Solar photovoltaic energy has gained great importance in the last couple of years, as its costs getlower and the total installed capacity increases. As a result of this, new technologies are arisingwithin the field, with the objective of increasing performance and reducing costs. One of themis the half-cell solar modules which, among other advantages, are said to perform better undershaded conditions compared to standard modules.This project checks the veracity of this statement. For that, a Matlab/Simulink model capable ofrepresenting the behavior of the JAM60S21-365-MR solar module has been created, andexperimentally calibrated with measurements performed in an actual panel. After the modelaccuracy has been checked, it has been used to simulate various shaded scenarios for standardand half-cell modules, to carry out an equivalent comparison between the two.The results for the model show a maximum error of 0.62% for the reference case, and of 6.06%for the worst 4-module-string simulation. This has been found to be an acceptable error, whichis created mainly as a result of temperature measuring inaccuracies and the rough estimation ofsolar cell model parameters. To reduce it, it is recommended that these issues are addressed.Which module does better under shading has been found to be dependent on multiple factors:The temperature and irradiance at which the module operates, its constructive parameters, thenumber of series or parallel connected devices and the shape and size of the shadow. This lastone is the one with the biggest impact in electrical power output. Because of it, the most usualcases for shadowing in PV facilities have been compared. For equivalent modules, shading in thedirection of the string of a single cell is less detrimental in half-cell modules; however, if thatshadow covers a whole row, it is equally damaging. If a full cell is 50% shaded in this scenario, a20% less power is lost in the half cell module compared to the normal one. On the other hand,shadowing in the direction on the bypass-diode line tends to slightly benefit standard modulesfor equal cell parameters if the shadowed full-cell percentage is below 50%, for both cell androw shading. However, as this value increases, half-cell modules tend to gain an advantage overstandard ones.

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Dans le contenu de l’amélioration des performances des piles à combustible, des catalyseurs Pt/Vulcan ont été greffés soit avec du polystyrène sulfonate (PSSA) soit avec de l'acide 4-phenysulfonique (PSA). L'influence du ratio du greffage, de la couche de diffusion de gaz et de la qualité de Nafion, sur les performances électrochimiques ont été étudiées en demi-pile et en assemblage membrane-électrodes (AME). La surface électrochimique du catalyseur a été améliorée en présence de la couche microporeuse sur le papier carboné en tant que couche de diffusion de gaz, aussi une densité de courant supérieure et une résistance de transfert de charge inférieure ont été observées. Pt/Vulcan catalyseurs ont été greffés des chaines PSSA avec 5, 10 et 20 wt.% 4-styrènesulfonate de sodium. Les résultats en demi-pile et en pile ont montré que des taux de sulfonation de 5 à 10 wt.% étaient optimaux. La sulfonation des catalyseurs a aussi été effectuée avec 5.8, 11.6, 18.0 et 23.3 wt.% PSA. Des résultats meilleurs ont été obtenus par la sulfonation. L'AME ayant 18.0 wt.% PSA a présenté une excellente stabilité pendant 3000 cycles de test de vieillissement accéléré. Moins de Nafion a entraîné une plus faible performance des demi-piles, aussi des AMEs ayant catalyseurs des greffé de 5 wt.% PSSA ou PSA. Cependant, celles contenant 10 et 20 wt.% de PSSA, ont montré un une densité de puissance élevé lors que la quantité de Nafion a diminué de 0.50 à 0.25 mg•cm-2 / In the development of the performances of PEM fuel cell, sulfonated Pt/Vulcan catalysts were prepared by grafting with either polystyrene sulfonate (PSSA) or with 4-phenysulfonic acid (PSA). The influences of the graft ratio, the amount of Nafion and the gas diffusion layer, on the electrochemical performances were studied in a half-cell and membrane electrode assembage (MEA). Larger electrochemical surface area of the catalyst was obtained in the presence of microporous layer on the carbon paper, as well as higher ORR current and lower charge transfer resistance. PSSA was grafted onto Pt/Vulcan catalysts by in-situ radical polymerization with 5, 10 and 20 wt.% sodium styrene sulfonate. It was presented in the half-cell tests and fuel cell tests that the catalysts grafted with 5 and 10 wt.% sulfonated groups performed improved properties. Pt/Vulcan catalysts were also grafted with 5.8, 11.6 18.0 and 23.3 wt.% PSA. Compared with non-functionalized catalysts, significant developments were achieved because of the sulfonation. The MEA with 18.0 wt.% PSA was studied in accelerated durability tests and showed excellent durability after 3000 cycles. For half-cells and MEAs with catalysts grafted with 5wt.% PSSA or PSA groups, low Nafion addition resulted in to lower performances. However, the MEAs with 10 and 20 wt.% PSSA exhibited an enhanced performance than the counterparts with 0.50 mg•cm-2 Nafion

Photovoltaic modules in desert areas benefit from high irradiation levels but suffer from harsh environmental stress factors, which influence the Levelized Cost of Electricity by decreasing the lifetime and performance and increasing the maintenance costs. Using optimized half-cell module designs mounted in the most efficient orientation according to the plant requirements can lead to reduced production costs, increased energy yield and longer service lives for PV modules in desert areas. In this work, we review the technical advantages of half-cell modules in desert regions and discuss the potential gains in levelized costs of electricity due to reduced material consumption, a higher cell-to-module power ratio, lower module temperatures, better yields, reduced cleaning cycles and finally, reduced fatigue in interconnection due to thermal cycling. We show that half-cell modules are the most cost-effective option for desert areas and are expected to have a relevant lower Levelized Cost of Electricity.

The objectives of this research were to investigate the effect of stay-in-place metal forms (SIPMFs) on the performance of concrete bridge decks in Utah. The research program included six bridge decks with SIPMFs and six decks without SIPMFs, which were all located within the Interstate 215 corridor in the vicinity of Salt Lake City, Utah, and therefore subject to similar traffic loading, climatic conditions, and maintenance treatments, including applications of deicing salts during winter months. All of the tested decks were constructed between 1984 and 1989 using epoxy-coated rebar. Several tests were performed at each of six locations on each deck, including visual inspection, chain dragging, hammer sounding, Schmidt hammer testing, half-cell potential testing, and chloride concentration testing. Because differences in deck age and average cover for the two deck types were found to be statistically significant, the collected data were subjected to analysis of covariance (ANOCOVA) testing, with age and cover as covariates. All calculated p-values were compared to the standard value of 0.05. The distress survey results indicate that the average crack width and crack density for decks without SIPMFs were greater by 41 and 25 percent, respectively, than the corresponding values for decks with SIPMFs and that decks without SIPMFs had more potholes than decks with SIPMFs. However, the delamination density for bridge decks with SIPMFs was 71 percent higher than that of decks without SIPMFs. The average Schmidt rebound number for decks with SIPMFs was higher than that for decks without SIPMFs by an equivalent of 1,400 psi. The half-cell potential for decks with SIPMFs was 0.123 lower than that of decks without SIPMFs, indicating that a more active state of corrosion exists on decks with SIPMFs. On average, the chloride concentration in the bridge decks with SIPMFs was 205 percent greater than the concentration in the decks without SIPMFs. Among all of the distress measurements evaluated in the ANOCOVA, crack width was the only parameter that was determined to be significantly different between the two types of decks at the time of testing. In addition, Schmidt rebound number, half-cell potential, and chloride concentration at 2-in. depth all yielded p-values less than 0.05, indicating that significant differences in these properties exist between decks with and without SIPMFs. Specifically, the decks with SIPMFs have a higher compressive strength, a more active state of corrosion, and a higher chloride concentration, which may all be attributable to elevated moisture contents in decks with SIPMFs arising from the reduction in deck surface area from which moisture may evaporate. These data indicate that decks with SIPMFs are clearly more susceptible to reinforcement corrosion compared to decks without SIPMFs and may therefore exhibit greater magnitudes of damage with time. Given these research findings, engineers should carefully compare the short-term advantages against the potential long-term disadvantages associated with the use of SIPMFs for concrete bridge deck construction. If SIPMFs are approved for use, engineers may consider applying surface treatments to the affected decks early in the deck life to minimize the ingress of chlorides into the concrete over time and therefore retard the onset of reinforcement corrosion.

The purpose of this research was to develop a new index for concrete bridge deck management in Utah. Data were collected in the summer of 2005 from 15 concrete bridge decks in the vicinity of Salt Lake City. The decks ranged from 2 to 21 years in age and were all constructed using epoxy-coated rebar. Visual inspection, sounding, Schmidt hammer testing, half-cell potential testing, and chloride concentration testing were performed on six 6-ft by 6-ft test areas randomly distributed within the single lane closed to traffic on each deck, and testing protocols followed American Society for Testing and Materials standards to the extent possible. Collected data were analyzed using statistics, and age, cover, and half-cell potential were ultimately selected for inclusion in a new Utah Bridge Deck Index (UBDI); these variables effectively reflect chloride-induced corrosion mechanisms active on Utah bridge decks, are highly correlated to delamination distresses, and are relatively easy to measure compared to chloride concentration. At the request of Utah Department of Transportation (UDOT) personnel, the UBDI equation was structured around a deduct system using a 100-point scale similar to the sufficiency rating system, in which a perfect bridge deck receives a score of 100. Coefficients were selected based largely on the judgment of the researchers and the UDOT personnel involved in the research, and threshold values for maintenance, rehabilitation, and replacement (MR&R) options were specified to be the same as those associated with the standard sufficiency ratings. The UBDI and corresponding MR&R recommendation were then provided for each of the bridge decks tested in this research; nine of the decks are recommended for preventive treatment, and six are recommended for rehabilitation. In addition, the possibility of treatment applications was considered, leading to required adjustments in the UBDI calculation; the treatment options that were considered include an epoxy seal, an HPC overlay, and an asphalt membrane overlay. Four case scenarios were developed to demonstrate the response of the revised UBDI equation to these treatments. Finally, as aids for UDOT personnel implementing this research, charts were created to facilitate rapid determination of the required number of half-cell potential and concrete cover measurements for different levels of reliability and tolerance. The UBDI developed in this research is recommended for implementation by UDOT personnel as a tool for optimizing the timing of MR&R treatments on concrete bridge decks similar to those evaluated in this project. In measuring cover and half-cell potential values, UDOT personnel should utilize the sampling guidelines presented in this report to ensure adequate characterization of each deck. Furthermore, to facilitate the inclusion of treatment effects in the UBDI, UDOT personnel should establish a policy of recording the types and dates of all MR&R treatments applied to bridge decks. As performance data are collected for specific treatments over time, the treatment lives proposed in this research for epoxy seals, HPC overlays, and asphalt membrane overlays should be revised as needed, and information for other treatments may be added. In addition, to maximize the predictive capabilities of the UBDI, more accurate relationships between half-cell potential values and deck age should be developed for estimating future deck condition.

Concrete bridge decks in Utah are experiencing observable deterioration due primarily to freeze-thaw cycles and the routine application of deicing salts during winter maintenance activities. Given the need for increasingly cost-effective strategies for bridge deck maintenance, rehabilitation, and replacement (MR&R), the Utah Department of Transportation (UDOT) initiated this research to ultimately develop a protocol offering guidance as to whether deteriorated bridge decks should be rehabilitated or replaced. While threshold values for various non-destructive condition assessment methods were proposed in earlier UDOT research, this work focused on implementing the recommended test criteria. Twelve bridges were identified by UDOT engineers for inclusion in the study, and data were collected from each deck to determine whether the bridge decks warranted rehabilitation or replacement based on the proposed threshold values. Several evaluation techniques were employed to assess concrete bridge deck condition, including visual inspection, hammer sounding and chaining, dielectric measurements, ground-penetrating radar imaging, resistivity testing, half-cell potential testing, and chloride concentration testing. The condition assessment testing confirmed that chloride-induced corrosion of reinforcing steel is the primary mechanism of deck deterioration and that inadequate cover over the upper steel mat facilitated accelerated corrosion damage in many instances. The bridge deck condition analyses produced from the results of non-destructive testing were compared to the visual inspection ratings assigned to each deck by UDOT. Concrete bridge deck condition data should be collected regularly through inspection and monitoring programs to facilitate prioritization of MR&R strategies for individual bridges and to evaluate the impact of such strategies on the overall condition of the network. Performance indices based on selected condition assessment parameters should be developed for use in bridge management activities, and mathematical deterioration models should be calibrated in order to forecast both network-level and project-level conditions and predict funding requirements for various possible MR&R strategies. Further research, including statistical analyses of the data presented in this report, should be completed to develop relevant mathematical deterioration models for predicting the service lives of concrete bridge decks in Utah.

Numerous methods have been developed to measure corrosion potential relating to chloride infiltration in concrete, including an emerging application of electrochemical impedance spectroscopy (EIS). EIS involves measurements of electrical impedance to evaluate the corrosion potential of steel reinforcement in concrete. With EIS, current is injected vertically into the concrete bridge deck between the surface and the embedded reinforcing steel, usually the top mat, to evaluate the degree to which the reinforcing steel is protected from chloride infiltration by the entire bridge deck system. The objectives of this research were to 1) investigate the sensitivity of EIS measurements obtained at various frequencies to specific deck properties, 2) recommend a particular frequency or range in frequency at which impedance measurements can differentiate among various levels of corrosion protection for reinforcing steel in concrete bridge decks, and 3) compare impedance values measured at the recommended frequency(ies) to more traditional test measurements relating to corrosion of reinforcing steel in concrete bridge decks. This research involved impedance testing of 25 concrete slabs, divided into five sets. The effects of sealant presence, curing time, temperature, moisture content, cover depth, water-to-cementitious materials ratio, air content, chloride concentration, and epoxy coating condition on individual impedance measurements were evaluated. For the controlled laboratory experiments, sealant presence, curing time, temperature, moisture content, cover depth, water-to-cementitious materials ratio, air content, and epoxy coating condition were shown to have a statistically significant effect on impedance measurements, with p-values less than 0.05. The statistical analyses indicated that impedance testing in the frequency range of approximately 100 Hz to 1 kHz would be expected to provide the best data about the degree to which the reinforcing steel is protected from chloride infiltration by a bridge deck system. In this frequency range, a high level of differentiation among levels of corrosion protection is expected, and a high speed of data collection is also possible. For the uncontrolled laboratory experiments, a single frequency of 200 Hz was selected for impedance testing. Statistical analyses were performed to compare impedance with more traditional test measurements relating to corrosion of reinforcing steel in concrete bridge decks. Longitudinal and transverse cover, dry and wet resistivity, dry and wet half-cell potential, dry linear polarization, and chloride concentration were determined to be correlated with impedance, with p-values less than 0.15.

This study involved a comparative investigation of chloride-induced corrosion detection techniques on loaded reinforced concrete slabs which were exposed to deicing salts and wetting-drying cycles to simulate typical aggressive environments in cold climates. The studied techniques involved linear polarization technique, galvanostatic pulse technique, electrochemical impedance spectroscopy, half-cell potential and concrete electrical resistivity mapping. The results showed that concrete quality and moisture content have a direct effect on corrosion activity, and these properties are represented well with concrete electrical resistivity. The galvanostatic pulse technique was shown to correlate well with electrochemical impedance spectroscopy, which was used as a benchmark for corrosion rate measurements in this study; however, the galvanostatic pulse technique was not capable of detecting corrosion activity in saturated concrete accurately. The results of this research do not support the criteria provided by the ASTM C876-09 standard for using half-cell potentials to estimate the probability of reinforcing steel corrosion in reinforced concrete structures.

This study involved a comparative investigation of chloride-induced corrosion detection techniques on loaded reinforced concrete slabs which were exposed to deicing salts and wetting-drying cycles to simulate typical aggressive environments in cold climates. The studied techniques involved linear polarization technique, galvanostatic pulse technique, electrochemical impedance spectroscopy, half-cell potential and concrete electrical resistivity mapping. The results showed that concrete quality and moisture content have a direct effect on corrosion activity, and these properties are represented well with concrete electrical resistivity. The galvanostatic pulse technique was shown to correlate well with electrochemical impedance spectroscopy, which was used as a benchmark for corrosion rate measurements in this study; however, the galvanostatic pulse technique was not capable of detecting corrosion activity in saturated concrete accurately. The results of this research do not support the criteria provided by the ASTM C876-09 standard for using half-cell potentials to estimate the probability of reinforcing steel corrosion in reinforced concrete structures.