Pablo Gamallo Otero

Simulation of the effect of p-layer properties on the electrical behaviour of a-Si:H thin film solar cells

Simulation data of the performance of amorphous silicon (a-Si:H) thin film solar cells using the software package Sentaurus TCAD (Synopsis Inc.) are presented. The Sentaurus software is configured with standard theoretical models describing e.g. the density of states in the mobility gap of a-Si:H, generation/recombination statistics, optical data of a-Si:H thin films etc. to calculate illuminated current voltage curves and the respective spectral response for the initial and degraded state of the solar cell. For the selected physical properties of the solar cell the simulation data predicts a maximum of the efficiency for an intrinsic a-Si:H layer thickness between 200–250 nm. Furthermore, a guideline for the optimization of the p-doped layer thickness and the doping concentration is given.

Learning Spanish-Galician translation equivalents using a comparable corpus and a bilingual dictionary

So far, research on extraction of translation equivalents from comparable, non-parallel corpora has not been very popular. The main reason was the poor results when compared to those obtained from aligned parallel corpora. The method proposed in this paper, relying on seed patterns generated from external bilingual dictionaries, allows us to achieve similar results to those from parallel corpus. In this way, the huge amount of comparable corpora available via Web can be viewed as a never-ending source of lexicographic information. In this paper, we describe the experiments performed on a comparable, Spanish-Galician corpus.

Automatic generation of bilingual dictionaries using intermediary languages and comparable corpora

This paper outlines a strategy to build new bilingual dictionaries from existing resources. The method is based on two main tasks: first, a new set of bilingual correspondences is generated from two available bilingual dictionaries. Second, the generated correspondences are validated by making use of a bilingual lexicon automatically extracted from non-parallel, and comparable corpora. The quality of the entries of the derived dictionary is very high, similar to that of hand-crafted dictionaries. We report a case study where a new, non noisy, English-Galician dictionary with about 12,000 correct bilingual correspondences was automatically generated.

An approach to acquire word translations from non-parallel texts

Few approaches to extract word translations from non-parallel texts have been proposed so far. Researchers have not been encouraged to work on this topic because extracting information from non-parallel corpora is a difficult task producing poor results. Whereas for parallel texts, word translation extraction can reach about 99%, the accuracy for non-parallel texts has been around 72% up to now. The current approach, which relies on the previous extraction of bilingual pairs of lexico-syntactic templates from parallel corpora, makes a significant improvement to about 89% of words translations identified correctly.

Does epidural versus combined spinal-epidural analgesia prolong labor and increase the risk of instrumental and cesarean delivery in nulliparous women?

STUDY OBJECTIVE To compare duration of labor, mode of delivery, and local anesthetic consumed in women who received labor analgesia with epidural or combined spinal-epidural technique. DESIGN Retrospective, observational study. SETTING Delivery room of a university hospital. PATIENTS 788 nulliparous women in labor at term with cervical dilation between three and 5 cm. INTERVENTIONS In Group E (epidural alone), parturients received an epidural solution of 8 mL (levobupivacaine 0.125% with fentanyl 5 microg/mL). In Group CSE (combined spinal-epidural), parturients received a spinal injection of levobupivacaine two mg with fentanyl 15 microg (total volume two mL). Then an epidural catheter was placed in all patients and connected to a patient-controlled analgesia pump (basal infusion rate of 8 mL/hr of 0.1% levobupivacaine and fentanyl two microg/mL, patient-controlled bolus dose of three mL, and lockout time of 30 min). MEASUREMENTS Labor duration, mode of delivery (spontaneous vaginal vs. instrumental delivery vs. cesarean section), and local anesthetic consumed, were recorded. MAIN RESULTS Labor analgesia was performed with an epidural technique in 322 patients (40.9%), and a combined spinal-epidural technique in 466 patients (59.1%), of whom 39 Group E women (12.1%) and 46 Group CSE women (9.9%) required cesarean section (P=ns). No differences in the mode of delivery were observed between the groups. Time from analgesia to delivery (Group E: 217 +/- 111 min vs. Group CSE: 213 +/- 115 min; P=ns), and epidural local anesthetic consumed (Group E: 35 +/- 20 mL vs. Group CSE: 33 +/- 20 mL; P=ns), were similar in both groups. CONCLUSIONS No significant differences were observed between epidural and combined spinal-epidural given for labor analgesia in nulliparous women in duration of labor, mode of delivery, or local anesthetic consumed.

Development of a very fast spectral response measurement system for silicon thin film modules

Nowadays it is possible to built a very fast spectral response (VFSR) measurement system by illuminating simultaneously the solar cell at multiple well defined wavelengths. This can be done by means of light emitting diodes (LEDs) available for a multitude of wavelengths, operating at different stimulation frequencies and analysis of the Fourier Transform of the generated solar cell current. For the purpose to measure the spectral response (SR) of silicon thin film solar cells a detailed characterization of LEDs emitting in the wavelength range from 300 nm to 1000 nm was performed. A VFSR equipment has been built implementing a selection of these LEDs and the difference of the short circuit current density (Jsc) determined from the SR with the VFSR results in about 1.8% in comparison to a conventional SR system with monochromator and lock-in amplifier technology. We have performed Jsc mappings in mini modules 10 cm × 10 cm with the VFSR system with the aim to show the potential and obstacles to perform Jsc mappings.

Simulation of the temperature dependence of a-Si:H solar cell current-voltage characteristics

Simulation data of the performance of amorphous hydrogenated silicon (a-Si:H) thin film solar cells using the software package Sentaurus TCAD (Synopsis Inc) are presented. The Sentaurus software is configured with standard theoretical models describing e. g. the density of states in the mobility gap of a-Si:H, generation/recombination statistics, optical data of a-Si:H thin films, etc. to calculate illuminated current voltage curves and the respective spectral response for the initial and degraded state of solar cell. The study of the temperature dependence of the electrical parameters of solar cell is realized. The simulations results were compared with experimental data measured in T-Solar laboratory obtaining a good coincidence.

Comparing Window and Syntax Based Strategies for Semantic Extraction

In this paper, we describe and compare two different approaches for extracting similar words from large corpora. In particular, we compared a method based on syntactic contexts with two strategies relying on windows of tagged words, one using word order and the other bags of words. On a Portuguese corpus of 12 million words, syntactic contexts produce significantly better results for both frequent and not very frequent words.In this paper, we describe and compare two different approaches for extracting similar words from large corpora. In particular, we compared a method based on syntactic contexts with two strategies relying on windows of tagged words, one using word order and the other bags of words. On a Portuguese corpus of 12 million words, syntactic contexts produce significantly better results for both frequent and not very frequent words.

Comparing Different Properties Involved in Word Similarity Extraction

In this paper, we will analyze the behavior of several parameters, namely type of contexts, similarity measures, and word space models, in th e task of word similarity extraction from large corpora. The main objective of the paper will be to describe experiments comparing different extraction syste ms based on all possible combinations of these parameters. Special attention will be p aid to the comparison between syntax-based contexts and windowing techniqu es, binary similarity metrics and more elaborate coefficients, as well as baseline word space models and Singular Value Decomposition strategies. The evaluation le ds us to conclude that the combination of syntax-based contexts, binary simila rity metrics, and a baseline word space model makes the extraction much mor e precise than other combinations with more elaborate metrics and complex models .In this paper, we will analyze the behavior of several parameters, namely type of contexts, similarity measures, and word space models, in the task of word similarity extraction from large corpora. The main objective of the paper will be to describe experiments comparing different extraction systems based on all possible combinations of these parameters. Special attention will be paid to the comparison between syntax-based contexts and windowing techniques, binary similarity metrics and more elaborate coefficients, as well as baseline word space models and Singular Value Decomposition strategies. The evaluation leads us to conclude that the combination of syntax-based contexts, binary similarity metrics, and a baseline word space model makes the extraction much more precise than other combinations with more elaborate metrics and complex models.

Using natural alignment to extract translation equivalents

Most methods to extract bilingual lexicons from parallel corpora learn word correspondences using relative small aligned segments, called sentences. Then, they need to get a corpus aligned at the sentence level. Such an alignment can require further manual corrections if the parallel corpus contains insertions, deletions, or fuzzy sentence boundaries. This paper shows that it is possible to extract bilingual lexicons without aligning parallel texts at the sentence level. We describe a method to learn word translations from a very roughly aligned corpus, namely a corpus with quite long segments separated by “natural boundaries”. The results obtained using this method are very close to those obtained using sentence alignment. Some experiments were performed on English-Portuguese and English-Spanish parallel texts.