Optimal configuration, design and operation of batch distillation processes

The overall objective of this thesis is to study the optimal configuration. design and operating policy of batch distillation processes in different separation scenarios. In so doing, this work also aims to provide conceptual insights and compare the performance of the traditional regular column against unconventional columns. In the first part of the thesis, the optimal operation of extractive batch distillation is investigated. A rigorous dynamic optimisation approach based on a detailed model is employed. In addition to the regular column, the optimal operation of the process in the unconventional middle vessel column is examined. The liquid and vapour stream configurations at the middle section of the column is explored for the first time, resulting in improved process performance. The performance of both columns are compared and the results show how their relative performances are affected by different feed compositions. The second part of the thesis is concerned with the simultaneous design and operation of batch distillation processes. The thesis proposes a stochastic optimisation methodology based on genetic algorithm and penalty function. Using the proposed methodology, the simultaneous optimal designs and operations of the regular column for different design scenarios are investigated using rigorous models. Furthermore, the optimal design of the unconventional multivessel column for multicomponent separation is studied for the first time. The effect of different factors such as objective function, feed composition, relative volatility, product specification and number of components on the optimal design of the multivessel system is investigated. A comparison of the performance of the multivessel system with the regular column is also presented. In the final part of the thesis, the feasibility of the genetic algorithm-penalty function approach in tackling simultaneous configuration selection, column sizing and operation is explored. In the case of binary mixture separation, the regular column was found to be more profitable for feeds with a high fraction of the light component whilst the inverted column is optimal for heavier feeds. There exists a flip point, the location of which is case study specific. For the multicomponent separation case study, the multivessel system is found to be superior to both the regular and inverted configuration

Output Feedback Image-Based Visual Servoing of Rotorcrafts

© 2018, Springer Nature B.V. This paper presents an improved output feedback based image-based visual servoing (IBVS) law for rotorcraft unmanned aerial vehicles (RUAVs). The control law enables a RUAV with a minimal set of sensors, i.e. an inertial measurement unit (IMU) and a single downward facing camera, to regulate its position and heading relative to a planar visual target consisting of multiple points. As compared to our previous work, twofold improvement is made. First, the desired value of the image feature of controlling the vertical motion of the RUAV is a function of other image features instead of a constant. This modification helps to keep the visual target stay in the camera’s field of view by indirectly adjusting the height of the vehicle. Second, the proposed approach simplifies our previous output feedback law by reducing the dimension of the observer filter state space while the same asymptotic stability result is kept. Both simulation and experimental results are presented to demonstrate the performance of the proposed controller

Solitons in Tonks-Girardeau gas with dipolar interactions

The existence of bright solitons in the model of the Tonks-Girardeau (TG) gas with dipole-dipole (DD) interactions is reported. The governing equation is taken as the quintic nonlinear Schr\"{o}dinger equation (NLSE) with the nonlocal cubic term accounting for the DD attraction. In different regions of the parameter space (the dipole moment and atom number), matter-wave solitons feature flat-top or compacton-like shapes. For the flat-top states, the NLSE with the local cubic-quintic (CQ) nonlinearity is shown to be a good approximation. Specific dynamical effects are studied assuming that the strength of the DD interactions is ramped up or drops to zero. Generation of dark-soliton pairs in the gas shrinking under the action of the intensifying DD attraction is observed. Dark solitons exhibit the particle-like collision behavior. Peculiarities of dipole solitons in the TG gas are highlighted by comparison with the NLSE including the local CQ terms. Collisions between the solitons are studied too. In many cases, the collisions result in merger of the solitons into a breather, due to strong attraction between them.Comment: 15 pages, 8 figures, accepted by J. Phys. B: At. Mol. Opt. Phy

cis-Oxoruthenium complexes supported by chiral tetradentate amine (N4) ligands for hydrocarbon oxidations

published_or_final_versio

Frequency Shift of Carbon-Nanotube-Based Mass Sensor Using Nonlocal Elasticity Theory

The frequency equation of carbon-nanotube-based cantilever sensor with an attached mass is derived analytically using nonlocal elasticity theory. According to the equation, the relationship between the frequency shift of the sensor and the attached mass can be obtained. When the nonlocal effect is not taken into account, the variation of frequency shift with the attached mass on the sensor is compared with the previous study. According to this study, the result shows that the frequency shift of the sensor increases with increasing the attached mass. When the attached mass is small compared with that of the sensor, the nonlocal effect is obvious and increasing nonlocal parameter decreases the frequency shift of the sensor. In addition, when the location of the attached mass is closer to the free end, the frequency shift is more significant and that makes the sensor reveal more sensitive. When the attached mass is small, a high sensitivity is obtained

Cost-minimization analysis of oral versus intravenous antibiotic treatment for Klebsiella pneumoniae liver abscess

A cost-minimization analysis was conducted for Klebsiella pneumoniae liver abscess (KLA) patients enrolled in a randomized controlled trial which found oral ciprofloxacin to be non-inferior to intravenous (IV) ceftriaxone in terms of clinical outcomes. Healthcare service utilization and cost data were obtained from medical records and estimated from self-reported patient surveys in a non-inferiority trial of oral ciprofloxacin versus IV ceftriaxone administered to 152 hospitalized adults with KLA in Singapore between November 2013 and October 2017. Total costs were evaluated by category and payer, and compared between oral and IV antibiotic groups over the trial period of 12 weeks. Among the subset of 139 patients for whom cost data were collected, average total cost over 12 weeks was $16,378 (95$14,620-$18,136) for the oral ciprofloxacin group and$20,569 (95% CI, $18,296-$22,842) for the IV ceftriaxone group, largely driven by lower average outpatient costs, as the average number of outpatient visits was halved for the oral ciprofloxacin group. There were no other statistically significant differences, either in inpatient costs or in other informal healthcare costs. Oral ciprofloxacin is less costly than IV ceftriaxone in the treatment of Klebsiella liver abscess, largely driven by reduced outpatient service costs.Trial registration: ClinicalTrials.gov Identifier NCT01723150 (7/11/2012)

Early postural blood pressure response and cause-specific mortality among middle-aged adults

Orthostatic hypotension (OH) is associated with increased total mortality but contribution of specific death causes has not been thoroughly explored. In this prospective study, authors followed up 32,068 individuals without baseline history of cancer or cardiovascular disease (69% men; mean age, 46 years; range, 26–61 years) over a period of 24 years. Hazard ratios (HRs) for total and cause-specific mortality associated with presence of OH and by quartiles of postural systolic blood pressure response (∆SBP) were assessed using multivariate adjusted Cox regression model. A total of 7,145 deaths (22.3%, 9.4 deaths/1,000 person-years) occurred during follow-up. Those with OH (n = 1,943) had higher risk of death due to injury (HR, 1.88; 1.37–2.57) and neurological disease (HR, 2.21; 1.39–3.51). Analogically, risk of death caused by injury and neurological disease increased across the quartiles of ∆SBP from hyper- (Q1SBP, +8.5 ± 4.7 mmHg) to hypotensive response (Q4SBP, −13.7 ± 5.7 mmHg; HR, 1.32; 1.00–1.72, and 1.84; 1.20–2.82, respectively) as did also risk of death due to respiratory disease (Q4SBP vs. Q1SBP: HR, 1.53; 1.14–2.04). In contrast, risk curve for cerebrovascular death was U-shaped with nadir in the mildly hypotensive 3rd quartile of ∆SBP (−5.0 ± 0.1 mmHg, Q3SBP vs. Q1SBP: HR, 0.75; 0.54–1.03; P for linear trend = 0.021). Additionally, cardiovascular mortality was increased among 5,805 rescreened participants (mean age, 53 years; 9.8% OH positive: HR, 1.54; 1.24–1.89, and Q4SBP vs. Q1SBP: 1.27; 1.02–1.57, respectively). In summary, increased mortality predicted by blood pressure fall on standing is associated with injuries, neurodegenerative, and respiratory diseases, as well as with cardiovascular disease in older adults. Moreover, both increase and pronounced decrease of SBP during early orthostasis indicate higher risk of cerebrovascular death

Feasibility Study of a Wearable Exoskeleton for Children: Is the Gait Altered by Adding Masses on Lower Limbs?

We are designing a pediatric exoskeletal ankle robot (pediatric Anklebot) to promote gait habilitation in children with Cerebral Palsy (CP). Few studies have evaluated how much or whether the unilateral loading of a wearable exoskeleton may have the unwanted effect of altering significantly the gait. The purpose of this study was to evaluate whether adding masses up to 2.5 kg, the estimated overall added mass of the mentioned device, at the knee level alters the gait kinematics. Ten healthy children and eight children with CP, with light or mild gait impairment, walked wearing a knee brace with several masses. Gait parameters and lower-limb joint kinematics were analyzed with an optoelectronic system under six conditions: without brace (natural gait) and with masses placed at the knee level (0.5, 1.0, 1.5, 2.0, 2.5 kg). T-tests and repeated measures ANOVA tests were conducted in order to find noteworthy differences among the trial conditions and between loaded and unloaded legs. No statistically significant differences in gait parameters for both healthy children and children with CP were observed in the five “with added mass” conditions. We found significant differences among “natural gait” and “with added masses” conditions in knee flexion and hip extension angles for healthy children and in knee flexion angle for children with CP. This result can be interpreted as an effect of the mechanical constraint induced by the knee brace rather than the effect associated with load increase. The study demonstrates that the mechanical constraint induced by the brace has a measurable effect on the gait of healthy children and children with CP and that the added mass up to 2.5 kg does not alter the lower limb kinematics. This suggests that wearable devices weighing 25 N or less will not noticeably modify the gait patterns of the population examined here.Cerebral Palsy International Research FoundationStavros S. Niarchos Foundatio

Trends and predictions of metabolic risk factors for acute myocardial infarction: findings from a multiethnic nationwide cohort

BACKGROUND: Understanding the trajectories of metabolic risk factors for acute myocardial infarction (AMI) is necessary for healthcare policymaking. We estimated future projections of the incidence of metabolic diseases in a multi-ethnic population with AMI. METHODS: The incidence and mortality contributed by metabolic risk factors in the population with AMI (diabetes mellitus [T2DM], hypertension, hyperlipidemia, overweight/obesity, active/previous smokers) were projected up to year 2050, using linear and Poisson regression models based on the Singapore Myocardial Infarction Registry from 2007 to 2018. Forecast analysis was stratified based on age, sex and ethnicity. FINDINGS: From 2025 to 2050, the incidence of AMI is predicted to rise by 194.4% from 482 to 1418 per 100,000 population. The largest percentage increase in metabolic risk factors within the population with AMI is projected to be overweight/obesity (880.0% increase), followed by hypertension (248.7% increase), T2DM (215.7% increase), hyperlipidemia (205.0% increase), and active/previous smoking (164.8% increase). The number of AMI-related deaths is expected to increase by 294.7% in individuals with overweight/obesity, while mortality is predicted to decrease by 11.7% in hyperlipidemia, 29.9% in hypertension, 32.7% in T2DM and 49.6% in active/previous smokers, from 2025 to 2050. Compared with Chinese individuals, Indian and Malay individuals bear a disproportionate burden of overweight/obesity incidence and AMI-related mortality. INTERPRETATION: The incidence of AMI is projected to continue rising in the coming decades. Overweight/obesity will emerge as fastest-growing metabolic risk factor and the leading risk factor for AMI-related mortality. FUNDING: This research was supported by the NUHS Seed Fund (NUHSRO/2022/058/RO5+6/Seed-Mar/03) and National Medical Research Council Research Training Fellowship (MOH-001131). The SMIR is a national, ministry-funded registry run by the National Registry of Diseases Office and funded by the Ministry of Health, Singapore

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO