Thermoeconomic optimization of insulation thickness considering condensed vapor in buildings

Developing technology and increasing population makes energy consumption more important. Most of energy is used for space heating in Turkey, consequently, insulation of external walls is too important. In the present work, optimum insulation thickness considering condensed vapor in existing buildings for Kutahya which is one of coldest cities in Turkey has been studied. The optimization is based on the thermoeconomic analysis. Since Kutahya is the most polluted city in Turkey, and the source of this pollution is energy consumption, it has become an obligation to save energy and to reduce its effects. In this study, exergy method with the different reference states which are normally available in a building has been used. The effect of condensed vapor on exergy also has been taken into account. The optimum insulation thickness determined as 0.060, 0.065, 0.075 m with a rate of 74.9%, 76.3% and 78.8% in the energy saving for indoor temperature of 18, 20 and 22 °C, respectively. Therefore, a decreasing in the air pollutants about at same rates has been obtained.     

Sharing the floodplain: Mediated modeling for environmental management

Complex ecosystems, such as the Upper Mississippi River (UMR), present major management challenges. Such systems often provide a range of ecosystem services that are differentially valued by stakeholders representing distinct interests (e.g., agriculture, conservation, navigation) or institutions (e.g., federal and state agencies). When no single entity has the knowledge or authority to resolve conflicts over shared resource use, stakeholders may struggle to jointly understand the scope of the problem and to reach reasonable compromises. This paper explores mediated modeling as a group consensus building process for understanding relationships between ecological, economic and cultural well-being in the UMR floodplain. We describe a workshop structure used to engage UMR stakeholders that may be extended to resource use conflicts in other complex ecosystems. We provide recommendations for improving on these participatory methods in structuring future efforts. In conclusion, we suggest that tools which facilitate collaborative learning, such as mediated modeling, need to be incorporated at an institutional level as a vital element of integrated ecosystem management.     

Carbon black reinforced C8 ether linked bismaleimide toughened electrically conducting epoxy nanocomposites

The present work deals with the toughening of brittle epoxy matrix with C8 ether linked bismaleimide (C8 e-BMI) and then study the reinforcing effect of carbon black (CB) in enhancing the conducting properties of insulating epoxy matrix. The Fourier transform infrared spectroscopy (FTIR) and Raman analysis indicate the formation of strong covalent bonds between CB and C8 e-BMI/epoxy matrix. The X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) analysis indicate the event of phase separation in 5 wt% CB loaded epoxy C8 e-BMI nanocomposites. The impact strength increased up to 5 wt% of CB loading with particle pull and crack deflection to be driving mechanism for enhancing the toughness of the nanocomposite and beyond 5 wt% the impact strength started to decrease due to aggregation of CB. The dynamic mechanical analysis (DMA) also indicates the toughness of the nanocomposites was improved with 5 wt% of CB loading due to the phase segregation between epoxy and C8 e-BMI in the presence of CB. The electrical conductivity was also increased with 5 wt% of CB due to classical conduction by ohmic chain contact.     

Optimized energy storage performance in BF-BT-based lead-free ferroelectric ceramics with local compositional fluctuation

BiFeO₃-based lead-free ferroelectric is considered a potential candidate for energy storage applications owing to its high spontaneous polarization. To tackle the compromise between high polarization and energy storage density, NaNbO₃ (NN) was introduced into 0.7BiFeO₃-0.3Ba(Hf_0.05Ti_0.95)O₃ (BF-BHfT) ceramics, where Nb⁵⁺ ions enter the BF-BHfT lattices and enhance resistivity, while Na⁺ ions occupied on the A-sites and smash the long-range ferroelectric order into polar nanoregions. Consequently, the ceramics could maintain high maximum polarization and low remanent polarization. High recoverable energy density (W_rec) of 5.2 J/cm³ and efficiency (88%) were recorded in 0.53BF-0.3BHfT-0.17NN ceramics. Besides, it exhibited good thermostability up to 120 °C (W_rec variation < 5%), frequency stability from 10 to 200 Hz (W_rec variation < 7%) and excellent fatigue resistance after 10⁴ cycles (W_rec variation < 0.2%). Under different electric fields the efficiency still maintains nearly constant. In charge-discharge test a W_dis of 3.7 J/cm³ was recorded, which proved 0.5³BF-0.3BHfT-0.17NN ceramics a promising candidate for energy storage applications.     

Elucidation the role of Co-MOF on hematite for boosting the photoelectrochemical performance toward water oxidation

Developing an efficient photoanode to convert solar energy into hydrogen fuel confronts big challenges owing to the sluggish water oxidation kinetics. Herein, we proposed a feasible method to coat Co-based metal-organic framework (Co-MOF) on Ti doped α-Fe₂O₃ and revealed its functions on the oxygen evolution reaction (OER) and photoelectrochemical (PEC) water oxidation. The Co-MOF/Ti–Fe₂O₃ showed a photocurrent density of 1.01 mA/cm² (1.23V_RHE) with a low turn-on voltage (V_on) of 0.80 V_RHE. The significant improvement of photocurrent density which was ca. 3 times higher than the pristine Fe₂O₃, was contributed by the improved charge separation efficiency on the surface rather than in the bulk. And this was validated by the increased trapping capacitance (C_trap) and reduced charge transport resistance (R_ct). Additionally, the low V_on was attributable to the compromise of introduced surface states and the catalytic effect of the Co-MOF. In this work, we discovered the Co-MOF not only offered catalysis sites for OER, but shed light on its influence on the overall PEC water oxidation, and led to an in-depth understanding of cocatalysts on the PEC water splitting.     

High-concentration coal–water slurry from Indian coals using newly developed additives

Coal–water slurry (CWS) holds promise to offer a long-term alternative to fuel oil, and also it is being conceived as an attractive fuel for power generation industry in India. The essential requirements of the CWS technology, viz., the additive package, concentration of additives, particle size distribution (PSD) of coal, solids loading, methodology for CWS formulation and its rheological properties, have been discussed and reported here. The effect of the two newly developed anionic additives in the formulation of CWS has been studied. The basic parameters were established taking beneficiated Ledo coal samples with 9.7% ash content. Ball milling of the coal samples in a wet grinding process could produce particle size distributions most suited for highly loaded CWS. Coal loadings to the extent of 70% in the CWS have been achieved using a concentration of 0.8 wt.% (on coal charge) of the naphthalene-based additive referred to as ‘P’. Using 0.9 wt.% of the naphthalene-toluene-based additive denoted as ‘R’, a coal loading of 69% has been achieved. The viscosities of the slurries were found to be below 1000 mPa s. The shelf lives of slurries were found to be 22 and 20 days with the use of additives P and R, respectively, in the CWS formulation. The two additives functioned well in CWS formulation with Sirka coal having relatively higher ash content (14.4%). Using the specified concentration of the additives P and R, the solid loadings of 67% and 65%, respectively, could be obtained under the established parameters. The lower values of solids loading from Sirka coal than that from Ledo coal in CWS formulation may be attributed to the higher percentages of oxygen-containing functional groups (O_OH and O_COOH), ash content and higher O/C ratio of Sirka coal.     

Influence of concrete composition on the characterization of fracture surface

An experimental method based on laser triangulation was used to measure the 3-D profile of fracture surface of concrete. The projective-covering method was established to determine the fractal characteristics of fracture surface. Based on the experiment, the influence of composition of concrete on the fractal dimension, including water–binder ratio, maximum aggregate size and aggregate type, was investigated. The variation of fractal dimension with the material composition was also analysed to make further understanding of fracture mechanism of concrete.     

Sodium dodecyl sulfate-assisted SILAR synthesis of nanostructured cadmium oxide films

Nanostructured CdO films were prepared on glass substrates by a surfactant – sodium dodecyl sulfate (SDS) – assisted SILAR technique. The influence of SDS concentrations of the growth solution on the structural, morphological and optical properties of the films was investigated and discussed. From the metallurgical microscope and scanning electron microscope images, it was seen that the surface morphology of the films are significantly enhanced by SDS addition. XRD investigations confirmed that the films have good crystallinity levels and are grown preferentially in (111) and (200) orientations. UV–vis. spectroscopy investigations showed that the bandgap and transmittance values of the films are affected dramatically by SDS concentrations.     

Characterizing delamination of fibre composites by mixed mode cohesive laws

A novel method is used for the determination of mixed mode cohesive laws and bridging laws for the characterisation of crack bridging in composites. The approach is based on an application of the J integral. The obtained cohesive laws were found to possess high peak stress values. Mixed mode cohesive stresses were found to depend on both the normal and tangential crack opening displacements. The bridging laws, which are to be used together with a mode mixity dependent crack tip fracture energy, were found to possess relative low bridging stresses; the peak normal bridging stress was approximately 2 MPa during pure Mode I and the maximum shear stress during pure Mode II was about 10 MPa.     

Influence of moisture absorption on the interfacial strength of bamboo/vinyl ester composites

Moisture absorption is a major concern for natural fibers used as reinforcement in structural composites. This paper reports a detailed study on the moisture sorption characteristics of bamboo strips and their influence on the interfacial shear strength (IFSS) of bamboo/vinyl ester composite. The IFSS determined by pull-out test decreased dramatically as the fabrication humidity increased. The bamboo strips provide a reservoir of moisture which diffuses into the interfacial region and inhibits the hardening of vinyl ester matrix. The interface of the bamboo/vinyl ester composite can also be damaged due to moisture exposure after fabrication. Post-fabrication exposure of composites to moisture was found to be less damaging than the moisture exposure during the composite fabrication. The IFSS of the composite decreased by nearly 40% in the first 9 d of water immersion. Further immersion up to 100 d did not cause any further reduction in interfacial shear strength.