Effect of impeller speed on mechanical and dissolution properties of high-shear granules

Impeller speed is one of the most crucial process variables that affect the properties of the granules produced in a high-shear granulator. Several reports can be found in literature that discuss the influence of impeller speed on the granules size. For instance some researchers like Knight report an increase of granule size with impeller speed [1] and [2], while others (Scheaefer et al. and Ramaker et al.) observed a decrease of granules size with increasing impeller speed [3] and [4]. However there is limited work reported in literature on the effect of the impeller speed on the mechanical properties of granules. Mechanical properties are important as they affect the performance of the granules on the other downstream process such as transportation and handling. The work reported here serves to address the missing in knowledge gap regarding the influence of impeller speed on mechanical properties granules. How the granulation system responds to the changes in the impeller speeds depends on binder that is used in the process. For this reason the two extreme cases, of a low viscosity binder system and high viscosity binder system are considered in this research. For low viscosity binder system it was observed that the granule size decreased with increasing impeller speed whilst for the high viscosity binder system the opposite was observed by Knight [1]. The granule strength, the Young's modulus and yield strength of the high viscosity granules increased with increasing impeller speed where as the opposite trends were observed for the low viscosity binder granules.

Multibody modelling of a TB31 and a TB32 crash test with vertical portable concrete barriers: model verification and sensitivity analysis.

In this article the multibody simulation software package MADYMO for analysing and optimizing occupant safety design was used to model crash tests for Normal Containment barriers in accordance with EN 1317. The verification process was carried out by simulating a TB31 and a TB32 crash test performed on vertical portable concrete barriers and by comparing the numerical results to those obtained experimentally. The same modelling approach was applied to both tests to evaluate the predictive capacity of the modelling at two different impact speeds. A sensitivity analysis of the vehicle stiffness was also carried out. The capacity to predict all of the principal EN1317 criteria was assessed for the first time: the acceleration severity index, the theoretical head impact velocity, the barrier working width and the vehicle exit box. Results showed a maximum error of 6% for the acceleration severity index and 21% for theoretical head impact velocity for the numerical simulation in comparison to the recorded data. The exit box position was predicted with a maximum error of 4°. For the working width, a large percentage difference was observed for test TB31 due to the small absolute value of the barrier deflection but the results were well within the limit value from the standard for both tests. The sensitivity analysis showed the robustness of the modelling with respect to contact stiffness increase of ±20% and ±40%. This is the first multibody model of portable concrete barriers that can reproduce not only the acceleration severity index but all the test criteria of EN 1317 and is therefore a valuable tool for new product development and for injury biomechanics research.

Queer Spaces, Sexual Violence and the Desire for Safety

Queer politics and spaces have historically been associated with ideals of sexual liberation. They are conceptualised as spaces where sex, and its intersections with intimacy, friendship and love can be explored outside of normative frameworks which value monogamous reproductive heterosexuality at the expense of other non-normative sexual expressions. In recent years, however, autonomous queer spaces such as the global Queeruption gatherings and other queer community spaces in Australia have become increasingly concerned with the presence and danger of sexual violence in queer communities. Almost without exception, this danger has been responded to through the creation of ‘safe(r) spaces’ policies, generally consisting of a set of guidelines and proscribed behaviours which individuals must agree to in order to participate in or attend the event or space. The guidelines themselves tend to privilege of sexual politics of affirmative verbal consent, insisting that such consent should be sought prior to any physical or sexual contact, inferring that a failure to do so is ethically unacceptable within. This chapter reflects on the attempts to construct queer communities as ‘safer spaces,’ arguing that the concepts of consent and safety are inadequate to develop a queer response to sexual violence. Such a response, it argues, must be based on the openness to possibilities and refusal of sexual restrictions and regulations that have always been central elements of queer theory and politics.

A bridge-monitoring tool based on bridge and vehicle accelerations

Previous research on damage detection based on the response of a structure to a moving load has reported decay in accuracy with increasing load speed. Using a 3D vehicle – bridge interaction model, this paper shows that the area under the filtered acceleration response of the bridge increases with increasing damage, even at highway load speeds. Once a datum reading is established, the area under subsequent readings can be monitored and compared with the baseline reading, if an increase is observed it may indicate the presence of damage. The sensitivity of the proposed approach to road roughness and noise is tested in several damage scenarios. The possibility of identifying damage in the bridge by analysing the acceleration response of the vehicle traversing it is also investigated. While vehicle acceleration is shown to be more sensitive to road roughness and noise and therefore less reliable than direct bridge measurements, damage is successfully identified in favourable scenarios.

Comparison of tack of pressure-sensitive adhesives (PSAs) at different temperatures

Pressure-sensitive adhesives (PSAs) have applications in the fields of packaging, joining, wound care, and personal care. Depending on the application of the PSA, different performance tests are carried out when new products are developed or the quality of the existing products is checked. Tack is the property of an adhesive that enables it to form instant bond on the surface under light pressure. The tack of a PSA strongly depends on the way the bond is created. Parameters such as the bonded area, contact time and the nature of tack materials all affect the tack force measured. In the development of any PSA, it is desirable to correlate the performance related properties such as tack and peel strength to the rheological behaviour. Finding these correlations would make it possible to evaluate the performance of a PSA using its rheological characteristics. In this investigation we have studied the influence of rheological behaviour of three different PSAs on their tackiness. The three different PSAs used in this study are a low molecular weight rosin ester, high molecular weight rosin ester, and dicyclopentadiene. Various rheological properties such as viscosity, phase angle, and elastic and viscous moduli are measured versus the frequency and temperature. Also the tack properties at various removal speeds and temperatures are evaluated. Analysis of the results indicates different performances of the three PSAs which could be related to their rheological properties, especially the phase angle, at different frequencies and temperatures. The PSA with high molecular weight rosin ester is more sensitive to temperature changes and showed drastic changes in tackiness from high temperature to low temperature. On the other hand, rosin ester with low molecular weight is less sensitive to temperature changes. © 2010 VSP.

Theoretical investigation of the use of a moving vehicle to identify bridge dynamic parameters

Pavements and bridges are subject to a continuous degradation due to traffic aggressiveness, ageing and environmental factors. A rational transport policy requires the monitoring of this transport infrastructure in order to provide adequate maintenance and guarantee the required levels of transport service and safety. This paper investigates the use of an instrumented vehicle fitted with accelerometers on its axles to monitor the dynamics of bridges. A simplified quarter carbridge interaction model is used in theoretical simulations and the natural frequency of the bridge is extracted from the spectra of the vehicle accelerations. The accuracy is better at lower speeds and for smooth road profiles. The structural damping of the bridge was also monitored for smooth and rough road profiles. The magnitude of peaks in the power spectral density of the vehicle accelerations decreased with increasing bridge damping and this decrease was easier to detect the smoother the road profile.

Efficiency improvement study for small wind turbines through flow control

In this study, a constant suction technique for controlling boundary layer separation at low Reynolds numbers was designed and tested. This was later implemented on small wind turbines. Small wind turbines need to operate in low wind speeds, that is, in low Reynolds number regimes – typically in the range 104–105. Airfoils are prone to boundary layer separation in these conditions, leading to a substantial drop in aerodynamic performance of the blades. Under these conditions turbines will have reduced energy output. This paper presents experimental results of applying surface-suction over the suction-surface of airfoils for controlling boundary layer separation. The Reynolds numbers for the experiments are kept in the range 8×104–5×105. The air over the surface of the airfoil is drawn into the airfoil through a slit. It is found that the lift coefficient of the airfoils increases and the drag reduces. Based on the improved airfoil characteristics, an analysis of increase in Coefficient of Power (CP), versus input power for a small wind turbine blade with constant suction is presented.

Navigating Risk: Understanding the Impact of the Conflict on Children and Young People in Northern Ireland:Special Issue: Northern Ireland: 20 Years After the Cease-Fires

Twenty years on from the 1994 cease-fires, Northern Ireland is a markedly safer place for children and young people to grow up. However, for a significant number, growing up in post-conflict Northern Ireland has brought with it continued risks and high levels of marginalization. Many young people growing up on the sharp edge of the transition have continued to experience troubling levels of poverty, lower educational attainment, poor standards of childhood health, and sustained exposure to risk-laden environments. Reflecting on interdisciplinary research carried out since the start of the “transition” to peace, this article emphasizes the impact that embedded structural inequalities continue to have on the social, physical, mental, and emotional well-being of many children and young people. In shining a light on the enduring legacy of the conflict, this article moves to argue that greater attention needs to be given to the ongoing socioeconomic factors that result in limited lifetime opportunities, marginalization, and sustained poverty for many young people growing up in “peacetime” Northern Ireland.

Field Measurements of a Full Scale Tidal Device

Field testing studies are required for tidal turbine device developers to determine the performance of their turbines in tidal flows. Full-scale testing of the SCHOTTEL tidal turbine has been conducted at Queen’s University Belfast’s tidal site at Strangford Lough, NI. The device was mounted on a floating barge. Testing was conducted over 48 days, for 288 h, during flood tides in daylight hours. Several instruments were deployed, resulting in an expansive data set. The performance results from this data set are presented here. The device, rated to 50 kW at 2.75 m/s was tested in flows up to 2.5 m/s, producing up to 19 kW, when time-averaged. The thrust on the turbine reached 17 kN in the maximum flow. The maximum system efficiency of the turbine in these flows reached 35%. The test campaign was very successful and further tests may be conducted at higher flow speeds in a similar tidal environment.

Tip Leakage Flow and Heat Transfer on Turbine Stage Tip and Casing: Effect of Unsteady Stator-Rotor Interactions

Unsteady simulations were performed to investigate time dependent behaviors of the leakage flow structures and heat transfer on the rotor blade tip and casing in a single stage gas turbine engine. This paper mainly illustrates the unsteady nature of the leakage flow and heat transfer, particularly, that caused by the stator–rotor interactions. In order to obtain time-accurate results, the effects of varying the number of time steps, sub iterations, and the number of vane passing periods was firstly examined. The effect of tip clearance height and rotor speeds was also examined. The results showed periodic patterns of the tip leakage flow and heat transfer rate distribution for each vane passing. The relative position of the vane and vane trailing edge shock with respect to time alters the flow conditions in the rotor domain, and results in significant variations in the tip leakage flow structures and heat transfer rate distributions. It is observed that the trailing edge shock phenomenon results in a critical heat transfer region on the blade tip and casing. Consequently, the turbine blade tip and casing are subjected to large fluctuations of Nusselt number (about Nu = 2000 to 6000 and about Nu = 1000 to 10000, respectively) at a high frequency (coinciding with the rotor speed).

Analysis of Transonic Limit Cycle Oscillations under Uncertainty

For the computation of limit cycle oscillations (LCO) at transonic speeds, CFD is required to capture the nonlinear flow features present. The Harmonic Balance method provides an effective means for the computation of LCOs and this paper exploits its efficiency to investigate the impact of variability (both structural a nd aerodynamic) on the aeroelastic behaviour of a 2 dof aerofoil. A Harmonic Balance inviscid CFD solver is coupled with the structural equations and is validated against time marching analyses. Polynomial chaos expansions are employed for the stochastic investiga tion as a faster alternative to Monte Carlo analysis. Adaptive sampling is employed when discontinuities are present. Uncertainties in aerodynamic parameters are looked at first followed by the inclusion of structural variability. Results show the nonlinear effect of Mach number and it’s interaction with the structural parameters on supercritical LCOs. The bifurcation boundaries are well captured by the polynomial chaos.

3D Efflux Velocity Characteristics of Marine Propeller Jets

The determination of the efflux velocity is key to the process of calculating the subsequent value of velocity at any other location within a propeller jet. This paper reports on the findings of an experimental investigation into the magnitude of the efflux velocities within the jets produced by four differing propellers. Measurements of velocity have been made using a 3D LDA system with the test propellers operating at a range of rotational speeds which bound typical operational values. Comparisons are made with existing predictive theories and to aid design engineers, methods are presented by which the 3D efflux velocity components, as well as the resultant efflux value, can be determined.

Optimizing geometric accuracy of four dimensional CT scans acquired using the wall and couch mounted Varian Real-Time Position Management camera systems

Objective:

The aim of this study was to identify sources of anatomical misrepresentation due to the location of camera mounting, tumour motion velocity and image processing artefacts in order to optimise the 4DCT scan protocol and improve geometrical-temporal accuracy.

A phantom with an imaging insert was driven with a sinusoidal superior-inferior motion of varying amplitude and period for 4DCT scanning. The length of a high density cube within the insert was measured using treatment planning software to determine the accuracy of its spatial representation. Scan parameters were varied including the tube rotation period and the cine time between reconstructed images. A CT image quality phantom was used to measure various image quality signatures under the scan parameters tested.

No significant difference in spatial accuracy was found for 4DCT scans carried out using the wall mounted or couch mounted camera for sinusoidal target motion. Greater spatial accuracy was found for 4DCT scans carried out using a tube rotation speed of 0.5s rather than 1.0s. The reduction in image quality when using a faster rotation speed was not enough to require an increase in patient dose.

4DCT accuracy may be increased by optimising scan parameters, including choosing faster tube rotation speeds. Peak misidentification in the recorded breathing trace leads to spatial artefacts and this risk can be reduced by using a couch mounted infrared camera.

This study explicitly shows that 4DCT scan accuracy is improved by scanning with a faster CT tube rotation speed.

Physicochemical Investigation of Adiponitrile-Based Electrolytes for Electrical Double Layer Capacitor

Structuring reductive media containing protic ionic liquids and their application to the formation of metallic nanoparticles

Herein, we present a facile method for the formation of monodispersed metal nanoparticles (NPs) at room temperature from M^(III)Cl₃ (with M = Au, Ru, Mn, Fe or V) in different media based on N,N-dimethylformamide (DMF) or water solutions containing a protic ionic liquid (PIL), namely the octylammonium formate (denoted OAF) or the bis(2-ethyl-hexyl)ammonium formate (denoted BEHAF). These two PILs present different structures and redox-active structuring properties that influence their interactions with selected molecular compounds (DMF or water), as well as the shape and the size of formed metal NPs in these solutions. Herein, the physical properties, such as the thermal, transport and micellar properties, of investigated PIL solutions were firstly investigated in order to understand the relation between PILs structure and their properties in solutions with DMF or water. The formation of metal NPs in these solutions was then characterized by using UV–vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and dynamic light scattering (DLS) measurements. From our investigations, it appears that the PILs structure and their aggregation pathways in selected solvents affect strongly the formation, growths, the shape and the size of metal NPs. In fact by using this approach, the shape-/size-controlled metal NPs can be generated under mild condition. This approach suggests also a wealth of potential for these designer nanomaterials within the biomedical, materials, and catalysis communities by using designer and safer media based on PILs.