Evaluation of Moisture Content Changes in Taiwan Red Cypress During Drying Using Ultrasonic and Tap-Tone Testing

Moisture content affects most of the important properties of wood, therefore it is important to control during drying and in use. The purpose of this study was to investigate moisture content changes in Taiwan red cypress during drying. Two types of nondestructive testing were used, ultrasonic and tap-tone. The results showed that ultrasonic and tap-tone velocities increased with decreasing moisture content with the major effect below the FSP. A second-order regression relationship was found between ultrasonic and tap-tone velocities with moisture content desorption during drying with a coefficient of determination of 0.77 and 0.88, respectively. Moreover, the effects of moisture content desorption on dynamic moduli, calculated from ultrasonic and tap-tone methods, were demonstrated. Finally, a new parameter (Vi/Vx), the ratio of initial velocity (before drying) to the velocity at any moisture content, was effectively applied to evaluate moisture content changes in wood during drying. The tap-tone method was found to be a reliable tool to measure moisture content changes during the drying of wood

Crushing Strength Sampling With Minimal Damage to Taiwania (Taiwania Cryptomerioides) Using a Fractometer

The Fractometer is a device that stresses radial increment cores in the direction of the fiber to measure crushing strength, which can provide a direct wood quality indicator for structural lumber. This study analyzes the pattern of the radial variation in Taiwania (Taiwania cryptomerioides Hay.) trunk wood crushing strength to explore its effect on the precision and efficiency of the sampling procedure in the outer increment core zone as an alternate nondestructive sampling method. A pith-to-bark 0.5-cm caliber core was extracted at breast height (1.3 m above the ground) from each tree and was separated into individual section groups. Then individual crushing strengths were determined using the Fractometer.In this study, the variation in crushing strength in the transverse direction increased from the pith outward to the bark side. An analysis of variance and correlation analysis were used to evaluate the data. The magnitude of the radial variation in crushing strength was smaller than the tree-to-tree variation. Including samples of at least 7.2 cm, 5.4 cm, and 2.4 cm near the bark side was found to be acceptable for the assessment of wood crushing strength for trees of Type A (DBH > 27 cm), Type B (DBH = 23~27 cm), and Type C (DBH > 23 cm), respectively

Evaluation of Wood Quality of Taiwania Trees Grown with Different Thinning and Pruning Treatments Using Ultrasonic-Wave Testing

The variations of Vtree, Vlumber, MOEtree, and MOElumber in the thinning and pruning treatments showed the similar trend. Results of this study also demonstrate that the effect of silvicultural practices on wood properties can be identified with the ultrasonic-wave properties of trees. This indicates that this non-destructive ultrasonic-wave technique can be provided basic information for future management practice and wood utilization of Taiwania

Effects of Planting Density on Visually Graded Lumber and Mechanical Properties of Taiwania

The purpose of this study was to investigate the effects of planting density on the quality of visually graded lumber, and the strength properties of 35-year-old Taiwania (Taiwania cryptomerioides Hay). The results are summarized as follows.(1) Lumber obtained from the site with type S planting density (6940 trees/ha) were mostly of better grade (84.6% including first and second grades), followed by type Q (2500 trees/ha) (69.1%), type R (3300 trees/ha) (62.5%), whereas poorer lumber was found mostly from trees with type P planting density (1000 trees/ha) (41.6%).(2) Specimens cut from trees of type S planting density site had the largest average values of ultrasonic velocity (Vu), dynamic modulus of elasticity obtained from transversal vibration (Edt), dynamic modulus of elasticity obtained from ultrasonic velocity (Edu), modulus of elasticity at bending (MOE), and modulus of rupture at bending (MOR), followed in decreasing order by those of type P, type R, and type Q sites.(3) Interrelations between Vu, Edu, Edt, MOE, and MOR can be represented by positive linear regression formulas. The differences were highly significant

Effect of Moisture Content on the Drill Resistance Value in Taiwania Plantation Wood

The effect of moisture content (MC) on the drill resistance values during desorption from a watersaturated condition of Taiwania (Taiwania cryptomerioides Hayta) plantation lumber was examined. Results showed that the drill resistance values tended to decrease with the decreasing of MC. Positive significant relationships were found among the MC, bulk density, and drill resistance values. This adjustment of density profiles could help the RESISTOGRAPH® to achieve a better measurement of the drill resistance profile of standing trees

Ring Characteristics and Compressive Strength of Japanese Cedar Trees Grown Under Different Silvicultural Treatments

The effects of different plantation spacings and thinning treatments on the ring characteristics, compressive strength, and dynamic modulus of elasticity (DMOE) of Japanese cedar (Cryptomeria japonica) trees were investigated. The results revealed that young trees of more-closely spaced plantations (3000 trees/ha) had higher wood density and compressive strength than those of more-widely spaced plantations (2200 trees/ha). Different (first and second) thinning treatments of the 2 initial spacings had little effect on ring characteristics or compressive strength. Overall, the average ring characteristics, compressive strength, and DMOE of 35-yr-old Japanese cedar at different plantation spacings and thinning treatments showed no statistically significant differences. The results suggest that using these silvicultural treatments with a longer rotation age will have no detrimental effects on the wood density, compressive strength, or DMOE

Embryo Development and Behavior in Sea Urchin (Tripneustes gratilla) Under Different Light Emitting Diodes Condition

This study aims to evaluate the effect of light-emitting diodes (LEDs) of different wavelengths on the embryonic development, covering behavior, righting behavior, and phototaxis of collector urchins (Tripneustes gratilla). The collector urchins were divided into three groups according to the type of LED illumination they received: full-spectrum (400–750 nm wavelength), red light (630 nm), or blue light (450 nm). The results of the embryonic development experiment indicated that the blue LED group had the highest proportion of embryos reaching the prism stage at the 24th hour and the highest proportion of embryos entering the 4-arm pluteus stage, but it also had the highest death rate at the 48th hour. The full-spectrum and red LED groups exhibited similar speeds of embryonic development. In the experiment on covering behavior performed on adult urchins, our findings indicated that the blue LED group gripped the most acrylic sheets for cover, exhibiting the most covering behavior, followed by the full-spectrum group and then the red LED group. Moreover, behavior varied with coloration, as collector urchins with a lower level of melanin exhibited more covering behavior than those with a higher melanin level. In addition, the righting behavior experiments demonstrated that the blue LED group spent the longest time righting themselves. It is possible that the relatively strong stimulation from the blue LED illumination led to a higher level of stress in the collector urchins and hence slowed their righting. The phototaxis experiment revealed the most significant negative phototactic response in collector urchins when they were under the blue LED light, followed by the full-spectrum light; the red LED light did not induce any positive or negative phototactic response in the collector urchins. This experimental result verified collector urchins’ high sensitivity to and dislike of the blue LED light. The study results confirmed that the blue LED light environment accelerated the embryonic development of collector urchins; however, the relatively strong stimulation from that light also caused them to engage in covering behavior or move away from the light. These results indicate that short-wavelength irradiation significantly affects the embryonic development and behavior pattern of this species