Recently, 3D printing has become one of the most popular additive manufacturing technologies. This technology has been utilised to prototype trial and produced components for various applications, ...such as fashion, food, automotive, medical, and construction. In recent years, automation also has become increasingly prevalent in the construction field. Extrusion printing is the most successful method to print cementitious materials, but it still faces significant challenges, such as pumpability of materials, buildability, consistency in the materials, flowability, and workability. This paper investigates the properties of 3D printed fibre-reinforced cementitious mortar prisms and members in conjunction with automation to achieve the optimum mechanical strength of printed mortar and to obtain suitable flowability and consistent workability for the mixed cementitious mortar during the printing process. This study also considered the necessary trial tests, which are required to check the mechanical properties and behaviour of the proportions of the cementitious mix. Mechanical strength was measured and shown to increase when the samples were printed using fibre-reinforced mortar by means of a caulking gun, compared with the samples that were printed using the same mix delivered by a progressive cavity pump to a 6 degree-of-freedom robot. The flexural strength of the four-printed layer fibre-reinforced mortar was found to be 3.44 ± 0.11 MPa and 5.78 ± 0.02 MPa for the one-layer. Moreover, the mortar with different types of nozzles by means of caulking is printed and compared. Several experimental tests for the fresh state of the mortar were conducted and are discussed.
Flow rate measurement in pipes is essential for many applications. Thus, there have been a variety of flow meters developed that incorporate different technologies. However, a typical limitation in ...flow meters is that the pipe must be full in order to get an accurate flow reading. In many cases, this is not possible for practical reasons. When the pipe is full, ultrasonic flow meters can calculate the flow rate using known properties of the pipe and fluid, namely the cross-section, propagation path and fluid sound velocity. However, when the pipe is only partially filled, the propagation path is unknown which leads to an inability to calculate the correct flow rate. This paper presents a cost-effective sensor fusion approach to extend the capabilities of transit time ultrasonic flow meters to handle such scenarios. The approach determines the propagation path using capacitance-based level sensing, combined with fluid velocities ascertained via an ultrasonic sensor, leading to a significantly more accurate estimation of flow rates. Experiments in low flow rate situations validated the efficacy of the proposed model, with a 92% reduction of mean error in the lowest water height when compared to a conventional ultrasonic flow meter.
Benefits of Omega-3 Docosahexaenoic acid (DHA) supplements are hindered by their poor solubility and bioavailability. This study investigated the bioavailability of various formulations of Omega-3 ...and tocopheryl phosphate mixture (TPM), following oral administration in rats, and assessed whether TPM could improve the oral absorption of DHA. The rats were administered with a high (265.7 mg/kg) or low dose (88.6 mg/kg) of DHA. TPM was examined at 1:0.1 w/w (low TPM dose) and 1:0.5 w/w (high TPM dose). Over 24 h, the DHA plasma concentration followed a TPM dose-dependent relationship, reflected in the higher mean C
values (78.39 and 91.95 μg/mL) and AUC values (1396.60 and 1560.60) for the low and high TPM, respectively. The biggest difference between the low dose DHA control (LDCont) and TPM formulations was at 4 h after supplementation, where the low and high TPM showed a mean 20% (ns) and 50% (
< 0.05) increase in DHA plasma concentrations versus the control formulation. After correcting for baseline endogenous DHA, the mean plasma DHA at 4 h produced by the LD-HTPM was nearly double (90%) the LDC control (
= 0.057). This study demonstrated that co-administering omega-3 with TPM significantly increases the bioavailability of DHA in the plasma, suggesting potential use for commercially available TPM + DHA fortified products.
Inkjet (powder-based) 3D Printing is a popular and widely used technology, which can be applied to print a wide range of specimens using different powder materials. This paper discusses the use of ...inkjet 3DP technology for construction applications using custom-made powder instead of commercial gypsum powder (ZP 151). The paper aims to address the differences between ZP 151 and CP (a custom-made construction-specific cement mortar powder) with regard to powder flowability, wettability, powder bed porosity and apparent porosity in 3DP specimens. An inkjet 3D printer is employed and experimental results verify that ZP 151 has a lower angle of repose, a higher contact angle and noticeably less porosity in the powder bed compared with the CP powder. Additionally, specimens printed with ZP 151 have a lower apparent porosity compared with CP specimens. The wettability for each of the powders was tested using contact angle goniometer, while the Optronis Cam-Recorder was used at 1000fps at 800×600pixel resolution images for the powder flowability tests. The bulk density tester was utilised to find the apparent porosity in the printed specimens. The paper also discusses the details of the printing procedure and dimensional accuracy of printed specimens.
•Measured dimensional accuracy of the three axis-aligned planes in the inkjet 3D printed specimens.•Studied the flowability of the dry cementitious powder and the commercial powder (gypsum).•Investigated the wettability of the powder-bed by conducting liquid droplet penetration tests.•Measured the porosity of the powder-bed and the apparent porosity of the printed specimens.•Performed a detailed characterization of cementitious and gypsum powders used in inkjet 3D printing.
The fourth industrial revolution (Industry 4.0) is transforming industries all around the world focusing on areas including advanced robotics and automation, sensor technology and data analytics. The ...authors are involved in a project developing a multi-robot material extrusion 3D printer to print a gravity separation spiral (GSS), an instrument used in the mining industry to separate mineral slurry into different density components. Compared with traditional mould-based manufacturing, this new additive manufacturing method will significantly reduce manufacturing tooling costs, improve the customisation to enable the production of bespoke GSS that each processes different minerals and reduce worker exposure to hazardous materials. Slicing and printing large-scale helical objects in conventional horizontal layer addition would result in an unreasonable amount of waste material from support structures, and poor surface quality due to step-wise bumps. This paper presents a novel slicing algorithm using concentric vertical ray lines to slice objects radially, enabling layers to be deposited progressively in the same fashion. This method can be applied in large-scale additive manufacturing where objects are printed by a robot in a radial direction, which is different from layered vertical printing in conventional additive systems. An example GSS is sliced to generate motion plans for a print head affixed to the end effector of a robot arm. Then through simulations, it is shown how a robot’s expected manipulability measure can be used to predict and ensure the successful completion of the print.
Additive manufacturing is a fabrication technology that is rapidly revolutionizing the manufacturing and construction sectors. In this paper, a review of various prototyping technologies for printing ...cementitious materials and selected 3D printing techniques are presented in detail. Benchmark examples are provided to compare three well-known printing techniques; inkjet printing (binder jetting), selected laser sintering (SLS), and extrusion printing (extrusion based process). A comprehensive search in the literature was conducted to identify various mix designs that could be employed when printing cementitious materials. Aspects of concrete mix design are described, and some new experiments are conducted to analyse the printability of new mixes by the authors. Future research in the area of the rheology of cementitious materials and its relationship with the structural performance of finished concretes are highlighted.
Hand osteoarthritis (OA) is an irreversible degenerative condition causing chronic pain and impaired functionality. Existing treatment options are often inadequate. Cannabidiol (CBD) has demonstrated ...analgesic and anti-inflammatory effects in preclinical models of arthritis. In this open-label feasibility trial, participants with symptomatically active hand OA applied a novel transdermal CBD gel (4% w/w) three times a day for four weeks to their most painful hand. Changes in daily self-reported pain scores were measured on a 0-10 Numeric Pain Rating Scale (NPRS). Hand functionality was determined via daily grip strength measures using a Bluetooth equipped squeeze ball and self-report questionnaire. Quality of life (QoL) ratings around sleep, anxiety, stiffness and fatigue were also measured. All self-report measures and grip strength data were gathered via smartphone application. Urinalysis was conducted at trial end to determine systemic absorption of CBD. Eighteen participants were consented and 15 completed the trial. Pain ratings were significantly reduced over time from pre-treatment baseline including current pain (- 1.91 ± 0.35, p < 0.0001), average pain (- 1.92 ± 0.35, p < 0.0001) and maximum pain (- 1.97 ± 0.34, p < 0.0001) (data represent mean reduction on a 0-10 NPRS scale ± standard error of the mean (SEM)). A significant increase in grip strength in the treated hand (p < 0.0001) was observed although self-reported functionality did not improve. There were significant (p < 0.005) improvements in three QoL measures: fatigue, stiffness and anxiety. CBD and its metabolites were detected at low concentrations in all urine samples. Measured reductions in pain and increases in grip strength seen during treatment reverted back towards baseline during the washout phase. In summary, pain, grip strength and QoL measures, using smartphone technology, was shown to improve over time following transdermal CBD application suggesting feasibility of this intervention in relieving osteoarthritic hand pain. Proof of efficacy, however, requires further confirmation in a placebo-controlled randomised trial.Trial registration: ANZCTR public trials registry (ACTRN12621001512819, 05/11/2021).
Multiple autonomous industrial robots can be of great use in manufacturing applications, particularly if the environment is unstructured and custom manufacturing is required. Autonomous robots that ...are equipped with manipulators can collaborate to carry out manufacturing tasks such as surface preparation by means of grit-blasting, surface coating or spray painting, all of which require complete surface coverage. However, as part of the collaboration process, appropriate base placements relative to the environment and the target object need to be determined by the robots. The problem of finding appropriate base placements is further complicated when the object under consideration is large and has a complex geometric shape, and thus the robots need to operate from a number of base placements in order to obtain complete coverage of the entire object. To address this problem, an approach for Optimization of Multiple Base Placements (OMBP) for each robot is proposed in this paper. The approach aims to optimize base placements for multi-robot collaboration by taking into account task-specific objectives such as makespan, fair workload division amongst the robots, and coverage percentage; and manipulator-related objectives such as torque and manipulability measure. In addition, the constraint of robots maintaining an appropriate distance between each other and relative to the environment is taken into account. Simulated and real-world experiments are carried out to demonstrate the effectiveness of the approach and to verify that the simulated results are accurate and reliable.
As additively manufactured components move away from short-term usability, such as single-use prototypes, towards commercial products used for longer periods of time, the long-term material ...properties, such as ageing and creep, are becoming increasingly important design considerations. Moreover, when additively manufactured components are designed for outdoor use, environmental stressors affect these long-term material properties in a process known as ‘weathering’. In this research paper, an initial set of experiments assessed the flexural creep behaviour of pellet-printed PETG after exposure to three accelerated environmental stressors: UV radiation, temperature and humidity. The outcomes thereof indicated that UV exposure was the only stressor to increase the creep compliance. A subsequent set of experiments increase the UV exposure duration from 100 to 200 h and excluded the effects of ageing on creep behaviour during creep tests. The outcome of this second series of experiments showed that the increase in creep compliance can be attributed to the effects of UV alone.
As robotic systems transition from traditional setups to collaborative work spaces, the prevalence of physical Human Robot Interaction has risen in both industrial and domestic environments. A ...popular representation for robot behavior is movement primitives which learn, imitate, and generalize from expert demonstrations. While there are existing works in context-aware movement primitives, they are usually limited to contact-free human robot interactions. This paper presents physical Human Robot Interaction Primitives (pHRIP), which utilize only the interaction forces between the human user and robot to estimate user intent and generate the appropriate robot response during physical human robot interactions. The efficacy of pHRIP is evaluated through multiple experiments based on target-directed reaching and obstacle avoidance tasks using a real seven degree of freedom robot arm. The results are validated against Interaction Primitives which use observations of robotic trajectories, with discussions of future pHRI applications utilizing pHRIP.
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