Exergy Analysis and Efficiency Improvement of a Coal Fired Thermal Power Plant in Queensland

Energy analysis is an important tool to improve energy efficiency of a thermodynamic system. The conventional method of energy analysis is based on the first law of thermodynamics, which focuses on conservation of energy. The limitation of this analysis is that it does not take into account properties of the system environment, or degradation of the energy quality through dissipative processes. Exergy analysis is very effective in this regard, as it deals with the usable energy with reference to environment. It is based on the second law of thermodynamics. The main purpose of exergy analysis is to identify where and how much exergy is destroyed. This destruction of exergy in a process is proportional to the entropy generation in it, which accounts for the inefficiencies due to irreversibility. This research conducts exergy analysis in one unit of a coal-fired power plant in Central Queensland, Australia. The exergy analysis identifies where and how much exergy is destroyed in the system and its components. Based on the analysis, it assesses different options to improve the efficiency of the system. It shows that only a small amount of useful energy can be recovered through a heat recovery system. Substantial improvement to the thermodynamic cycle is possible, but it requires considerable alteration of the power generation system

Measuring frequency fluctuations in nonlinear nanomechanical resonators

Advances in nanomechanics within recent years have demonstrated an always expanding range of devices, from top-down structures to appealing bottom-up MoS$_2$ and graphene membranes, used for both sensing and component-oriented applications. One of the main concerns in all of these devices is frequency noise, which ultimately limits their applicability. This issue has attracted a lot of attention recently, and the origin of this noise remains elusive up to date. In this Letter we present a very simple technique to measure frequency noise in nonlinear mechanical devices, based on the presence of bistability. It is illustrated on silicon-nitride high-stress doubly-clamped beams, in a cryogenic environment. We report on the same $T/f$ dependence of the frequency noise power spectra as reported in the literature. But we also find unexpected {\it damping fluctuations}, amplified in the vicinity of the bifurcation points; this effect is clearly distinct from already reported nonlinear dephasing, and poses a fundamental limit on the measurement of bifurcation frequencies. The technique is further applied to the measurement of frequency noise as a function of mode number, within the same device. The relative frequency noise for the fundamental flexure $\delta f/f_0$ lies in the range $0.5 - 0.01~$ppm (consistent with literature for cryogenic MHz devices), and decreases with mode number in the range studied. The technique can be applied to {\it any types} of nano-mechanical structures, enabling progresses towards the understanding of intrinsic sources of noise in these devices.Comment: Published 7 may 201

Getting it right: The case for supervisors assessing process in capstone projects

© 2015 TEMPUS Publications. Capstone projects represent the culmination of an undergraduate engineering degree and are typically the last checkpoint measure before students graduate and enter the engineering profession. In Australia there is a longstanding interest in and commitment to developing quality capstone experiences.Anational study into the supervision and assessment of capstone projects has determined that whilst there is relative consistency in terms of what project tasks are set and assessed, there is not comparable consistency in how these tasks or assignments are marked. Two interconnected areas of assessing process and the role of the supervisor in marking are identified as contentious. This paper presents some findings of a national case study and concludes that whilst further investigation is warranted, assessing process as well as project products is valuable as is the need for greater acceptance of project supervisors as capable of making informed, professional judgments when marking significant project work

Wick's Theorem and a New Perturbation Theory Around the Atomic Limit of Strongly Correlated Electron Systems

A new type of perturbation expansion in the mixing $V$ of localized orbitals with a conduction-electron band in the $U\to\infty$ Anderson model is presented. It is built on Feynman diagrams obeying standard rules. The local correlations of the unperturbed system (the atomic limit) are included exactly, no auxiliary particles are introduced. As a test, an infinite-order ladder-type resummation is analytically treated in the Kondo regime, recovering the correct energy scale. An extension to the Anderson-lattice model is obtained via an effective-site approximation through a cumulant expansion in $V$ on the lattice. Relation to treatments in infinite spatial dimensions are indicated.Comment: selfextracting postscript file containing entire paper (10 pages) including 3 figures, in case of trouble contact author for LaTeX-source or hard copies (prep0994

Lack of access to medical care during Hurricane Sandy and mental health symptoms

© 2018 The Authors Destruction caused by natural disasters compromises medical providers’ and hospitals’ abilities to administer care. Hurricane Sandy was particularly devastating, resulting in massive disruptions of medical care in the region. This study aimed to determine whether a lack of access to medical care during Hurricane Sandy was associated with posttraumatic stress disorder (PTSD) symptoms and other mental health/substance abuse outcomes. A secondary aim was to examine whether having a chronic illness moderates those associations. Self-reported medical access and mental health symptomatology were obtained from New York City and Long Island residents (n = 1669) following Hurricane Sandy under the Leaders in Gathering Hope Together project (10/23/2013–2/25/2015) and Project Restoration (6/5/2014–8/9/2016). Multivariable logistic regressions were utilized to determine the relationship between lack of access to medical care and mental health outcomes. Of the 1669 participants, 994 (59.57%) were female, 866 (51.89%) were white, and the mean age was 46.22 (SD = 19.2) years old. Those without access to medical care had significantly higher odds of showing symptoms of PTSD (AOR = 2.71, CI = [1.77–4.16]), as well as depression (AOR = 1.94, CI = [1.29–2.92]) and anxiety (AOR = 1.61, CI = [1.08–2.39]) compared to those with access. Lack of access to care was associated with a 2.12 point increase in perceived stress scale score (SE = 0.63). The interaction between having a chronic illness and lack of access to medical care was not significantly associated with any outcomes. The findings emphasize the importance of making medical care more accessible to patients, both chronically and acutely ill, during natural disasters to benefit their physical as well as their mental health

Inhibition of γ-secretase induces G2/M arrest and triggers apoptosis in breast cancer cells

γ-Secretase activity is vital for the transmembrane cleavage of Notch receptors and the subsequent migration of their intracellular domains to the nucleus. Notch overexpression has been associated with breast, colon, cervical and prostate cancers. We tested the effect of three different γ-secretase inhibitors (GSIs) in breast cancer cells. One inhibitor (GSI1) was lethal to breast cancer cell lines at concentrations of 2 μM and above but had a minimal effect on the non-malignant breast lines. GSI1 was also cytotoxic for a wide variety of cancer cell lines in the NCI60 cell screen. GSI1 treatment resulted in a marked decrease in γ-secretase activity and downregulation of the Notch signalling pathway with no effects on expression of the γ-secretase components or ligands. Flow cytometric and western blot analyses indicated that GSI1 induces a G2/M arrest leading to apoptosis, through downregulation of Bcl-2, Bax and Bcl-XL. GSI1 also inhibited proteasome activity. Thus, the γ-secretase inhibitor GSI1 has a complex mode of action to inhibit breast cancer cell survival and may represent a novel therapy in breast cancer

Landau-cutkosky rules, scale invariance, and the marginal fermi liquid

With the aid of the reduced graph expansion relating different order multiple interaction vertices and the exact spectral densities, we show that a strongly coupled Fermi system can allow solutions for the spectral density which scale under simultaneous scale changes in the energy and temperature. This implies a functional form for the spectral density which falls off as a power [mu] of frequency between 0 and -1. The theory describes ZkF = 0 quasiparticles with a Fermi surface consistent with Luttinger's theorem while the spin and charge susceptibilities have imaginary parts of the form ([omega]/T)T1+2[mu] at low energies. The approach reproduces some features of both the Luttinger liquid and marginal Fermi liquid phenomenologies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29889/1/0000242.pd