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In the past five years, perovskite solar cells (PSCs) based on organometal halide perovskite have exhibited extraordinary photovoltaic (PV) performance. However, the PV measurements of PSCs have been widely recognized to depend on voltage scanning condition (hysteretic current density-voltage [J-V] behavior), as well as on voltage treatment history. In this study, we find that varied PSC responses are attributable to two causes. First, capacitive effect associated with electrode polarization provides a slow transient non-steady-state photocurrent that modifies the J-V response. Second, modification of interfacial barriers induced by ion migration can modulate charge-collection efficiency so that it causes a pseudo-steady-state photocurrent, which changes according to previous voltage conditioning. Both phenomena are strongly influenced by ions accumulating at outer interfaces, but their electrical and PV effects are different. The time scale for decay of capacitive current is on the order of seconds, whereas the slow redistribution of mobile ions requires several minutes.

Earth’s biodiversity and human societies face pollution, overconsumption of natural resources, urbanization, demographic shifts, social and economic inequalities, and habitat loss, many of which are exacerbated by climate change. Here, we review links among climate, biodiversity, and society and develop a roadmap toward sustainability. These include limiting warming to 1.5°C and effectively conserving and restoring functional ecosystems on 30 to 50% of land, freshwater, and ocean “scapes.” We envision a mosaic of interconnected protected and shared spaces, including intensively used spaces, to strengthen self-sustaining biodiversity, the capacity of people and nature to adapt to and mitigate climate change, and nature’s contributions to people. Fostering interlinked human, ecosystem, and planetary health for a livable future urgently requires bold implementation of transformative policy interventions through interconnected institutions, governance, and social systems from local to global levels.

This paper presents a coordinated voltage control scheme for improving the network voltage profile and for minimizing the steady-state loading of the STATCOM to effectively support the system during contingencies. The paper addresses implementation issues associated with primary voltage control and optimal tracking secondary voltage control for wind parks based on self-excited induction generators which comprise STATCOM and under-load tap changer (ULTC) substation transformers. The voltage controllers for the STATCOM and ULTC transformer are coordinated and ensure the voltage support. In steady-state operation, the voltage is controlled by only stepping the tap changer when the voltage is outside the deadband region of the ULTC to minimize the number of taps changes. Thus, the STATCOM will be unloaded and ready to react with higher reactive power margin during contingencies. In the paper, the effects of the short circuit ratio of the interconnection and the inherent communication delay between the wind park and the remote bus on the performance of the controllers and the maximum critical clearing time of fault are considered. Simulation results are presented to demonstrate the performance of the controllers in steady-state and in response to system contingency situations.

Single wall carbon nanohorn (SWCNH) were neutron-bombarded to a dose of 3.28 x 10(16) n/cm(2). The Wigner or stored energy was determined by a differential scanning calorimeter and was found 5.49 J/g, 50 times higher than the Wigner energy measured on graphite flakes treated at the same neutron dose. The activation energy for the thermal annealing of the accumulated radiation damage in SWCNH was determined in the range 6.3-6.6 eV against a typical activation energy for the annealing of the radiation-damaged graphite which is in the range of 1.4-1.5 eV. Furthermore the stored energy in neutron-damaged SWCNH is released at 400-430 degrees C while the main peak in the neutron-damaged graphite occurs at 200-220 degrees C. The radiation damaged SWCNH were examined with FT-IR spectroscopy showing the formation of acetylenic and aliphatic moieties suggesting the aromatic C=C breakdown caused by the neutron bombardment.

An overview of the state of the art dye solar module technology and innovations required for further development is presented.

The synthesis and liquid crystalline properties of two novel series of triphenylenes with 4 or 5 pentafuoropentyloxy tails and 1 or 2 alkoxy tails of varying length are reported. All compounds form wide-range hexagonal columnar phases. The isotropisation temperatures and the corresponding enthalpy changes for the compounds with 4 or 5 fluorinated tails are higher than for the compounds with 6 alkoxy tails, and also higher than for compounds with 6 fluorinated tails. These results indicate that the best ordering is obtained for compounds with a mix of fluorinated and non-fluorinated tails. With increasing length of the alkyl tails in HAT compounds with 4 or 5 fluoroalkoxy tails, the isotropisation temperatures decrease and the d-spacings as observed by XRD increase. All fluorocontaining compounds have a strong tendency for spontaneous homeotropic alignment on surfaces, both hydrophilic and hydrophobic.

Abstract Within the high heat extraction cooling technologies, stepwise varying width microchannel cooling schemes have demonstrated their capacity to provide high temperature uniformities with low pressure drops. In this study, a method to tailor the design of this kind of cooling device to the needs on an application is developed. The resulting geometry is experimentally tested. A global thermal resistance coefficient of 2.35·10−5 m2 K/W has been found, improving near three-fold the performance in a millimetrical scale for the same flow rate. The temperature profile of the wall temperature is quite uniform, validating the design of the cooling device. A numerical model is developed and validated through comparison with experimental results. It shows the smoothing effect of the Thermal Interface Material (TIM) on the temperature profile and the improvement of both the thermal resistance coefficient and the temperature uniformity with the increase of the flow velocity.

The transformation of electricity network users from passive to active agents, as a result of decreasing costs of distributed energy resources, requires several adaptions, one of which is revising the distribution network charges. Often current network charge designs do not ensure network cost recovery and lack to incentivize efficient network investments and usage. New network charge methodologies are required to guide and incentivize customers in an efficient way while maximizing system economic efficiency. This paper proposes an efficient methodology that ensures network cost recovery while promoting efficient usage of the network as well as efficient network investments. The proposed network charge design consisting of two components: a peak coincidence network charge (PCNC) and fixed charge. The PCNC is a forward-looking charge as it considers the cost of future network reinforcements required and assigned to consumers during peak hours of the network utilization. Fixed charges allocate the residual of the network costs following Ramsey-pricing principles. This paper compares the outcome from economic optimum customers response to four different network charges: (i) volumetric charges (ii) fixed charges (iii) peak demand charge (iv) fixed charges + PCNC. Two case studies for two different load profiles are simulated using linear programming on Matlab to minimize their total costs within each charges design, considering the possibility of buying electricity from the grid and investing on onsite generation or curtail load. Finally, the paper highlights through the case studies how customer s response is highly influenced by different network charge designs, and compare the consequences of these responses in terms of network cost recovery and total system costs. The paper concludes with practical issues that need to be considered for the implementation of the proposed network charges design. info:eu-repo/semantics/draft