Agricultural expansion is the main driver of forest and biodiversity loss. As a countermeasure, Voluntary Sustainability Standards (VSS) try to enhance sustainability in agricultural production but ...evidence if VSS reduce deforestation at country level is lacking. We used annual certification data of seven VSS (Fairtrade, Rainforest Alliance, UTZ, 4 C, Round Table on Sustainable Palm Oil (RSPO), GlobalGAP, Organic) certifying five food commodities (cocoa, coffee, tea, palm oil, banana) and data on tree cover loss in humid tropical primary forest to study the impact of VSS on primary forest loss in 67 tropical countries. Using two generalised additive models (GAMs), one with VSS separately and one with VSS coverage aggregated, we found only Fairtrade to coincide with lower tree cover loss in primary forests at country level while we observed higher tree cover loss with higher certification for UTZ, RSPO and Organic. Using spatially explicit certification data in Google Earth Engine, we did not observe an effect of VSS on tree cover loss, thereby raising doubts on the potential of VSS to govern deforestation free supply chains. Reasons for this might be, among others, certification displacing unsustainable agriculture to other regions (leakage), weak or insufficiently enforced VSS criteria, and outcomes being context specific depending on, for example, institutional factors.
•Impact of Voluntary Sustainability Standards (VSS) on primary forests at country level.•Study covers seven VSS, five food commodities and 67 tropical countries.•VSS coverage in general has no effect on tree cover loss in primary forests.•Several VSS coincide with higher forest loss; lower forest loss observed for Fairtrade.•Leakage, weak VSS criteria and low enforcement might explain limited effects.
Under partial shading conditions (PSCs), the I‐V curve of PV systems consist of multiple local maximum power points (MPP's) and one global MPP which is required to extract the peak power of solar PV. ...In this article, an improved variable step size‐radial basis function algorithm (VSS‐RBFA) based MPPT controller is implemented to track the MPP with high speed. The advantages of proposed MPPT controller are high convergence speed, reduced oscillations across MPP, and takes less time to track MPP. Also, a universal high step‐up boost converter (HSBC) is proposed in this work to step up the PV voltage. The attractive features of HSBC are continuous input current, high voltage gain, less voltage stress on switches, and wide input and output operation. The proposed converter continuous conduction mode (CCM) and discontinuous conduction mode (DCM) of operations are compared successfully at the steady‐state operating condition. The simulation results of the proposed PV fed HSBC system is validated under uniform and PSC's of solar PV. In addition, the proposed converter results are verified experimentally by using a programmable DC source.
An improved VSS‐RBFA based MPPT controller.
This paper demonstrates an integration of wind-solar fed microgrid enabled with improved power quality (PQ) performance and seamless operational mode transition capability. Wind turbine is a variable ...speed type realized by a doubly fed induction generator (DFIG). Solar photovoltaic (SPV) array is integrated to DC-link of DFIG's back-to-back converters via a maximum power extraction DC/DC converter. DC-link is also supported by battery-energy-storage to maintain voltage level and continuity of power during low generation and grid outage. An adaptive variable step size gradient descent total least squares (VSS-GDTLS) based power injection control is implemented for grid-side-converter during grid-tied operation to improve PQ performance. VSS is sum of square of active unit-template and instantaneous fundamental weight. This approach improves convergence compared to conventional fixed step approach. Seamless transition is achieved by using a pre-filter enabled frequency and phase angle estimation tool. A complex band-pass filter (CBF) enabled second-order generalized-integrator type frequency locked loop (SOGI-FLL) technique is used for frequency and phase angle estimations. Microgrid laced with control techniques is tested on a laboratory setup and various dynamic conditions are emulated to validate satisfactory performance of microgrid.
•A novel auxiliary active noise control system based on signal reconstruction is proposed.•A signal reconstruction model for multi-networks based on decomposition optimization is design.•The Bat ...Algorithm is used to optimize the weights of online AANC controller.•Results demonstrate that proposed system can balance modeling efficiency and accuracy.
Faced with the problem of existing active control systems failing to obtain a reference signal and reducing or deteriorating the effectiveness of interior noise control, an Auxiliary Active Noise Control system (AANC) based on signal reconstruction technology is proposed, which main contains offline update of multi-network weights and online AANC controller. Firstly, considering the non-linear and non-stationary of the interior noise, and aiming to balance the modeling efficiency and accuracy of algorithms, based on the data fusion and compression sensing technology, a signal reconstruction model for multi-networks based on decomposition optimization is design; Then, in the online AANC controller, the offline calculation of the weight of signal reconstruction model is used to obtain the reconstruction reference signal of the control position, and based on the reconstructed signal, the controller achieves adaptive suppression of passenger ear-sides noise through the VSS-LMS algorithm. Finally, the effectiveness of the proposed AANC is verified using real vehicle data. The results show that the proposed system achieves the balance the modeling efficiency and accuracy, and is superior to existing ANC system in terms of robustness, guaranteeing the stable operation of the interior noise control.
A new driving circuit using PWM method is developed for use in mini‐LED backlight. Analytical results demonstrate that current error rates caused by ±0.3 V VTH variations of TFTs and 0.5 V VSS I‐R ...rise are below 9.96%. Moreover, the power consumption is reduced by 16.09% compared with 6T1C circuit. Author Keywords
•Nonpolar direction Ga2O3 Nanowires catalyzed by Cu3As: insights into As layer epitaxy.•Control composition and interfacial abruptness in vapor-solid-solid nanowires.•Influences of growth temperature ...on the structural and growth mechanism of the Ga2O3 NWs were investigated via unique ternary alloy phase diagram.
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To accurately control semiconductor nanowires’ (NW) physical characteristics defining electronic, optical and sensor applications, it is necessary to understand their potential growth mechanism. In this study, the Ga2O3 NW growth orientation is found to be dependent on their Cu3As catalyst structure via vapor-solid-solid (VSS) mechanism. The Ga2O3 NWs are synthesized by vapor transport method at 700 °C below the Cu3As alloy eutectic temperature, which forms a solid structure on top of the NWs. The NWs have relatively uniform diameter of 40–60 nm and prefer to grow along direction. Energy-dispersive X-ray spectroscopy (EDS) and high-resolution transmission electron microscope (HRTEM) data provide strong evidence that the harvested Ga2O3 NWs are epitaxially grown from Cu3As-based (cubic and hexagonal) catalyst seeds. And Ga2O3{110} |Cubic Cu3As {210}, Ga2O3{110} |Cubic Cu3As {110} and Ga2O3 {110} | hexagonal Cu3As {110} have relatively low mismatch compared to other interface lattice planes, providing a key insight into the growth process according to the VSS mechanism. The thermodynamics driven composition changes in the growth process are elaborated in detail.
•This paper proposes a cluster sparsity-induced affine projection algorithm for clustersparse system identification.•A variable step-size is developed to address the problem of tradeoff between ...convergence rate and steady-state misalignment.•Simulation results are provided to verify the effectiveness of the proposed algorithm and the variable step-size strategy.
The affine projection algorithm (APA) is widely used in various applications of adaptive filtering due to its decorrelating property. However, when the unknown system to be estimated is a cluster-sparse one, the APA cannot make full use of its cluster-sparsity characteristic to accelerate convergence rate. In this paper we propose a cluster-sparsity-induced APA (CSI-APA) to promote the performance of the adaptive filter for estimating cluster-sparse systems. When the number of elements in each cluster of the adaptive filter weights is set to one, the CSI-APA reduces to a sparsity-induced APA (SI-APA). Like other fixed step-size adaptive filtering algorithms, the proposed CSI-APA needs to make a trade-off between convergence rate and steady-state misalignment. To address this problem, the step-size of the CSI-APA is optimized by minimizing the mean-square deviation (MSD) at each iteration and a variable step-size CSI-APA (VSS-CSI-APA) is developed. Simulation results are provided to show the superior performance of the proposed algorithms.
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