Modeling mass loading effects in industrial cyclones by a combined Eulerian–Lagrangian approach

Cyclone separation is studied by means of numerical simulations. While the gas flow is modeled by a modified Reynolds stress (RS) model, the behavior of the particles is pictured by a combined Eulerian–Lagrangian approach. A mono-disperse Eulerian particle phase is utilized to account for inter-particle collisions, while the effects of fractional separation and particle-wall collisions are considered by poly-disperse Lagrangian particles. The above particle models interact in two ways. On the one hand, the Lagrangian particles determine the local mean diameter of the substitute Eulerian particle class. On the other hand, especially in regions of high particle concentration, the Eulerian particle phase exerts an additional collisional force onto the Lagrangian particle trajectories. An industrial cyclone is chosen as a test case and the numerical results are evaluated with respect to pressure drop as well as to global and fractional separation efficiency. In this context the influence of the cyclone’s mass loading and wall roughness is highlighted. Simulations indicate that the separation efficiency improves with increasing mass loading until an excess loading is reached while at the same time the pressure drop is reduced. Furthermore, it can be shown that rough walls lead to a reduction of separation efficiency while simultaneously the pressure drop decreases. The simulations results are compared with both an analytic theory of Muschelknautz [Die Berechnung von Zykonabscheidern für Gase. Chem Ing Techn 44, (1+2):63–71, 1972] as well as with real plant measurements.     

The effect of leader emotional intelligence on leader–follower chemistry: a study of construction project managers

Extending Nicolini’s notion of project ‘chemistry’, a ‘leader–follower chemistry’ model associated with the quality of dyadic interpersonal communication in construction projects is developed. The focus is on the project manager as leader in an attempt to deepen understanding of the effect of a project manager’s emotional intelligence (EI) on the quality of interpersonal communication with their followers, being other members of the project team. While a project manager’s EI, with its associated emotional competencies, is often seen as critical in achieving good relationships with members of the project team, it remains a largely understudied concept, particularly in construction projects. Primary data collected using a series of analytical surveys and live observations of site-based project meetings was used to examine the relationship between a project manager’s emotional competencies, particularly sensitivity and expressiveness, and leader–follower chemistry. Overall, 68 construction professionals participated in the study. The findings suggest that a project manager’s emotional sensitivity and expressiveness (particularly head gestures) may explain variance in the quality of leader–follower chemistry. Based on the empirical evidence in the context of team communication, a leader–follower chemistry model is introduced, which emphasizes the importance of leaders’ emotional sensitivity and expressiveness in a leader–follower communication dyad. The model may be particularly salient in complex project networks with a large number of prominent actors.     

Three-dimensional power system stabilizer

Power system stabilizers (PSSs) are used to enhance damping of power system oscillations through excitation control of synchronous generator. The objective of the PSS is to generate a stabilizing signal, which produces a damping torque component on the generator shaft. Conventional PSSs are designed with the phase compensation technique in the frequency domain and include the lead-lag blocks whose parameters are determined according to a linearized power system model. The performance of conventional PSSs (CPSSs) depends upon the generator operating point and the system parameters, but a reasonable level of robustness can be achieved depending on the tuning method. This paper presents a new three-dimensional PSS (3D PSS), which uses rotor speed deviation, rotor acceleration and load angle deviation as input signals. The 3D PSS attempts to return the generator to the state-space origin, based on the generator’s trajectory in state-space and the achievement of torque equilibrium. The 3D PSS is robust to system parameters changes. The proposed algorithm was implemented in a digital control system, tested in a laboratory environment on a synchronous generator connected to the power system, and then compared with CPSS. Experimental results show that the proposed PSS achieves better performance than the CPSS in damping oscillations.     

Main chain and segmental dynamics of semi interpenetrating polymer networks based on polyisoprene and poly(methyl methacrylate)

Main chain and segmental dynamics of polyisoprene (PI) and poly(methyl methacrylate) (PMMA) chains in semi IPNs were systematically studied over a wide range of temperatures (above and below T_g of both polymers) as a function of composition, crosslink density, and molecular weight. The immiscible polymers retained most of its characteristic molecular motion; however, the semi IPN synthesis resulted in dramatic changes in the motional behavior of both polymers due to the molecular level interpenetration between two polymer chains. ESR spin probe method was found to be sensitive to the concentration changes of PMMA in semi IPNs. Low temperature spectra showed the characteristics of rigid limit spectra, and in the range of 293-373 K, complex spectra were obtained with the slow component mostly arising out of the PMMA rich regions and fast component from the PI phase. We found that the rigid PMMA chains closely interpenetrated into the highly mobile PI network imparts motional restriction in nearby PI chains, and the highly mobile PI chains induce some degree of flexibility in highly rigid PMMA chains. Molecular level interchain mixing was found to be more efficient at a PMMA concentration of 35 wt.%. Moreover, the strong interphase formed in the above mentioned semi IPN contributed to the large slow component in the ESR spectra at higher temperature. The shape of the spectra along with the data obtained from the simulations of spectra was correlated to the morphology of the semi IPNs. The correlation time measurement detected the motional region associated with the glass transition of PI and PMMA, and these regions were found to follow the same pattern of shifts in α-relaxation of PI and PMMA observed in DMA analysis. Activation energies associated with the T_g regions were also calculated. T_50G was found to correlate with the T_g of PMMA, and the volume of polymer segments undergoing glass transitional motion was calculated to be 1.7 nm³. C-13 T_1ρ measurements of PMMA carbons indicate that the molecular level interactions were strong in semi IPN irrespective of the immiscible nature of polymers. The motional characteristics of H atoms attached to carbon atoms in both polymers were analyzed using 2D WISE NMR. Main relaxations of both components shifted inward, and both SEM and TEM analysis showed the development of a nanometer - sized morphology in the case of highly crosslinked semi IPN.     

Cherry leafroll virus: Impact on olive fruit and virgin olive oil quality

We performed a survey on the yield, quality, and chemical characteristics of virgin olive oils from two olive varieties in Croatian Istria: Frantoio and Ascolana tenera, on Cherry leafroll virus‐infected and virus‐noninfected trees and on two harvest dates. Free acidity, peroxide value, specific spectrophotometric absorptions at 232 and 270 nm, fatty acid composition, total phenols, o‐diphenols, oil color, and pigments were determined. Infected olives had lower oil yield and maturity index versus healthy ones. Oils from infected fruits had significant lower value of K₂₃₂ and K₂₇₀ and very elevated total phenols content compared to those obtained from healthy olives. Infected Frantoio gave a lower content of o‐diphenols than the healthy ones, which is in contrast to infected Ascolana that had higher values. The aim of this study is to determine the chemical changes in virgin olive oils from healthy and infected trees related to virus influence. According to our knowledge, this is the first survey on the possible influence of viruses on olive fruits, oil yield, and virgin olive oil quality. Practical applications : There are only few papers which analyze the influence of viruses on crops (especially influence on wine quality) and their effects on yield or other agronomic parameters. This work evaluates for the first time the impact of Cherry leafroll virus on the quality of virgin olive oil obtained from Frantoio and A. tenera varieties in terms of basic parameters related to the hydrolitic and oxidative status, content in antioxidant compounds, and in pigments as well as in fatty acid composition.     

Magnetic current loop as a source model for finite thin‐wire antennas

The paper deals with the concept of magnetic current loop as a source model for finite thin‐wire antennas. The formulation is based on the Pocklington integro‐differential equation with reduced kernel, which is handled by means of various numerical techniques, mostly using the Galerkin–Bubnov variant of Indirect Boundary Element Method. Extensive numerical experiments were carried out on various dipole and monopole antennas using different sources (delta gap, magnetic frill, and magnetic current loop), and results for input admittance are compared with measured data. The magnetic current loop source ensures accurate solution for input admittance. Copyright © 2014 John Wiley & Sons, Ltd.     

AGE@HOME: Radio-Enabled Environments for Independent Ageing

Ageing populations is a phenomenon over the world. The challenges of daily living for the elderly form the basis of the independent living platform proposed in this article. The AGE@HOME platform is intended to detect unusual activity or inactivity in a home, and is designed to alert caregivers and public health service providers of critical environmental situations in the home (for instance, abnormally high temperature) or unusual behavioural patterns (for instance, the prolonged stillness of a resident). The platform taps into the potential of combining automatic data capture, identification, and sensor technology in order to create a simple and non-intrusive care system. The article presents the decision logic that forms the basis of the system, before describing the software program and graphical user interfaces that were developed based on that logic. A random simulation of the software was run, confirming the decision logic as initially conceived. The simulation also verified that the software could be used in a real-life scenario, in which physical sensors provide data in real-time to the central controller.     

The narcotic properties of xenon and the prospects for its use in anesthesiology

An alkaline phosphatase was purified from conidia of a Neurospora crassa wild type strain. The M(r) of the purified native enzyme was estimated as ca 145,000 and 110,000 by gel filtration, in the presence and absence of magnesium ions, respectively. A single polypeptide band of M(r) 36,000 was detected by SDS-PAGE, suggesting that the native enzyme was a tetramer of apparently identical subunits. Conidial alkaline phosphatase was an acidic protein (pl = 4.0 +/- 0.1), with 40% carbohydrate content. Optimal pH was affected by substrate concentration and magnesium ions. Low concentrations of calcium ions (0.1 mM) had slight stimulatory effects, but in excess (5 mM) caused protein aggregates with decreased activity. The enzyme specificity against different substrates was compared with those reported for constitutive or Pi-repressible alkaline phosphatases produced by N. crassa. The results suggested that the conidial alkaline phosphatase represented a different class among other such enzymes synthesized by this organism.     

Improvement of the cogeneration plant economy by using heat accumulator

The optimisation code ACOM (Advanced Cogeneration Optimisation Model) is used with purpose of assessing influence of the district heat accumulator on the Elektrana-Toplana (EL-TO) Zagreb cogeneration plant economic performance. The plant supplies hot water for district heating, steam for industry and electric power. It is possible to achieve economic benefits by charging the accumulator during the day time, when the electricity price is high, and by releasing district heat during cheap night hours, when other parts of equipment may be shut down. The consequences of this strategy are the decrease of total annual electricity production and fuel consumption, whereby the savings of some 1.8 mil Euro/a are achieved with the reduction of CO₂ emission by about 23,000 t/a or 6.4% and SO_x by about 200 t/a or 16.9%.     

An approach for reduction of the volume loss in the rigid-plastic FEM using two-step updating procedure

The volume loss, as a direct consequence of the geometry updating procedure used in the conventional penalty rigid-plastic finite element method (RPFEM), is primarily caused by the application of the widely used forward Euler time integration method. In order to decrease this undesired consequence, the combination of the two-step Adams-Bashforth time integration method and the volumetrically elastic and deviatorically RPFEM is proposed as a new approach. The cylinder upsetting process was simulated using in-house finite element code. The results of simulations, obtained for the various levels of friction factors and height reductions, show that the proposed method gives a significantly lower volume loss. Also, the results of the friction factor determination procedure utilising the ring compression test for three lubrication conditions demonstrate the capabilities of the proposed method.