Bark proportion of Scots pine industrial wood

Bark characteristics are not only used in the forest-wood supply chain, for example to calculate standing volumes, but also to transform wood volumes and masses. In this study, bark thickness, bark volume and bark mass were analyzed on the basis of 150 Scots pine discs, with a mean diameter of 13 cm. The mean double bark thickness was 3.02 mm, the mean bark volume proportion was 5.6% and mean bark mass proportion was 3.3%. Bark proportions were significantly affected by the log-specific variables ‘diameter over bark’, ‘proportion of bark damage’ and ‘double bark thickness’.

Porous Multiphase Microcharacteristics Research of New Cement-Based Grouting Material Concretion

As an excellent inorganic hydraulic cementitious material, new cement-based grouting material (abbreviated as NCG) has a wide application prospect in grouting engineering. Four types of water-cement ratio (W/C ratio) NCG concretions were systematically researched on the solid-phase composition, microscopic morphology, nanoscale pore characteristics and micron-scale multiphase microscopic characteristics through SEM, TGA-DSC, BET, MIP, and 3D-XRM in combination with hydration reaction mechanism. The NCG concretion is characterized as a spatial network structure formed by dendritic or columnar ettringite (AFt) crystals, filled with calcium silicate hydrate gel (C–S–H) and aluminum gel (AH3). In the solid phase, the mass of AFt is the highest, about 65%, the mass of C–S–H is about 20%, and the mass of AH3 is the least, about 15%. In nanoscale, the pore size of NCG concretion is concentrated in about 50 nm–3 μm, and the volume proportion reaches about 90%, which can be used as the characteristic parameter of pore-phase. With the increase of W/C ratio and age, the MPD of pore decreases, and the probability of the MPD-pore increases, and the dispersion of the probability of pores increases. In nanoscale, the porosity of NCG concretion is as high as 60%. With the increase of W/C ratio and age, the porosity of NCG concretion increases, but the effect on the density of solid-phase is little. In micron scale, the regular characteristics related to diameter of pore-phase and gel-phase are similar, showing a three stage formula: as their diameter increases, the number of monocases decreases and its rate of reduction gradually slows down, the volume-proportion decreases first and then increases, the differentiation of volume between the monocases increases gradually, and the differentiation between monocases shape and sphere is bigger, and its shape characteristics are more diverse and discrete.

A Study Regarding the Mechanical Properties of a Hybrid Matrix with Various Volume Proportions of Dammar

This paper studies the influence of the volume proportion between components on the mechanical behaviour of a hybrid resin obtained by combining the natural resin Dammar and epoxy resin. We analyse three sets of hybrid resin samples, in which we used a Dammar volume proportion of 60%, 70%, and 80% respectively and epoxy resin (employed together with its associated reinforcement in order to generate a quick process of polymerization). Following the tensile test we found the characteristic curves, the tensile strength and the elongation at break for each of the three types of resins. We also looked into the vibration damping properties of bars made of this resin. We experimentally determined the frequency and the damping coefficient of the first particular vibration mode for one bar taken out of each set of resins, with one end fixed and the other free. On the basis of the results, we calculated the loss coefficient for each type of resin.

Experimental Investigation of Thermal Conductivity and Viscosity of SiO2/Multiwalled Carbon Nanotube Hybrid Nanofluids

In this study, the thermal conductivity and viscosity of SiO2/multiwalled carbon nanotube (MWCNTs) hybrid nanofluids are investigated. The volume fraction of the nanofluids varied in the range of 0.5% to 2%, while the SiO2 to MWCNTs volume proportion is either 95-5 or 90-10. The nanofluids are synthesized using a wet chemical method and a two-step technique is used to disperse nanoparticles in glycerol (base fluid). The thermal conductivities and viscosities of the nanofluids are measured using a modified transient hot-wire method and falling ball viscometer, respectively. The colloidal stability of the dispersion was investigated visually. Effective application of an ultrasonic disruptor and a suitable surfactant (gum arabic) enhance the dispersion behavior. When the effects of temperature and volume fraction on the thermal conductivity and viscosity of SiO2/multiwalled carbon nanotube (MWCNTs) hybrid nanofluids are studied, the results showed that the thermal conductivity of nanofluids increased with an increase in the volume fraction and temperature. Further, their viscosities increased with an increase in the volume fraction but decreased when the temperature increased. The thermal conductivity and viscosity of the hybrid nanofluids increased by 16.7% and 105.4%, respectively, at a volume fraction of 2% and volume proportion of 90-10. The experimental results are compared with those predicted by classical theoretical models. Two correlations for thermal conductivity and viscosity of hybrid nanofluids are proposed on the basis of the experimental results.

Experimental Research into the Mechanical Behaviour of Dammar and Sandarac - Based Bio Resins

In this paper, we examine two types of Dammar-based bio resins. In the first type, Dammar alone is used as natural resin, while in the second type a mixture of 70% Dammar and 30% Sandarac is used. Three sample sets were made of each of these resins with a bio resin volume proportion of 55, 65 and 75% respectively, the rest being epoxy resin (used, together with the associated reinforcing material, to generate a quick polymerization process). A SEM analysis is carried out and the surface roughness of each of the studied materials. A series of mechanical properties, determined by tensile testing, are presented. We have determined the characteristic curves, tensile strength and modulus of elasticity and the influence of the epoxy resin volume proportion on the mechanical behaviour of bio resins.

Quantitative 3D Trajectory Measurement for Percutaneous Endoscopic Lumbar Discectomy

Background: Percutaneous endoscopic lumbar discectomy (PELD) has become an increasingly popular minimally invasive spinal surgery. Due to the technical evolution of PELD, the focus of decompression has shifted from the central nucleus to the subannular-protruded disc herniation, which allows direct neural decompression. Surgical entry into the spinal canal leads to the greater possibility of bony structure obstruction, thus the location and direction of the working channel are crucial. The existing preoperative measuring methods mainly rely on 2-dimensional (2D) x-ray images or MRI cross-sections. Because the bony structure and the trajectory are 3-dimensional (3D), the relationship between the anatomical lumbar structure and the working channel cannot be precisely evaluated. Objectives: To investigate a 3D method and quantitatively evaluate the trajectory for percutaneous endoscopic lumbar discectomy (PELD). Study Design: Technical note. Setting: Pain medicine center of a university hospital. Methods: Twenty patients suffering from L4/5 disc herniation were enrolled in this study. After reconstructing the preoperative CT images, the virtual trajectory was placed into the intervertebral foramen through gradient-changing angulations in relation to the coronal and transverse planes. The overlapping portion of the virtual trajectory and the lumbar vertebrae was evaluated. In addition, the probability of atypical structure involvement was calculated. Results: As cephalad angulation (CA) increased, the intersection volume of the L4 inferior articular process increased, while the total intersection volume, the intersection volume of the L5 superior articular process, the intersection volume of the facet joint, and the volume proportion of L5 superior articular process intersection in the facet joint all decreased. As coronal plane angulation (CPA) increased, the total intersection volume, the intersection volume of the L4 inferior articular process, and the intersection volume of the facet joint all increased, while the volume proportion of the L5 superior articular process intersection in the facet joint decreased. When CA increased to 15°-20°, there was a high probability of atypical structure involvement, whereas such a probability in the groups of CA 0° (CPA 15°, 20°, and 25°), CA 5° and CA 10° was low. Limitations: Only patients with L4/5 herniation were evaluated in this study. Conclusions: In terms of the regularity, the ideal angulation for L4/L5 PELD is CPA 5°-10° and CA 5°-10°, which can lead to a relatively low level of total damage to the bony structure, minimal damage to the facet joint, and negligible involvement of atypical structures. Key words: Lumbar disc herniation, percutaneous endoscopic lumbar discectomy (PELD), transforaminal, trajectory, 3D method, quantitative measurement, angulation, bony structure obstruction

Processing of Cu-Cr alloy for combined high strength and high conductivity

High strength and high conductivity (HSHC) are two intrinsic properties difficult to combine in metallic alloy design because; almost all strengthening mechanisms also lead to reduced conductivity. Precipitation hardening by nano-sized precipitates had proven to be the most adequate way to achieve the optimum combination of strength and conductivity in copper based alloys. However, established precipitation strengthened Cu- alloys are limited to very dilute concentration of solutes thereby limiting the volume proportion hardening precipitates. In this work, we report the investigation of the reprocessing of higher Cr concentration Cu- based alloys via rapid solidification. It is found that the rapid solidification in the as-cast ribbon imposed combined solution extension and ultra-refinement of Cr rich phases. X-ray diffraction evidences suggest that the solid solution extension was up to 6wt%Cr. Lattice parameters determined confirmed the many folds extension of solid solution of Cr in Cu. Thermal aging studies of the cast ribbons indicated that peak aging treatments occurred in about twenty minutes. Peak aged hardness ranged from about 200 to well over 300Hv. The maximum peak aged hardness of 380Hv was obtained for alloy containing 6wt.%Cr but with conductivity of about 50%IACS. The best combined strength/conductivity was obtained for 4wt.%Cr alloy with hardness of 350HV and conductivity of 80% IACS. The high strengths observed are attributed to the increased volume proportion of semi-coherent Cr rich nano-sized precipitates that evolved from the supersaturated solid solution of Cu-Cr that was achieved from the high cooling rates imposed by the ribbon casting process. The rapid overaging of the high Cr concentration Cu-Cr alloy is still a cause for concern in optimising the process for reaching peak HSHC properties. It is still important to investigate a microstructural design to slow or severely restrict the overaging process. The optimum HSHC property reported here is a rare combination of high strength (>350Hv ~ 900MPa) and conductivity (50 – 80% IACS) found in metallic alloys.

Processing of Cu-Cr alloy for combined high strength and high conductivity

High strength and high conductivity (HSHC) are two intrinsic properties difficult to combine in metallic alloy design because; almost all strengthening mechanisms also lead to reduced conductivity. Precipitation hardening by nano-sized precipitates had proven to be the most adequate way to achieve the optimum combination of strength and conductivity in copper based alloys. However, established precipitation strengthened Cu- alloys are limited to very dilute concentration of solutes thereby limiting the volume proportion hardening precipitates. In this work, we report the investigation of the reprocessing of higher Cr concentration Cu- based alloys via rapid solidification. It is found that the rapid solidification in the as-cast ribbon imposed combined solution extension and ultra-refinement of Cr rich phases. X-ray diffraction evidences suggest that the solid solution extension was up to 6wt%Cr. Lattice parameters determined confirmed the many folds extension of solid solution of Cr in Cu. Thermal aging studies of the cast ribbons indicated that peak aging treatments occurred in about twenty minutes. Peak aged hardness ranged from about 200 to well over 300Hv. The maximum peak aged hardness of 380Hv was obtained for alloy containing 6wt.%Cr but with conductivity of about 50%IACS. The best combined strength/conductivity was obtained for 4wt.%Cr alloy with hardness of 350HV and conductivity of 80% IACS. The high strengths observed are attributed to the increased volume proportion of semi-coherent Cr rich nano-sized precipitates that evolved from the supersaturated solid solution of Cu-Cr that was achieved from the high cooling rates imposed by the ribbon casting process. The rapid overaging of the high Cr concentration Cu-Cr alloy is still a cause for concern in optimising the process for reaching peak HSHC properties. It is still important to investigate a microstructural design to slow or severely restrict the overaging process. The optimum HSHC property reported here is a rare combination of high strength (>350Hv ~ 900MPa) and conductivity (50 – 80% IACS) found in metallic alloys.

Processing of Cu-Cr alloy for combined high strength and high conductivity

High strength and high conductivity (HSHC) are two intrinsic properties difficult to combine in metallic alloy design because; almost all strengthening mechanisms also lead to reduced conductivity. Precipitation hardening by nano-sized precipitates had proven to be the most adequate way to achieve the optimum combination of strength and conductivity in copper based alloys. However, established precipitation strengthened Cu- alloys are limited to very dilute concentration of solutes thereby limiting the volume proportion hardening precipitates. In this work, we report the investigation of the reprocessing of higher Cr concentration Cu- based alloys via rapid solidification. It is found that the rapid solidification in the as-cast ribbon imposed combined solution extension and ultra-refinement of Cr rich phases. X-ray diffraction evidences suggest that the solid solution extension was up to 6wt%Cr.Lattice parameters determined confirmed the many folds extension of solid solution of Cr in Cu. Thermal aging studies of the cast ribbons indicated that peak aging treatments occurred in about twenty minutes. Peak aged hardness ranged from about 200 to well over 300Hv. The maximum peak aged hardness of 380Hv was obtained for alloy containing 6wt.%Cr but with conductivity of about 50%IACS. The best combined strength/conductivity was obtained for 4wt.%Cr alloy with hardness of 350HV and conductivity of 80% IACS. The high strengths observed are attributed to the increased volume proportion of semi-coherent Cr rich nano-sized precipitates that evolved from the supersaturated solid solution of Cu-Cr that was achieved from the high cooling rates imposed by the ribbon casting process. The rapid overaging of the high Cr concentration Cu-Cr alloy is still a cause for concern in optimising the process for reaching peak HSHC properties. It is still important to investigate a microstructural design to slow or severely restrict the overaging process. The optimum HSHC property reported here is a rare combination of high strength (>350Hv ~ 900MPa) and conductivity (50 – 80% IACS) found in metallic alloys.