Search

Solid oxide fuel cells are thought to be capable of a wide range of fuels, but the direct utilization of hydrocarbon fuels increases the risk of carbon deposition at the anode. In this research, a novel full cell structure supported by porous Gd 0.1 Ce 0.9 O 1.95 (GDC) skeleton is proposed and anode material Ba(Ce 0.9 Y 0.1) 0.8 Ni 0.2 O 3–δ (BCYN) is proposed to be impregnated on the skeleton to form a multi-functional anode. In the operating reductional atmosphere, Ni is reduced from the BCYN and provides electrochemical catalyticity, and BCYN can absorb water on its surface to prevent carbon deposition. 5% Cu is also applied to the anode to increase electron conductivity by impregnation, and it doubles the peak power density. The composite Ba(Ce 0.9 Y 0.1) 0.8 Ni 0.2 O 3–δ @CuO anode is evaluated and found to have good carbon deposition resistance with 3% humidified C 2 H 6 in constant current operation for 120 h, and withstand 3% humidified CH 4 in OCV condition for nearly 160 h. [Display omitted] • The novel full cell structure supported by porous Gd 0.1 Ce 0.9 O 1.95 skeleton. • Ba(Ce 0.9 Y 0.1) 0.8 Ni 0.2 O 3–δ is impregnated on skeleton to form multi-functional anode. • Cu is applied to the anode to increase electron conductivity by impregnation. • The anode has carbon deposition resistance withstand 3% humidified CH 4 and C 2 H 6. [ABSTRACT FROM AUTHOR]

The CRTS II slab track, which is connected in a longitudinal direction, is one of the main ballastless tracks in China, with approximately 7365 km of operational track. Temperature loading is a very vital factor leading to slab track damages such as warping and cracking. While existing research on temperature distribution rests on either site tests in special environments or theoretical analysis, the long-term temperature field characteristics are not clear. Therefore, a long-term temperature field test for the CRTS II slab track on bridge-subgrade transition section was conducted to analyze the temperature field. A GA-BP (genetic algorithm optimized back propagation) neural network was trained on the test data to predict the temperature field. The vertical and lateral temperature distributions in four typical days were carried out. We found that the temperature along the track was distributed in a nonlinear manner. This was particularly distinct in the vertical direction for depths of less than 300 mm. The highest and lowest daily temperatures and the daily range of the temperature were analyzed. With the increasing depth, the daily highest temperatures and range of the temperature were smaller, the daily lowest temperatures were higher, and the time corresponding to this peak value appeared later in the day. Both the highest and lowest daily temperature could be predicted using the GA-BP neural network, though the accuracy in predicting the highest temperature was higher than that in predicting the lowest temperature. [ABSTRACT FROM AUTHOR]

Abstract The CRTS II slab track, which is connected in a longitudinal direction, is one of the main ballastless tracks in China, with approximately 7365 km of operational track. Temperature loading is a very vital factor leading to slab track damages such as warping and cracking. While existing research on temperature distribution rests on either site tests in special environments or theoretical analysis, the long-term temperature field characteristics are not clear. Therefore, a long-term temperature field test for the CRTS II slab track on bridge-subgrade transition section was conducted to analyze the temperature field. A GA-BP (genetic algorithm optimized back propagation) neural network was trained on the test data to predict the temperature field. The vertical and lateral temperature distributions in four typical days were carried out. We found that the temperature along the track was distributed in a nonlinear manner. This was particularly distinct in the vertical direction for depths of less than 300 mm. The highest and lowest daily temperatures and the daily range of the temperature were analyzed. With the increasing depth, the daily highest temperatures and range of the temperature were smaller, the daily lowest temperatures were higher, and the time corresponding to this peak value appeared later in the day. Both the highest and lowest daily temperature could be predicted using the GA-BP neural network, though the accuracy in predicting the highest temperature was higher than that in predicting the lowest temperature.

The duration of load (DOL) effect in structure timber refers to the degradation of strength and stiffness that occurs under long-term continuous loading. This paper investigated the DOL effect in structure timber using DOL tests and DOL damage models. Based on the empirical-fitted formulae, the DOL coefficients were derived for three long-term sustained loads in bending, tension perpendicular to grain, and shear parallel to grain, and the results were compared and analyzed with the Madison equation, Gerhards model, Nielsen model, and Foschi and Yao model derivations to verify the applicability of the DOL empirical model and the three DOL damage models. The results show that based on the historical data of the DOL tests, the Madison empirical formula was found to be better applied to the derivation of DOL coefficients under the bending and tension perpendicular to grain long-term sustained loading, and the derivation of DOL coefficients under shear loading is not satisfactory. Among the three DOL damage models, the Foschi and Yao model was better than the Gerhards and Nielsen models for fitting the DOL test results under bending, tension perpendicular to grain, and shear parallel to grain. The DOL coefficients derived based on the Foschi and Yao model are more comparable to test results and resemble those derived from the Madison formula. [ABSTRACT FROM AUTHOR]

Excessive nitrogen (N) input is an important factor influencing aquatic ecosystems and has received increasing public attention in the past decades. It remains unclear how N input affects the denitrifying bacterial communities that play a key role in regulating N cycles in various ecosystems. To test our hypothesis—that the abundance and biodiversity of denitrifying bacterial communities decrease with increasing N—we compared the abundance and composition of denitrifying bacteria having nitrous oxide reductase gene (nosZ I) from sediments (0–20 cm) in five experimental ponds with different nitrogen fertilization treatment (TN10, TN20, TN30, TN40, TN50) using quantitative PCR and pyrosequencing techniques. We found that (1) N addition significantly decreased nosZ I gene abundance, (2) the Invsimpson and Shannon indices (reflecting biodiversity) first increased significantly along with the increasing N loading in TN10–TN40 followed by a decrease in TN50, (3) the beta diversity of the nosZ I denitrifier was clustered into three groups along the TN concentration levels: Cluster I (TN50), Cluster II (TN40), and Cluster III (TN10–TN30), (4) the proportions of Alphaproteobacteria and Betaproteobacteria in the high-N treatment (TN50) were significantly lower than in the lower N treatments (TN10–TN30). (5) The TN concentration was the most important factor driving the alteration of denitrifying bacteria assemblages. Our findings shed new light on the response of denitrification-related bacteria to long-term N loading at pond scale and on the response of denitrifying microorganisms to N pollution. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of creep on prestressed strings beam, a creep model was fitted with the test data through bending tests on prestressed plywood beam strings under long-term loading, and the correlation coefficient and variation law of the creep model were obtained. The results showed that the overall correlation coefficients R² of the power-law model and the logarithmic model fitted were 0. 99 and 0. 98 respectively, and the overall correlation coefficient R² of the mechanical model fitted was 0. 83. The research results showed that the power-law model can accurately predict the creep law of the prestressed glulam beam string. [ABSTRACT FROM AUTHOR]

This study investigated the annual variation of the indoor thermal environment in a typical canteen kitchen and tried to evaluate the actual working status of the exhaust fume system. Parameters were measured in the canteen kitchen, including indoor environment (temperature, humidity, air velocity); outdoor environment (temperature; humidity); exhaust fume system (temperature, airflow rate, oil fume concentration, energy consumption), and makeup air system (temperature, humidity, air velocity) from April 2019 to January 2020. In addition, we also interviewed the chef's thermal comfort in this kitchen. From the data available, we could find that 82.92% of the working hours in summer were above the acceptable range. Only 17.08% of the working hours were within the tolerance range (26–32 °C). The questionnaire results showed that 83.33% of chefs felt hot in summer. Most chefs' wet sensations in the four seasons were neutral, and 91.6% of the chefs felt dissatisfied with the draft sensation. In addition, 88.33% of the chefs felt the fume overflowing from the exhaust hood. This may be because the exhaust fume system of the canteen kitchen was operated under the air velocity of 9.18 ± 1.6 m/s, and its exhaust airflow rate was 10,634.80 ± 189.30 m3/h, which is lower than the minimum exhaust airflow rate (12,312 m3/h). The measurement results indicated that the exhaust fume system could not remove the waste heat and fume pollutants effectively. [ABSTRACT FROM AUTHOR]

The duration of load (DOL) effect in structure timber refers to the degradation of strength and stiffness that occurs under long-term continuous loading. This paper investigated the DOL effect in structure timber using DOL tests and DOL damage models. Based on the empirical-fitted formulae, the DOL coefficients were derived for three long-term sustained loads in bending, tension perpendicular to grain, and shear parallel to grain, and the results were compared and analyzed with the Madison equation, Gerhards model, Nielsen model, and Foschi and Yao model derivations to verify the applicability of the DOL empirical model and the three DOL damage models. The results show that based on the historical data of the DOL tests, the Madison empirical formula was found to be better applied to the derivation of DOL coefficients under the bending and tension perpendicular to grain long-term sustained loading, and the derivation of DOL coefficients under shear loading is not satisfactory. Among the three DOL damage models, the Foschi and Yao model was better than the Gerhards and Nielsen models for fitting the DOL test results under bending, tension perpendicular to grain, and shear parallel to grain. The DOL coefficients derived based on the Foschi and Yao model are more comparable to test results and resemble those derived from the Madison formula.

[Objectives] To explore the stability of Naomai Xingshen Capsules. [Methods] Accelerated test and long-term test were carried out to investigate the changes in properties, identification, moisture, disintegration time and microbial limit of Naomai Xingshen Capsules. [Results] There were basically no changes in all indicators for the three batches of samples (after 6-month accelerated test and 24-month longterm test), and they all met the requirements of quality standards. [Conclusions] The preparation of Naomai Xingshen Capsules is stable and reliable, and the stability test provides a reliable basis for its expiration date. [ABSTRACT FROM AUTHOR]

High-temperature heat pipes, utilizing alkali metals as working fluids, are essential heat transfer components in cooling systems of nuclear reactors. To assess the long-term isothermal behavior and heat transfer performance variation of high-temperature sodium heat pipes, this research presents the design and construction of a long-duration experimental test rig for high-temperature heat pipes. A 100-hour experimental investigation was conducted under operating conditions of 900 °C. The results demonstrate that the heat pipes can operate stably for extended periods after startup. The average temperature at the condenser section gradually increased, while the overall temperature difference fluctuation decreased. The magnitude of temperature difference reduction was measured to be 2.3 °C, and the effective thermal resistance of the heat pipe decreased to 0.0639 K/W. These results suggest an enhancement in both the isothermal performance and heat transfer capability characteristics of the sodium heat pipe after long-term testing. This study provides valuable insights for the design and assessment of high-temperature heat pipe systems in nuclear reactor cooling applications. [ABSTRACT FROM AUTHOR]

The experiment was to study the stability of feed additive lysozyme dimer in influencing factors and accelerated test, determined the validity period of the product through long-term test. Three batches of lysozyme dimer samples were taken for influencing factor test (high temperature test, high humidity test and light test), accelerated test and long-term test, the moisture, dimer content and enzyme activity of lysozyme dimer were detected as inspection indicators. The results showed that the lysozyme dimer was relatively stable in the influence factor test, accelerated test and long-term test. The validity period of the product was preliminarily determined to be 12 months after the validity period prediction analysis. The experiment indicates that lysozyme dimer is relatively stable. The product can be packed in compound paper bags and stored in dry and ventilated places. [ABSTRACT FROM AUTHOR]

[Objectives] To investigate the stability of Shuji tablets. [Methods] Accelerated test and long-term test were used to investigate the changes of tablet properties, weight difference, alcohol-soluble extract, disintegration time and microbial limit. [Results] All the indicators of the three batches of samples (after 6 months of accelerated test and 18 months of long-term test) basically remained unchanged and all met the standards of the quality standard. [Conclusions] The preparation is stable and reliable, and the stability test provides a reliable basis for its validity. [ABSTRACT FROM AUTHOR]

In recent decades, fuel cells have been widely used in energy generation. In a PEMFC, considering the specific application, two types of oxidants are used. Durability tests, which are highly costly products, are of crucial importance in evaluating the lifetime of fuel cells. The purpose of the present paper is to investigate the performance of a fuel cell by changing the type of oxidant from air to pure oxygen. Because of the presence of impurities in the air oxidant, a cell with air oxidant is more sensitive to operating conditions than one with pure oxygen. In this experiment, a single fuel cell was assembled and used for testing. The lifetime test was carried out in constant current, and the voltage decay rate was reported. Effects of various parameters, like air stoichiometry, Dew point Temperature, and Pressure, have been investigated. Increasing the stoichiometry of the oxidant to 3 greatly increased the voltage of the fuel cell, but no significant increase in the fuel cell voltage was observed in stoichiometries above this value. A comparison of inlet gas temperatures demonstrated that the fuel cell had the best performance at 75 °C, but due to the fluctuation of the output voltage at this temperature, the temperature was decreased to 65 °C. Finally, upon performing durability test with pure oxygen for 9 hours and comparing the results with those of air oxidant, the possibility of using a fuel cell with two different oxidants has been confirmed.

This study investigated the annual variation of the indoor thermal environment in a typical canteen kitchen and tried to evaluate the actual working status of the exhaust fume system. Parameters were measured in the canteen kitchen, including indoor environment (temperature, humidity, air velocity); outdoor environment (temperature; humidity); exhaust fume system (temperature, airflow rate, oil fume concentration, energy consumption), and makeup air system (temperature, humidity, air velocity) from April 2019 to January 2020. In addition, we also interviewed the chef’s thermal comfort in this kitchen. From the data available, we could find that 82.92% of the working hours in summer were above the acceptable range. Only 17.08% of the working hours were within the tolerance range (26–32 °C). The questionnaire results showed that 83.33% of chefs felt hot in summer. Most chefs’ wet sensations in the four seasons were neutral, and 91.6% of the chefs felt dissatisfied with the draft sensation. In addition, 88.33% of the chefs felt the fume overflowing from the exhaust hood. This may be because the exhaust fume system of the canteen kitchen was operated under the air velocity of 9.18 ± 1.6 m/s, and its exhaust airflow rate was 10,634.80 ± 189.30 m3/h, which is lower than the minimum exhaust airflow rate (12,312 m3/h). The measurement results indicated that the exhaust fume system could not remove the waste heat and fume pollutants effectively.

External constraint is an action that arises when a structure cannot deform freely. This deformation may be caused by imposed deformation. These deformations lead to support reactions and internal forces only in statically indeterminate systems and are proportional to the absolute values of the structural stiffness. The structural stiffness is significantly reduced by creep of concrete. The classical models for calculating the creep impact on constraint forces assume linear‐elastic or linear‐viscoelastic behavior. The influence of the reinforcement on the creep deformation is neglected as well as the effect of cracking. For this reason, experiments were carried out to obtain results on the creep‐induced degradation of constrained forces caused by imposed deformations. Long‐term experiments were performed on a two‐span beam on which the constraint force was applied by lifting the middle support. Dimensions of the test bodies were l/w/h = 7.3 m/0.4 m/0.2 m. Measurements were carried out on two test bodies, one conventional reinforced test body and one post‐tensioned test body. Thus, the stiffness of a cracked and non‐cracked test body was given. As a result, the influence of the reinforcement as well as effect of crack formation can be taken into account. The experiment lasted over a period of 500 days. The aim is to compare the results of the theoretical models taking into account different stiffness and different creep behavior with the measured test results. [ABSTRACT FROM AUTHOR]

Summary: Competing risks data arise frequently in clinical trials, and a common problem encountered is the overall homogeneity between two groups. In competing risks analysis, when the proportional subdistribution hazard assumption is violated or two cumulative incidence function (CIF) curves cross; currently, the most commonly used testing methods, for example, the Gray test and the Pepe and Mori test, may lead to a significant loss of statistical testing power. In this article, we propose a testing method based on the area between the CIF curves (ABC). The ABC test captures the difference over the whole time interval for which survival information is available for both groups and is not based on any special assumptions regarding the underlying distributions. The ABC test was also extended to test short‐term and long‐term effects. We also consider a combined test and a two‐stage procedure based on this new method, and a bootstrap resampling procedure is suggested in practice to approximate the limiting distribution of the combined test and two‐stage test. An extensive series of Monte Carlo simulations is conducted to investigate the power and the type I error rate of the methods. In addition, based on our simulations, our proposed TS, Comb, and ABC tests have a relatively high power in most situations. In addition, the methods are illustrated using two different datasets with different CIF situations. [ABSTRACT FROM AUTHOR]

Copyright of Technisches Messen is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mg–Al and Mg–Fe mixed oxides with a constant molar ratio (3:1) were tested in the transesterification of rapeseed oil with methanol in a fixed-bed reactor. The mixed oxides were obtained from parent layered double hydroxides by calcination at 500 °C. The synthesized materials were characterized by several experimental techniques such as XRD, TG-MS, TPD-CO 2 , DRIFT and SEM. The transesterification was carried out at different weight hour space velocities (WHSVs; 1, 2 and 3 h-1) and different reaction temperatures (115, 150 and 200 °C), with every parameter tested for 32 h. Moreover, the stability of the catalysts was tested by the determination of the metal content in the reaction mixture. The ester yield increases with decreasing WHSV and with increasing reaction temperature. The Mg–Al mixed oxides were more active for all WHSVs and for temperatures of 115 °C and 150 °C due to the lower crystallite size and particularly higher concentration of basic species. For the reaction temperature of 200 °C, the catalyst activity was almost the same for both catalysts. A long-term catalytic test (300 h) for the verification of the catalyst lifetime and stability was also carried out with insignificant leaching of metals. Image 100137 • Mg–Al and Mg–Fe mixed oxides used as heterogeneous catalysts for transesterification. • Temperature and weight hour space velocity effects were tested in a fixed-bed reactor. • The long-term stability (300 h), including the leaching of metals, was studied. • Mg–Al were more active than Mg–Fe because of higher concentration of basic sites. • The ester yield was stable for 300 h: 86% for Mg–Al and 50% for Mg–Fe. [ABSTRACT FROM AUTHOR]

Abstract Understanding soil health condition is essential to the sustainability and stability of the entire ecosystem of farmland. The primary objective of this study was to improve the soil health index (SHI) based on principle component analysis (PCA) and develop a new analysis method for soil health assessment based on Meta-Analytic Hierarchy Process (Meta-AHP), which provides consistent minimum data sets (MDS), weight and scoring function for different locations, studies and management. The thirteen variables of MDS that exhibited sensitivity to management between organic and conventional soil were selected by meta-analysis. The indicator weight was assigned by a combination of experts scoring, AHP and meta-analysis. To test the applicability and sensitivity of the soil health assessment by Meta-AHP, a sixteen-year long-term test was assessed by the conventional SHI method (cSHI) and Meta-AHP. The results showed that similar evaluation results and significant positive correlations (**P < 0.01, n = 9) between the two evaluated methods were observed, and the results calculated using Meta-AHP had the best discrimination under different plant systems due to the higher F values when compared with the cSHI. This study developed a sensitive and consistent SH assessment framework that can be used applied to a variety of location, study, and soil management systems. Graphical abstract Unlabelled Image Highlights • Meta-analysis improved the sensitivity of minimum data sets in soil health assessment. • Analytic Hierarchy Process could adjust weight for soil health assessment. • Accuracy of Meta-AHP method was testified by Long-term experiment of organic farming. [ABSTRACT FROM AUTHOR]

Despite the great advantages of high-temperature polymer electrolyte membrane (HT-PEM) fuel cells over the low-temperature (LT) PEM alternative, such as enhanced reaction kinetics and higher tolerance against impurities like CO due to the higher operation temperature, the achievement of high lifetimes still remains a challenge. In order to improve the durability of the fuel cell, extensive research has been carried out on alternatives for the individual components. For this reason, this paper conducted extended long-term tests with three three membrane electrode assemblies (MEAs) from one manufacturer under different operational scenarios. The MEAs differed mainly by the membranes used and showed significantly different behaviors. While the first MEA reached the end of life already after 2600 h, the second one could pass 9800 h almost without any problems. The third MEA proved resistant to adverse conditions. For all three MEAs, extensive electrochemical characterizations and μ-CT examinations for the analysis of long-term stability are shown.

The vegetable oil has become a frontier area of research in rural and remote areas for small or decentralized power generation applications. However, the biggest challenge in use of straight vegetable oil (SVO) in a diesel engine is the problem of injector deposits. Soy-lecithin has been identified as bio-additive to overcome the deposits problem due to its natural surfactant and emulsifying properties. Though short-term performance test using soy-lecithin as bio-additive with non-edible karanj oil showed quite good results, its effect on engine performance during long-term test needs to be experimentally investigated for its reliability. The key objective of the current work is to examine the performance of diesel engine operated with karanj oil ( Pongamia pinnata ) by adopting a novel strategy of periodic dosing of bio-additive during a long-term test. This study also intends to focus on lubricating oil analysis to evaluate the effectiveness of soy-lecithin as bio-additive with karanj oil. Long-term engine test was performed on a Cummins DXP, direct injection diesel genset at a constant speed and load for 130 h. A test was conducted by adopting a novel strategy of periodic dosing of bio-additive in karanj oil in a repeated cycle during engine running condition. Experimental results showed that immediately switched over to additive improved the performance of engine but its continuous use lead to degradation of engine performance. Thus, running of engine continuously with either additive or w/o additive independently would lead to degradation of the engine performance but with periodic dosing of soy-lecithin as bio-additive improved the performance of the engine. The present work suggests the strategy of running the engine with bio-additive in discreet dosages for 2 h after every 7–8 h of engine run without additive in a repeated cycle. This approach would lead to smooth running of the engine which is an improvement over the baseline performance of karanj oil either with or without soy-lecithin alone. The lubricating oil analysis revealed the normal physicochemical properties and normal wear metal level within the discarding limit after 130 h of the long run test. The information coming out of this research would be helpful to researchers working with SVO to overcome the engine problems for its long-term durability or endurance test by adding an additive in a strategic manner. [ABSTRACT FROM AUTHOR]

A 5-cell solid oxide fuel cell (SOFC) stack with external manifold structure is assembled and underwent a durability test with an output of 250 W for nearly 4400 h when current density and operating temperature are 355 mA/cm 2 and 750 °C. Cells used in the stack are anode-supported cells (ASC) with yttria-stabilized zirconia (YSZ) electrolytes, Ni/YSZ hydrogen electrodes, and YSZ based composite cathode. The dimension of the cell is 150 × 150 mm (active area: 130 × 130 mm). Ceramic-glass sealant is used in the stack to keep the gas tightness between cells, interconnects and manifolds. Pure hydrogen and dry air are used as fuel and oxidant respectively. The stack has a maximum output of 340 W at 562 mA/cm 2 current density at 750 °C. The stack shows a degradation of 1.5% per 1000 h during the test with 2 thermal cycles to room temperature. After the test, the stack was dissembled and examined. The relationship between microstructure changes of interfaces and degradation in the stack are discussed. The microstructure evolution of interfaces between electrode, contact material and current collector are unveiled and their relationship with the degradation is discussed. [ABSTRACT FROM AUTHOR]

The present paper reports on the data of the Ni-Zr 0.9 Sc 0.1 O 1.95 anode polarization resistance long-term test (1500 h) at 600 °С in the wet hydrogen and 30% H 2 + 70% H 2 O. The results are presented for two type of anodes: initial and impregnated with ceria. The fast degradation of both types of anodes in 30% H 2 + 70% H 2 O was observed. After the long-term tests in 30% H 2 + 70% H 2 O at 600 °C, heating and exposure at 900 °C in wet hydrogen leads to the restore of anode performance. At the termination of the 1500 h test, the area polarization specific resistance of Ni-Zr 0.9 Sc 0.1 O 1.95 remained almost unchanged as compared to the initial value, whereas for impregnated anodes the polarization resistance increased three times. The observed phenomena were explained by the OH − ions adsorption at the positively charged nickel surface. During the long-term tests at 600 °С the electrode microstructure did not change and the significant sintering of highly disperse ceria was not observed. [ABSTRACT FROM AUTHOR]

A solid oxide short stack composed of 6 Ni-YSZ supported cells, YSZ electrolyte and GDC-LSC oxygen electrode has been tested for 10,700 hours in steam electrolysis. Initial degradation was followed by a global stabilization of the performance after lowering the current density, with a degradation rate below 0.5% kh−1. Post-test analysis has been conducted on two repeating units (RUs) to highlight the most significant microstructure alterations. Nickel depletion was observed in the hydrogen electrode close to the interface with the electrolyte. Formation of small pores in the electrolyte was detected along the grain boundaries. A consequent detachment related to this phenomenon was observed in proximity of the GDC compatibility layer. At the oxygen electrode side, the formation of a ∼1 µm dense mixed layer of GDC and YSZ was observed. Strontium from the LSC electrode migrated through GDC pores and reacted with YSZ, forming evident SrZrO3 inclusions. Distinct accumulation of silicon at the Ni/YSZ interface and chromium on the GDC barrier layer have been observed in both RUs. Despite this range of alterations observed, the stack degradation remained limited, testified from the fact that performance decay between 4,000 and 10,000 hours of operation was virtually nil. [ABSTRACT FROM AUTHOR]

Telescopic crowns are used to connect removable dental prostheses with the remaining dentition. Several material combinations are used for manufacturing primary and secondary crowns. The present experimental study analysed the influence of different material combinations on the long-term development of surface roughness and pull-off forces. Six different material combinations were tested. Secondary crowns were manufactured either by casting or electroforming. Each material combination was tested with n = 10 specimens. A material testing device with integrated power sensors was used for 10,000 cycles per test. Signs of wear were identified by surface roughness measurements, and visualized by a scanning electron microscope (SEM) and X-ray spectroscopy (EDX) technologies. Statistical significances were tested by using the U-Test with Bonferroni correction. The choice of materials and the manufacturing process were found to influence the long-term development of pull-off forces as well as wear-associated surface roughness. Combinations of different groups of materials for primary and secondary crowns showed favourable results. Worse results were found for the combination pure titanium and pure titanium and the combination high gold alloy and electroformed gold. Wear-associated surface roughness was higher for combinations of similar or identical groups of materials. For manufacturing telescopic crowns, combinations of different groups of materials are preferred. For secondary crown manufacturing, electroforming is superior to casting. [ABSTRACT FROM AUTHOR]

Nowadays, the operating temperature of polymer electrolyte membrane fuel cell stacks is typically limited to 80 °C due to water management issues of membrane materials. In the present work, short-term operation at elevated temperatures up to 120 °C and long-term steady-state operation under automotive relevant conditions at 80 °C are examined using a 30-cell stack developed at DLR. The high temperature behavior is investigated by using temperature cycles between 90 and 120 °C without adjustment of the gases dew points, to simulate a short-period temperature increase, possibly caused by an extended power demand and/or limited heat removal. This galvanostatic test demonstrates a fully reversible performance decrease of 21 ± 1% during each thermal cycle. The irreversible degradation rate is about a factor of 6 higher compared to the one determined by the long-term test. The 1200-h test at 80 °C demonstrates linear stack voltage decay with acceptable degradation rate, apart from a malfunction of the air compressor, which results in increased catalyst degradation effects on individual cells. This interpretation is based on an end-of-life characterization, aimed to investigate catalyst, electrode and membrane degradation, by determining hydrogen crossover rates, high frequency resistances, electrochemically active surface areas and catalyst particle sizes. [ABSTRACT FROM AUTHOR]

The chemical looping concept provided a novel way to achieve carbon separation during the production of energy or substances. In this work, hydrogen generation with inherent CO capture in single packed bed reactor via this concept was discussed. Two oxygen carriers, FeO 60 wt.% and FeO 55 wt.%/CuO 5 wt.% supported by AlO, were made by ball milling method. First, according to the characteristics of the reduction breakthrough curve, a strict fuel supply strategy was selected to achieve simultaneous CO capture and H production. Then, in the long term tests using CO as fuel, it was proved that CuO addition improved hydrogen generation with the maximum intensity of 3700 µmol H2·g FeO compared with Fe-Al of 2300 µmol H2·g FeO. The overall CO capture efficiency remained 98%-98.8% over 100 cycles. Moreover, the reactivity of deactivated materials was recovered nearly like that of fresh ones by sintering treatment. Finally, two kinds of complex gases consist of CO, H, CH and CO were utilized as fuels to test the feasibility. The results showed all components could be completely converted by Fe-Cu-Al in the reduction stage. The intensity of hydrogen production and the overall CO capture efficiency were in the range of 2000-2400 µmol H2·g FeO and 89%-95%, respectively. [ABSTRACT FROM AUTHOR]

In this work, the feasibility of a 150 cm 2 high-temperature proton exchange membrane fuel cell (HT-PEMFC) stack operated with modified proton exchange membranes is demonstrated. The short fuel cell stack was manufactured using a total of three 50 cm 2 membrane electrode assemblies (MEAs). The PEM technology is based on a polybenzimidazole (PBI) membrane. The obtained results were compared with those obtained using a HT-PEMFC stack with unmodified membranes. The membranes were cast from a PBI polymer synthesized in the laboratory, and the modified membranes contained 2 wt.% micro-sized TiO 2 as a filler. Long-term tests were performed in both constant and dynamic loading modes. The fuel cell stack with 2 wt.% TiO 2 composite PBI membranes exhibited an irreversible voltage loss of less than 2% after 1100 h of operation. In addition, the acid loss was reduced from 2% for the fuel cell stack with unmodified membranes to 0.6% for the fuel cell stack with modified membranes. The results demonstrate that introducing filler into the membranes enhances the durability and stability of this type of fuel cell technology. Moreover, the fuel cell stack system also exhibits very rapid and stable power and voltage output responses under dynamic load regimes. [ABSTRACT FROM AUTHOR]

Telescopic crowns are used to connect removable dental prostheses with the remaining dentition. Several material combinations are used for manufacturing primary and secondary crowns. The present experimental study analysed the influence of different material combinations on the long-term development of surface roughness and pull-off forces. Six different material combinations were tested. Secondary crowns were manufactured either by casting or electroforming. Each material combination was tested with n = 10 specimens. A material testing device with integrated power sensors was used for 10,000 cycles per test. Signs of wear were identified by surface roughness measurements, and visualized by a scanning electron microscope (SEM) and X-ray spectroscopy (EDX) technologies. Statistical significances were tested by using the U-Test with Bonferroni correction. The choice of materials and the manufacturing process were found to influence the long-term development of pull-off forces as well as wear-associated surface roughness. Combinations of different groups of materials for primary and secondary crowns showed favourable results. Worse results were found for the combination pure titanium and pure titanium and the combination high gold alloy and electroformed gold. Wear-associated surface roughness was higher for combinations of similar or identical groups of materials. For manufacturing telescopic crowns, combinations of different groups of materials are preferred. For secondary crown manufacturing, electroforming is superior to casting.

Abstract: Selective CO methanation was carried out over 10 wt%Ni/TiO2 and 0.5 wt%Ru–10 wt%Ni/TiO2, and the durability was examined. During the long-term test, both catalysts abated CO concentration from 0.25% (dry base) to less than 0.05% above ca. 175 °C with CO2 methanation suppressed. Ru–Ni/TiO2 exhibited the high activity of CO methanation compared to Ni/TiO2 during the test. Furthermore, for more than 5500 h, Ru–Ni/TiO2 maintained a wide temperature window for selective CO methanation (>50 °C), where CO and CH4 concentrations were <0.05% and <1%, respectively, at a high gas hourly space velocity of 10,000 h−1. Over Ni/TiO2 and Ru–Ni/TiO2, CO2 methanation activity was initially enhanced, and then stabilized. The initial promotion of CO2 methanation activity is possibly due to the reduction of NiO which remained unreduced after the prereduction by H2 at 450 °C. [Copyright &y& Elsevier]

[Display omitted] • A long-term test of methane-assisted waste cooking oil valorization was performed. • The process was carried out in a fixed bed reactor with a tailored catalyst. • The properties of feed and product oils were determined. • The quality of product oil was improved and reached biodiesel standards. • The successful operation confirmed the technique's feasibility for industrialization. Developing novel, renewable and environmentally friendly fuel resources is a critical and urgent need for realizing a sustainable energy supply. Waste cooking oil (WCO), which was previously inappropriately treated or discarded, is a prominent biomass source with unique advantages for fuel production. Methane is another naturally abundant and cost-effective resource if it can be directly used in various chemical processes. The studies regarding WCO-based biodiesel production and methane-assisted biomass upgrading processes have been already established. Inspired by the concepts, a WCO valorization process under a methane environment can be expected to be promising both economically and environmentally. In this work, a 30-day long-term waste cooking oil valorization process under methane over a specifically designed catalyst was performed. The feed and product oils were comprehensively analyzed, in terms of viscosity, density, flash point, cloud point, freezing point, pour point, free fatty acid content, iodine number, total acid number, water content, ash content, organochlorine content, cetane number, heating value, oxidative stability, residual carbon, as well as distillation and elemental analyses. It was confirmed that the WCO valorization process under methane is successfully achieved with greatly improved oil qualities, overcoming the disadvantages of WCO-derived biodiesel for practical use and complying well with the corresponding renewable diesel standards, and thus demonstrating strong feasibility for further industrialization. [ABSTRACT FROM AUTHOR]

Molten carbonate electrolysis cells have recently gained interest for the sustainable production of H 2 or syngas to substitute fossil fuels. However, they can be also used for CO 2 sequestration, as they pump it from one electrode inlet to the opposite electrode outlet. Thus, they can easily be applied to segregation of CO 2 from H 2 based fuels while also increasing the fuel heat of combustion for example after a steam reforming reactor. To explore the use of molten carbonate electrolysis cell for this application, in this work the authors investigate the performance of the cell under different operating conditions in term of both operating temperature and fuel electrode gas composition. Polarization curves, gas crossover and electrochemical impedance spectroscopy are used to evaluate specific issues (high electrolyte losses due to water and temperature) or benefits (excess of H 2 O in regard to CO 2 that allows for higher CO 2 capture rate). After, a series of long-term tests at −150 mA cm−2 and 650 °C are performed to demonstrate long term stability. In particular, before electrolyte loss made the performance unstable, different cells are operated for about 1000 h with an average voltage of about 1.14 V demonstrating also the repeatability of such tests. [Display omitted] • Molten carbonate electrolysis cells can be used for CO 2 capture and H 2 upgrading. • Different molten carbonate electrolysis cells were operated for performance study. • Long-term operations (1000 h) were successfully achieved with repeatability. [ABSTRACT FROM AUTHOR]

Abstract: The disposal of chromated copper arsenate (CCA)-treated waste wood is becoming a serious problem in many countries due to potential leaching of hazardous elements from in-service use in the environment or disposal of solutions after remediation; therefore, it is necessary to develop proper remediation techniques. The effects of concentration, extraction period, temperature, and sequential extraction on the extraction of Cr, Cu, and As from CCA-treated wood using [S,S]-ethylenediaminedisuccinic acid (EDDS), ethylenediaminetetraacetic acid (EDTA), and nitrilotriacetic acid (NTA) were studied. Mobility of metal in the samples was evaluated by using a sequential extraction scheme that could give the information needed to explain different extraction efficiencies for different metals. Results of long-term leaching tests of CCA-treated wood before and after EDDS extraction were used to evaluate Cr, Cu, and As leachability. Kinetic experiments showed that 6 h was the optimum extraction time for all metals and CCA-treated wood. Experimental results showed that EDDS is a very effective chelating agent for the extraction of Cr, Cu, and As from CCA-treated wood. Increased temperature significantly enhanced the extraction efficiency of CCA metals, especially Cr and As. The much better extractability of Cu compared to Cr and As by chelating agents can be attributed to the presence of larger weakly bound fractions. The CCA-treated woods after EDDS extraction have met the EPA's TCLP regulatory limit and could be classified as a non-hazardous waste according to identification standard of hazardous wastes. [Copyright &y& Elsevier]

This paper presents the results of long term experiments of four point bending test with structural laminated glass plates. For experiments 6mm thick annealed Soda-Lime-Silica Glass and three different interlayer laminates were used: Polyvinyl butyral (PVB), Ethylene vinyl acetate (EVA), DuPont's SentryGlas (SG). These types of laminates were chosen because there is a wide range of their possible practical application in buildings’ constructions. Bending creep tests were carried out by applying the four point bending test model. Applied dimensions of the laminated glass plates and loading scheme are from the standard EN 1288-3. Three specimens were tested with the same interlayer laminated glass plates. Tests were successively carried out at three temperatures: + 20°C, + 30°C, + 40°C. Every test took 24hours interval at each temperature, so in total one full experiment took 72hours with one type of interlayer. The deflections at the middle of specimens, volatile displacement between two glass sheets and longitudinal strains at the middle of the laminated plate were measured. In the paper the comparisons of the experimental results between the glass panels with various laminates and at different temperatures are presented. [ABSTRACT FROM AUTHOR]

Abstract: The influence of co-existing gases on the hydrogen permeation was studied through a Pd-coated V89.8Cr10Y0.2 alloy membrane. Preliminary hydrogen permeation experiments have been confirmed that hydrogen flux was 6.26 ml/min/cm2 for a Pd-coated V89.8Cr10Y0.2 alloy membrane (thick: 0.5 mm) using pure hydrogen as feed gas. Also, the hydrogen permeation flux decreased with decrease of hydrogen partial pressure at constant pressure when H2/CO2 and H2/CO2/H2S mixture applied as feed gas respectively and permeation fluxes were satisfied with Sievert's law in different feed conditions. It was found from XRD and SEM results after permeation test that the Pd-coated V89.8Cr10Y0.2 alloy membrane had good stability and durability for various mixture feeding conditions. [Copyright &y& Elsevier]

Abstract: This study examines the operating characteristics and durability of a small direct methanol fuel cell (DMFC) stack (volume: 39.6cm3). To investigate the operating characteristics in a real multi-user operating mode, various load cycles (such as gradual acceleration and deceleration), two operating modes (current mode or voltage mode) and four interrupted operating methods (load on–off, load–methanol on–off, load–air on–off, and load–methanol–air on–off) are used. The durability of the DMFC stack is examined at a constant voltage of 2.4V (0.4V per cell) by using the load–methanol–air on–off mode for more than 2000h. In these tests, the DMFC stack exhibits a rapid, stable and dynamic response regardless of the load cycle and operating mode, though the stack performance and response behaviour vary with the interrupted operating modes. Among the operating modes, the air-interruption modes exhibit better stability and higher performance. Moreover, the load–methanol–air on–off mode provides the stack with good durability and a high performance in a long-term test of 2045h. [Copyright &y& Elsevier]

At NISER-IoP detector laboratory an initiative is taken to build and test Gas Electron Multiplier (GEM) detectors for ALICE experiment. The optimisation of the gas flow rate and the long-term stability test of the GEM detector are performed. The method and test results are presented. [ABSTRACT FROM AUTHOR]

Abstract: In the present paper, a proton exchange membrane fuel cell (PEMFC) using 20wt.% Pt/C as anode and cathode catalysts, and ambient air at cathode was operated at a current density of 160mAcm−2 for 2250h. The measurement results showed that electrochemically active specific areas (S EAS) of both electrode catalysts calculated from CV curves after test evidently decreased. The decay rate of S EAS of anode catalyst was much lower than that of cathode one. X-ray diffraction (XRD), energy dispersive analysis of X-ray (EDAX), and X-ray photoelectron spectrometry (XPS) were employed to characterize the anode and cathode catalysts before and after the life test. The XRD results showed that their crystal structures were perfect, the particle size of new Pt/C catalyst was about 2.5nm, however, the particle sizes of anode and cathode ones markedly increased, and were about 4.9nm and 6.8nm, respectively, after the life test. Furthermore, the size of cathode catalyst was much bigger than that of anode one after test. The Pt element was also found in Nafion® film as shown in EDAX result. The XPS results presented that the content of Pt oxidation states in cathode was much more than that in anode, and the corrosion of carbon support in cathode was also more severe than that in anode after the life test. The experimental results indicated that the increase of particle size of Pt/C catalyst was illustrated with the dissolution/redeposition mechanism. The degradation of cathode catalyst for oxygen electroreduction was one of the main factors affecting on the performance decay of PEMFC. [Copyright &y& Elsevier]

Abstract: Thin wall permeator tubes have been produced by diffusion welding of Pd–Ag foils. These dense metal membranes are proposed for separating and producing ultra-pure hydrogen as a result of their complete hydrogen selectivity. Furthermore, they present high hydrogen permeation fluxes as well as reduced costs on account of their reduced metal thickness. The reliability of these membrane tubes has been continuously tested during over 12 months of experimental campaign in presence of thermal and hydrogenation cycles. The permeability tests have been carried out measuring the hydrogen fluxes under controlled conditions of temperature and trans-membrane differential pressure. In particular, the behaviour of the membrane tube has been investigated in a wide range of temperatures (150–400°C) and pressures (100–200kPa) in order to simulate the use within permeators and membrane reactors where processes for producing hydrogen from hydrocarbons takes place. At temperature of 350–400°C hydrogen permeability values around 1.0×10−8 molm−1 s−1 Pa−0.5 have been measured and they are comparable with the literature data. A new mechanical design (finger-like configuration) of the membrane module has ensured the long life of the Pd–Ag permeator. The complete hydrogen selectivity of the membrane has been demonstrated by the tests. [Copyright &y& Elsevier]

[Display omitted] • The MnO 2 nanowires were wrapped by the Ni(OH) 2 nanosheets in the MnO 2 -Ni(OH) 2 composites. • 1.0 nw MnO 2 -1.0 @CP electrode showed cell voltage of 1.64 V and a low Tafel slope of 68 mV dec−1. • Faradaic efficiency of 96.2% kept on for 300 h. • The synergy between nw MnO 2 and ns Ni(OH) 2 accompanies a lattice oxygen participant adsorbate evolving mechanism. To improve and maintain the oxygen evolution reaction (OER) performance of MnO 2 in water electrolysis for a long time, this study attempts to utilize Ni(OH) 2 nanosheets (ns), which have excellent electrochemical properties. Nanocomposites of MnO₂ and Ni(OH) 2 were directly grown on a carbon paper (CP) electrode using hydrothermal synthesis. The MnO 2 nanowires (nw) appeared to be wrapped by the Ni(OH) 2 nanosheets in the MnO 2 -Ni(OH) 2 composites. The MnO 2 -Ni(OH) 2 composite electrode exhibited better OER performance than the nw MnO 2 @CP or ns Ni(OH) 2 @CP electrodes. In particular, in a 1.0 M KOH alkaline electrolyte, the 1.0 nw MnO 2 -1.0 ns Ni(OH) 2 @CP electrode showed the highest OER performance with a cell potential of 1.64 V and Tafel slope of 68 mV dec−1 at a 10 mA cm−2 of current density (η = 0.41 V). The X-ray photoelectron spectroscopy of nw MnO 2 - ns Ni(OH) 2 @CP before and after the OER revealed the formation of more oxygen vacancies, which served as OH-adsorption sites, leading to higher OER activity. The stability of the 1.0 nw MnO 2 -1.0 ns Ni(OH) 2 @CP electrode was demonstrated through 300 h-OER long-term tests, which yielded a high Faradaic efficiency of 96.2%. The lattice oxygen transfer plays a significant role in enhancing the intrinsic activity of catalysts during OER. The synergy between nw MnO 2 and ns Ni(OH) 2 accompanies a lattice oxygen participant adsorbate evolving mechanism. [ABSTRACT FROM AUTHOR]

A systematic study is carried out to determine the optimum electrospinning preparation condition to prepare an adequate electrospun nanofibrous membrane (ENM) for direct contact membrane distillation (DCMD). A structural properties investigation of ENM was carried out because of the significant impact of its architectural structure, nanofiber diameter, inter-fiber space and ENM thickness, on DCMD performance. The morphology, hydrophobicity, mechanical properties, crystallinity and DCMD desalination were investigated. A long-term DCMD experiment (100 h) was carried out using 30 g/L NaCl aqueous solution, both in the feed and permeate side of the optimum ENM membrane to evaluate its potential to produce drinkable water in case of lack of distilled water, for instance in a remote area, emergency situation, and/or portable system. In this case, drinkable water could be produced after 28 h with a permeate flux of 57.5 kg/m2.h and a salt rejection factor greater than 99.9%. Another long-term DCMD experiment (65 h) was conducted using 30 g/L NaCl aquesous solution as feed but at a higher temperature and distilled water as permeate to evaluate the desalination stability, wettability and scaling of the optimum ENM. A permeate flux of 58.5 kg/m2.h was obtained with a salt rejection factor greater than 99.9%. [Display omitted] • Electrospinning parameters dictate the ENMs morphology, hydrophobicity, and porosity. • The nanofiber diameter and ENM thickness affect membrane properties and performance. • ENMs can be developed for long-term direct contact membrane distillation (DCMD) tests. • ENMs could be a good candidate for portable DCMD to produce drinkable water. • ENMs can be used for water production in remote areas and emergency situations. [ABSTRACT FROM AUTHOR]

An electrochemical remediation technology, referred to as E lectro c hemical G eo- O xidation (ECGO) was tested in field to assess its potential to treat polychlorinated biphenyls (PCBs) contaminated sediments from New Bedford Harbor (NBH), Massachusetts. The primary objective was to evaluate the effectiveness of ECGO for reducing PCB levels under the anaerobic conditions typical of saturated and submerged sediments. The ECGO treatment of aerated and un-aerated (anaerobic) samples of the NBH sediments began on November, 2003 and lasted over four-years until early July, 2008. During 2003–2006 seven sampling events occurred, and the last sampling was done on March, 2010, about 20 months after the treatment power was turned off on July 12, 2008. Full PCB congener analyses (EPA 22 1668A) and partial PCB scans (EPA Method 8082) were performed on samples collected from the ECGO test cells and the control cell. At the end of the first 30-month period, the sample analyses indicated about 30% reduction in total PCB levels in un-aerated ECGO test cell compared to the control. The eighth and final sampling in March 2010 showed that total PCBs had been greatly reduced in the un-aerated test cell, from about 40,000 μg/kg (ppb) to 200 μg/kg (ppb). Conversely, PCB levels in sediments contained in the aerated ECGO test cell remained relatively unchanged compared to the pre-test level and control. This represented a greater than 90% reduction in total PCBs relative to the 2003 starting levels and the control sample average. The final results indicated that ECGO was effective at degrading PCBs in a reducing environment. [ABSTRACT FROM AUTHOR]

Despite the great advantages of high-temperature polymer electrolyte membrane (HT-PEM) fuel cells over the low-temperature (LT) PEM alternative, such as enhanced reaction kinetics and higher tolerance against impurities like CO due to the higher operation temperature, the achievement of high lifetimes still remains a challenge. In order to improve the durability of the fuel cell, extensive research has been carried out on alternatives for the individual components. For this reason, this paper conducted extended long-term tests with three three membrane electrode assemblies (MEAs) from one manufacturer under different operational scenarios. The MEAs differed mainly by the membranes used and showed significantly different behaviors. While the first MEA reached the end of life already after 2600 h, the second one could pass 9800 h almost without any problems. The third MEA proved resistant to adverse conditions. For all three MEAs, extensive electrochemical characterizations and μ-CT examinations for the analysis of long-term stability are shown. [ABSTRACT FROM AUTHOR]

• The research of a tool wear and tool durability is an important issue of manufacturing today. • A synergic effect of cutting speed and depth on the wear of HSS-PM cutters was investigated. • Several types of wears were identified on the cutting tools resulted in a worse quality of the machined surface. • Tool wear development has an impact on the machining process stability and it affects also a change of chip. Tool durability is an important parameter in the evaluation of the performance of the cutting tools and inserts. It is directly connected with tool wear that significantly affects the quality of the workpiece. Only from an understanding of the nature behind the machining process in given conditions (a combination of cutting parameters, machined material, tool characteristics including its material, etc.), a tool wear mechanism can be identified and consequently estimate the tool life and its durability. The article deals with a durability of the milling cutters produced from the high-speed steel via powder metallurgy (HSS-PM) and coated by AlTiN coat. Effects of a varying combination of cutting speed and depth of cut to tool wear and surface roughness had been also investigated within the long-term tests. Conventional milling was selected as a technology to test the durability of HSSE-PM shank milling cutters at which the steel 1.4301 (AISI 304, DIN 1.4301) as a material that is very difficult to cut was machined without a coolant. Within the research, the tool wears in several points on a cutting edge were evaluated, while several types of tool wear have been identified. Achieved data were statistically processed and based on them the development of the tool wear of individual milling cutters in time has been processed as well as a dependency of the tool wear on cutting speed and cutting depth has been plotted. The accompanying phenomenon of tool wear increasing is a deteriorated quality of surface roughness and change in a chip formation. The average values of surface roughness Ra relative to machining time achieved by milling cutters working at a specific depth of cut were also assessed. The pictures of the chips approved that along with tool wear increasing the chip becomes thinner with larger rugged relief. [ABSTRACT FROM AUTHOR]

• Design and construction of a novel standard sized a-Si PV/T system are introduced. • Long-term experimental results of the system at medium temperature are presented. • Distributed parameter model is established and validated by experiments. • An insight to heat transfer and power generation is provided. • The technical and thermodynamic feasibility at medium temperature is demonstrated. Medium temperature photovoltaic/thermal (PV/T) systems have immense potential in the applications of absorption cooling, thermoelectric generation, and organic Rankine cycle power generation, etc. Amorphous silicon (a-Si) cells are promising in such applications regarding the low temperature coefficient, thermal annealing effect, thin film and avoidance of large thermal stress and breakdown at fluctuating temperatures. However, experimental study on the a-Si PV/T system is rarely reported. So far the feasibility of medium temperature PV/T systems using a-Si cells has not been demonstrated. In this study, the design and construction of an innovative a-Si PV/T system of stainless steel substrate are presented. Long-term outdoor performance of the system operating at medium temperature has been monitored in the past 15 months. The average electrical efficiency was 5.65%, 5.41% and 5.30% at the initial, intermediate and final phases of the long-test test, accompanied with a daily average thermal efficiency from about 21% to 31% in the non-heating season. The thermal and electrical performance of the system at 60 °C, 70 °C and 80 °C are also analyzed and compared. Moreover, a distributed parameter model with experimental validation is developed for an inside view of the heat transfer and power generation and to predict the system performance in various conditions. Technically, medium temperature operation has not resulted in interruption or observable deformation of the a-Si PV/T system during the period. The technical and thermodynamic feasibility of the a-Si PV/T system at medium operating temperature is demonstrated by the experimental and simulation results. [ABSTRACT FROM AUTHOR]