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Injection moulding is an important industry, providing a significant percentage of the demand for plastic products throughout the world. The process consists of many variables which directly or indirectly influence the part quality and cycle time. The first step in optimizing the process parameters is identifying the most significant variables affecting the desired output. For this purpose, various Design of Experiments methods (DOE) have been developed to investigate the effect of the experimental variables on the output and predict the required settings to achieve the optimal value of the output. In this study we investigate the application of DOE for a commercial injection moulded component which suffers from a long cycle time and high shrinkage. The Taguchi method has been used to analyze the effect of four input variables on the two output variables: cycle time and shrinkage. The component has been simulated in the Moldflow software to validate the predicted output and optimized settings of the variables from the DOE. Comparison of the simulation result and the predicted value from the DOE illustrated good accordance. The calculated optimal setting with the Taguchi method reduced the cycle time from 40s to about 23s and met the shrinkage criteria for this commercial part.

Injection moulding is an extremely important industrial process, being one of the most commonly-used plastic formation techniques. However, the industry faces many current challenges associated with demands for greater product customisation, higher precision and, most urgently, a shift towards more sustainable materials and processing. Accurate real-time sensing of the material and part properties during processing is key to achieving rapid process optimisation and set-up, reducing down-times, and reducing waste material and energy in the production of defective products. While most commercial processes rely on point measurements of pressure and temperature, ultrasound transducers represent a non-invasive and non-destructive source of rich information on the mould, the cavity and the polymer melt, and its morphology, which affect critical quality parameters such as shrinkage and warpage. In this paper the relationship between polymer properties and the propagation of ultrasonic waves is described and the application of ultrasound measurements in injection moulding is evaluated. The principles and operation of both conventional and high temperature ultrasound transducers (HTUTs) are reviewed together with their impact on improving the efficiency of the injection moulding process. The benefits and challenges associated with the recent development of sol-gel methods for HTUT fabrication are described together with a synopsis of further research and development needed to ensure a greater industrial uptake of ultrasonic sensing in injection moulding.

The design and development of a switched beam antenna at 2.45 GHz industrial, scientific and medical band for wireless sensor network applications is presented in this paper. The antenna is capable of switching the beam pattern in directions such as in the boresight direction 0°, ±63° and as a bidirectional endfire radiator (±85°). The directive gain of the antenna is 3.9, 5.8 and 5.8 dBi in respect to those angles. The shift in the resonance frequency is found to be negligible irrespective of the direction of the switched beam. The realized gain of the proposed antenna in the steering direction is found to be better than a standard microstrip patch antenna on the same size of the substrate and ground plane. The antenna was designed and optimized through simulations using CST microwave studio and the prototype was experimentally tested using R&S ZVB8 network analyser.

The design and development of a new multi-directional switched beam antenna at 2.45 GHz for wireless sensor network applications is proposed in this paper. The beam of the antenna can be switched towards the boresight 00, at an angle of ± 800 in both azimuth and elevation planes. The two ports when excited with a 900 phase difference lead to a circular polarisation in the beam directed towards the boresight. It is also worth noting that the resonance frequency of the antenna remains within the 2:1 VSWR bandwidth irrespective of the direction of the switched beam.

A microstrip-fed truncated monopole antenna with radiation pattern and polarization reconfigurability is presented. The antenna fabricated on a substrate of dielectric constant 4.4 and thickness 1.6 mm is highly compact with an overall dimension of only 0.25λs × 0.25λs. The pattern of the antenna is omnidirectional and is reconfigurable with the polarization in the orthogonal planes. The proposed antenna is suitable for 2.4-GHz wireless applications with a bandwidth of 95 MHz. The measured gain of the antenna is -1.1 dBi at the resonant frequency. The simulation (Ansoft HFSS) and measurement (R&S ZVB8 Vector Network Analyzer) results are also discussed.

The design, fabrication, and performance analysis of a Polyimide Loop antenna is presented. This design is particularly intended for wearable wireless body area network applications where safe, conformal, and flexible antennas are desirable. The performance of the Polyimide Loop antenna was compared to that of a standard copper wire loop antenna. Both antennas demonstrated comparable free space performances. When the antennas were placed in close proximity to human tissue both experienced a shift in the resonance frequency due to on-body coupling. The Polyimide Loop antenna was also tested in flexed conditions and a minimal shift in resonance frequency was observed. The flexible polyimide loop antenna was shown to have a superior on body coupling compared to the equivalent rigid copper wire loop.

The design, fabrication, and performance analysis of a 2.45GHz dipole antenna embedded in a PDMS substrate is presented. This design is particularly intended for wearable wireless body area network applications where safe, conformal, and flexible antennas are desirable. The performance of the PDMS antenna was measured and compared to that of a standard copper wire dipole antenna fabricated from copper wire through on-body testing and simulation. Both antennas demonstrated comparable free space performances. The PDMS dipole was tested in flexed conditions and a minimal shift in resonance frequency was observed. To demonstrate the antenna's suitability for on-body communication, two identical antennas were used to measure the on-body coupling effect. The PDMS dipole antenna was shown to have a superior on body coupling compared to the equivalent rigid copper wire dipole.

The goal of this study was to explore the use of compression-normalized electromyography (CNEMG) to estimate mean, peak, and cumulative loading of the low back in workers of five heavy industries u ...

Background Direct/ measurement of work activities is costly, so researchers need to distribute resources efficiently to elucidate the relationships between exposures and back injury. Methods This study used data from full-shift electromyography (EMG; N¼133) to develop three exposure metrics: mean, 90th percentile and cumulative EMG. For each metric, the components of variance were calculated between- and within-subject, and betweengroup for four different grouping schemes: grouping by industry (construction, forestry, transportation, warehousing and wood products), by company, by job and by quintiles based on exposures ranked by jobs within industries. Attenuation and precision of simulated exposureeresponse relationships were calculated for each groupingschemetodetermineefficientsamplingstrategies. Results As expected, grouping based on exposure quintiles had the highest between-group variances and lowest attenuation, demonstrating the lowest possible attenuation with this data. Conclusion There is potential for grouping schemes to reduce attenuation, but precision losses should be considered and whenever possible empirical data should be employed to select potential exposure grouping schemes.

Elemental mercury spills in households still occur with unfortunate regularity. Devices that contain enough mercury to pose exposure concerns are common to many homes. Response to household spills differs substantially from industrial settings and improper response can increase the risk of harmful health effects. Suggested inhalation exposure levels for residential settings are much different than occupational guidelines. The characteristics of the exposed population in homes differ greatly from industrial workplace spills. Exposure assessment in the home requires the use and understanding of non-occupational guidance. The current occupational OSHA permissible exposure limit and ACGIH threshold limit value are 100 μg/m3 and 25 μg/m3, respectively. By contrast, the Agency for Toxic Substances and Disease Registry (ATSDR) Minimum Risk Level (MRL) for elemental mercury vapors is 0.2 μg/m3, well below occupational levels. The derivation of the MRL considers sensitive populations and 24 hour-a-day, seven days-a-week lifetime exposure. Occupancy criteria of 1.0 μg/m3 and 3.0 μg/m3 for residential and commercial settings have been proposed. These low levels dictate sophisticated analytical equipment or laboratory methods of analysis. Two cases illustrate how difficult it may be to assess hazards based solely on spill amount. In both cases a direct reading cold vapor atomic absorption unit was used to measure airborne mercury concentrations. Case A involved a broken thermometer spill (about 0.5 g) in a master bedroom that was cleaned using a household vacuum. Airborne concentrations throughout the home exceeded recommended exposure levels for residential settings (range of 2.5–14 μg/m3). Case B involved a broken thermostat spill (about 3.0 g) cleaned with a shop vacuum. Exposure levels were less than 1 μg/m3 throughout the home (range 0.4–0.7 μg/m3). When vacuums are used to remove mercury, quantities of mercury as small as that associated with a fever thermometer can represent an exposure hazard. The difference in exposure levels between the two cases is thought to be related to the operational differences between vacuum cleaners and the impact they had on vapor production. Unfamiliarity with the hazards posed by seemingly small amounts of mercury in the home and workplace can lead to undesirable and often costly consequences.

A new reconfigurable low profile microstrip patch antenna with switchable propagating modes for wireless body area network is presented. The directivity gain of the antenna is 6.8 dBi in the off-body mode, and 6.4 dBi in the on-body mode. The prototype covers the ISM 2.45 GHz band. The operating frequency of the antenna remains the same irrespective of the direction to which the beam is steered.

Network lifetime is a significant performance challenge for wireless sensor networks (WSNs) as sensor nodes generally rely on limited power sources such as batteries. One solution is to reduce the overall energy consumption from the physical to application layers. However, the residual energy of nodes across a network can vary greatly due to differences in battery capacity, traffic, energy harvesting, and topology location. Therefore reducing overall energy consumption may still result in some nodes exhausting their energy resource much more rapidly and failing faster than others. In this paper, besides the energy efficiency, the optimization of energy consumption among nodes on the basis of residual energy is studied, in order to prolong the network lifetime. The concept utility energy is introduced to aid selection of relay candidates in the proposed opportunistic routing protocol (U-OR). Simulation results show that the U-OR protocol can prolong network lifetime by at least 260%. Furthermore, this low overhead protocol can be used in large-scale WSNs.

A gain enhanced planar Yagi-Uda antenna with pattern reconfiguration is presented. The prototype provides an omnidirectional pattern as well as a high-gain directive pattern, which can be reconfigured on two orthogonal planes. For the first time, the principle of a Yagi-Uda antenna combined with pattern reconfiguration is implemented without complexity on a planar prototype. The pattern reconfiguration is achieved by alternately switching the driven and reflector elements of the Yagi-Uda antenna. The prototype concept was simulated using CST Microwave Studio, fabricated on a substrate of dielectric constant 4.4 and tested using an R&S ZVB8 network analyser. The gain variation with the reflector and director parameters is also analysed and presented.

Unreliability is an inherent property of wireless links. In opportunistic networks, these intermittent links are exploited, instead of mitigated, by temporal and/or spatial diversities in order to improve the network performance such as energy efficiency, delay, throughput and so on. Simulation is always an important method for the research in this challenged domain and a suitable simulator or simulation framework can greatly improve the research efficiency. The previous simulators or frameworks for opportunistic networks mainly focus on the design of upper layers but neglect the impact of physical layer on these layers. However, the reality of physical layer simulation is vital to the design of upper layers. In this paper, a simulation framework is developed using the MiXiM framework as basis which can simulate complex wireless physical environment. In this work, an integrated solution for simulation and analysis is provided including all communication layers and network performance analysis modules at each layer. This framework can help the researchers in this domain focus more on the design of protocols and less time on constructing a simulation tool.

In this paper, we investigate the performance of a 2.45 GHz annular cylindrical dielectric resonator antenna when mounted on the human torso. An impedance bandwidth of 3.7% was obtained centered at 2.45 GHz. The antenna was designed to achieve an omnidirectional radiation pattern similar to a monopole antenna which can effectively couple the electromagnetic waves between the wireless sensors nodes placed at different locations on the human body. The on-body efficiency of the antenna was 52.6% when placed at a height of 2 mm from a muscle tissue phantom at 2.45 GHz.

Wireless Sensor Networks (WSNs) are gaining an increasing industry wide adoption. However, there remain major challenges such as network dimensioning and node placement especially in Built Environment Networks (BENs). Decisions on the node placement, orientation, and the number of nodes to cover the area of interest are usually ad-hoc. Ray tracing tools are traditionally employed to predict RF signal propagation; however, such tools are primarily intended for outdoor environments. RF signal propagation varies greatly indoors due to building materials and infrastructure, obstacles, node placement, antenna orientation and human presence. Because of the complexity of signal prediction, these factors are usually ignored or given little weight when such networks are analyzed. The paper’s results show the effects of the building size and layout, building materials, human presence and mobility on the signal propagation of a BEN. Additionally, they show that antenna radiation pattern is a key factor in the RF propagation performance, and appropriate device orientation and placement can improve the network reliability. Further, the RSS facility in RF transceivers can be exploited to detect the presence and motion of humans in the environment.