Modelling the robustness properties of HVAC plant under feedback control

Most existing building simulation programs fail to capture sufficient of the underlying dynamics of nonlinear HVAC plant and some have restricted room space modelling capabilities for low-time-horizon analyses. In this work, a simplified model of a room space with hot water heating and a chilled ceiling system is developed for the main purpose of analysing control system response. The room model is based on a new approach to lumped capacitance modelling and the heating and chilled ceiling emitters are modelled using third-order descriptions. Control system components are treated in detail and both controllers are ‘tuned’ at a nominal region of plant operation using a gradient-descent-based optimization procedure. Robustness qualities of the controllers are analysed with reference to extremes in plant operating conditions. A key feature of the work is the transparency of the modelling procedure, designed to have appeal to researchers as well as practitioners involved with HVAC control system design problems

Thermal comfort based fuzzy logic control

Most heating, ventilation and air conditioning (HVAC) control systems are considered as temperature control problems. In this work, the predicted mean vote (PMV) is used to control the indoor temperature of a space by setting it at a point where the PMV index becomes zero and the predicted percentage of persons dissatisfied (PPD) achieves a maximum threshold of 5%. This is achieved through the use of a fuzzy logic controller that takes into account a range of human comfort criteria in the formulation of the control action that should be applied to the heating system to bring the space to comfort conditions. The resulting controller is free of the set up and tuning problems that hinder conventional HVAC controllers. Simulation results show that the proposed control strategy makes it possible to maximize the indoor thermal comfort and, correspondingly, a reduction in energy use of 20% was obtained for a typical 7-day winter period when compared with conventional control

Limitation of the Press-Schechter Formalism

The Press-Schechter(PS) formalism for the mass function of the collapsed objects are reanalyzed. The factor of two in the Press-Schechter formalism is argued to be correct in the sharp $k$-space filter even when we use the another approach proposed by Jedamzik(1994) in the cloud-in-cloud problem, which is different from the previous approach by Peacock & Heavens(1990) and Bond et al.(1991). The spatial correlation of the density fluctuations, however, had been neglected in the cloud-in-cloud problem. The effects of this spatial correlation is analyzed by using the Jedamzik formalism and it is found that this effect alter the PS mass function especially on larger mass scales. Furthermore the exact formula of deriving mass function is shown. We also find that the probability of the overlap of the collapsed objects can be neglected on very small mass scales while it might not be neglected on other mass scales.Comment: 23 pages, uuencoded compressed Postscrip

Axon Initial Segment Integrity in Aging and Traumatic Brain Injury

According to the Center for Disease Control’s (CDC) report to the Congress, there are 2.2 million emergency department visits; 80,000 hospitalizations; and 50,000 deaths each year due to traumatic brain injury. Adults 65 years and older account substantially for the majority of the hospitalization and deaths. Over 70% of the traumatic brain injuries of the older adults are classified as mild to moderate; however, even with these milder injuries, older adults present with a significantly higher morbidity and mortality compared to all other age groups (LeBlanc et al., 2006). With that in mind, it seems essential to develop a deeper understanding of the causes behind higher mortality and morbidity of traumatic brain injury in the elder population. It is well documented that increased age is accompanied by increased CNS inflammation. Recently, our laboratory showed that inflammation drives brain pathology. Specifically, we reported that the axon initial segment of cortical neurons was structurally and functionally compromised in an inflamed CNS environment. With this in mind, we proposed that age-related inflammation predisposes that brain to exacerbated pathologic consequence. To test this hypothesis, we administered a mild to moderate central fluid percussion brain injury in aged and young adult mice. Using immunocytochemical labeling against the axon initial segment protein ankyrinG combined with laser scanning confocal microscopy, we quantitatively compared axon initial segment number and length between age groups and within age groups with and without injury. Additionally, we also quantified global axonal pathology by immunolabeling for amyloid precursor protein (APP) positive swelling as an indicator of compromised axonal transport. We proposed that ankyrinG labeling will be both reduced in the aged injured mice compared against aged uninjured, young adult injured and young adult non-injured. We observed a significant increase in APP accumulations due to injury independent of aging, and due to aging independent of injury. No significant changes in the effect of injury between young and aged injured mice were observed. Although AIS length was not altered between age groups following injury, our results demonstrate that the elderly population presents with significantly shorter initial segments. The consequence of this shortening is not clear but may reflect compensatory changes in the brain to maintain homeostasis

A Rare Xanthogranulomatous Oophoritis Presenting as Ovarian Cancer

Xanthogranulomatous inflammation is an uncommon form of chronic inflammation that is destructive to affected organs; it is characterized by the presence of lipid-filled macrophages with admixed lymphocytes, plasma cells, and neutrophils. Only a few cases of xanthogranulomatous oophoritis have been reported to date. We describe a rare case of xanthogranulomatous oophoritis with involvement of omentum

Directed Explicit Model Checking with HSF-SPIN

We present the explicit state model checker HSF-SPIN which is based on the model checker SPIN and its Promela modeling language. HSF-SPIN incorporates directed search algorithms for checking safety and a large class of LTL-specified liveness properties. We start off from the A* algorithm and define heuristics to accelerate the search into the direction of a specified failure situation. Next we propose an improved nested depth-first search algorithm that exploits the structure of Promela Never-Claims. As a result of both improvements, counterexamples will be shorter and the explored part of the state space will be smaller than with classical approaches, allowing to analyze larger state spaces. We evaluate the impact of the new heuristics and algorithms on a set of protocol models, some of which are real-world industrial protocols

Chromaticity in all-reflective telescopes for astrometry

Chromatic effects are usually associated with refractive optics, so reflective telescopes are assumed to be free from them. We show that all-reflective optics still bears significant levels of such perturbations, which is especially critical to modern micro-arcsecond astrometric experiments. We analyze the image formation and measurement process to derive a precise definition of the chromatic variation of the image position, and we evaluate the key aspects of optical design with respect to chromaticity. The fundamental requirement related to chromaticity is the symmetry of the optical design and of the wavefront errors. Finally, we address some optical engineering issues, such as manufacturing and alignment, providing recommendations to minimize the degradation that chromaticity introduces into astrometry.Comment: 10 pages, 8 figure

CHARGE TRANSFER SPECTROPHOTOMETRIC METHODS FOR THE DETERMINATION OF TWO ANTIHISTAMINIC DRUGS IN PHARMACEUTICAL FORMULATIONS

Objective: Simple, accurate and precise spectrophotometric methods have been developed for the determination of two antihistaminic drugs (desloratadine (DES) and ebastine (EBS)) in pure forms and pharmaceutical formulations. Methods: The proposed methods were based on the charge transfer complexation reaction of both drugs as ‘n' electron donor with chloranilic acid (p-CLA) or 2, 3-Dichloro-5,6-dicyano-p-benzoquinone (DDQ) as π acceptors to give highly coloured complex species. The coloured products were quantitated spectrophotometrically at 459 and 460 nm using DDQ and at 532 and 533 nm using p-CLA for DES and EBS, respectively. Optimization of the different experimental conditions were studied. Results: Beer's law was obeyed in the concentration ranges of 5.0-120 and 10-180 mg mL-1 with good correlation coefficients were ≥ 0.9995 and 0.9992 and a relative standard deviation (R.S.D.) of ≤ 0.98 and 1.24% using DDQ and p-CLA methods, respectively. The molar absorptivity, Sandell's sensitivity, detection and quantification limits were also calculated. The developed methods were successfully applied for determination of the studied drugs in pharmaceutical formulations with good accuracy and precision and without interferences from common additives by applying the standard addition technique. Conclusion: The developed methods have been validated statistically for their accuracy, precision, sensitivity, selectivity, robustness and ruggedness as per ICH guidelines and the results compared favorably with those obtained using the reported methods

An efficient ionic liquid-based cloud point extraction to preconcentrate mercury in environmental samples and hair of occupational workers before spectrophotometric detection

ABSTRACT. Mercury preconcentration in environmental samples and hair of occupational workers prior to spectrophotometric detection was described using a unique, eco-friendly, and quick ionic liquid-based cloud point extraction method. The discovered method used an ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate with Triton X-114 as an extracting phase in the presence of a new chelating agent 3-(2-hydroxy-5-ethoxycarbonylphen-1-ylazo)-1,2,4-triazole at pH 7.0 to separate mercury and measure the complex spectrophotometrically at wavelength 550 nm. The effects of several analytical factors on extraction performance were investigated. With a correlation coefficient of 0.9997. The calibration graph was linear in the range of 2.0-400 µg/L. The limit of detection and preconcentration factor, respectively, were 0.5 µg/L and 100. The relative standard deviation of 100 and 300 µg/L mercury (n = 10) was 1.5 and 2.2, respectively, indicating the precision and reliability of the new IL-CPE approach. The accuracy of the proposed approach confirmed through the certified reference materials analysis. The applicability of the established technique was demonstrated successfully by the estimation of trace mercury in environmental samples and hair of occupational workers.     KEY WORDS: Mercury, Ionic liquid-based cloud point extraction, Environmental and hair samples, Spectrophotometry   Bull. Chem. Soc. Ethiop. 2022, 36(4), 767-778.                                                         DOI: https://dx.doi.org/10.4314/bcse.v36i4.