Standard MC Research Articles

Application of a fungicide system on tomato in open ground conditions in Primorsky Krai

Relevance. Tomato is one of the most beloved and popular vegetables among Primorye residents. But in the monsoon climate, the Far Eastern Primorye has the most intense infectious background in Russia. The yield losses of tomato fruits from alternariosis annually amount to 30% or more. Losses from late blight on the background of epiphytotics in years with wet and cold summers, as observed in 2019, depending on the stability of the variety, can reach from 17 to 100%. Despite the fact that the development and use of biological means of control has recently been a priority, it is still too early to abandon chemical protection measures. High efficiency and versatility of the correctly selected scheme of application of fungicides, short processing time – all this gives a quick and reliable result in protecting tomato crops and reducing the harmfulness of the complex of diseases.Methodology. The research was carried out in 2019-2021 at the Primorsky Vegetable Experimental Station (PVES) – a branch of the Federal Scientific Vegetable Center in the monsoon climate of the coastal zone of Primorsky Krai. We studied the effect of chemical preparations Signum, Orvego and their tank mixture with igum + Orvego on the development of diseases, yield indicators and the structure of the tomato crop varieties Odyssey, and Fitilek. Agrotechnics of cultivation are generally accepted in Primorsky Krai for tomato culture.Results. Testing of chemical fungicides in the conditions of Primorsky Krai showed that the development of alternariasis, starting with the appearance of the first signs of damage in the first half of the growing season, effectively restrains the fungicide Signum, contributing to the preservation of the working leaf surface. It is advisable to use the tank mixture With igum + Orvego starting from the first or second decade of August, when a complex of phytopathogens develops on the leaf surface. The introduction of these two fungicides into the tank mixture leads to an increase in the biological and economic effectiveness of protective measures in the fight against alternariasis and late blight of tomatoes, compared with the standard fungicide Acrobat MC. Joint Signum Processing+Orvego, by reducing the intensity of disease development and the share of the non-commodity part of the crop, has a beneficial effect on the mass of commercial fruit and contributes to a more complete realization of the productive potential of Odyssey and Fitilek varieties.

The Fast Simulation Chain in The ATLAS Experiment

The physics program in the ATLAS experiment at the Large Hadron Collider has achieved high-quality and competitive physics results since its inception, based on large and accurate datasets of simulated Monte Carlo events. Generating these billions of Monte Carlo using the Geant4 framework requires significant computing resources. As such the ATLAS CPU is limited and taking into account the expected increase of the average number of proton-proton collisions during the high luminosity LHC phase, a very fast detector simulation is critical when high accuracy is not needed. In order to solve this problem and to meet the challenge of simulated sample statistics requirements, fast alternatives approaches have been developed by ATLAS to replace the algorithms currently used in the standard MC production chain. This document provides a description of the Fast simulation chain tools and also presents the latest physics performance studies: Fast tracking detector simulation, Fast digitization and Pile-up simulation.

An iDTMC-based Monte Carlo depletion of a 3D SMR with intra-pin flux renormalization

Improved deterministic truncation of the Monte Carlo (iDTMC) solution method has been applied to neutronic depletion analyses of a nuclear reactor in this work. The theoretical background on the iDTMC method and material depletion calculation is briefly discussed, and the concept of an intra-pin renormalization scheme is presented to determine the detailed power and flux profiles with the pin-wise homogenized iDTMC solutions. The iDTMC method is applied and evaluated in a 100 MWth 3-dimensional small modular reactor (SMR) problem. Burnup-dependent multiplication factors, pin power distributions, and material densities are estimated by the iDTMC method and compared with the reference and standard Monte Carlo solutions. Numerical performance is investigated in terms of real standard deviation, root-mean-square and relative errors, computing time, and figure-of-merit. The numerical results demonstrate that the iDTMC method is superior to the standard MC method in estimating the burnup-dependent reactor eigenvalue and 3D pin-wise power distribution.

Seismic reliability evaluation of spatially correlated pipeline networks by quasi-Monte Carlo simulation

The reliability assessment of pipeline networks under nature disasters helps to improve the disaster prevention capability and overall resilience of pipeline networks. For the earthquake hazard, the seismic damage of pipelines in the network is usually correlated due to the spatial correlation of critical parameters, including characteristics of pipeline, soil properties and ground motions. This paper proposes a framework to evaluate the seismic reliability of pipeline network under spatially correlated parameters based on the quasi-Monte Carlo (QMC) simulation. The influence of spatial correlated random variables on the seismic reliability of pipeline network is investigated with explicit consideration of the correlated random variables including the peak ground velocity, the wall thickness and the yield stress of pipe segment. The framework has been implemented in seismic reliability evaluation of two pipeline networks. The result shows that the QMC method has better simulation accuracy than the standard MC method under same sampling numbers. The spatial correlations have different influences on the seismic connectivity reliability of pipeline networks with different topological redundancy and parallelism of connective paths from sources to user nodes. For the pipeline network with greater redundancy and parallelism, the model without considering the spatial correlations overestimates the network connectivity reliability.

Application of unified constraint-dependent Master Curve in fracture assessment of cracked pressure vessels

In this work, the application of the unified constraint-dependent Master Curve (UCMC) in fracture assessment based on the newly developed T0-Ad* correlation equation (T0 is the MC reference temperature, and Ad* is a new unified constraint parameter) has been investigated for cracked pressure vessels. A large number of three-dimensional (3D) finite element analyses have been conducted to calculate the parameter Ad* and the crack driving force parameter KJ for various axial semi-elliptical surface cracks. Based on the KJ-Ad* two-parameter, the locations of crack initiation along the crack fronts were predicted. The fracture prediction results of the UCMC method have been comparatively analyzed with those of the conventional standard MC (SMC) method. It has been shown that for most shallow cracks with lower constraint, the application of the UCMC method can reduce the conservatism of the SMC method. For some deeper and longer cracks with higher constraint, the UCMC method may eliminate slight non-conservative fracture assessment of the SMC method. The UCMC method can incorporate both in-plane and out-of-plane constraints in cracked structures, and it may be possibly applicable to wide ranges of structural geometries, crack sizes, materials, temperatures and loading levels.

Rejection-Free Monte Carlo Simulation of QUBO and Lechner–Hauke–Zoller Optimization Problems

Many studies have attempted to develop simple and efficient methods for solving global optimization problems. Simulated annealing (SA) has been recognized as a powerful tool for performing this task. In this study, we implemented a rejection-free Monte Carlo (RFMC) algorithm, which is a kernel of rejection-free SA (RFSA). We showed its validity and advantage in obtaining globally optimal solution for quadratic unconstrained binary optimization (QUBO) and spin-glass problem embedded in the Lechner–Hauke–Zoller (LHZ) architecture. Landscapes of success probabilities of finding the globally optimal solution as well as feasible solutions were evaluated as a function of a set of hyper-parameters used to characterize the weights of cost and penalty functions. We demonstrated that the efficiency of RFMC was greatly enhanced compared to that of standard MC. Furthermore, we found that the landscapes for QUBO and those for LHZ problem show considerably different views. When we focus on a specific class of problems, the smaller the problem size, the more scattered is the success probability. We also show that the success probabilities can be further improved by avoiding inefficiencies due to cycling of state transitions using short-term memory mechanisms. We suggest a reasonable strategy to tune hyper-parameters and find the correct global solution using RFSA.

A196 MORE MICROSCOPIC THAN WAS THOUGHT: A RARE CASE OF ISOLATED LYMPHOCYTIC ILEITIS WITHOUT MICROSCOPIC COLITIS

Abstract Background Microscopic colitis (MC) is a chronic inflammatory disease of the colon characterized by lymphocytic infiltration with (collagenous colitis) or without (lymphocytic colitis) the expansion of collagen fibres, and the normal macroscopic appearance of the mucosa on ileocolonoscopy. Recent studies have shown that the ileum may be involved in MC, occurring concurrently with colonic disease, however there is sparse literature on isolated lymphocytic ileitis without colitis. Aims We describe the case of isolated small bowel lymphocytosis without evidence of lymphocytic colitis to highlight the utility of random biopsies of the terminal ileum in cases where microscopic colitis is a diagnostic consideration. Methods A 70-year-old female known for cutaneous mastocytosis presented with six weeks of abdominal pain, non-bloody diarrhea, intolerance to oral intake and significant weight loss. Computed-tomography showed evidence of possible mesenteric panniculitis. Colonoscopy revealed a normal colon and normal-appearing mucosa of the terminal ileum. Random mucosal biopsies were taken to assess for microscopic colitis, with terminal ileal biopsies revealing significant lymphocytic infiltration consistent with lymphocytic ileitis. Biopsies throughout the colon revealed normal colonic mucosa without evidence of concurrent microscopic colitis. Gastroscopy was macroscopically unremarkable and random biopsies in the stomach and duodenum were negative for Helicobacter pylori and lymphocytosis. Immunostaining of the gastric, duodenal, terminal ileal and colonic biopsy specimens were negative for CD25, CD117 and tryptase, indicating the absence of gastrointestinal mastocytosis. Results The patient was diagnosed with lymphocytic ileitis and given the known response of MC to budesonide, she was treated with eight weeks of budesonide with clinical improvement leading to remission of her symptoms. Conclusions This case illustrates a rare incidence of isolated ileal microscopic ileitis without colitis that responded well to standard MC treatment, thereby underscoring the utility of random biopsies in the terminal ileum and throughout the colon when microscopic colitis is on the differential diagnosis. Funding Agencies None

Exploiting non-taxonomic relations for measuring semantic similarity and relatedness in WordNet

Various applications in computational linguistics and artificial intelligence employ semantic similarity to solve challenging tasks, such as word sense disambiguation, text classification, information retrieval, machine translation, and document clustering. To our knowledge, research to date rely solely on the taxonomic relation “ISA” to evaluate semantic similarity and relatedness between terms. This paper explores the benefits of using all types of non-taxonomic relations in large linked data, such as WordNet knowledge graph, to enhance existing semantic similarity and relatedness measures. We propose a holistic poly-relational approach based on a new relation-based information content and non-taxonomic-based weighted paths to devise a comprehensive semantic similarity and relatedness measure. To demonstrate the benefits of exploiting non-taxonomic relations in a knowledge graph, we used three strategies to deploy non-taxonomic relations at different granularity levels. We conduct experiments on four well-known gold standard datasets. The results of our proposed method demonstrate an improvement over the benchmark semantic similarity methods, including the state-of-the-art knowledge graph embedding techniques, that ranged from 3.8%–23.8%, 1.3%–18.3%, 31.8%–117.2%, and 19.1%–111.1%, on all gold standard datasets MC, RG, WordSim, and Mturk, respectively. These results demonstrate the robustness and scalability of the proposed semantic similarity and relatedness measure, significantly improving existing similarity measures.

Validation of histogram‐based virtual source models for different IGRT kV‐imaging systems

Image-guided radiotherapy (IGRT) improves tumor control but its intensive use may entrain late side effects caused by the additional imaging doses. There is a need to better quantify the additional imaging doses, so they can be integrated in the therapeutic workflow. Currently, no dedicated software enables to compute patient-specific imaging doses on a wide range of systems and protocols. As a first step toward this objective, we propose a common methodology to model four different kV-imaging systems used in radiotherapy (Varian's OBI, Elekta's XVI, Brainlab's ExacTrac, and Accuray's Cyberknife) using a new type of virtual source model based on Monte Carlo calculations. We first describe our method to build a simplified description of the photon output, or virtual source models (VSMs), of each imaging system. Instead of being constructed using measurement data, as it is most commonly the case, our VSM is used as the summary of the phase-space files (PSFs) resulting from a first Monte Carlo simulation of the considered x-ray tube. Second, the VSM is used as a photon generator for a second MC simulation in which we compute the dose. Then, the proposed VSM is thoroughly validated against standard MC simulation using PSFs on the XVI system. Last, each modeled system is compared to profiles and depth-dose-curve measurements performed in homogeneous phantom. Comparisons between PSF-based and VSM-based calculations highlight that VSMs could provide equivalent dose results (within 1% of difference) than PSFs inside the imaging field-of-view (FOV). In contrast, VSMs tend to underestimate (for up to 20%) calculated doses outside of the imaging FOV due to the assumptions underlying the VSM construction. In addition, we showed that the use of VSMs allows reducing calculation time by at least a factor of 2.8. Indeed, for identical simulation times, statistical uncertainties on dose distributions computed using VSMs were much lower than those obtained from PSF-based calculations. For each of the four imaging systems, VSMs were successfully validated against measurements in homogeneous phantoms, and are therefore ready to be used for future preclinical studies in heterogeneous or anthropomorphic phantoms. The cross system modeling methodology developed here should enable, later on, to estimate precisely and accurately patient-specific 3D dose maps delivered during a large range of kV-imaging procedures.

Multilevel Monte Carlo applied for uncertainty quantification in stochastic multiscale systems

AbstractThe aim of this study is to evaluate the performance of multilevel Monte Carlo (MLMC) sampling technique for uncertainty quantification in stochastic multiscale systems. Two systems, a chemical vapor deposition chamber and a catalytic flow reactor, subject to multiple parameter uncertainty, were considered. The distributions of the systems' observables were estimated using standard MC sampling and polynomial chaos expansions (PCE), where the coefficients were calculated by nonintrusive spectral projection. The MLMC technique was used to efficiently sample the two systems and accurately estimate the data necessary for constructing the PCE expressions. The results show that the usage of MLMC improved the precision of identification of PCE versus the traditional heuristic approach and lowered the computational cost of uncertainty quantification compared to standard MC.

Uji Anti Jamur Ekstrak Buah Mengkudu (Morinda citrifolia L.)

Noni is a plant that has the potential to be used as traditional medicinal ingredients. This study aims to determine the inhibition of noni extracts (Morinda citrifolia L.) in inhibiting the growth of the fungus Candida albicans. This type of research is experimental. A total of 150 grams of dried noni fruit that has been mashed, macerated with three different types of solvents namely aquades, acetone and n-hexane to obtain thick extract. Preparation of the fungus suspension was Candida albicans made by mixing the media Nutrient Broth with 5 ose test fungus that were equated with turbidity of a standard MC. Farland. The fungus suspension made was implanted on the Sabouroud Dextrose agar to solidify and divided into 7 sterile petri dishes. Testing the inhibition of fungi using the method of wells. Each cup is made of 1 hole diameter of 3 cm in the center. Tests were carried out by adding non-solvent aquades fruit extract into the 1 cup, acetone noni fruit extract into the cup 2, n-hexane solvent noni fruit extract into the cup 3, for 3 other plates added with three solvents as negative control, while for 1 cup added to the cup fungal infection drug is nystatin as a positive control, each as much as 1 mL. Measurement data were analyzed using the formula of the percentage of inhibition. Inhibitory power of noni fruit extract using distilled water is 3.55%, noni fruit extract using acetone solvent is 50.15%, noni fruit extract using n-hexane solvent that is equal to 38.83%. negative control of aquades, acetone and n-hexane solvent has no inhibitory power while positive control of nystatin is 9.73%. Noni fruit extract using acetone solvent has the strongest inhibitory ability. It can be concluded that the noni fruit extract has fungal inhibitory effect on the growth of the fungus Candida albicans

Multilevel Monte Carlo by using the Halton sequence

AbstractMonte Carlo (MC) simulation depends on pseudo-random numbers. The generation of these numbers is examined in connection with the Brownian motion. We present the low discrepancy sequence known as Halton sequence that generates different stochastic samples in an equally distributed form. This will increase the convergence and accuracy using the generated different samples in the Multilevel Monte Carlo method (MLMC). We compare algorithms by using a pseudo-random generator and a random generator depending on a Halton sequence. The computational cost for different stochastic differential equations increases in a standard MC technique. It will be highly reduced using a Halton sequence, especially in multiplicative stochastic differential equations.

Image characteristics and quantitative analysis of multicolor imaging in eyes with cystoid macular edema

Objective To observe the imaging features of cystoid macular edema (CME) in multicolor imaging (MC), and to evaluate the value of MC in the diagnosis of CME. Methods Descriptive case series study. From August 2017 to June 2018, 42 eyes of 37 patients with CME diagnosed in the people's Hospital of Wuhan University were included in the study. Among them, there were 24 males and 13 females, with an average age of 48.51±10.29 years. There were 14 eyes with diabetic retinopathy, 14 eyes with central retinal vein occlusion, 8 eyes with branch retinal vein occlusion, 4 eyes with uveitis, and 2 eyes with Eales disease. The macular color fundus photography (CFP) was performed with Visucam 200 non-mydriatic fundus camera of Zeiss company in Germany. MC, frequnce domainoptical OCT (SD-OCT) and FFA were examined by Spectralis HRA2 + OCT of Heidelberg company in Germany. According to the MC standard method, five images, including 488 nm blue reflection (BR), 515 nm green reflection (GR), 820 nm infrared reflection (IR) imaging and standard MC and blue-green enhancement (BG), were obtained at the same time. Compared with SD-OCT, CFP and MC images were scored. Friedman M test and Wilcoxon signed rank test were used for statistical analysis. Results The standard MC and BG images showed blue-green uplift area or petal-shaped appearance, surrounded by green reflection areas with clear boundaries. BR image can be seen in the low reflexes area. On the GR image, there were patches or cystic low reflection areas, surrounded by a slightly high reflection. On the IR image, patches or cystoid high reflexes can be seen, surrounded by low reflection dark areas with clear boundaries. The average scores of CFP, standard MC, GB, IR, GR and BR were 1.20±0.94, 3.05±0.99, 2.90±1.04, 2.55±1.27, 2.00±0.94, 0.51±0.85 respectively, and the differences were statistically significant (χ2= 151.61, P=0.000). The score of CFP were significantly lower than that of standard MC (Z=-5.421), BG (Z=-5.354), IR (Z=-4.714), GR (Z=-4.438) and higher than that of BR (Z=-3.435). The differences were statistically significant (P=0.000, 0.000, 0.000, 0.000, 0.001). Conclusions The quality of MC imaging is better than that of CFP. Combined with SD-OCT, it can be used as an assistant method to diagnose CME. Key words: Macular edema/diagnosis; Tomographyoptical coherence; Fluorescein angiography; Multicolor imaging

Peak-to-average power ratio reduction and improved bit error rate performance of orthogonal frequency division multiplexing system using discrete Fourier transform precoder and root-based nonlinear companding

High peak-to-average power ratio (PAPR) is the biggest problem of orthogonal frequency division multiplexing (OFDM) systems. To compensate this problem, we suggested a technique that is based on the combination of discrete Fourier transform (DFT) and root-based nonlinear companding. Since DFT precoding is a linear technique, it reduces PAPR by distorting the phase with minimum system complexity. Moreover, root-based μ-law companding (RMC) is also adopted to further minimize PAPR by changing probability density function from Rayleigh distribution that OFDM signals follow. By knowing that standard μ-law companding (MC) only enlarges the low amplitude of the signals and does not influence high peaks. However, RMC not only expands low-power signals but also compresses higher amplitude of the OFDM signals simultaneously unlike standard MC. In comparison to other mentioned techniques, the proposed technique (DFT-precoded RMC) accomplishes significant PAPR minimization of the OFDM systems. When complementary cumulative distribution function = 10 − 4, the proposed technique reduces PAPR up to 1.98 and 1.99 dB for subcarriers N = 128 and subcarriers N = 256 quadrature phase shift keying (QPSK)-based OFDM system, respectively. At an error probability of 10 − 4, the bit error rate (BER) performance of the proposed technique improves by 0.23 and 0.18 dB over Anoh et al.’s technique for subcarriers N = 128 and N = 256, QPSK, and additive white Gaussian noise channel, respectively. Also, for multipath Rayleigh fading channel, the BER performance of the proposed technique is improved over Anoh et al.’s and RMC techniques at the same BER.

Flat-Histogram Monte Carlo as an Efficient Tool To Evaluate Adsorption Processes Involving Rigid and Deformable Molecules.

Monte Carlo simulations are the foundational technique for predicting thermodynamic properties of open systems where the process of interest involves the exchange of particles. Thus, they have been used extensively to computationally evaluate the adsorption properties of nanoporous materials and are critical for the in silico identification of promising materials for a variety of gas storage and chemical separation applications. In this work we demonstrate that a well-known biasing technique, known as "flat-histogram" sampling, can be combined with temperature extrapolation of the free energy landscape to efficiently provide significantly more useful thermodynamic information than standard open ensemble MC simulations. Namely, we can accurately compute the isosteric heat of adsorption and number of particles adsorbed for various adsorbates over an extremely wide range of temperatures and pressures from a set of simulations at just one temperature. We extend this derivation of the temperature extrapolation to adsorbates with intramolecular degrees of freedom when Rosenbluth sampling is employed. Consequently, the working capacity and isosteric heat can be computed for any given combined temperature/pressure swing adsorption process for a large range of operating conditions with both rigid and deformable adsorbates. Continuous thermodynamic properties can be computed with this technique at very moderate computational cost, thereby providing a strong case for its application to the in silico identification of promising nanoporous adsorbents.

ЭНЕРГЕТИЧЕСКИЕ СИСТЕМЫ СУДОВЫХ ДИЗЕЛЬНЫХ ЭНЕРГЕТИЧЕСКИХ УСТАНОВОК: ОБОСНОВАНИЕ ТРЕБОВАНИЙ К НАДЕЖНОСТИ

The article touches upon reliability issues of energy management systems (EMS) of marine power plants in emergency situations caused by disturbance of the working media consumption and their subsequent recovery. The mathematical model of processes allows to determine the nature of changes in temperature and pressure of water and lube oil in EMS systems. The requirements to the characteristics of automatic control systems of the marine power plant have been formulated. Basic provisions of the reliability theory are followed by presentation of methods of calculating reliability indices of complex technical systems. The article presents the results of the study of non-stationary modes and reliability indices. Reasonable requirements for automated control systems were obtained through the analysis of working environments and of equipment operating in non-stationary modes, non-exceedance of safety limits of marine power plant operation being taken as the admissibility criterion. Besides, there are possible special modes resulted from emergency situations caused by the power plant equipment failure. Hence, for operation and design of the analyses it is important to study changes of working media in the circulation systems, which resulted from the failure of the pumps. Basic circuit of lubrication and cooling systems of the ship diesel power plants has been approved as recommended by the company "MAN B&W" for slow speed diesel engines standard series MC. Among the recommended schemes there was approved the scheme of the main engine with an autonomous cooling circuit. Schematic diagram of energy systems of a diesel power plant has been made under recommendations of the engine developer. Specifications of the component parts of the ship diesel power plant have been taken as standard for manufactured machinery. A low running L90MC-C four-cylinder main engine manufactured by "MAN B&W" was chosen as a research sample. A mathematical model, as applied to the given problem, consists of 10 algebraic equations for nonsteady working media consumption and 18 differential equations for nonsteady heat transfer in heat exchangers, as well as equations for transport delay in the lubrication systems of internal combustion engines.

Efficiency Potential of p- and n-type High Performance Multicrystalline Silicon

Seed-assisted growth of multicrystalline (mc) silicon ingots has led to a significant increase in mc silicon material quality (so called high performance multicrystalline silicon, “HPM Si”) and thus efficiencies of p-type mc silicon solar cells in the past years. Additionally, recent research revealed a high efficiency potential of n-type standard mc silicon due to its large tolerance to many metallic impurities. This suggests a high potential of n-type high performance mc silicon with a low density of dislocation clusters. In this study, the efficiency potential of p- and n-type high performance mc silicon, produced under identical conditions in the same laboratory crystallization furnace, is investigated after different high efficiency solar cell processing steps. The prediction of solar cell efficiencies by an “Efficiency limiting bulk recombination analysis” (ELBA) discloses a very high potential with material related losses of less than 1%abs. compared to the cell limit. In combination witha high efficiency cell concept featuring a full area passivated rear contact (TOPCon), efficiencies exceeding 20% on isotextured n-type HPM samples and close to 22% on samples with an improved texture are predicted. To support these predictions with results on actual devices, solar cells were fabricated. First results on cell level indicate high Voc and Jsc values in the range predicted by ELBA simulations and an efficiency of 19.3%.

Improvement of VOC for thin RST solar cells by enhanced back side passivation

The Ribbon on Sacrificial Template (RST) casting process enables the production of silicon ribbon wafers below 100 μm thickness for thin solar cells. It is a kerf-loss free direct wafer casting method which means that energy-intensive silicon material can be saved. Furthermore, thin solar cells have lower requirement on the charge carrier lifetime because smaller diffusion lengths are sufficient to separate the carriers. For this contribution, an established lab-type PERC solar cell process was applied on <100 μm thick RST wafers. This cell process was developed further by using an ICP PECVD tool to deposit SiNx:H as capping layer on the Al2O3 passivation layer at the back side of the solar cell. This reduces damaging of the Al2O3 passivation layer by ion bombardment using a PECVD tool with direct plasma. With this improvement it was possible to increase VOC to up to 611 mV, which is a new record for 1.5 Ωcm RST material. Furthermore, an efficiency of 16.1 % was achieved which means also a new record for RST material. To compare RST solar cells equitably with standard references, 1 Ωcm FZ wafers and 1 - 1.5 Ωcm standard multicrystalline wafers with initial thickness of 200 - 250 μm were etched back to 100 μm and were also processed into solar cells. The effect of wafer thickness and the difference in material quality between RST and standard mc material was analyzed by means of IV data, wavelength depending IQE measurements and LBIC maps.

Parallelized traveling cluster approximation to study numerically spin-fermion models on large lattices

Lattice spin-fermion models are important to study correlated systems where quantum dynamics allows for a separation between slow and fast degrees of freedom. The fast degrees of freedom are treated quantum mechanically while the slow variables, generically referred to as the "spins," are treated classically. At present, exact diagonalization coupled with classical Monte Carlo (ED + MC) is extensively used to solve numerically a general class of lattice spin-fermion problems. In this common setup, the classical variables (spins) are treated via the standard MC method while the fermion problem is solved by exact diagonalization. The "traveling cluster approximation" (TCA) is a real space variant of the ED + MC method that allows to solve spin-fermion problems on lattice sizes with up to 10(3) sites. In this publication, we present a novel reorganization of the TCA algorithm in a manner that can be efficiently parallelized. This allows us to solve generic spin-fermion models easily on 10(4) lattice sites and with some effort on 10(5) lattice sites, representing the record lattice sizes studied for this family of models.

Potential Gain in Multicrystalline Silicon Solar Cell Efficiency by n-Type Doping

This study aims for a quantitative investigation of the material limitations and the efficiency potential of an entire multicrystalline (mc) n-type silicon block in comparison with an mc p-type block of the same purity level in order to predict the potential of mc n-type silicon for the industrial production of solar cells. Therefore, two standard mc silicon blocks were crystallized under identical conditions (same high purity feedstock, crucible system, and temperature profiles), only differing in their type of doping. The material quality of wafers along the whole block height is analyzed after different solar cell process steps by photoluminescence imaging of the diffusion length. The bulk recombination related efficiency losses are assessed by an “efficiency limiting bulk recombination analysis (ELBA),” combining injection dependent lifetime images with PC1D cell simulations. The influence of the base resistivity variation along the block is considered in the PC1D cell simulations and backed up by Sentaurus Device simulations. This analysis predicts a significantly higher material-related efficiency potential after typical solar cell processes along the whole block height for mc n-type silicon compared with mc p-type silicon. In addition, the efficiency potential for mc n-type silicon depends less on block position.