Wood Poles Research Articles

Plasticizer Combinations and Performance of Wood Flour–Poly(Lactic Acid) 3D Printing Filaments

Wood flour-poly(lactic acid) 3D printing filaments were prepared via a melt extrusion method. Poplar wood flour and poly(lactic acid) (PLA) were used as raw materials, and different combinations of glycerol and tributyl citrate (TBC) (4% glycerol, 2% glycerol + 2% TBC, 4% TBC) were used as plasticizers. A 3D printer was used to print the filaments into standard test specimens with dimensions of 150 mm × 10 mm × 0.2 mm at the printing temperature of 220 °C. The performance of wood flour-poly(lactic acid) 3D printing filaments in terms of their interfacial compatibility, mechanical properties, melt index (MI), water absorption, and heat stability was tested under different plasticizer combinations. The results showed that under the condition of same dosage of plasticizer, the order of MI for the 3D printed filaments from high to low was 4% glycerol > 2% glycerol + 2% TBC > 4% TBC, which indicated that glycerol was more favorable for the extrusion processing of the composite filaments. However, in terms of compatibility, mechanical properties, water absorption, and thermal stability, the 3D printing filaments with 4% TBC showed better performance compared with other groups.

Environmental Profile of CBA (Copper-Boron-Azole)-Treated Wooden Utility Poles: A Developing Country Case

Environmental Profile of CBA (Copper-Boron-Azole)-Treated Wooden Utility Poles: A Developing Country Case

Integrated control of wood destroying basidiomycetes combining Cu-based wood preservatives and Trichoderma spp.

The production of new generation of wood preservatives (without addition of a co-biocide) in combination with an exchange of wood poles on identical sites with high fungal inoculum, has resulted in an increase of premature failures of wood utility poles in the last decades. Wood destroying basidiomycetes inhabiting sites where poles have been installed, have developed resistance against wood preservatives. The objective of the in vitro studies was to identify a Trichoderma spp. with a highly antagonistic potential against wood destroying basidiomycetes that is capable of colonizing Cu-rich environments. For this purpose, the activity of five Trichoderma spp. on Cu-rich medium was evaluated according to its growth and sporulation rates. The influence of the selected Trichoderma spp. on wood colonization and degradation by five wood destroying basidiomycetes was quantitatively analyzed by means of dry weight loss of wood specimens. Furthermore, the preventative effect of the selected Trichoderma spp. in combination with four Cu-based preservatives was also examined by mass loss and histological changes in the wood specimens. Trichoderma harzianum (T-720) was considered the biocontrol agent with higher antagonistic potential to colonize Cu-rich environments (up to 0.1% CuSO4 amended medium). T. harzianum demonstrated significant preventative effect on wood specimens against four wood destroying basidiomycetes. The combined effect of T. harzianum and Cu-based wood preservatives demonstrated that after 9 months incubation with two wood destroying basidiomycetes, wood specimens treated with 3.8 kg m-3 copper-chromium had weight losses between 55–65%, whereas containers previously treated with T. harzianum had significantly lower weight losses (0–25%). Histological studies on one of the wood destroying basidiomycetes revealed typical decomposition of wood cells by brown-rot fungi in Cu-impregnated samples, that were notably absent in wood specimens previously exposed to T. harzianum. It is concluded that carefully selected Trichoderma isolates can be used for integrated wood protection against a range of wood destroying basidiomycetes and may have potential for integrated wood protection in the field.

Treatment of a mixed wood preservative leachate by a hybrid constructed wetland and a willow planted filter.

The performance and removal mechanisms of a hybrid constructed wetland (HCW) followed by a willow planted filter (WPF) were evaluated for the treatment of a leachate contaminated by wood pole preservatives (pentachlorophenol (PCP) and chromated copper arsenate) to reach the storm sewer discharge limits. The HCW aimed to dechlorinate the PCP and polychlorodibenzo-p-dioxins/polychlorodibenzofuran (PCDD/F) and to remove metals by adsorption and precipitation. The HCW was efficient in removing PCP (>98.6%), oil, arsenic (99.4%), chromium (>99.2%), copper (>99.6%%) and iron (29%) to under their discharge limits, but it was unable to reach those of Mn and PCDD/F, with residual concentrations of 0.11 mg Mn/L and 0.32 pg TEQ/L. Iron and manganese could be removed but were subsequently released by the HCW due to low redox conditions. No dechlorination of PCDD/F was observed since its chlorination profile remained the same in the different sections of the HCW. Adsorption was the most probable removal mechanism of PCDD/F. The WPF was able to remove some residual contamination, but it released Mn at a gradually decreasing rate. Total evapotranspiration of the leachate by a larger fertilized WPF and the construction of an underground retention basin are proposed to prevent any discharge of PCDD/F traces in the environment.

Life cycle assessment of the environmental influence of wooden and concrete utility poles based on service lifetime

Purpose Many applications of life cycle assessment do not consider the variability of the service lifetime of different structures, and this may be a relevant factor in an environmental impact assessment. This paper aims to determine the influence of the service lifetime on the potential environmental impacts of wooden and concrete poles in the electricity distribution system.

Maintenance optimization for power distribution systems subjected to hurricane hazard, timber decay and climate change

Electric power systems are vulnerable to extensive damage due to hurricanes with most of the damage concentrated on overhead distribution systems. There is evidence that climate change will affect future hurricane patterns. Additionally, wood poles, which are most commonly used in distribution systems, are susceptible to decay. The scarcity of resources and increasing demand for higher reliability warrant the use of optimization techniques for wood pole maintenance planning. This paper presents a framework for optimal maintenance of wood poles subjected to non-stationary hurricane hazard and decay. Maintenance cost, service life, and system performance are considered separately and simultaneously in the optimization. Periodic chemical treatment and repair of decayed poles using fiber-reinforced polymer are considered. The distribution system of a virtual city assumed to be in Florida is used to demonstrate the framework. The results of the single-objective optimization indicate that the objective that maximizes service life resulted in higher optimal maintenance time. However, delaying maintenance will lead to a larger probability of pole failure, higher corrective maintenance cost, and lower system performance. The result of the multi-objective optimization is closer to the result of the cost-based optimization because the cost function is more sensitive to the variation of maintenance time.

Round dwellings of the saka epoch

Based on the excavation materials from the settlement Tuyetas studied by the author on the territory of Karaganda Region, the characteristics of such a type of Saka dwellings as round houses are considered. According to archaeological research, on the territory of Kazakhstan rounded frame dwellings, along with rectangular, were commonly widespread in the Bronze Age. The frame house with round plan is known from the materials of Saka time Zhetysu (settlement Butakty-1). On the settlement Tuyetas on the excavated area of 408 square meters the remains of foundations of round houses and two annexes were revealed. The author suggests that it was the house of the yurt-shaped form with a powerful stone base with a minimum width of 1 m and a wooden top. The construction with the overall diameter of about 13 m had several rooms, extensive grounds which were also made of stone. One round room with a diameter of about 33,5 m was in the centre. Wooden poles on the frame walls of the room at the same time supported the upper structure of the house. Houses of round plan were opened at the Saka settlement Sarybuyrat, located near the settlement of Tuyetas. This type of construction is recorded in a number of other not yet studied settlements in Central Kazakhstan. The study of Saka settlements in Central Kazakhstan is at the initial stage. The source base should be broadened for a comprehensive analysis of many aspects, including features and types of dwellings.

Nondestructive bending tests on Douglas-fir utility poles as a potential tool for pole sorting and for prediction of their behavior in service

Abstract Wood poles are a critical part of the electrical transmission system in North America. Wood poles are normally selected on the basis of visual features such as knots, slope of grain or other defects, but there is currently no simple, nondestructive bending (NDB), pre-flexural testing for sorting poles prior to use. In the present paper, the potential for NDB based on bending below the proportional limit was examined to calculate modulus of elasticity (MOE) and thereby predict actual modulus of rupture as determined by destructive bending (MORDB). The investigation was performed on 92 full length 13.3-m long Douglas-fir pole sections. Pre-flexural testing was reasonably correlated with MOEDB, but less well correlated with MORDB. The testing also revealed that visual selection of the best face of a pole, which is used to select a pole oriented to line direction (the “best face”), was poorly correlated with pre-flexing. Increasing the number of NDB tests did not noticeably improve the prediction. The results suggest that pre-flexing might be useful for identifying poles’ performance in service, if more data are available.

KOKSHAROVSKY KHOLM AND CHERTOVA GORA, TWO NEOLITHIC SANCTUARIES IN THE URAL AND IN WESTERN SIBERIA: SIMILARITIES AND DIFFERENCES

Two Neolithic sanctuaries are compared: Koksharovsky Kholm in the middle Ural and Chertova Gora in western Siberia. Both apparently represent related but separate populations represented by the Koshkino-Boborykino and Kozlov-Poludenka decorative traditions dating to the 7th–5th millennia BC (calibrated). Sanctuaries were arranged on high salient promontories. At Koksharovsky Kholm, the ritual meaning of the place was accentuated by two ditches separating the sacral space from the dwelling area. Another attribute of this sanctuary were variously sized and shaped structures made of wooden poles or slabs. At Koksharovsky Kholm, remains of much smaller (less than 1 × 1 m) structures resembling chests were found, and at Chertova Gora, birch-bark box-like containers. Stone tools from the two sites differ. Parallels include intact or broken clay vessels, metal rods with incisions, flint arrowheads, etc. Some appear to have been made for ritual purposes, and some were broken intentionally. Offerings of artifacts were accompanied by sacrificing wild animals, birds, and fishes. At Chertova Gora, an offering of hemp grains was found. Parallels with Mansi, Khanty, and Udmur may imply ideological continuity.

Performance of copper treated utility poles and posts used in service for several years

Copper based wood preservatives are among the most important wood preservatives for heavy-duty applications. Wood treated with copper-based preservatives performs excellently if applied according to preservative specifications. If used improperly, premature failures can appear. In order to elucidate the properties of copper treated wood in use, utility poles and posts treated with copper-based preservatives were investigated. Poles were cut into smaller specimens, and copper and chromium penetration, retention, mechanical properties, extractive content, short-term water uptake and fungicidal properties were then determined. The results clearly showed that wood retains its properties if treated with sufficient amounts of copper-based wood preservatives. Insufficient amounts of preservatives applied result in premature failures of wood commodities. Regardless of the type of wood preservative used, the central part of spruce wood poles and piles is the weakest point, where the majority of the failures occurs.

An equivalent boundary model for effects of adjacent spans on wind reliability of wood utility poles in overhead distribution lines

Overhead distribution lines in the United States are primarily supported by wood poles. These utility poles are vulnerable to high wind loads from hurricanes which has resulted in a large number of power outages during past hurricanes, especially in coastal areas. Risk management of distribution systems requires development of distribution line models to reliably assess their performance under hurricanes. However, modeling the entire distribution line is not practically feasible as they are very long and consist of a large number of spans. The present study proposes analytical models to capture boundary effects of adjacent spans on the wind response of the pole of interest via equivalent springs and wind-induced forces. The stiffness of conductors (cables) is derived through a simplified solution that considers the shape of the conductors under lateral static gust wind and gravity loadings; this model is shown to be very accurate when compared to the exact analytical as well as Finite Element solutions. Deterministic and probabilistic studies are performed to assess the impact of boundary conditions on the performance of the poles; results indicate that pole boundaries may have a considerable impact on the estimates of failure probabilities especially when the extent of difference in the properties of adjacent spans is not negligible. Specifically, neglecting boundary effects from neighboring spans may result in underestimation of failure probabilities of stronger poles and overestimation of failure probabilities of weaker poles as load sharing effects among the poles are not considered. The proposed boundary model enables more reliable hurricane risk assessment of power distribution systems to effectively manage the risk of outages.

Three materials that transformed Israeli playground design in the 1970s: fibreglass, wooden poles and reinforced concrete

ABSTRACTThis article examines the way in which material and design dimensions can be integrated into the history of playgrounds built in Israel in the 1970s – a decade that saw a variety of new materials introduced to play facilities in the local market: fibreglass, reinforced concrete and wooden poles. Based on Attfield and Brookshaw’s approach to material culture, five interviews with makers, selected newspaper articles and literature and comparative analysis of six playgrounds, the story of the material, its design and manufacturing unfolds. The article examines the effect of materiality on the forms of play facilities, children’s experience of play and the ideas of play in Israel at that time, as well as the way in which local cultural and social conceptions were expressed in playground design. It argues that the materiality of those playgrounds reflected their creators’ attitude toward children’s play and was manifested in a wide variety of play facilities.

Rapid fabrication of a four-layer PMMA-based microfluidic chip using CO2-laser micromachining and thermal bonding

A smart design method to transform the original two-layer microfluidic chip into a four-layer 3D microfluidic chip is proposed. A novel fabrication method is established to rapidly and effectively produce a four-layer microfluidic chip device made entirely from polymethylmethacrylate (PMMA). Firstly, the CO2-laser cuts the PMMA sheets by melting and blowing away vaporized material from the parent material to obtain high-quality channels of the microfluidic chip. An orthogonal experimental method is used to study its processing stability. In addition, a simple, rapid thermal bonding technique is successfully applied in fabricating the four-layer microfluidic chip, which has a bond strength of 1.3 MPa. A wooden pole is used to improve the accuracy of the alignment. Finally, a mixing experiment with blue ink and water is carried out, which proves that this smart design method and rapid manufacturing technology are successful.

Calendar-based age replacement policy with dependent renewal cycles

ABSTRACTIn this article, we introduce an age-based replacement policy in which the preventive replacements are restricted to specific calendar times. Under the new policy, the assets are renewed at failure or if their ages are greater than or equal to a replacement age at given calendar times, whichever occurs first. This policy is logistically applicable in industries such as utilities where there are large and geographically diverse populations of deteriorating assets with different installation times. Since preventive replacements are performed at fixed times, the renewal cycles are dependent random variables. Therefore, the classic renewal reward theorem cannot be directly applied. Using the theory of Markov chains with general state space and a suitably defined ergodic measure, we analyze the problem to find the optimal replacement age, minimizing the long-run expected cost per time unit. We further find the limiting distributions of the backward and forward recurrence times for this policy and show how our ergodic measure can be used to analyze more complicated policies. Finally, using a real data set of utility wood poles’ maintenance records, we numerically illustrate some of our results including the importance of defining an appropriate ergodic measure in reducing the computational expense.

Characterizing impedance profiles for leakage currents from HV insulators on wooden poles

In this paper, the impedance characteristic profiles of wooden power poles altering the leakage current from high voltage (HV) insulators are investigated to better understand the role of wood in leakage current signatures. A comparison with past research shows the capacitive components of a pole's impedance have previously been ignored, however, has little effect on using an impedance value for effective resistance. Examining the impedance properties of typical Copper Chromium Arsenate (CCA) impregnated wood for 66 kV distribution poles shows dangerous conductance properties of wood at this voltage, providing an explanation for these poles catching fire at triple the rate of 22 kV distribution poles. After a systematic investigation of wood used for poles, a preliminary impedance characteristic of wooden poles in Victoria, Australia is established for the first time, where the pole is weathered, CCA impregnated and operating at 22 kV under both dry and wet weather conditions.

Experimental verification of an orthotropic finite element model for numerical simulations of ultrasonic testing of wood poles

Ultraso nic testing is a non-destructive and non-invasive method which has been used for internal condition assessment of wood poles in electric transmission and distribution lines. The reliability of this method of evaluation relies on a good understanding of propagation of ultrasonic waves in wood. However, a full-waveform analysis in ultrasonic testing is rarely performed in practice because of difficulties in establishing realistic values for the elastic parameters, modeling the material damping and characterizing the dynamic response of an ultrasonic transmitter. In this paper, a calibrated orthotropic finite element model for numerical simulations of ultrasonic testing of a sound red pine pole is presented. In the calibrated model, the dynamic modulus of elasticity in the radial and tangential directions, Poisson’s ratio and damping ratios are estimated from ultrasonic testing; whereas the dynamic modulus of elasticity in the longitudinal direction is estimated from transverse-vibration testing. The measured response of an ultrasonic transmitter to a one-cycle sinusoidal pulse of 50 kHz is used as dynamic excitation and introduced in the numerical model as displacement-time history. Results of the first arrival of compression waves and the frequency response magnitude computed at three receiver locations are in good agreement with the obtained ones from ultrasonic testing. The calibrated orthotropic finite element model will be used for a better understanding of propagation of surface and compression waves in ultrasonic testing for the detection of early stages of decay in wood poles.

Habitat use in juvenile and adult life stages of the sedentary fish Hippocampus guttulatus

Understanding of the spatial distribution and habitat use in different stages of a life cycle represents the essential aspect of threatened species management and conservation. In the present paper, the spatial and temporal patterns of habitat use in juvenile and adult life stages of the long-snouted seahorse Hippocampus guttulatus in the Mar Piccolo of Taranto (Apulia—Italy) (40°28′N, 17°16′W) were examined. From October 2012 to January 2014, monthly visual censuses were conducted in six coastal habitats of a focal area (Buffoluto site). Of a total of 317 individuals of the long-snouted seahorse that were sighted, 148 were juveniles, 82 adult females and 87 adult males. Our results showed significant differences in the habitat use between adult and juvenile life stages of H. guttulatus. Adult individuals were mainly concentrated within Cladophora prolifera beds and the wood poles of a mussel farm at 2–4 m of depth, while juvenile individuals were mainly present in shallower water (0.4–1 m) on artificial hard substrates covered by a brown algae turf. Assessing and describing the habitat use within different life stages of H. guttulatus represent a useful tool to support species conservation by protecting the habitats it uses.

Dynamic Echo Information Guides Flight in the Big Brown Bat.

Animals rely on sensory feedback from their environment to guide locomotion. For instance, visually guided animals use patterns of optic flow to control their velocity and to estimate their distance to objects (e.g., Srinivasan et al., 1991, 1996). In this study, we investigated how acoustic information guides locomotion of animals that use hearing as a primary sensory modality to orient and navigate in the dark, where visual information is unavailable. We studied flight and echolocation behaviors of big brown bats as they flew under infrared illumination through a corridor with walls constructed from a series of individual vertical wooden poles. The spacing between poles on opposite walls of the corridor was experimentally manipulated to create dense/sparse and balanced/imbalanced spatial structure. The bats’ flight trajectories and echolocation signals were recorded with high-speed infrared motion-capture cameras and ultrasound microphones, respectively. As bats flew through the corridor, successive biosonar emissions returned cascades of echoes from the walls of the corridor. The bats flew through the center of the corridor when the pole spacing on opposite walls was balanced and closer to the side with wider pole spacing when opposite walls had an imbalanced density. Moreover, bats produced shorter duration echolocation calls when they flew through corridors with smaller spacing between poles, suggesting that clutter density influences features of the bat’s sonar signals. Flight speed and echolocation call rate did not, however, vary with dense and sparse spacing between the poles forming the corridor walls. Overall, these data demonstrate that bats adapt their flight and echolocation behavior dynamically when flying through acoustically complex environments.

Structural Assessment of Fiber-reinforced Polymer Composite Electric Poles

Engineers are increasingly tasked with designing and operating structures that incorporate the philosophy of resiliency across a variety of critical infrastructure sectors. Electric distribution and transmission systems are examples of the critical infrastructure sectors. The majority of existing electrical poles supporting electric distribution systems in the United States are made out of wood. It is estimated that up to 3.6 million existing electric wood poles have to be replaced every year. One of the primary hardening strategies is upgrading wooden electric poles and supporting structures with stronger materials that withstand hurricane-force winds. This paper presents finite element analysis of fiber-reinforced polymer composite poles including parametric studies on geometric characteristics, fiber orientation, number of layers, and lamina thickness.

Methods to reduce the risk of wooden pole ignition

A number of reported wooden pole ignition incidences show evidence that the source was located near the pole bolt/pin mounting hardware. This has been observed for environmentally stressed insulators, as well as for larger overhead equipment in situations where the wooden pole has become the dominant part of the leakage conduction path through loss/deterioration of a case ground conductor. In both of these cases, the bolt-to-wood interface is the focal point for the leakage current. A mechanism which can cause pole ignition in these situations is examined with comprehensive details. This paper suggests a novel method to reduce the risk of wooden pole ignition. The mathematical basis of the suggested method is also explained.