Fouling of waste heat recovery : numerical and experimental results

Numerical results are presented to investigate the performance of a partly-filled porous heat exchanger for waste heat recovery units. A parametric study was conducted to investigate the effects of inlet velocity and porous block height on the pressure drop of the heat exchanger. The focus of this work is on modelling the interface of a porous and non-porous region. As such, numerical simulation of the problem is conducted along with hot-wire measurements to better understand the physics of the problem. Results from the two sources are then compared to existing theoretical predictions available in the literature which are unable to predict the existence of two separation regions before and after the porous block. More interestingly, a non-uniform interface velocity was observed along the streamwise direction based on both numerical and experimental data.

Incidence and fatality of serious suicide attempts in a predominantly rural population in Shandong, China : a public health surveillance study

Objectives To estimate the incidence of serious suicide attempts (SSAs, defined as suicide attempts resulting in either death or hospitalisation) and to examine factors associated with fatality among these attempters. Design A surveillance study of incidence and mortality. Linked data from two public health surveillance systems were analysed. Setting Three selected counties in Shandong, China. Participants All residents in the three selected counties. Outcome measures Incidence rate ( per 100 000 person-years) and case fatality rate (%). Methods Records of suicide deaths and hospitalisations that occurred among residents in selected counties during 2009–2011 (5 623 323 person-years) were extracted from electronic databases of the Disease Surveillance Points (DSP) system and the Injury Surveillance System (ISS) and were linked by name, sex, residence and time of suicide attempt. A multiple logistic regression model was developed to examine the factors associated with a higher or lower fatality rate. Results The incidence of SSAs was estimated to be 46 (95% CI 44 to 48) per 100 000 person-years, which was 1.5 times higher in rural versus urban areas, slightly higher among females, and increased with age. Among all SSAs, 51% were hospitalised and survived, 9% were hospitalised but later died and 40% died with no hospitalisation. Most suicide deaths (81%) were not hospitalised and most hospitalised SSAs (85%) survived. The fatality rate was 49% overall, but was significantly higher among attempters living in rural areas, who were male, older, with lower education or with a farming occupation. With regard to the method of suicide, fatality was lowest for non-pesticide poisons (7%) and highest for hanging (97%). Conclusions The incidence of serious suicide attempts is substantially higher in rural areas than in urban areas of China. The risk of death is influenced by the attempter’s sex, age, education level, occupation, method used and season of year.

Bats respond to polarity of a magnetic field

Bats have been shown to use information from the Earth's magnetic field during orientation. However, the mechanism underlying this ability remains unknown. In this study we investigated whether bats possess a polarity- or inclination-based compass that could be used in orientation. We monitored the hanging position of adult Nyctalus plancyi in the laboratory in the presence of an induced magnetic field of twice Earth-strength. When under the influence of a normally aligned induced field the bats showed a significant preference for hanging at the northern end of their roosting basket. When the vertical component of the field was reversed, the bats remained at the northern end of the basket. However, when the horizontal component of the field was reversed, the bats changed their positions and hung at the southern end of the basket. Based on these results, we conclude that N. plancyi, unlike all other non-mammalian vertebrates tested to date, uses a polarity-based compass during orientation in the roost, and that the same compass is also likely to underlie bats' long-distance navigation abilities.

Impact of PV units in LV feeders on distribution system reliability

Re-supplying loads on outage through cross-connect from adjacent feeders in a distribution system may cause voltage drop and hence require load shedding. However, the surplus PV generated in some of the LV feeders can prevent load shedding, and improve reliability. In order to measure these effects, this paper proposes the application of Direct Load Flow method[1] in reliability evaluation of distribution systems with PV units. As part of this study, seasonal impacts on load consumption together with surplus PV output power injection to higher voltage networks are also considered. New indices are proposed to measure yearly expected energy export, from LV to MV and from MV to higher voltage network.

On the topic of competency and excellence of our graduate engineers

Problem solving is an essential element of civil engineering education. It has been I observed that students are best able to understand civil engineering theory when there is a ' practical application of it. Teaching theory alone has led to lower levels of comprehension and motivation and a correspondingly higher rate of failure and "drop-out". This paper analyses the effectiveness of introducing practical design projects at an early stage within a civil engineering undergraduate program at Queensland University of Technology. In two of the essential basic subjects, Engineering Mechanics and Steel Structures, model projects which simulate realistic engineering exercises were introduced. Students were required to work in small groups to analyse, design and build the lightest I most efficient model bridges made of specific materials such as spaghetti, drinking straw, paddle pop sticks and balsa wood and steel columns for a given design loading/target capacity. The paper traces the success of the teaching strategy at each stage from its introduction through to the final student and staff evaluation.

Project-based civil engineering courses

Problem solving is an essential element of civil engineering education. It has been observed that students are best able to understand civil engineering theory when there is a practical application of it. Teaching theory alone has led to lower levels of comprehension and motivation and a correspondingly higher rate of failure and “drop-out”. This paper analyses the effectiveness of introducing practical design projects at an early stage within a civil engineering undergraduate program at Queensland University of Technology. In two of the essential basic subjects, Engineering Mechanics and Steel Structures, model projects which simulate realistic engineering exercises were introduced. Students were required to work in small groups to analyse, design and build the lightest / most efficient model bridges made of specific materials such as spaghetti, drinking straw, paddle pop sticks and balsa wood and steel columns for a given design loading/target capacity. The paper traces the success of the teaching strategy at each stage from its introduction through to the final student and staff evaluation.

Experimental Study of crack propagation in carbon steel using acoustic emission

Acoustic emission technique has become a significant and powerful structural health monitoring tool for structures. Researches to date have been done on crack location, fatigue crack propagation in materials and severity assessment of failure using acoustic emission technique. Determining severity of failure in steel structures using acoustic emission technique is still a challenge to accurately determine the relationship between the severity of crack propagation and acoustic emission activities. In this study three point bending test on low carbon steel samples along with acoustic emission technique have been used to determine crack propagation and severity. A notch is introduced at the tension face of the loading point to the samples to initiate the crack. The results show that the percentage of load drop of the steel specimen has a reciprocal relationship with the crack opening i.e. crack opening zones are influenced by the loading rate. In post yielding region, common acoustic emission signal parameters such as, signal strength, energy and amplitudes are found to be higher than those at pre-yielding and at yielding.

Versatility of polymethacrylate monoliths for chromatographic purification of biomolecules

Polymethacrylate monoliths, specifically poly(glycidyl methacrylate-co-ethylene dimethacrylate) or poly(GMA-co-EDMA) monoliths, are a new generation of chromatographic supports and are significantly different from conventional particle-based adsorbents, membranes, and other monolithic supports for biomolecule purification. Similar to other monoliths, polymethacrylate monoliths possess large pores which allow convective flow of mobile phase and result in high flow rates at reduced pressure drop, unlike particulate supports. The simplicity of the adsorbent synthesis, pH resistance, and the ease and flexibility of tailoring their pore size to that of the target biomolecule are the key properties which differentiate polymethacrylate monoliths from other monoliths. Polymethacrylate monoliths are endowed with reactive epoxy groups for easy functionalization (with anion-exchange, hydrophobic, and affinity ligands) and high ligand retention. In this review, the structure and performance of polymethacrylate monoliths for chromatographic purification of biomolecules are evaluated and compared to those of other supports. The development and use of polymethacrylate monoliths for research applications have grown rapidly in recent times and have enabled the achievement of high through-put biomolecule purification on semi-preparative and preparative scales.

Large-volume methacrylate monolith for plasmid purification : process engineering approach to synthesis and application

The extent of exothermicity associated with the construction of large-volume methacrylate monolithic columns has somewhat obstructed the realisation of large-scale rapid biomolecule purification especially for plasmid-based products which have proven to herald future trends in biotechnology. A novel synthesis technique via a heat expulsion mechanism was employed to prepare a 40 mL methacrylate monolith with a homogeneous radial pore structure along its thickness. Radial temperature gradient was recorded to be only 1.8 °C. Maximum radial temperature recorded at the centre of the monolith was 62.3 °C, which was only 2.3 °C higher than the actual polymerisation temperature. Pore characterisation of the monolithic polymer showed unimodal pore size distributions at different radial positions with an identical modal pore size of 400 nm. Chromatographic characterisation of the polymer after functionalisation with amino groups displayed a persistent dynamic binding capacity of 15.5 mg of plasmid DNA/mL. The maximum pressure drop recorded was only 0.12 MPa at a flow rate of 10 mL/min. The polymer demonstrated rapid separation ability by fractionating Escherichia coli DH5α-pUC19 clarified lysate in only 3 min after loading. The plasmid sample collected after the fast purification process was tested to be a homogeneous supercoiled plasmid with DNA electrophoresis and restriction analysis.

Getting away with murder: An examination of detected homicides staged as suicides

Staged crime scenes involve an offender deliberately altering evidence to simulate events to mislead investigators. Despite likely occurring more often than reported in the literature due to success in offender deception, the exact frequency of staged crime scenes is unknown. In an attempt to bridge this gap, a legal database was searched for detected staged scenes. A total of 115 cases were examined, and this study reports on 16 staged suicides that were examined through descriptive analysis. Findings indicate the frequent involvement of firearms, hanging, or asphyxia; and that offenders are usually known to victims, although not necessarily intimately.

Achieving service quality through service innovation exploration-exploitation: The critical role of employee empowerment and slack resources

Purpose This study investigates the effects of service innovation exploration-exploitation on financial performance through the delivery of quality services. Additional emphasis is also given to examining the extent to which employee empowerment and slack resources enhance or suppress the performance benefits of service firms engaging in service innovation exploration versus exploitation. Design/methodology/approach Data were drawn from a multi-informant survey of service firms using a drop-and-collect approach. The survey gathered data from managers, customer service employees and customers to test the hypotheses. Findings The results show that excelling at both exploitative and exploratory innovation helps enhance the quality of services, which in turn yield superior financial performance. Further, empowering employees enhances the relationship between exploratory and exploitative service innovation and service quality. We also show that the extent managers’ perceived their market to be competitive influences in the pursuit of high levels of both service innovation exploration and exploitation and that this relationship is impacted by the extent they believe they have available slack resources. Practical implications The findings suggest that service firms need to pursue both exploitation and exploration at high levels simultaneously and empower their employees to stay ahead of competitors in delivering quality services, which ultimately contribute to the achievement of superior financial outcomes. Also, the findings highlight the importance of employee empowerment, market competitiveness and slack resources in the pursuit of high levels of both service innovation exploration and exploitation. Originality/value These findings and our theory indicate that this study is the first to empirically examine organizational ambidexterity in the context of service innovation exploration – exploitation adopting the principles of combined and balanced innovation. The study provides insights into the critical role of customers’ perceptions of service quality in contributing to firms’ financial performance. Our insights are unique in that the study incorporates managers, employees and customers in an integrated service innovation model.

Playing Pranks: Traditions, communities & co-creative cultural performance practice

Pranks, hoaxes and practical jokes are co-creative cultural performance practices that appear across times, contexts and cultures. These practices include everyday play amongst families, friends and coworkers, entertainment programs such as Prank Patrol, Punked or Scare Tactics, and aesthetic and activist pranks perpetrated by situationist artists, guerrilla artists, and, most recently, culture ‘jammers’ or ‘hackers’ intent on turning capitalist systems back on themselves. Although it can, in common usage, describe almost any show off behaviour, a prank in the strictest definition of the term is a performance that deploys a very specific set of strategies. It is an act of trickery, mischief, or deceit, that must be taken as real, and momentarily cause real fear, anger or worry for an unwitting spectator-become-performer, who is meant to play along until the trick is revealed and their response can be represented back to the prankster, other spectators, or society as a whole, either for the sake of entertainment or for the sake of commentary on a cultural phenomenon. A prank, in this sense, deliberately blurs the boundaries between daily and dramatic performance. It creates a moment of uncertainty, in which both the prankster’s ability to be creative, clever, or culturally astute, and the prankee’s ability to play along, discern the trick, discern the point of the trick, and, in the end, be duped, be a good sport, or even play/pay the prankster back, are both put to the test. In this paper, I consider a number of pranking traditions popular where I am in Australia, from the community-building pranks of footballers, bucks parties and ‘drop bear’ tales told to tourists, to the more controversial pranks of radio shock jocks, activists and artists. I use performance, spectatorship and ethical theory to examine the engagement between prankster, pranked spectator, and other spectators, in this most distinctive sort of community-driven performance practice, and the way it builds and breaks status, social and other sorts of relationships within and between specific communities.

Experimentally reduced hip-abductor muscle strength and frontal-plane biomechanics during walking

Researchers have postulated that reduced hip-abductor muscle strength may have a role in the progression of knee osteoarthritis by increasing the external knee-adduction moment. However, the relationship between hip-abductor strength and frontal-plane biomechanics remains unclear. To experimentally reduce hip-abduction strength and observe the subsequent changes in frontal-plane biomechanics. Descriptive laboratory study. Research laboratory. Eight healthy, recreationally active men (age = 27 ± 6 years, height = 1.75 ± 0.11 m, mass = 76.1 ± 10.0 kg). All participants underwent a superior gluteal nerve block injection to reduce the force output of the hip-abductor muscle group. Maximal isometric hip-abduction strength and gait biomechanical data were collected before and after the injections. Gait biomechanical variables collected during walking consisted of knee- and hip-adduction moments and impulses and the peak angles of contralateral pelvic drop, hip adduction, and ipsilateral trunk lean. Hip-abduction strength was reduced after the injection (P = .001) and remained lower than baseline values at the completion of the postinjection gait data collection (P = .02). No alterations in hip- or knee-adduction moments (hip: P = .11; knee: P = .52) or impulses (hip: P = .16; knee: P = .41) were found after the nerve block. Similarly, no changes in angular kinematics were observed for contralateral pelvic drop (P = .53), ipsilateral trunk lean (P = .78), or hip adduction (P = .48). A short-term reduction in hip-abductor strength was not associated with alterations in the frontal-plane gait biomechanics of young, healthy men. Further research is needed to determine whether a similar relationship is true in older adults with knee osteoarthritis.

A coordinated voltage control approach for coordination of OLTC, voltage regulator, and DG to regulate voltage in a distribution feeder

Integration of small-scale electricity generators, known as distributed generation (DG), into the distribution networks has become increasingly popular at the present. This tendency together with the falling price of the synchronous-type generator has potential to give DG a better chance at participating in the voltage regulation process together with other devices already available in the system. The voltage control issue turns out to be a very challenging problem for the distribution engineers since existing control coordination schemes would need to be reconsidered to take into account the DG operation. In this paper, we propose a control coordination technique, which is able to utilize the ability of DG as a voltage regulator and, at the same time, minimize interaction with other active devices, such as an on-load tap changing transformer and a voltage regulator. The technique has been developed based on the concept of control zone, line drop compensation, dead band, as well as the choice of controllers' parameters. Simulations carried out on an Australian system show that the technique is suitable and flexible for any system with multiple regulating devices including DG.

Simulating droplet motion on virtual leaf surfaces

A curvilinear thin film model is used to simulate the motion of droplets on a virtual leaf surface, with a view to better understand the retention of agricultural sprays on plants. The governing model, adapted from Roy et al. (2002 J. Fluid Mech. 454, 235–261) with the addition of a disjoining pressure term, describes the gravity- and curvature driven flow of a small droplet on a complex substrate: a cotton leaf reconstructed from digitized scan data. Coalescence is the key mechanism behind spray coating of foliage, and our simulations demonstrate that various experimentally observed coalescence behaviours can be reproduced qualitatively. By varying the contact angle over the domain, we also demonstrate that the presence of a chemical defect can act as an obstacle to the droplet’s path, causing break-up. In simulations on the virtual leaf, it is found that the movement of a typical spray size droplet is driven almost exclusively by substrate curvature gradients. It is not until droplet mass is sufficiently increased via coalescence that gravity becomes the dominating force.