Search

Highlights As is well known, Laser print paper is usually produced with high‐quality chemical wood pulp. The laser print waste paper fiber (LPWF) is a high‐quality secondary fiber, and the research and development of high‐value utilization technology for laser print waste paper has attracted much attention in the field of renewable resource recycling. In this study, LPWF was used to reinforce poly(lactic acid) (PLA) composites in the field, and the composites were modified with bioenzyme, cationic polyacrylamide (CPAM), and nano‐silicon carbide (Nano‐SiC) to enhance the interfacial compatibility of LPWF/PLA composites. The study systematically investigated the effects of various modification methods on the characteristics and degradability of composites made from laser print waste paper fiber reinforced PLA resin matrix. The results showed that the mechanical properties of the composites treated with CPAM and Nano‐SiC were significantly improved, with tensile strengths of 54.3 and 59.5 MPa, and flexural strengths of 85.1 and 91.5 MPa, respectively, and the water absorption of the composites was reduced after the modification treatment, while the thermal stability was improved. The degradation performance of the composites in various water environments indicated that the inclusion of LPWF accelerated the water degradation rate of the composites, with the maximum degradation rate of the composite reaching 1.26% in 30 days. Laser print waste paper is an excellent quality recyclable fiber resource. Four modifiers were used to modify LPWF/PLA composites. Characteristics and degradability of the composites were investigated. Significantly improved properties of CPAM and Nano‐SiC modified composites. The degradation rate of composites is increased by the addition of LPWF. [ABSTRACT FROM AUTHOR]

In this paper, a titanium dioxide/covalent organic framework (TiO2/COF) composite was prepared and its photocatalytic removal of dye was investigated. Using tetrabutyl titanate as a titanium source, TiO2 nanomaterial was prepared by sol‐gel method. In the presence of TiO2, TiO2/COF core‐shell composite was prepared by solvothermal synthesis using melamine and 1,4‐phthalaldehyde as ligands. The prepared materials are characterized by SEM, TEM, XPS, XRD, TG, FTIR, BET, EPR, PL, and UV‐Vis‐DRS techniques. Using malachite green as a model of dye wastewater, the photocatalytic degradation performance of TiO2/COF composites was investigated under the irradiation of ultraviolet light. The results show that the modification of COF significantly improves the photocatalytic efficiency of TiO2, the degradation rate increases from 69.77 % to 93.64 %, and the reaction rate constant of the first‐order kinetic equation is increased from 0.0078 min−1 to 0.0192 min−1. Based on the free radical capture experiment, the photocatalytic degradation mechanism of TiO2/COF was discussed, and the feasibility of its photocatalytic degradation of malachite green was theoretically clarified. Accordingly, a simple and practical method for photocatalytic degradation of malachite green was constructed, which has potential application value in the degradation of dye wastewater. [ABSTRACT FROM AUTHOR]

Statement of Problem: Direct resin composite bonding offers a highly esthetic, minimally invasive option for the treatment of anterior teeth however the challenge to improve their longevity remains. Direct resin composite restorations are limited by the risk of staining which may be influenced by the final surface roughness (Ra) of composite achieved. Purpose: The purpose of this review is to investigate, using a systematic approach, whether the final surface roughness of anterior composite restorations is affected by the interaction between resin composite and polishing systems. Materials and Methods: The review was conducted by 3 independent reviewers and included articles published up to January 21, 2021. Three electronic databases were searched: Medline, Embase, and Web of Science. Studies assessing a quantitative effect of polishing methods on the Ra of direct composite resin materials published after the year 2000 and restricted to the English language were included. Results: The database search for the effect of polishing systems on composite materials retrieved 125 eligible studies. Twelve duplicate records were removed. The resulting records were screened using title and abstract leading to 38 reports which were sought for retrieval. Application of eligibility criteria led to 11 studies included in the review. Hand searching of these studies yielded no additional papers. Conclusions: There is insufficient evidence to determine whether combination of composite and polisher influences final Ra. More research is required to determine if there is an optimum combination of polisher and composite. Clinical Implications: Polishing should be completed following planned finishing procedures. The approximation to the final surface and which finishing burs to use, if any, should be considered when planning a restoration. Durafill VS predictably achieves an acceptable Ra by different polishers. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate analytical and experimental flexural behavior of a latest composite beam model. The cross section comprises tapered inverted steel T‐beam embedded within the RC concrete slab, by simple steel reinforcement bar bent in to L‐shape as shear connectors welded to web. The slab is reinforced with longitudinal and transverse bars fixed on the top of L‐shape connectors. The paper shows the structural behavior difference between the composite model with a tapered inverted steel T‐beam and the composite model with non‐tapered inverted steel T‐beam. Failure modes either by cracking of compression concrete or L‐shape connection failure, will be investigated. Suggested designing curves and valuable equations will be presented. This model is of a great bid for roofs and fast accommodations, due to its convenience, flexibility, cost‐effective and availability of its low‐priced components. [ABSTRACT FROM AUTHOR]

The continuous updating and iteration of electronic devices brings about a significant accumulation of heat. It is urgent to enhance the thermal properties of polymer‐based composites to alleviate the heat dissipation problem in the microelectronics industry. In this paper, the hot drawing process was introduced to increase the crystallinity of ultra‐high molecular weight polyethylene (UHMWPE) fiber and improve its thermal conductivity. The ultra‐high molecular weight polyethylene fiber/epoxy resin (UHMWPE fiber/Epoxy) composites with high thermal conductivity were prepared by compositing UHMWPE fiber with epoxy resin under vacuum conditions. Due to the good crystallinity of the UHMWPE fiber (86%), an efficient thermal conduction path is provided for phonons in the axial direction along the fibers. The results show that the thermal conductivity of the composites reaches a maximum of 3.51 W/mK (in‐plane), which is 17.47 times higher than that of the epoxy resin (0.19 W/mK). The thermography pictures indicate that the composites have better heat transfer capacity with an increase in the draw ratio (λ). In addition, the composites also have the characteristics of low density and low electrical conductivity. These researches will provide a new idea for the preparation of all‐polymer composites with high thermal properties. Highlights: A hot drawing process was introduced to increase the crystallinity of UHMWPE fiber for improving thermal conductivity.High crystallinity facilitates the reduction of phonon scattering and the transmission of thermal energy by phonons.The obtained polymer composites exhibit an ultra‐high in‐plane thermal conductivity. [ABSTRACT FROM AUTHOR]

Highlights Basalt fibers, known as “green materials without pollution in the 21st century”, have gained widespread attention due to its good mechanical properties. Basalt fiber‐based composites have applications in various fields such as construction, transportation, energy, and protection. However, as an inorganic fiber material, basalt fiber is hard and brittle and prone to catastrophic failure, reducing the safety of the material. Therefore, it is important to strengthen the toughness of basalt fiber‐based composites. This paper reviews the contributions made by researchers in recent years to enhance the toughness of basalt fiber reinforced composites. It mainly focuses on four aspects: physical and chemical modification of fibers surface, mixed application of multiple fibers, different textile and 3D printing technology, and design of biomimetic structures. Through these methods, the toughness of basalt fiber‐reinforced composite materials was increased by 10%–90%. In today's advocacy for green industrial development, the research and application of basalt fibers are very important for advancing the process of green development. These contributions can promote the application of basalt fiber in engineering fields. Basalt fiber is a green material without pollution. Basalt fiber reinforced composites is the key material for engineering field. Strengthening interfacial adhesion can significantly improve the toughness of composites. Basalt fibers can serve as an alternative to glass fibers in composite materials. The hybridization of basalt fibers with soft fibers can effectively enhance the toughness of composites. [ABSTRACT FROM AUTHOR]

Layered design is an important method for improving the loss factor of damping materials. However, the composite loss factor does not increase with the increase of the number of layers of the damping material. In response to this issue, this paper investigates the mechanism by combining experimental and simulation analyses. First, for the damping material itself, the relationship between the material loss factor and the number of damping layers was studied based on dynamic mechanical analysis. Second, for the composite structure of damping material and substrate, the relationship between the composite loss factor and the number of damping layers of the free damping structure was obtained by the cantilever resonance method, and the influence of material and structure parameters on the composite loss factor was clarified by finite element analysis. Finally, for aiming at the composite structure of damping material with constraint layer and substrate, the mechanism of the influence of the number of layers of layered damping material on the uncertainty of the composite loss factor was further investigated and discussed. The results indicated that for free damping structures, the composite loss factor increases with the increase of the number of damping layers only when the elastic modulus of the damping layer is similar to that of the substrate. For constrained damping structures, only when the constraint layer is relatively thin and has a certain amount of density and modulus, the composite loss factor of the constrained damping structure increases as the number of damping layers increases. Highlights: The mechanism by which the number of layers of damping material affects the composite loss factor has been clarified.The composite loss factor does not necessarily increase as the number of layers of damping material increases.The composite loss factor of a free damping structure is mainly influenced by the Young's modulus of the damping layer.The composite loss factor of constrained damping structures is mainly influenced by the thickness, density, and modulus of the constrained layer. [ABSTRACT FROM AUTHOR]

Copyright of Bautechnik is the property of Wiley-Blackwell 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.)

One of the important research components of photocatalytic research is the development of new photocatalysts, and recent studies have shown the rise of borate‐type photocatalysts. This paper focuses on the photoreduction of potassium dichromate and the photodegradation of rhodamine B by two borate composites under simulated sunlight. A coral‐like borate was obtained by sol‐gel preparation and then assembled by photodeposition with Pt nanoparticles dots or CuO particles to obtain the new composites with excellent performance. The kinetic constants of photocatalytic properties of 2 %Pt/Gd0.85Ce0.15B5O9 and 2.5 %CuO/Gd0.90Ce0.10B5O9 samples in the reduction and degradation reactions are 0.0050 min−1 and 0.0150 min−1, which are 25 and 4.2 times of the intrinsic GdB5O9 sample respectively. The results of the study indicate the research promise of developing new visible photocatalysts based on borates, especially for photocatalytic applications for pollutant removal. [ABSTRACT FROM AUTHOR]

One of the important research components of photocatalytic research is the development of new photocatalysts, and recent studies have shown the rise of borate‐type photocatalysts. This paper focuses on the photoreduction of potassium dichromate and the photodegradation of rhodamine B by two borate composites under simulated sunlight. A coral‐like borate was obtained by sol‐gel preparation and then assembled by photodeposition with Pt nanoparticles dots or CuO particles to obtain the new composites with excellent performance. The kinetic constants of photocatalytic properties of 2 %Pt/Gd0.85Ce0.15B5O9 and 2.5 %CuO/Gd0.90Ce0.10B5O9 samples in the reduction and degradation reactions are 0.0050 min−1 and 0.0150 min−1, which are 25 and 4.2 times of the intrinsic GdB5O9 sample respectively. The results of the study indicate the research promise of developing new visible photocatalysts based on borates, especially for photocatalytic applications for pollutant removal. [ABSTRACT FROM AUTHOR]

Ultrasonic guided waves (UGWs) based structural health monitoring (SHM) systems are widely used in several engineering fields for real‐time damage detection, since they are particularly sensitive to material local changes, induced, i.e., by a damage. This paper aims to investigate on the use of SHM systems in additively manufactured laminate. Specifically, a flat panel made of XSTRAND GF30‐PA6 material, fabricated by Ultimaker S5 fused filament fabrication (FFF) based 3D printer, is used as a case study. Signals recorded by a piezoelectrics (PZTs) array are analyzed to highlight the dispersive behavior of symmetric, S0, mode along different measurement paths in the excitation frequency range of 100–300 kHz. [ABSTRACT FROM AUTHOR]

MXenes have unique properties such as high electrical conductivity, excellent mechanical properties, rich surface chemistry, and convenient processability. These characteristics make them ideal for producing flexible materials with tunable microstructures. This paper reviews the laboratory research progress of flexible MXene and its composite materials for supercapacitors. And introduces the general synthesis method of MXene, as well as the preparation and properties of flexible MXene. By analyzing the current research status, the electrochemical reaction mechanism of MXene was explained from the perspectives of electrolyte and surface terminating groups. This review particularly emphasizes the composite methods of freestanding flexible MXene composite materials. The review points out that the biggest problem with flexible MXene electrodes is severe self‐stacking, which reduces the number of chemically active sites, weakens ion accessibility, and ultimately lowers electrochemical performance. Therefore, it is necessary to composite MXene with other electrode materials and design a good microstructure. This review affirms the enormous potential of flexible MXene and its composite materials in the field of supercapacitors. In addition, the challenges and possible improvements faced by MXene based materials in practical applications were also discussed. [ABSTRACT FROM AUTHOR]

The bolted joint is widely used to connect different composite structures in the aerospace field, and the joint is usually the weakest part, and its performance is widely influenced by temperature. This paper aims to investigate the static tensile behavior of the composite‐aluminum four‐nailed joint structure at different temperatures. Carbon fiber epoxy resin matrix composites with a layup of [(0/45)2s]2 are selected to fabricate specimens, and the test temperatures are room temperature (RT, 25 °C), 60 °C, 100 °C, and 150 °C, respectively. The surface strain field and damage evolution inside the specimens are monitored at different stages of the loading process by combining the digital image correlation (DIC) and X‐ray computed tomography (CT) techniques. During the loading process at RT, a sudden drop in load occurs after structural yielding, and the following secondary bearing is observed; however, at higher temperatures, the load continuously decreases until final failure after it reaches the peak value. Moreover, the rearrangement of stress distribution around the bolts at higher temperatures relieves the asymmetric secondary bending of the joint. The experimental findings in this study provide valuable guidance for the structural design and safety assessment for composite‐aluminum bolted joints at different temperatures. Highlights: The loading process shows five stages at RT and four stages at higher temperatures.Extrusion damage led by shear cracks appears earlier at higher temperatures.Load on the upper and lower bolts is closer as the temperature increases.Higher temperatures relieve the asymmetric secondary bending of the joint. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are recently used in triboelectric nanogenerator (TENG) to enhance output performance. Although functional groups tremendously influence the output performance of TENG, the effect of functional groups for MOFs on the output performance is yet not systematically studied. In this paper, polydimethylsiloxane (PDMS) composite TENG is designed based on isostructural UiO‐66‐R (R = H, NH2, NO2, and Br) family filler, and the effect of filler with various functional groups on the output performance of the TENG is first systematically studied. All the composites TENG harvest a higher output performance than the pure PDMS TENG. The TENG follows an output performance trend of PDMS@UiO‐66‐NO2 > PDMS@UiO‐66‐Br > PDMS@UiO‐66 > PDMS@UiO‐66‐NH2 > PDMS. The PDMS@UiO‐66‐NO2 TENG exhibits an open‐circuit voltage of ≈191 V and a current of ≈17.3 µA, which are 3.6 times and 4.25 times over that of the PDMS TENG. The working mechanism of the composite TENG is discussed in detail through experimental analysis. This work first proves a novel strategy to improve the output performance by functionalized filler MOFs with large electron‐withdrawing functional groups, and guides us on how to choose high‐efficiency triboelectric filler. [ABSTRACT FROM AUTHOR]

In this paper, the epoxy resin composite filled with wood fiber and fly ash cenosphere was prepared. In order to improve the bonding properties between wooden fiber/fly ash cenosphere and epoxy resin, the grafting treatment of wooden fiber and fly ash cenosphere surfaces was carried out here using KH550 type silane coupling agent. The effects of different process parameters on the surface modification effect of wooden fiber and fly ash cenosphere were investigated, the mechanical properties and energy absorption characteristics of the materials before and after the filler modification were tested, and the microscopic interfacial structures of the matrix with wooden fiber and fly ash cenosphere were investigated by scanning electron microscopy. Meanwhile, based on LS‐DYNA simulation software, the energy‐absorbing performance of energy‐absorbing boxes prepared from AA6061 aluminum alloy and modified wooden fiber‐fly ash cenosphere/epoxy resin composites were compared in low‐velocity collisions. [ABSTRACT FROM AUTHOR]

This paper presents the background, results and conclusions of a series of fire tests with DELTABEAM® composite beams supporting prestressed hollowcore slabs (HCS) concerning the shifted direct support in fire situation. When designing a slab system consisting of DELTABEAM® and HCS in fire situation, the current European design codes and product approvals for both products do not cover the special issues "indirect / shifted direct" and "flexible" support that arise from combining beams and HCS. A test program of single HCS unit shear tests and system fire tests has been carried out to assess these issues. The presented paper will give an overview of the test program and a detailed look at the shifted direct support situation for load transfer from the slab to the beam. [ABSTRACT FROM AUTHOR]

The second generation of Eurocode 4 has been developed through several project teams that report to CEN TC250 Subcommittee 4 (CEN/TC250/SC4) 'Design of composite steel and concrete structures', which is chaired by Dr Graham Couchman. Given that work on the revised version of Eurocode 4 is nearing completion, this paper presents a selection of the changes that will be included, together with some of the technical challenges that needed to be overcome. Finally, further enhancements that might be considered worthy for inclusion within future editions of this standard are presented. [ABSTRACT FROM AUTHOR]

In this study, four typical biocomposites from lignin blended with poly‐3‐hydroxybutyrate‐3‐hydroxyhexanoate (PHBH) using inorganic nanoparticles (INPs) (SiO2, MMT, CaCO3, and BN) as fillers were evaluated, which enhanced the thermal, mechanical, and barrier properties of composites. The results revealed that the selection of suitable INPs doped into the lignin/PHBH (L/P) composites was an important approach to achieve available function. MMT/L/P nanocomposites were significantly higher than those of untreated L/P composites in thermal stability (Tmax exceed 10%) and barrier properties (water vapor and oxygen resistance increased by 48% and 46%), and BN particles increased the initial thermal decomposition temperature by 8%. The elongation at break of CaCO3/L/P and BN/L/P composites were increased by 344% and 319%, while SiO2/L/P composites had the best tensile strength (18.8 MPa). Besides, the INPs/L/P nanocomposites in this paper exhibited excellent ultraviolet (UV) resistance and might become potential anti‐UV packaging materials for grease foods. [ABSTRACT FROM AUTHOR]

In this paper, the double‐element composites were developed, which contained the epoxy resin as matrix phase and carbon black rubber powder as toughening materials. Quasi‐static compression tests on epoxy resin and different mass fractions carbon black rubber powder‐epoxy resin composites were performed in room temperature to test their compression properties. The energy absorption performance and the energy absorption efficiency of the composites were calculated according to the compression curve. The fracture characteristics of the micro appearance of the compressed material specimen were observed by scanning electron microscope. The deformation mode of the composite was analyzed. By systematically analyzing the effects of carbon black rubber powder content on the mechanical properties of carbon black rubber powder‐epoxy resin, it was found that carbon black rubber powder as a reinforced material could effectively improve the brittleness of epoxy resin, the yield strength and the adsorption properties and efficiency of composites. With the mass fraction of carbon black rubber powder increasing, the energy absorption performance of carbon black rubber powder‐epoxy resin first increases and then decreases. The most significant performance observed was at a mass fraction of 5 % in carbon black rubber powder‐epoxy resin composites. [ABSTRACT FROM AUTHOR]

Bismaleimide resin (BMI) is a thermosetting resin with excellent properties. However, due to its poor toughness as a cured product, this paper uses hyperbranched polyimide (HBPI) and nano‐SiO2 in a synergistic manner to improve the performance of BMI. Isophorone diisocyanated tripolymer (IPDI trimer) and methyl nadic anhydride (MNA) were used to synthesize HBPI, and then we investigated the effect of the synergistic modification on the mechanical and thermal properties and the modification mechanism of HBPI and nano‐SiO2. The experiments showed that the most significant improvements were achieved at the addition of 40 and 3 wt% of HBPI and nano‐SiO2 respectively, with the impact strength of the materials increasing by 97.2%, fracture toughness indexes GIC and KIC increased by 36.7% and 34.6% respectively and glass transition temperature (Tg) was reduced. The SEM results showed that the nanoparticles were uniformly dispersed and further validated the synergistic modification mechanism. [ABSTRACT FROM AUTHOR]

Sandwich composite structures are widely used in various industries namely, aerospace, automotive, packaging, biomedical, civil and electronics due to their high specific strength and energy absorption capabilities. Mechanical properties of sandwich structure depend on material properties of face sheet and core, and strength of face sheet‐core interface. Most commonly used composite materials are carbon fiber reinforced plastics, glass fiber reinforced plastics, ceramic matrix composites, and metal matrix composites. Several researchers have used nano‐fillers namely, nano‐clay, carbon nanotube, and nano‐silica for improvement of mechanical properties of composite structures. In this paper, an extensive literature review has been discussed regarding influence of various material and geometrical parameters on mechanical properties of sandwich composite structure. Initially, influence of various fiber reinforcement and nano‐fillers on mechanical properties are discussed. Then, deformation behavior and mechanical properties of honeycomb core is elaborated. Further, influence of temperature variation on composite structure is discussed. Moreover, crucial insights on reviewed literature are presented and future advancements in the field of sandwich composite structure are discussed. [ABSTRACT FROM AUTHOR]

The automotive industry continues to be one of the most dynamic and innovative. A revolution in propulsion systems that are becoming increasingly complex and must meet a number of extremely stringent environmental pollution requirements is currently witnessed. On the other hand, one of the systems that remains unchanged is the braking system that has been proving its efficiency for a very long time but with gradual continuous improvements. The presented work is based on tests and experiments performed in collaboration with the manufacturer Fermit S.A. which is one of the most experienced and long‐standing actors in the automotive industry in Romania. They produce a wide range of brake pads for the automotive, heavy duty, and railway industries. Starting from the experiments that offer the input data in the modeling and simulation activity, the paper presents the analysis of the behavior of a braking plate produced by Fermit S.A. Based on the geometry provided by the manufacturer, the properties of the composite material that forms the basis of the braking element and the experimental data that are presented, an analysis is made with finite elements in which to study, analyze, and interpret data such as displacements and stress states that occur in the structure formed by the composite material and the metal support plate on which it is deposited. [ABSTRACT FROM AUTHOR]

Summary: To obtain a good explosive suppressant, KH2PO4/montmorillonite composite powder was prepared by the solvent‐antisolvent method by using montmorillonite as the carrier and KH2PO4 as the supported particles. Flame propagation inhibition and explosion inhibition of aluminum‐silicon alloy dust by the KH2PO4/montmorillonite composite powder were investigated in a vertical quartz glass combustion tube and 20‐L spherical explosive tank, respectively. The results showed that the flame propagation of aluminum‐silicon alloy dust was basically suppressed as the inerting ratio of KH2PO4/montmorillonite composite powder was 1.2, and the explosion of aluminum‐silicon alloy dust was basically inhibited as the inerting ratio of KH2PO4/montmorillonite composite powder was 1.8. The flame and explosion inhibition mechanism of KH2PO4/montmorillonite composite powder on aluminum‐silicon alloy dust was further analyzed in this paper. [ABSTRACT FROM AUTHOR]

On the way to the real industrial applications of the metal matrix composite foams, the machining issue is highly critical in terms of dimensional accuracy, surface quality, and design diversity. Therefore, especially for lightweight automotive and aerospace components, the drilling machinability properties of cellular glass‐added aluminum composite foams were examined in this paper, and this is the first initiative in the literature specific to millimeter‐scale glass and aluminum‐zinc matrix combination. To comprehend the drilling properties, the outputs of thrust force, cylindricity, material removal rate, specific cutting coefficient, circularity error, damage factor, surface roughness, and chip formation were measured elaboratively. The results showed that cylindricity and damage factor of foams elevated with the increased feed rates (from 0.05 mm×rev−1 to 0.2 mm×rev−1) and cutting speeds (from 25 m×min−1 to 100 m×min−1). Maximum thrust force value reached up to 150 N for 0.2 mm×rev−1 feed and 25 m×min−1 cutting speed. Besides, specific cutting coefficient values ranged between 360 MPa and 114 MPa. The highest surface roughness of 58.3 μm was obtained with the lowest cutting speed of 25 m×min−1, and the long/continuous chip structure converted into a separate/short structure based on rising feed and cutting speeds. [ABSTRACT FROM AUTHOR]

In recent years, the propagation of ultrasonic guided waves (UGW) along the structure to inspect has amply proven to be an excellent strategy for the health monitoring of isotropic and composite structures (SHM—structural health monitoring). For the proper development of the SHM system, the finite element method (FEM) must be mentioned, since the possibility to study the UGW in very complex structures, even characterized by different materials. Successfully locating any possible damage and identifying its severity are key factors in SHM, thus allowing to reduce the design costs. Numerically, the damage can be modeled with several approaches but it is still not clear which is the best solution to accurately reproduce the UGW mechanisms in a faulty structure. The objective of this paper is to study the various effects that different severities of damage can have on UGW propagation. For the scope, various numerical approaches are considered and the results are compared. [ABSTRACT FROM AUTHOR]

The performance of short carbon fibers (CFs) reinforced rigid polyurethane (RPU) composites is largely restricted by poor interfacial strength and damage‐tolerance. In order to optimize the performance of CFs/RPU composites, we prepared CFs with a new structure starting from the modified CFs morphology. In this paper, a new type of fiber morphology, which was string‐like copper‐plated CFs (string‐like Cu‐CFs) were prepared by the electrodeposition method. The structure of the string copper could increase the contact area of the CFs and the RPU matrix and mechanical interlocking. At the same time, the surface roughness of the CFs could be enhanced, thereby promoting the formation of irregular interfaces. Ordinary CFs composite materials showed the low strength and toughness, due to the more stress concentrations generated around the fiber ends. By adding string‐like Cu‐CFs into the RPU matrix, the pinning effect was achieved due to the special fiber structure, which improved the strength and toughness of the string‐like Cu‐CFs/RPU. Compared with pure RPU, the tensile strength, bending strength, and impact strength of string‐like Cu‐CFs/RPU composites were improved by 15.3, 148.3, and 171.4%, respectively. At the same time, the string‐like Cu‐CFs formed a more continuous conductive network inside the RPU matrix, which significantly improved the electrical conductivity of the composites. [ABSTRACT FROM AUTHOR]

The paper presents results of the studies on porous composites obtained using lyophilization method based on the solutions of the following polymers: chitosan, sodium alginate and polylactide, as well as ZnO‐doped CaO–SiO2–P2O5 bioglass. The researchers took the advantage of zinc ions demonstrating the bactericidal, immune‐stimulating, and tissue‐regenerating functions in the organism. The cytotoxicity of the composites was tested on L929 cells by means of the direct and the indirect contact method. The antibacterial properties were determined against the gram‐negative bacteria Pseudomonas aeruginosa and the gram‐positive bacteria Staphylococcus aureus at 24, 48 hours, and 7 days. The study demonstrated that changes due to cytotoxicity effect of the composites depend on the type of polymer and on the duration of contact with cells. The composite with polylactide was found to be the least toxic for L929 cells. ZnO added to the chemical composition of bioglass ensured bactericidal effects. The antibacterial properties of the composites depended on the ZnO content, bioglass grain size, polymer type, and composite microstructure. The composites presented in this paper are innovative as biomaterials for filling bone cavities because they can be a matrix for cells and have an antibacterial effect while supporting the regeneration of damaged tissue. [ABSTRACT FROM AUTHOR]

The fused filament fabrication (FFF) process of polymer‐based composites has been developed due to its capability to make complex geometries and shapes with reasonable mechanical properties. However, the improvement of mechanical properties of the obtained parts and products are still under study and are interesting for designers. There are several strategies to enhance these desired properties of produced pieces, for example optimizing the process parameters and/or using different architecting designs. This paper presents the effect of some overriding process parameters (liquefier temperature, print speed, layer height, and platform temperature) on the temperature evolution and mechanical behavior of PA6 reinforced with chopped carbon fibers produced by FFF. Due to deposition of multilayers, there is a cyclic profile of temperature in the FFF process, which is a considerable note related to fabrication and consequently the strength of the manufactured parts. In parallel with the study of process parameters effect, this cyclic temperature profile has been measured. The preliminary results related to physicochemical and mechanical properties revealed that differences in crystallinity percentage exist and failure stress/strain can be considered as an indicator to evaluate the mechanical properties of FFF manufactured products. Moreover, measuring the temperature profile of the deposited filaments revealed that process parameters have a considerable influence on the cooling process of deposited filaments which itself affects the bonding of adjacent filaments. The higher temperatures led to slower cooling rate. Finally, the results confirm the impact of mentioned parameters roles on the bonding formation in the FFF process and also the subsequent obtained mechanical properties of the printed parts. Therefore, selection of the optimized and suitable process parameters is an important design consideration. [ABSTRACT FROM AUTHOR]

In this paper, a novel composite photocatalyst, ferric oxide–bismuth oxyhalide (Fe2O3‐BiOCl0.5Br0.5) has been synthesized, characterized, and used for the degradation of methyl orange through advanced oxidation process under ambient conditions (sunlight, pH 7.0, and temperature 25°C). The catalyst has been characterized by using UV‐Vis spectrophotometer, Fourier transform infrared (FTIR) spectroscopy, Raman spectrometer, scanning electron microscopy (SEM), energy dispersive X‐ray analysis (EDX), and X‐ray diffractometer (XRD) techniques. The catalyst shows appreciable activities under natural sunlight conditions. From the XRD patterns and SEM images, it is observed that the elongation along the z axis in the crystal lattice of BiOCl0.5Br0.5 in the catalyst can lead to a lattice distortion induced internal electric field which can help in charge carrier separation and transport. The Fe2O3‐BiOCl0.5Br0.5 catalyst shows more than 90% photodegradation efficiency of methyl orange in 90 min of sunlight exposure. The presence of magnetic ferric oxide in the composite photocatalyst helps to isolate the catalyst from the reaction mixture by using an external magnet, and thus, the Fe2O3‐BiOCl0.5Br0.5 catalyst can be reused repeatedly, towards degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

Natural fiber is well-known reinforcement filler in polymer-matrix composites. Composite components like organic polymers and natural fibers are natural fire conductors as the natural fiber consists of cellulose, hemicellulose, and lignin, and hence are as highly flammable as wood. Natural fiber reinforced composite materials are progressively being used in a variety of applications where their fire response is a hazardous consideration, for example, in the automotive (transportation) and building-construction industries. As a result, an awareness of their performance or response during a fire and the use of conventional fire retardants are of great importance, as they are subject to thermal decomposition when exposed to intensive high heat or fire sources. In this review paper, fire flammability is the main concern for cellulosic and non-cellulosic fiber-reinforced polymer composites, especially epoxy composites. This paper reviews the literature on the recent developments in flammability studies concerning polymers, epoxy polymers, cellulosic-fibers, and non-cellulosic fiber-reinforced epoxy bio-composites. The prime objective of this review is to expand the reach of 'fire retardants for polymer materials and composites' to the science community, including physicists, chemists, and engineers in order to broaden the range of their applications. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Generally, the ultraviolet photodetector devices based on ZnO/PEDOT composites were fabricated by spin coating of PEDOT solutions on ZnO nanorods array, which needs the polymer disperesed in solvent. In this paper, an electrochemical deposition method was proposed for the prepparation of ZnO/PEDOT‐type conducting polymers composites for ultraviolet photodetector. The poly(3,4‐proplene‐dioxythiophene) (PProDOT) and poly(3,4‐ethylenedioxy‐thiophene)(PEDOT) were selected as PEDOT‐type conducting polymers. The structure of composite materials was characterized by UV‐vis, XRD, Raman, SEM,EDS and XPS analysis. The effects of different polymers on the UV sensing ability of ZnO nanorods were studied. The structural results showed that the composites were successfully prepared by electrochemical deposition method indicating that the electrochecmial method was an effective way to prepraration of this type composites.The photoelectric performance test showed that the structure of the polymer chain affected the responsiveness of the materials, and the response time of ZnO/PProDOT was 14 s shorter than that of ZnO/PEDOT, and it displayed an excellent long‐term stability. After deposition of PProDOT, the UV responsivity of ZnO nanorods was increased from 2.5 A W−1 to 27.5 A W−1, and the external quantum efficiency and detectivity were significantly improved, implying that the PProDOT can be ideal candidate material for ultraviolet photodetector. [ABSTRACT FROM AUTHOR]

As polymer‐based thermoelectric (TE) materials possess attractive features such as light weight, flexibility, low toxicity and ease of processibility, an increasing number of conducting polymers and their composites with high TE performances have been developed in recent years. Up to date, however, the research focusing on the structure‐performance relationship remains rare. In this paper, two series of poly(Schiff base)s with either C=C or C≡C linker and their metallopolymers were synthesized and doped with single‐walled carbon nanotubes to evaluate how the linking groups affected the TE properties of the resulting composites. Apart from the effect exerted by the morphology, experimental results suggested that the linkers played a key role in determining the band gaps, preferred molecular conformation and extent of conjugation of the polymers, which became key factors that influenced the TE properties of the resulting materials. Additionally, upon coordination with transition metal ions, the TE properties could be tuned readily. [ABSTRACT FROM AUTHOR]

Activated carbon is widely regarded as a potential CO2 adsorbent because of its special texture. Activated carbon captures CO2 mainly through physical adsorption due to the characteristics of surface structure and pore structure, which makes the adsorbent sensitive to temperature and relatively low in selectivity. In order to solve these problems, much effort has been made in new developments, including synthesis activated carbon‐based composites, which can not only improve its CO2 capture capacity and stability, but also improve its selectivity. This paper reviews the recent research focused on the activated carbon‐based composites using in postcombustion CO2 capture. The status and development of activated carbon‐based composites are presented in four parts as activated carbon/metal composite, activated carbon/zeolite composite, activated carbon/metal organic framework composite, and activated carbon/carbon material composite. The details of synthesis method, synthesis condition, modification method, and CO2 adsorption performance are introduced. Simultaneously, the characteristics, advantages, and potential challenges of the composites are also summarized. This work will provide important parameters in the applications of activated carbon‐based adsorbents for postcombustion CO2 capture and give suggestions on future research efforts. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The contact problem between two bodies: plate and semi-cylindrical bar is studied in this paper. The analysis concerns the contact pressure distribution along the contact region, as well as the deflection of the plate. Furthermore, the case of a composite plate covered with the auxetic layer is also considered. The influence of the Poisson's ratio of the layer on the behavior of the plate is studied. The contact pressure distribution along the contact area is analyzed using finite element analysis. [ABSTRACT FROM AUTHOR]

A sandwich-structured composite is a special class of composite materials that is fabricated by attaching two thin but stiff layers to a lightweight but thick core. Composites analyzed in this paper consist of two different materials: auxetic and structural steel. The optimization criterion is minimum compliance for the load case where the frame's top boundary is downward loaded. Outer layers are made of steel while the middle layer is two-phase solid material composite. Only the middle layer is optimized by means of minimization of the objective function defined as the internal strain energy. In the first part of this paper we study the application of the solid isotropic material with penalization (SIMP) model to find the optimal distribution of a given amount of materials in sandwich-structured composite. In the second part we propose a multilayered composite structure in which internal layers surfaces are wavy. In both cases the total energy strain is analyzed. [ABSTRACT FROM AUTHOR]

The natural cottony aspect of silk‐floss tree fruit fiber allied with its high‐cellulose content turned our attention for their application at the nanocellulose production since spares the prerefining and pulping processes that are obligatory for the size reduction of the main cellulosic fiber sources. This study presents preparation and characterization of cellulose nanofibers (CNFs) using mechanical defibrillation to explore their potential in the preparation of polymer composites using polyvinyl acetate (PVAc) emulsion. We characterized and subjected silk‐floss fruit fiber to four chemical treatments. Based on the degree of delignification, treatments with sodium chlorite (II) and their mixture with methanol and toluene (IV) were chosen for further studies. The resulting CNFs were characterized by Fourier‐transform infrared, X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and scanning and transmission electron microscopy. Composites were prepared using several amounts (0.50‐1.00 wt%) of CNFs and their tensile strengths were determined. Composites containing 1.00% CNFs (Treatment II) were found to exhibit lowest strength while those with 0.5% CNFs (Treatment IV) showed the highest strength with 351% and were 518% higher resistant than the PVAc matrix, respectively. [ABSTRACT FROM AUTHOR]

In this paper, ternary silicone dielectric elastomer micro‐nanocomposites were prepared by mixing barium titanate (BT) nanoparticles or 3‐mercaptopropylethoxy‐bis(tridecyl‐pentaethoxy‐siloxane) (Si747)‐modified BT (BT‐Si747) with hexagonal boron nitride (BN) microplatelets into methyl vinyl silicone rubber (MVSR). BN platelets as physical barriers improve the dispersion of BT nanoparticles, so the MVSR/BT/BN composites achieve the higher electric breakdown field. The Si747 in MVSR/BT‐Si747/BN composites can be grafted on BT nanoparticles surface while the mercapto groups of Si747 can react with double bonds of MVSR, which increases interfacial interaction to improve the mechanical property. As a result, the tensile strength and elongation at break of MVSR/30 wt%BT‐Si747/30 wt%BN composite are 3.43 MPa and 2705%, which is 2.4 and 4.4 times as high as the MVSR/30 wt%BT/30 wt%BN composite, respectively. The MVSR/BT‐Si747/BN composites exhibit higher actuation performance under lower electric fields due to simultaneous increase in dielectric constant and decrease in elastic modulus. The MVSR/10 wt%BT‐Si747/10 wt%BN composite obtains an actuated strain of 8.81% at 47.48 kV/mm, which is twice as high as pure MVSR (4.4% at 60.21 kV/mm). The used method in this experiment is simple, effective, and low cost, and prepared ternary micro‐nanocomposites have potential applications in dielectric actuators. [ABSTRACT FROM AUTHOR]

Sandwich panels with a core of corrugated cardboard The goal of a research project of the Institute for Steel Construction and Materials Mechanics was to determine the utilization of corrugated cardboard as a core material for sandwich panels for roof and wall cladding. In contrast to common core materials, corrugated cardboard is recyclable and consists of renewable raw materials. The bearing behaviour depends mainly on the paper types and on the orientation of the anisotropic material inside the panel. The weakest orientation has similar stiffness and strength as common core materials. However, these can be exceeded many times by other core orientations. Investigations of the most important building physical parameters have shown that the fire behaviour is slightly better than that of most PU‐sandwich panels. The thermal conductivity in the weakest core orientation is comparable to that of mineral wool, the stronger core orientations show higher thermal conductivity. [ABSTRACT FROM AUTHOR]

Solutions using rolled sections instead of plated beams are strongly developed in Poland [1‐7]. One of the ideas is to use rolled sections HL1100 out of S460 steel for span region and variable height of girder at the piers (using different composite solutions) what has become a standard bridge type for continuous min. 3‐span bridges with internal spans range 50‐60 m. It took less than 10 years to come from the idea to standard market product. Appropriate R&D works have been carried out. The idea of using rolled section leaded to implementation of the double‐composite action and composite dowels and this way new structural forms of bridges appeared in Poland. The driving force for innovation in composite bridges in Poland is the design‐and‐build formula, international collaboration, open‐minded (not so conservative) young engineers and good economy for bridge market in Poland nowadays. In the paper applications of the considered solutions are presented. [ABSTRACT FROM AUTHOR]

The imperfections stemming from manufacturing or construction practices have effects on capacities of structural columns. Bow imperfections or residual stresses are commonly investigated and well known examples of these imperfections. Since the composite construction generally has different stages than reinforced concrete or steel construction, there are other sources of imperfections for this field. Different approaches to consider geometrical imperfections are studied for this paper. These are namely the approach of EN‐1992‐1‐1 [1],EN 1994‐1‐1 [2] and EN 13670 [3]. Eurocode 2 and Eurocode 4 specify geometric imperfection for columns differently. Former introduces them as load eccentricity and latter introduces them as bow imperfections. EN 13670 giving the construction tolerances for reinforced concrete structures, has different methods to limit geometrical imperfections. For the purpose of comparing different approaches and their effect on capacity calculations, several composite columns were simulated using physical and geometrical non‐linear analysis, their load‐deflection relationships were monitored and capacities compared. An outlook of the ongoing investigation for the adaptation of geometrical imperfection for composite columns is further discussed. [ABSTRACT FROM AUTHOR]

Composite column design in accordance with EN 1994‐1‐1 can be computed by the general method or by simplified methods. For the general method, EN 1994‐1‐1 refers to a comprehensive FE‐Analysis. However, the recent Eurocode 4 does not provide sufficient guidance for the application of the general method and there is not a harmony in the literature on how to do it. Additional information may be found as non‐contradictory complementary information (NCI) in National Annexes (NA). This paper points out the procedure for the general method and refers to the changes and additional information provided by the draft of prEN 1994‐1‐1:2021. Furthermore, the modelling and computation by FE‐Analysis for several software applications are presented by implementing specified initial bow imperfections and predefined residual stresses for the steel section. The results obtained with the general method's approach are compared with that calculated by simplified method by the European buckling curves. In addition, the impact of different stress‐strain curves for concrete and strain limits introduced by Codes are investigated. [ABSTRACT FROM AUTHOR]

Materials with unusual mechanical properties can be potentially used as matrices to create high-performance lightweight composites. The appearance of materials with negative Poisson's ratio (auxetics), has led to the evaluation of auxetic composites for possible engineering applications. Because the experimental evaluation of composites with specific properties is expensive and time consuming, computational modelling and simulation provide efficient alternatives to predict the parameters of the composites. In this paper a finite element method was used to find the engineering constants (Young's modulus and Poisson's ratio) of auxetic composites consisting of concentric cylindrical inclusions made of combinations of auxetic and classic (non-auxetic) materials. It has been observed that not only the mechanical properties of the different composite phases influence the effective mechanical properties of the whole composite, but also the location of the same material phases do matter. [ABSTRACT FROM AUTHOR]

Geopolymer‐based glass‐ceramic matrix composites can be processed at room temperature and a heat treatment below 100°C leads to matrix hardening thanks to the geopolymerization mechanisms. The stabilization of the matrix into glass‐ceramics is achieved via a post‐curing at high temperature. This paves the way of the utilization of cost‐effective liquid composite molding processes, for which all the necessary equipment is already available for processing temperature ranges related to polymer matrix composites, provided that the rheological behavior of the precursor is suitable to conveniently permeate the fibrous preform. The paper describes the thixotropic rheological behavior of a reference suspension at processing temperature (10°C‐20°C) and its evolution along aging at −18°C. The changes are interpreted in terms of geopolymerization mechanisms (dissolution and polycondensation) and suspension rheology (predominance of hydrodynamic effects at high shear rate). On this basis, a phenomenological modeling framework, combining two Krieger‐Dougherty equations, is proposed to build a relationship between the effective viscosity of the suspension and the phenomena involved during aging (dissolution of aluminosilicate particles) and shearing (microstructure scalar variable). [ABSTRACT FROM AUTHOR]

Fabric reinforced cementitious matrix (FRCM) is a composite consisted of high‐strength fibers impregnated in a cement‐based mortar, and is commonly used for strengthening reinforced concrete and masonry structures. Comprehending the tensile behavior of FRCM is important to achieve a reliable and accurate design of FRCM strengthening systems. The current paper reports on the results of an experimental study on the tensile characterization of FRCM. A total of 40 FRCM specimens (410 × 50 mm, varied in thickness) were prepared and tested. The tensile characterization tests were conducted according to AC 434 guidelines using clevis‐grip mechanism. The tests were used to assess the effect of two parameters: (a) fabric type (carbon/glass) and (b) number of fabric plies (one/two/three/four). The results showed that the tensile strength of carbon‐FRCM specimens was approximately 1.33 times that of the glass‐FRCM counterparts. Three distinct failure modes were observed, namely, (a) ductile fabric slippage in carbon‐FRCM (up to three plies of fabric); (b) brittle fabric delamination in carbon‐FRCM with four plies of fabric; and (c) brittle fabric rupture in glass‐FRCM systems. The FRCM tensile load‐carrying capacity had proportionally increased with the number of fabric plies; less significant effect (within 20%) was observed on the corresponding ultimate tensile stresses (considering the net fabric area as the effective area). [ABSTRACT FROM AUTHOR]

Several high‐performance reinforcements may be used in epoxy‐based composites. These commonly undergo chemical and/or physical treatments to enhance their interfacial interactions with polymer matrices. One recent technology comprises the use of ionic liquids (IL) as compatibilizers. This strategy may result in the development of composite materials with greater performance or multifunctional characteristics. Herein, an overview in the area of IL‐modified reinforcements and their effect on epoxy‐based composites is presented. The PRISMA protocol was followed for the review, and the focus of these studies was on the modification of carbon nanotubes, followed by graphene/graphite nanoplatelets and bio‐fillers. The most used IL were those based on imidazolium cation, especially 1‐butyl‐3‐methylimidazolium chloride. In most cases, when IL are used, the reinforcement displays stronger interactions with the epoxy matrix, depending the treatment route employed. Improved interfacial interactions are cited as the main reason for the improvement in the composite mechanical and thermal performances. It was also found that strategies for using low IL content, or routes that enable recovery of the salts after fiber/particle treatment, are still required, as well as the study of the influence of different amounts/types of IL on the structure of fillers and their relationships with the composite properties. [ABSTRACT FROM AUTHOR]

In this paper, silicone‐coated intumescent flame retardants was prepared by an efficient and simple approach, aiming at enhancing the flame‐retardant efficiency and smoke suppression properties. The surface of expandable graphite (EG) was treated prior to the coverage of nonflammable silicone. The resultant silicone‐modified EG hybrid (SEG) was combined with ammonium polyphosphate (APP) and applied as a flame‐retardant and smoke‐suppressant for ultrahigh molecular weight polyethylene (UHMWPE). Compared with UHMWPE/APP/EG (with 15 wt% APP/EG), UHMWPE/APP/SEG (with 15 wt% APP/SEG) gives decrement by 18.5% in the peaks of the heat release rate, 6.33% in total heat release and 13.6% in total smoke release, whereas increment by 23% in tensile strength and 12.1% in elongation at break, respectively. It is suggested that the introduction of silicone on the surface of EG can improve the interfacial compatibility between EG and UHMWPE. Moreover, it can lead to forming more char residue and reducing the release of smoke particulates during combustion process of the composites. [ABSTRACT FROM AUTHOR]

In this paper, an efficient flame retardant, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) was covalently grafted onto the surface of expandable graphite (EG). The resultant DOPO‐grafted expandable graphite (EG‐g‐DOPO) was characterized by Fourier transform infrared spectroscopy, energy dispersive spectroscopy, and X‐ray photoelectron spectroscopy (XPS), respectively. The thermal stability of EG‐g‐DOPO was also evaluated by thermogravimetric analysis (TGA). Moreover, a series of flame‐retardant ultra‐high‐molecular‐weight polyethylene (UHMWPE) composites with various concentrations of EG‐g‐DOPO were prepared and evaluated. The results show that the UHMWPE composite with 20 wt% EG‐g‐DOPO possesses a satisfactory UL‐94 flame‐retardant grade (V‐0) and a high limiting oxygen index (30.6%). The residual char of the UHMWPE composite with higher EG‐g‐DOPO concentration shows more compact and integrated, providing an efficient barrier for heat release. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of factors essential to air spring and undercarriage design to determine their influence on air spring fatigue life. Two sets of factors were chosen for the investigation: those relating to the design of the air spring itself (cord angle, diameter difference) and those relating to the design of the undercarriage (lever length, eccentricity, lever eccentricity, inclination). A full factorial experiment, whereby interactions between all the factors are investigated, would demand 729 experiments. Using Taguchi methods, the number of experiments required is dramatically reduced, using only 27 experiments to determine the influence of 6 factors and 3 interactions. Taguchi analysis shows here that factors inherent to air spring design have a much greater influence on fatigue life than those factors inherent to undercarriage design. Interaction between these factors has also revealed that there is no optimal cord angle for all air springs. [ABSTRACT FROM AUTHOR]

At the small area scale simple methods for forecasting total populations are often employed because of a lack of data for cohort-component models, concerns about the reliability of these models for forecasting small population totals, and resource constraints. To date, a select number of authors have assessed the forecast accuracy of several individual, averaged, and composite models. This paper extends this stream of work by evaluating a large number of models on new datasets. The aims of the paper are to examine the performance of (a) 10 individual forecasting models (some of which are well known; others less so); (b) averages of every combination of 2, 3, 4, and 5 of the individual models (627 in total); and (c) composite models based on population size and growth rates (200,000 in total). Do averaged and composite models outperform individual models? Using new small area population datasets, forecasts from 2001 to 2031 were produced for three case study countries, Australia, New Zealand, and England & Wales. Both forecast accuracy and credibility (avoidance of negatives; degree of constraining to state populations) were assessed in 2011; for 2031, just credibility was evaluated. Of the individual models, constant share of growth (positive shares only) and constant share of population performed the best. A small proportion of averaged and composite models outperformed the best individual models in forecast accuracy. Several recommendations for the practice of small area population forecasting are made. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Bug resolution refers to the activity that developers perform to diagnose, fix, test, and document bugs during software development and maintenance. Given a bug report, we would like to recommend the set of bug resolvers that could potentially contribute their knowledge to fix it. We refer to this problem as developer recommendation for bug resolution. In this paper, we propose a new and accurate method named DevRec for the developer recommendation problem. DevRec is a composite method that performs two kinds of analysis: bug reports based analysis (BR-Based analysis) and developer based analysis (D-Based analysis). We evaluate our solution on five large bug report datasets including GNU Compiler Collection, OpenOffice, Mozilla, Netbeans, and Eclipse containing a total of 107,875 bug reports. We show that DevRec could achieve recall@5 and recall@10 scores of 0.4826-0.7989, and 0.6063-0.8924, respectively. The results show that DevRec on average improves recall@5 and recall@10 scores of Bugzie by 57.55% and 39.39%, outperforms DREX by 165.38% and 89.36%, and outperforms NonTraining by 212.39% and 168.01%, respectively. Moreover, we evaluate the stableness of DevRec with different parameters, and the results show that the performance of DevRec is stable for a wide range of parameters. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]