High Density Polyethylene Tubes Research Articles

Axial compression test on strengthening concrete cylinders by Fe-SMA/FRP-HDPE tube and rubber concrete cladding layer

This paper proposed a new method to strengthen and repair concrete columns, which combined active and passive confinement. The method involved the use of iron-based shape memory alloy (Fe-SMA) strips to quickly exert active confinement to these columns, followed by the use of fiber-reinforced polymer (FRP) and high-density polyethylene (HDPE) tubes as external passive confinement to improve the load-bearing capacity, durability, and ductility of concrete columns. Rubber concrete that performs high energy consumption and certain strength was used as the cladding layer to improve the impact resistance of the concrete column. This paper explored the effect of this method on the bearing capacity performance of concrete columns through axial compression tests and set three test variables, including different net-spacing of Fe-SMA, different FRP wrapping forms, and different FRP layers. The test outcomes showed that all three test variables obviously improved the load-bearing capacity and ductility of concrete columns, peculiarly when applying active confinement. Eventually, this paper proposed a theoretical model to predict the peak compressive strength of the specimen, which can provide a reference for designing this active-passive confinement strengthening method.

A Novel Positive-Contrast Magnetic Resonance Imaging Line Marker for High-Dose-Rate (HDR) MRI-Assisted Radiosurgery (MARS).

Magnetic resonance imaging (MRI) can facilitate accurate organ delineation and optimal dose distributions in high-dose-rate (HDR) MRI-Assisted Radiosurgery (MARS). Its use for this purpose has been limited by the lack of positive-contrast MRI markers that can clearly delineate the lumen of the HDR applicator and precisely show the path of the HDR source on T1- and T2-weighted MRI sequences. We investigated a novel MRI positive-contrast HDR brachytherapy or interventional radiotherapy line marker, C4:S, consisting of C4 (visible on T1-weighted images) complexed with saline. Longitudinal relaxation time (T1) and transverse relaxation time (T2) for C4:S were measured on a 1.5 T MRI scanner. High-density polyethylene (HDPE) tubing filled with C4:S as an HDR brachytherapy line marker was tested for visibility on T1- and T2-weighted MRI sequences in a tissue-equivalent female ultrasound training pelvis phantom. Relaxivity measurements indicated that C4:S solution had good T1-weighted contrast (relative to oil [fat] signal intensity) and good T2-weighted contrast (relative to water signal intensity) at both room temperature (relaxivity ratio > 1; r2/r1 = 1.43) and body temperature (relaxivity ratio > 1; r2/r1 = 1.38). These measurements were verified by the positive visualization of the C4:S (C4/saline 50:50) HDPE tube HDR brachytherapy line marker on both T1- and T2-weighted MRI sequences. Orientation did not affect the relaxivity of the C4:S contrast solution. C4:S encapsulated in HDPE tubing can be visualized as a positive line marker on both T1- and T2-weighted MRI sequences. MRI-guided HDR planning may be possible with these novel line markers for HDR MARS for several types of cancer.

Tubing material considerably affects measurement delays of gas-phase oxygenated per- and polyfluoroalkyl substances

ABSTRACT Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants associated with negative health impacts. Assessments of tubing-related measurement bias for volatile PFAS are lacking, as gas-wall interactions with tubing can delay quantification of gas-phase analytes. We use online iodide chemical ionization mass spectrometry measurements to characterize tubing delays for three gas-phase oxygenated PFAS – 4:2 fluorotelomer alcohol (4:2 FTOH), perfluorobutanoic acid (PFBA), and hexafluoropropylene oxide dimer acid (HFPO-DA). Perfluoroalkoxy alkane and high-density polyethylene tubing yielded relatively short absorptive measurement delays, with no clear dependence on tubing temperature or sampled humidity. Sampling through stainless steel tubing led to prolonged measurement delays due to reversible adsorption of PFAS to the tubing surface, with strong dependence on tubing temperature and sample humidification. Silcosteel tubing afforded shorter measurement delays than stainless steel due to diminished surface adsorption of PFAS. Characterizing and mitigating these tubing delays is crucial for reliable quantification of airborne PFAS. Implication statement Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants. Many PFAS are sufficiently volatile to exist as airborne pollutants. Measurements and quantification of airborne PFAS can be biased from material-dependent gas-wall interactions with sampling inlet tubing. Thus, characterizing these gas-wall interactions are crucial for reliably investigating emissions, environmental transport, and fates of airborne PFAS.

Compression behavior of concrete columns strengthened by a hybrid BFRP/HDPE tube coupled with a crumb rubber concrete cladding layer

A previous study proved that the confinement of fiber-reinforced polymer (FRP) effectively improves the load capacity and ductility of concrete columns. High-density polyethylene (HDPE) material, which exhibits excellent erosion resistance and high ductility, possesses enormous potential for strengthening structural columns. Based on the discussion, the combination of these two materials as hybrid confinement is investigated in this study. As an energy-dissipating material with excellent ductility, rubber concrete is employed in the hybrid strengthening method as an anti-collision layer. A novel composite system that comprises external FRP-HDPE confinement and an infilled rubber concrete layer is proposed in this study. An experimental test investigates its compressive strength, and three variables are considered, including the diameter of the HDPE tube, the layers of FRP sheets, and the addition of rubber particles in rubber concrete. The test results show that the ultimate compressive strength of specimens is improved with an increase in the diameter of the HDPE tube and layers of the FRP sheet, while the higher addition of rubber particles can reduce the compressive strength. However, these three variables have a positive effect on the deformation capacity of the specimens. A theoretical model is proposed for predicting the ultimate axial stress of specimens, which can provide a reference for designing this hybrid reinforcement.

Friction stir welding of tube-to-tubesheets for thermoplastic shell and tube heat exchangers

Recently, there is a real demand for thermoplastic shell-and-tube heat exchangers because of their antifouling and chemically inert properties. A novel non-conventional joining technique is developed for creating efficient thermoplastic tube-to-tubesheet joints (TTJs) using the friction stir welding (FSW) process. The carbon black reinforced high-density polyethylene sheet and tube materials are used. A highly ductile joint with a maximum strength of 517 N (42 % greater than adhesives), and a maximum leak path of 3 mm (77 % of remaining tubesheet thickness) was achieved using FSW. The proposed technique was found promising and reliable for developing TTJs for thermoplastic shell-and-tube heat exchangers.

Full-Scale Model Experimental Study of the HDPE Multitube Saddle of an Extradosed Bridge

For an extradosed bridge, the main function of the saddle structure is to steer the cable in the pylon. The saddle is one of the most important and key structures in the cable prestressing system. Focusing on the high-density polyethylene (HDPE) multitube saddle structure and cement slurry filling, the mechanical properties of the saddle are analyzed and verified in detail by a full-scale model test. It is shown that the numerical analysis results are consistent with the test results. Under 1.8 times the designed load (7171.4 kN), the test strain values of each section are less than the calculated strain values, which indicates that the saddle structure design is safe and that the saddle structure meets the design requirements. Friction resistance between the steel strands and the HDPE tube can resist unbalanced cable forces on either side of the saddle during construction and operation. According to the test, the maximum value of the static friction coefficient between cable and HPDE tube is 0.093. The cement slurry stress is basically in the linear elasticity range under the test conditions. After further increasing the cable tension, the cement slurry inside the saddle is compacted, without any cracks or crushing phenomena. This demonstrates that the saddle is safe and reliable.

Flexural behavior of HDPE tubular beams filled with self-compacting geopolymer concrete

This paper proposes a new hybrid composite tubular beam system that consists of an exterior high-density polyethylene (HDPE) tube with interior steel tube and self-compacting geopolymer concrete (SCGC). The flexural behavior of composite tubular beams with SCGC encased in HDPE tubes was investigated experimentally and theoretically. A total of twenty-two specimens was tested, including twelve confined and ten unconfined specimens. The test variables include the presence of confinement (confined or unconfined), HDPE tube thickness and interior diameter, presence of inner steel tube, cross section of inner layer (circular or square), and presence of SCGC filling in inner layer. The failure mode, flexural strength and fracture energy are examined based on measured load–deflection data by four point bending test. Results indicated that the HDPE confinement provided significant enhancement in flexural response and especially the ductility of specimens, demonstrating considerably large plastic deformations before failure. A theoretical methodology was developed to predict the ultimate flexural load capacity. The analysis was conducted based on the combination of classical beam theory and the modification of a previously proposed methodology. Results of the analysis confirmed the high accuracy of proposed methodology in predicting ultimate flexural capacity of HDPE tube-confined beams.

Clinical utility and value contribution of an MRI-positive line marker for image-guided brachytherapy in gynecologic malignancies

PurposeThe purpose of this study was to investigate the utility of a novel MRI-positive line marker, composed of C4:S (cobalt chloride–based contrast agent) encapsulated in high-density polyethylene tubing, in permitting dosimetry and treatment planning directly on MRI. Methods and MaterialsWe evaluated the clinical feasibility of the C4:S line markers in nine sequential brachytherapy procedures for gynecologic malignancies, including six tandem-and-ovoid and three interstitial cases. We then quantified the internal resource utilization of an intraoperative MRI-guided procedural episode via time-driven activity-based costing, identifying opportunities for cost-containment with use of the C4:S line markers. ResultsThe C4:S line markers demonstrated the strongest positive signal visibility on 3D constructive interference in steady state (CISS)/FIESTA-C followed by T1-weighted sequences, permitting accurate delineation of the applicator lumen and thus the source path. These images may be fused along with traditional T2-weighted sequences for optimal tumor and anatomy contouring, followed by treatment planning directly on MRI. By eliminating postoperative CT for fusion and applicator registration from the procedural episode, use of the C4:S line markers could decrease workflow time and lower total delivery costs per procedure. ConclusionsThis analysis supports the clinical utility and value contribution of the C4:S line markers, which permit accurate MRI-based dosimetry and treatment planning, thereby eliminating the need for postoperative CT for fusion and applicator registration.

In pursuit of a replacement for conventional high-density polyethylene tubes in ground source heat pumps from their composites – A comparative study

Ground-source heat pumps, as the most environmentally friendly and energy-efficient air conditioning technology, suffer from a great required length of ground heat exchanger, partly arising from the low thermal conductivity of high-density polyethylene tubes commonly used in ground heat exchangers. In an attempt to find a replacement with an acceptable thermal conductivity for high-density polyethylene tubes, in this study, first, a comprehensive comparative study on fillers commonly used in thermally conductive polymer composites and resulting high-density polyethylene composites was conducted. Then, based on the advantages and disadvantages presented, an appropriate composite was selected and applied in the modeling of a case study to demonstrate the effect of thermal conductivity of the tube on the borehole length of the ground heat exchanger. The findings indicated that low-temperature in situ expandable graphite was a suitable filler to add to high-density polyethylene polymer, resulting in a composite with acceptable thermal and rheological properties. Investigating the effect of thermal conductivity of the tube on the borehole length revealed some intriguing findings. First, using a composite with a thermal conductivity of approximately 1.4 Wm−1 K−1, for instance, the affordable high-density polyethylene composite filled with 10 wt% of low-temperature in situ expandable graphite, the length of the ground heat exchanger reduced by a notable amount of 10 %, which is more than 68 % of the maximum potential for reducing borehole length could be achieved by improving thermal properties of the tube. Furthermore, using polymer composites with thermal conductivity in the range of 2 Wm−1 K−1 could obviate the need for using metal tubes, which are used even nowadays in certain cases. However, due to the lack of results of some specific test, such as Hydrostatic Design Basis, the mechanical properties of the newly introduced composite require further investigation.

Per‐ and polyfluoroalkyl substances in environmental sampling products: Fact or fiction?

AbstractCan per‐ and polyfluoroalkyl substances (PFAS) be transferred from the common field and other commercial products during sampling? Special handling and care are always advised when collecting samples for PFAS analysis to avoid sample contamination. The potential presence of PFAS in common consumer products and in equipment typically used to collect environmental samples, coupled with the need for very low reporting limits heightens this concern. In this paper, the authors investigate what the potential for cross‐contamination is from a number of commonly used products, with the emphasis on evaluating what the possible worst‐case scenario for cross‐contamination could be. Polytetrafluoroethylene (PTFE), low‐density polyethylene (LDPE), and high‐density polyethylene (HDPE) tubing, pump bladders, and other materials are evaluated along with associated products such as aluminum foil and plastic storage bags. In the experimental design of this study, the products themselves are not analyzed directly for PFAS. Rather, a series of experiments are performed utilizing a leaching procedure to evaluate the potential for cross‐contamination and false‐positive environmental sampling results. This study was performed in a series of experimental batches over the course of a 1‐year period. Analytical results are presented along with experimental observations and recommendations.

Mechanical Behavior of the HDPE Tubes Used in Water Supply Networks Determined with the Four-Point Bending Test

Abstract High density polyethylene (HDPE) is a basic material in the field of liquid transportation used in the construction of the pipes of the water supply system, namely the tube. It is clear that a good knowledge of the mechanical properties of the high density polyethylene used for fabrication of the tubes is important in engineering, due to large use of such materials. In the paper experimental four-point bend tests are made in order to obtain the flexural characteristics of the tube made from the HDPE. Tubes and fittings made from this material are characterized by a long service life and their maintenace costs are reduced. The results are presented in the paper and can be used in practice and in further research.

Heat Transfer of Polyolefin Covered STS Corrugated Tube for Surface Water Source Heat Pump

Recently, high density poly ethylene (HDPE) tube has been utilized in surface water source heat pump (SWSHP) as a surface water heat exchanger (SWHE). Stainless steel (STS) corrugated tube has much higher heat transfer coefficient (U value) than HDPE tube in SWHE. However, this material cannot be perfectly protected from corrosion when exposed to aggressive water environments. The goal of this work is to increase U value of SWHE when STS corrugated tube is perfectly protected from corrosion by covering polyolefin material on its corrugated surface. In order to verify the thermal performance of proposed tube, U values and friction factors of the proposed tube were compared with those of the HDPE tube. For the evaluation on possible applicability of proposed tube, the economic evaluation of the proposed tube was also performed based on the result from test bed experiments. The results show that the proposed tube leads to 4.65 times higher U value and 2 times higher friction factor than HDPE smooth tube. Despite with the increased friction loss and installation cost, it was revealed that the proposed tube can achieve COP due to enhanced heat transfer performance.

Atmospheric pressure surface modification and cross‐linking of UHMWPE film and inside HDPE tube by transporting discharge

In this work, the surface modification of ultra‐high‐molecular‐weight polyethylene (UHMWPE), a linear polymer, by a helium transporting discharge at atmospheric pressure was investigated by means of FTIR, AFM, XPS, ToF‐SIMS, and contact angle measurements. Two types of discharge configurations, that is, jet and glow of the transporting discharge for the surface treatment of polymer substrates were studied. The results show that the position of the UHMWPE polymer substrates plays an important role in the surface modification and stability of the treatment. The polymer substrates placed inside the transporting discharge tube present more stable wettability and surface modification. In addition, the transporting discharge was used to modify the inner surface of the high density polyethylene tube.

Experimental development of natural convection heat transfer correlations for spiral-helical surface water heat exchangers (1385-RP)

Surface water heat pump systems utilize surface water bodies, such as lakes, reservoirs, and rivers, as heat sources and heat sinks. Closed-loop surface water heat pumps use submerged heat exchangers to extract or reject heat from the surface water body. Heat transfer between the heat exchanger and the lake is generally governed by buoyancy driven natural convection. One form of surface water heat exchanger is the spiral-helical heat exchanger, which is usually fabricated from high-density polyethylene tubing. Though the exterior convective resistance is an important part of the design calculation, convection correlations suitable for spiral-helical surface water heat exchangers are not available. In the current article, the authors cover an experimental study involving heat rejection experiments and heat extraction experiments on nine different spiral-helical configurations with three different high-density polyethylene tube sizes. Standard high-density polyethylene and thermally enhanced high-density polyethylene heat exchangers were also tested and compared. Convection correlations for spiral-helical heat exchangers were developed for heat extraction and heat rejection conditions. Heat transfer rate predicted with the correlations is compared against experimental data.

3D finite element assessment of the effects of energy loops on the load capacity and settlement of bored piles installed in sand

Three-dimensional finite element analyses were carried out to study the geotechnical behaviour of piles fitted with high-density polyethylene (HDPE) tubes as energy loops for harnessing ground heat. The objective was to examine whether the existing analysis methods for conventional piles are applicable to energy piles. Using PLAXIS 3D software, simulations were done for 60 cases of energy piles comprising variously configured HDPE tubes. It was found that HDPE tubes inevitably interact with the soil around the pile such that 6–11 HDPE tubes decreased the load capacity by 18–70%, while 3–4 HDPE tubes had an optimum reinforcing effect on the soil, thereby increasing the load capacity by 30–75% depending on the pile size. However, the tubes had little effect on settlement at ultimate load. Thus, the work highlighted the limitation of conventional methods of analysis and the geotechnical effect of HDPE tubes installed to protrude from the base of an energy pile.

Simulation of extrusion of high density polyethylene tubes

The production of extruded polyethylene films rods, tubes and pipes is a typical industrial process that has been extensively investigated over many years. In this study the extrusion of High Density Polyethylene (HDPE) tubes was simulated by using the 3D finite element simulation software StarCCM+®. The simulation was applied in order to examine the influence of design and operational parameters on the characteristics and the soundness of the tube and for optimizing the overall quality of the product. Two alternative die configurations were studied; one with a four inputs head and the other with an eight inputs head. From the results obtained it is concluded that extrusion with the eight inputs head die design results in better overall pipe quality; this design was implemented successfully in an industrial production line.

Numerical Study of Compact Terahertz Gas Laser Based on Photonic Crystal Fiber Cavity

We report a compact terahertz (THz) gas laser based on the cavity photonic crystal fiber (PCF). This compact structure consists of a large air core PCF constructed by high-density polyethylene tubes. The 2.52 THz wave can be generated in the reaction cell filled with the CH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> OH gas. The reaction cell should shrink the volume of THz sources. The saturation intensity is analyzed based on the rate equations theory. Numerical calculations show that the THz wave can realize the fundamental mode transmission and obtain a lower confinement loss of 5.6 dB/m and the flat bending loss spectrum. The optimum pressure, pump threshold are analyzed and the THz output power can reach the magnitude of 10 mW. We combined the THz pump technology and the excellent transmission characteristics of the PCF together. This compact THz gas laser gives a new method to realize the THz source with high beam quality, low transmission loss, well-distributed bending shape and small size.

GERMINATION EFFECT OF DIFFERENT SUBSTRATES ON GRUMIXAMA SEEDS

Grumixama belongs to the Myrtaceae family, members of which have simple leaves, which are generally leaf-opposed, with whole margins, an evergreen color. The Myrtaceae family includes about 140 genera and over 3,000 species. Grumixama is rarely cultivated and its production is normally used in the manufacture of bulk candy, syrup, liqueurs and jams. Because it is rarely cultivated there is virtually no agronomic information about the cultivation of this fruit tree, in particular relating to seedling production and seed germination. The objective of this study was to evaluate grumixama seed germination in two substrates; Tecnomax® (based on pine bark) and washed sand. Sowing was performed in 110 cm3 volume, high-density polyethylene tubes filled with the respective substrates. Sixty days after sowing the germination percentage was evaluated. The height, stem diameter and number of leaves were evaluated at 120 days, when the seedlings had an average height of 10 cm. The pine bark substrate provided the best germination and development of quality grumixama seedlings compared to the washed sand.

A Curved Electromagnetic Energy Harvesting System for Wearable Electronics

In this paper, a new curved electromagnetic energy harvesting system is designed, developed, and tested. This system is able to capture energy through oscillatory motion and proposes the use of a curved oscillatory electromagnetic harvester over the regular linear electromagnetic harvester due to its ability to harvest energy in two directions while walking/running. This paper also examines how the curvature of an oscillatory energy harvester affects its conversion efficiency from kinetic energy to electrical energy which is then stored. An enameled copper coil, having 1000 windings, is fixed at the center of a high-density polyethylene tube, in which a freely moving neodymium iron boron (NdFeB) magnet is housed. The $0.21~{\mathrm{ m}} \times 0.016~\text{m}$ harvester curved at a 0.25 m radius is able to produce the no load dc voltages of between 2.55 and 4.07 V when shaken at frequencies ranging from 2 to 5Hz. The 0.140 kg prototype is also tested by the human body motion during walking and running. The experimental results show that the harvester could generate a power of 5.185 mW.

Performance of water source heat pump system using high-density polyethylene tube heat exchanger wound with square copper wire

Surface water source heat pump system is an energy-efficient heat pump system. Surface water heat exchanger is an important part of heat pump system that can affect the performance of the system. In order to enhance the performance of the system, the overall heat transfer coefficient (U value) of the water exchanger using a 32A square copper coiled high-density polyethylene tube was researched. Comparative experiments were conducted between the performance of the coiled high-density polyethylene tube and the 32A smooth high-density polyethylene tube. At the same time, the coefficient of performance of the heat pump was investigated. According to the result, the U value of the coiled tube was 18% higher than that of the smooth tube in natural convection and 19% higher in forced convection. The coefficient of performance of the heat pump with the coiled tube is higher than that with the smooth tube. The economic evaluation of the coiled tube was also investigated.