Preparation of SnS quantum dots for solar cells application by an in-situ solution chemical reaction process

SnS quantum dots (QDs) with size of 8 nm were synthesized by an in-situ room temperature solution chemical reaction process. Stannous chloride, as Sn precursor, was coated on the TiO₂ photo-anodes to form a solid precursor film. Ammonium sulfide was dissolved into ethanol to form anionic reaction solution. SnS quantum dots were generated by immersing the Sn-coated TiO₂ photo-anodes into the anionic solution. The structure, morphology and optical absorption properties of the SnS/TiO₂ photoanodes were investigated by means of XRD, SEM, TEM and UV–vis measurements. The photovoltaic properties of the SnS QDs sensitized TiO₂ solar cells were optimized by changing the number of deposition cycles of the SnS QDs. It turns out that the SnS/TiO₂ solar cell with 20 deposition cycles exhibited the best photovoltaic performance with an open-circuit voltage V_oc of 510 mV, a short-circuit current density Jsc of 2.41 mA, a fill factor FF of 0.49 and a power conversion efficiency η of 0.61% under AM 1.5 illumination. This result is interpreted in terms of minimization of the charge transfer resistance. The performance will drop for further deposition because the charge transfer resistance will increase due to QDs agglomeration.     

Parallel programming model for the Epiphany many-core coprocessor using threaded MPI

The Adapteva Epiphany many-core architecture comprises a 2D tiled mesh Network-on-Chip (NoC) of low-power RISC cores with minimal uncore functionality. It offers high computational energy efficiency for both integer and floating point calculations as well as parallel scalability. Yet despite the interesting architectural features, a compelling programming model has not been presented to date. This paper demonstrates an efficient parallel programming model for the Epiphany architecture based on the Message Passing Interface (MPI) standard. Using MPI exploits the similarities between the Epiphany architecture and a conventional parallel distributed cluster of serial cores. Our approach enables MPI codes to execute on the RISC array processor with little modification and achieve high performance. We report benchmark results for the threaded MPI implementation of four algorithms (dense matrix–matrix multiplication, N-body particle interaction, five-point 2D stencil update, and 2D FFT) and highlight the importance of fast inter-core communication for the architecture.     

Computational architectures for sonar array processing in autonomous rovers

This paper presents design of novel embedded computational architectures for real time, in-motion mapping based on ultrasound sensors for use in resource constrained autonomous rovers. Autonomous rovers are a class of real time systems that are constrained for size, weight, on-board computational resources and power. Embedded computing architectures designed for implementing the mapping and navigational algorithms must optimize the use of these resources. In the process of map generation, raw sensor data obtained from an array of ultrasound sensors is filtered for sensor noise using probabilistic sensor model, and probabilistic data fusion methods are employed for spatial and temporal correlation of data for improving the map. In this paper, we present a System-on-Chip design based design space exploration of embedded computational architectures for implementation on field programmable gate arrays. We seek to exploit system level, region level and sensor level parallelism in the mapping algorithm for enhancing the throughput. Design space exploration is carried out by employing existing soft core processors, designing custom co-processors and data path modules and integrating them using parallel and pipelined data flow approaches. Results of mapping a test area on all the architectures are compared to characterize the performance and suitability of the proposed architectures.     

The quantitative risk assessment of MINI,MIDI and MAXI Horizontal Directional Drilling Projects applying Fuzzy Fault Tree Analysis

The risk level of the HDD project is a key parameter when assessing the project feasibility and making the project pricing. It is also a starting point for introducing the risk management strategy which aims to reduce the number of installation failures and their negative consequences. The objective of this work was to develop a new mathematical model for the qualitative and quantitative risk assessment of HDD projects of various sizes (MINI, MIDI and MAXI), which allows to consider the installation specificity (the optional possibility of applying various tools and machines). The risk assessment was carried out applying the Fuzzy Fault Tree Analysis. The unwanted events were divided into 4 classes: problems with the ground, machines, environment and management. Applying the fuzzy set theory in the proposed model made it possible to decrease the uncertainty, the lack of precision and the difficulties with gaining the crisp values of the basic events probability, which occur in the conventional Fault Tree Analysis. The practical application of the proposed model for the MINI, MIDI and MAXI HDD projects was shown on four examples.     

Perovskite oxides successfully catalyze the electrolytic hydrogen production from oilfield wastewater

Although Pt/C has long been regarded as the most effective HER catalyst, the use of complicated water systems is challenged by high costs and contaminant interference. Therefore, it was shown in this paper that a low-cost perovskite oxide, SrCo_0.7Fe_0.3O_3-δ(SCF-X, where X denotes annealing temperature), could be used in oil-field wastewater to promote electrochemical reactions for hydrogen production and that its catalytic activity can be impacted by calcination temperature. And, the outstanding catalytic activity of SCF-800 and 850 is primarily caused by crystal structure distortions and the presence of Co³⁺/Co⁴⁺ coupling pairs as a result of electron transfer between Co and Fe, which increases the concentration of reactive oxygen species. Furthermore, there is now more interest in SCF-850 due to its exceptional stability. In complicated systems, the current work provides a feasible route for perovskite catalysts to produce hydrogen.     

Development of a Ru catalyst supported on HY zeolite for the oxidative decomposition of NH3 triggered at room temperature

On-site hydrogen production from the oxidative decomposition of NH₃ with a catalyst is highly required in the countryside where external heat is hardly supplied. In this study, Ru-based zeolite catalysts were prepared by impregnation and subsequent washing using RuCl₃·3H₂O and HY zeolite or H-MOR zeolite for the oxidative decomposition of NH₃. The H-MOR-supported Ru catalyst could not be self-heated by feeding 80% NH₃/20% O₂ to the catalyst bed at room temperature. By contrast, the HY-supported Ru catalyst underwent self-heating to approximately 773 K upon feeding the reactants owing to the heat released by NH₃ adsorption and oxidation, leading to excellent performance for the oxidative decomposition of NH₃ during five cycles of start-up tests. Characterization results indicated that the Cl-free Ru/HY catalyst exhibited self-heating due to the presence of small well-dispersed Ru metal particles and a large amount of surface acidic sites.     

Floor Planning of 3D IC Design Using Hybrid Multi-verse Optimizer

Wireless Personal Communications - Several research works have been undergone in the 3D IC floor planning concepts due to its higher demand and technological improvement. Floor planning is a...     

Hydrogen production via supercritical water gasification of glycerol enhanced by simple structured catalysts

The supercritical water gasification (ScWG) technology is a promising alternative for H₂-rich gas production from renewable sources, such as residual glycerol from biodiesel manufacture. Combined with heterogeneous catalysts, the ScWG process can achieve improved selectivity towards the desired products and high conversion efficiency in short reaction times. In this work, the efficiency of a synthesized Ni-based catalyst supported in cordierite (CRD) honeycomb structure on the ScWG of glycerol was evaluated and compared with two commercial automotive catalysts. Initially, to determine the best experimental conditions, the ScWG experiments were conducted in the absence of catalysts at constant conditions pressure (25 Mpa) and volumetric flow rate (10 mL min⁻¹). The temperature range of 400–700 °C and glycerol feed composition between 10 and 34 wt% were evaluated. The catalysts evaluated were characterized by SEM-EDS, XRD, N₂ adsorption/desorption, XRF, WDS and TGA. The liquid and gaseous products were analyzed by TOC and gas chromatography, respectively. Results indicated that Ni/CRD catalyst showed the highest H₂ yield (5.38 mol H₂ per mol of glycerol fed) and long-term stability. Additionally, a comparison between the experimental results on the ScWG of glycerol and simulated thermodynamic equilibrium data was also reported. Thus, results demonstrated the great potential of the prepared catalyst to improve H₂-rich gas production from glycerol gasification.