electron transport layer and active layer, and the other is between active layer and hole transport layer. Considering the massive defects at the grain boundaries (GBs), they lower the potential barriers significantly. The defect density at GBs is therefore reduced via the in situ passivation of PbI₂ crystals. The hysteresis index is decreased from 22.43% down to 1.04%, and results in an improvement in efficiency from 17.12% up to 20.10%. Following the understanding of defect-induced hysteresis, an approach to improve the hysteresis is provided, which can be integrated into the fabrication process and widely applied to enhance the performance of PSCs.     

Trajectory Analysis of Forest Cover Change in the Tropical Dry Forest of Burkina Faso,West Africa

Forest cover decline is one of the most important environmental issues in the tropics. The present study was carried out in Burkina Faso, West Africa, and aimed at assessing the trajectories of forest cover change and measuring landscape metrics of the trajectory classes in order to better understand the processes of change. Landsat and ASTER images acquired over a period of 30 years were used for cover change detection and the Fragstats package was used to compute landscape metrics with five unifying change classes. Results showed a substantial increase in cropland with concurrent decline in forest cover. Deforestation represented 63% of the Percentage of Landscape (PLAND) in 2006, while reforestation accounted for only 28%. Both of these classes had high Normalized Landscape Shape Index (NLSI) values, indicating that they were present as scattered small patches. The old cultivation (30-year permanent cropland) was aggregated (IJI ≈ 0) while deforestation exhibited highly interspersed patches. The old forest and old cultivation presented lower Area Weighted Fractal Dimension Index (FRAC_AM), but deforestation and reforestation had the higher FRAC_AM. These results confirmed that there was a high level of deforestation and fragmentation in southern Burkina Faso and justify the need for a proper management plan to ensure the sustainable use of forest resources.     

Semi-Empirical Technique for Computation of Glass Density

We present a semi-empirical technique for computation of glass density based on the enthalpy landscape approach. The technique incorporates thermal history and entropy effects into a scaling factor, which is determined using a computed enthalpy versus volume curve and a single experimental density value. We demonstrate the technique on a series of calcium aluminosilicate glasses.     

Urban Livelihoods and Social Networks: Emerging Relations in Informal Recycling in Kaduna, Nigeria

This paper examines the dynamics of the relationships found within existing networks in informal recycling in Kaduna, Nigeria. Special attention is paid to power relations. Informal recycling is a major livelihood activity in cities in the south. Beyond the poverty perspective, the nature of informal recycling makes it an appropriate tool to use to capture the complexity and dynamism of social relations and power within networks. It consists of a variety of interrelated activities performed by different groups. The deep interconnections and interdependences necessitate the formation of networks. Drawing on empirical data, the paper reports that the networks found in Kaduna span the household, community, city, and intercity levels. The relations are informal but, in many cases, well structured. Crucially, the paper reveals that the networks are characterized by dependent relations. Those with greater access to financial and social capitals drive the system and play a greater role in shaping network rules and relations. However, no single actor or group has a monopoly on power. The interdependences mean that the different groups rely on each other, and power becomes much more diffused. Furthermore, network relations are embedded in specific sociocultural contexts. Age and gender are identified as crucial determinants in the dynamics of power and bargaining. The paper argues for a recognition of the diversity and inherent complexity of social networks and the adoption of an analytical approach that is more sensitive to the positionality and power of actors than that found in traditional ??social capitalist?? analysis.     

How to learn from the resilience of Human–Machine Systems?

This paper proposes a functional architecture to learn from resilience. First, it defines the concept of resilience applied to Human–Machine System (HMS) in terms of safety management for perturbations and proposes some indicators to assess this resilience. Local and global indicators for evaluating human–machine resilience are used for several criteria. A multi-criteria resilience approach is then developed in order to monitor the evolution of local and global resilience. The resilience indicators are the possible inputs of a learning system that is capable of producing several outputs, such as predictions of the possible evolutions of the system's resilience and possible alternatives for human operators to control resilience. Our system has a feedback–feedforward architecture and is capable of learning from the resilience indicators. A practical example is explained in detail to illustrate the feasibility of such prediction.     

Topology optimization of periodic layouts of dielectric materials

A topology optimization method is used to design two dimensional periodic structures with desirable transmission properties by distributing two materials of different permittivity over a rectangular representative cell. A plane wave expansion of the electric field at the input and output boundaries is used in the analysis. This allows non-homogeneous material distributions near the boundaries. Numerical examples are used to verify the robustness of the method and to investigate the importance of retaining higher modes in the expansions. It is found that the optimization problem typically admits possibly many local optima and the relevance of higher modes depends on the nature of the solution found. In some instances, higher modes play an important role and using only the dominant mode in the analysis is shown to result in errors in the evaluation of the performance of the design.     

Verapamil, a phenylalkylamine Ca2+ channel blocker, inhibits ATP-sensitive K+ channels in insulin-secreting cells from rats

Radioisotopic and electrophysiological techniques were used to assess the effects of verapamil, a phenylalkylamine Ca2+ channel blocker, on K+ permeability of insulin-secreting cells. Verapamil provoked a concentration-dependent inhibition of 86Rb (42K substitute) outflow from prelabelled and perifused rat pancreatic islets. This property appears to be inherent to the phenylalkylamine Ca2+ channel blockers since gallopamil, a methoxyderivative of verapamil, but not nifedipine, a 1,4-dihydropyridine Ca2+ channel blocker, inhibited 86Rb outflow. The experimental data further revealed that verapamil interacted with a Ca2+-independent, glucose- and glibenclamide-sensitive modality of 86Rb extrusion. Moreover, verapamil prevented the increase in 86Rb outflow brought about by BPDZ 44; a potent activator of the ATP-sensitive K+ channel. Single-channel current recordings by the patch clamp technique confirmed that verapamil elicited a dose-dependent inhibition of the ATP-dependent K+ channel. Lastly, under experimental conditions in which verapamil clearly inhibited the ATP-sensitive K+ channels, the drug did not affect 45Ca outflow, the cytosolic free Ca2+ concentration or insulin release. It is concluded that the Ca2+ entry blocker verapamil inhibits ATP-sensitive K+ channels in pancreatic beta cells. This effect was not associated with stimulation of insulin release.     

Strength improvement in silty clay by microbial-induced calcite precipitation

Bulletin of Engineering Geology and the Environment - The application of MICP (microbial-induced calcite precipitation) to clays has been restricted due to their low permeability and small pore...     

Compact and accurate concept of laser wavemeters based on ellipsometry

Common laser wavemeters are based on a scanning Michelson interferometer. Displacements of the moving mirror as long as tens of centimeters are needed to reach a relative accuracy of 1 × 10(-6) (1σ) on the unknown laser wavelengths. Such a long displacement range makes the system very sensitive to mechanical vibrations and to misalignments of the laser beams. The purpose of this paper is to demonstrate a new concept of laser wavemeter based on the measurements of the ellipsometric parameters ψ and Δ of the laser beams. Experimental results show that a 10(-6) (1σ) accuracy level could be reach with a displacement range of only 4 μm. Implementations of the device are described. Comparisons between our polarimetric wavemeter and a calibrated wavemeter are presented for two lasers, an extended cavity laser diode at 656 nm and a 532 nm green line Nd:YAG laser.